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A SYMPOSIUM PRESENTED AT A MEETING OF THE CHICAGO OPHTHALMOLOGICAL SOCIETY, NOVEMBER 17, 1913.
PRESIDENT CHICAGO OPHTHALMOLOGICAL SOCIETY (1914); FORMER PROFESSOR OPHTHALMOLOGY, CHICAGO EYE, EAR, NOSE AND THROAT COLLEGE; ASSISTANT SURGEON, ILLINOIS CHARITABLE EYE AND EAR INFIRMARY; OPHTHALMIC SURGEON, OAK PARK HOSPITAL.
EDWARD JACKSON, A.M., M.D. Prof. Ophth. Univ. Colo.; Emer. Prof. Ophth. Phila. Polyclinic; Ex-Ch. Sec. Ophth. A.M.A.; Ex-Pres. Am. Acad. Med. and Am. Acad. Ophth. and Oto-Laryng.; Mem. Am. Ophth. Soc. and Honorary Mem. Chicago Ophth. Society.
JOHN ELMER WEEKS, M.D., D.Sc. Prof. Ophth. Univ. and Bellevue Hosp. Med. Coll., N.Y.; Ophth. Surg. N.Y. Eye and Ear Inf.; Mem. Am. Ophth. Soc.; Hon. Mem. Chicago Ophth. Soc. and Royal Hungarian Med. Soc. Budapest.
GEORGE EDMUND DE SCHWEINITZ, A.M., LL.D., M.D. Prof. Ophth. Univ. Penn.; Ophth. Surg. Univ. Hosp., Phila. Hosp., Orthop. Hosp. and Inf. for Nerv. Dis.; Consult. Ophth. Surg, Phila. Polyclinic; Honorary Member Chicago Ophth. Soc.
ROBERT HENRY ELLIOT, M.D., B.S. LOND., Sc.D. EDIN., F.R.C.S. ENG., ETC., LIEUT.-COLONEL, I.M.S. Supt. Gov. Ophth. Hosp., Madras. India; Prof. Ophth. Med. Coll., Madras; Fellow Univ. of Madras; Honorary Member Chicago Ophthalmological Society, U.S.A.
CASEY A. WOOD, M.D., C.M., D.C.L. Prof. Ophth. Univ. Ill.; Late Prof. Ophth. N. W. Univ.; Ex-Pres. Am. Acad. of Med.; Am. Acad. Ophth. and of the Chicago Ophth. Soc.; Ophthalmic Surg. St. Luke's Hosp.; Consulting Ophth. Surg. St. Luke's and Cook County Hosp.; Ex-Ch. Ophth. Sec. A.M.A.; Editor System Ophth. Therapeutics. Sys. Ophth. Operations and American Encylopedia Ophthalmology.
FRANCIS LANE, A.B., M.D. Pathologist and Asst. Ophthalmic Surgeon Ill. Char. Eye and Ear Inf.; Instructor in Ophth. Rush Med. Coll.; Asst, Ophth. Surg. Presbyterian Hospital.
E. V. L. BROWN, M.D. Asst. Prof. Pathology of the Eye, Univ. Chicago; Asst. Prof. Ophth. Rush Med. College; Ophth. Surg. Ill. Eye and Ear Inf. and Cook County Hosp.; Mem. Am. Ophth. Soc.
NELSON M. BLACK, PH.G., M.D. Author of The Development of the Fusion Center in the Treatment of Strabismus; Examination of the Eyes of Transportation Employes; Artificial illumination a Factor in Ocular Discomfort, etc.
FRANK C. TODD, M.D. Prof. Ophth. and Oto-Laryng., Univ. Minn.; Chairman Sec. Ophth. A.M.A. and second Vice-Pres. A.M.A.; Ophth. Surg. Univ. and Hill Crest Hospital.
ALBERT EUGENE BULSON, JR., B.S., M.D. Prof. Ophth. Ind. School Med.; Ex-Ch. Sec. Ophth. A.M.A.; Ophth. Surg. St. Joseph's Hospital; Editor Jour. Ind, Slate Med. Assn.
I. Etiology and Classification of Glaucoma.
Etiologic factors include: obstruction of lymph spaces, especially the angle of the anterior chamber; blood pressure, arterial, capillary and venous; affinity of tissues for fluids; alterations of the intra-ocular fluids; inflammations in the eye ball; and failure of a nerve apparatus to control fluid in the globe. Classification: various types of glaucoma constituting clinical entities must be recognised, as: simple glaucoma, recurring exacerbations, congestive, mechanical, and increased tension arising during uveal inflammations.
Discussion by DR. FRANCIS LANE, Chicago.
(a) Changes taking place in corneal tissue.
(b) Iris angle with particular reference to the ligamentum pectinatum.
(c) Variations in the condition of the ciliary body.
(d) Consideration of the anatomical changes that take place in glaucoma secondary to retinal and chorioidal hemorrhage.
DR. JOHN E. WEEKS, New York City.
Discussion by DR. E. V. L. BROWN, Chicago.
III. Concerning Non-surgical Measures for the Reduction of Increased Intra-ocular Tension.
(a) The use of myotics; their preparation, method of administration, and explanation of their action.
(b) Reduction of increased intra-ocular tension by means of various mechanical measures, notably massage, vibration massage, suction massage, electricity and diathermy.
(c) Indirect reduction of increased intra-ocular tension, brought about by lowering the general vascular pressure.
(d) The relation of osmosis, lymphagogue activity, the absorption of edema, the stimulation of capillary contractility, and the lowering of the affinity of ocular colloids for water in their relation to the reduction of increased intra-ocular tension.
DR. GEORGE EDMUND DE SCHWEINITZ, Philadelphia.
Discussion by DR. NELSON M. BLACK, Milwaukee.
(a) The aim of the operation is the formation of a foreign-body-free fistula.
(b) It is most important to leave uveal tissue untouched.
(c) Method of doing this explained.
(d) The area available for trephining.
(e) Method of increasing that area.
(h) Technique of using trephine.
(i) The operation is not difficult.
(j) The operation valuable as a prophylactic measure.
DR. ROBERT H. ELLIOT, F.R.C.S., Lieut.-Col. I.M.S., Madras, India.
Discussion by DR. FRANK C. TODD, Minneapolis.
V. Operations Other than Scleral Trephining for the Relief of Glaucoma.
Most of the ordinary surgical procedures employed for lowering intra-ocular tension furnish a permanent cure of certain fairly well defined varieties of glaucoma. They also relieve the symptoms and retard the progress of other varieties of the disease, even if they do not perform a cure. In a third class of cases, they either have no effect whatever in arresting the disease or they hasten its march towards blindness.
What operative procedure gives, on the whole, the best results? In other words, what operation is the easiest of performance, is the least likely to be attended by serious complications and is available for the largest number of cases? Reasons for believing that of the better known procedures simple iridectomy is the least effective, while those interventions producing a large, thin, scleral filtration-cicatrix are the most valuable.
DR. CASEY A. WOOD, Chicago.
It is convenient to start with the conception that glaucoma is increased tension of the eyeball, plus the causes and effects of such increase; although a broad survey of the facts may reveal a clinical entity to be called glaucoma, without increased tension constantly or necessarily present, and cases of increased intra-ocular tension not to be classed as glaucoma.
The physiologic tension of the eyeball is essential to ocular refraction, and closely related to ocular nutrition. Fully to understand the mechanism for its regulation would carry us far toward an understanding of the causes of glaucoma. Normal tension is maintained with a continuous flow of fluid into the eye and a corresponding outflow. Complete interruption of the nutritional stream would be speedy death; partial interruption may be held responsible for most of the visual impairment and pain of glaucoma.
The balance of intra-ocular pressure is not maintained by the slight distensibility of the sclero-corneal coat. Increased pressure does not open new channels for the escape of intra-ocular fluid; if, indeed, it does not tend to close the normal channels.
The affinity of the tissues for water, or, as Fischer explains it, the affinity of the tissue colloids for water, seems too little related to the requirements of ocular function to furnish the needed regulation of tension. The lymph spaces and blood-channels of the eye are large, as compared with the mass of its tissue colloids. In these spaces and channels must be sought a means for rapid response to the need for regulation of intra-ocular tension. Fischer has shown, that when the enucleated eyeball is placed in a weak solution of hydrochloric acid, the swelling of the tissue colloids is sufficient in a few hours, to burst the sclero-corneal coat. But this is an eye in which all nutritional changes have ceased. He brings together many facts to support the view that in the living tissues impaired circulation, and especially diminished oxidation, are the chief causes of increased affinity of the colloids for water. Such affinity increased by the impairment of the intra-ocular circulation, may well constitute a factor making for malignancy in glaucoma. But it can hardly explain the original departure from a normal pressure balance.
We must assume that intra-ocular pressure is kept down to the normal limit, by the prompt response of a regulative mechanism, which diminishes the flow of fluid into the eye, or permits its more rapid escape, whenever fluid tends to accumulate in the eye and increase its tension.
Little has been done to show that increase of fluid entering into the eye is the cause of glaucoma. A normal, or even a low arterial blood pressure is sufficiently above the normal intra-ocular pressure to furnish a source of increased fluid in the eye. Increased arterial pressure has been found in a large proportion of cases of glaucoma; and may be necessary to the production of the highest intra-ocular tension. A sudden relaxation of the arterial walls, that would permit the arterial blood pressure to make itself felt in the eye, might cause an important rise of intra-ocular tension and may be a factor in the etiology of acute attacks. It affords a possible mechanism through which may be produced the recognized glaucomatous effects of certain nerve disturbances. But such attacks are not commonly associated with noticeable flushing of the head and face generally; and paralysis of the cervical sympathetic is known to lower the intra-ocular tension.
Capillary blood pressure must lie between the arterial blood pressure and the venous blood pressure. It must be closely associated with the nutritional processes like secretion or inflammation; beyond this we know little about it. The association of increased blood pressure with glaucoma seems to be generally an indirect one through vascular lesions and disturbances of nutrition.
A reservoir with a free outlet can only fill during a flood; and then quickly empties itself again. The outflow channels in the normal eye provide for carrying away of the waste products of such an active nutrition, that it is hard to think they will become inadequate in glaucoma until there has been a marked decrease from their normal capacity. Priestley Smith has pointed out that the glaucomatous eye softens more slowly than the normal eye after enucleation, in spite of the fact that a greater force is operating to drive fluid out of the eye. In his recent tonometric studies Schoenberg noted that under manipulation the glaucomatous eye softened more slowly than the normal eye; and suggests this diminished drainage as an important evidence of glaucoma.
Obstructed outflow might begin in an abnormal tendency of the tissues to retain fluid, a tendency that Fischer might locate in the colloids. The increase of intra-ocular pressure noted in cases of uveal inflammation, to be presently referred to, may be due to some such tendency. But it is rational to ascribe to obstruction of the filtration angle of the anterior chamber, the important part it has been supposed to play in the pathology of glaucoma. However this obstruction may be brought about, whether by thickening of the iris root during dilatation of the pupil, pushing forward of the iris root by the larger ciliary processes of age, or the enlarged crystalline lens pressing on the ciliary processes; or by inflammatory adhesion of the iris to the filtration area; ballooning of the iris, or its displacement by traumatic cataract; or adhesion to the cornea after perforating ulcer in the secondary glaucomas; or whether the obstruction is due to the accumulation of experimental precipitates, as shown by Schreiber and Wengler, or possibly of pigment granules into Fontana's space; or a process of sclerosis closing the spaces by contraction of new-formed connective tissue, or the covering over with proliferating implanted epithelium following injury opening the anterior chamber; glaucoma follows impairment of this drainage space, and lessened outflow through it. This blocking of the angle of the anterior chamber must be regarded as an established fact in the etiology of glaucoma. But because it is so definitely established, and because so much work has been done with reference to it, we may attach to it an undue importance.
The escape of the outflow of fluid from the eye is ultimately through the veins. The general venous blood pressure is so low (often negative in the great veins of the neck during inspiration) that no obstacle can come from it to the ocular outflow. The venous blood pressure permits the eyeball to become perfectly soft. We have all seen tension of 5 mm., or even less; and general venous pressure does not rise to the normal intra-ocular tension. Increased intra-ocular pressure requires that there must be some obstacle that keeps the intra-ocular fluid from reaching the general venous system. This may be in the lymph drainage system of the eye; but it may also be in the ocular veins themselves.
Experimentally the eyeball can be made to burst by tying all the venous outlets from it. I have seen very high intra-ocular tension develop in a few hours after general thrombosis of the orbital veins. The absence of the canal of Schlemm is noted in congenital buphthalmos. The enlargement of the anterior perforating veins is an old symptom of chronic glaucoma. Obstruction to outflow of blood through the vorticose veins, by the increased intra-ocular pressure, has long been a recognized explanation of the malignant tendency of glaucoma—a part of the vicious circle established in this disease. There is reason that we should give careful attention to the views of Heerfordt and Zirm, that obstruction to the venous outflow may be the effective cause of the disease. Zirm believes the venous plexus of the choroid is an essential part of the mechanism for the regulation of intra-ocular tension, the necessary vaso-motor control depending on nerve centers situated in the iris.
The accurate control of normal intra-ocular pressure, by mutual adjustment of inflow and outflow of fluid, is scarcely conceivable without some highly specialized, extremely sensitive nerve mechanism to preside over it. This is suggested by analogy with the regulation of secretion in the lacrimal, salivary, or peptic glands, or the maintenance of blood pressure in the heart and arteries. Clinical observations point the same way. Many patients connect their attacks (especially their earlier ones of ocular discomfort, impaired vision, haloes around the light, and dilated pupil) with social excitement, anxiety, worry, anger or fatigue. A patient of mine gave up her card parties, because an exciting game generally ended in blurred vision, a rainbow around the light, and a dilated pupil, and sometimes an aching eye. Another woman watching beside her dying husband and exposed to extreme cold, had her first attack of glaucoma, so severe as to destroy the sight of one eye. The other eye, also affected at the time, recovered good vision, and has remained several years without a second attack and without treatment.
Laqueur's first attack occurred at the end of a long exhausting morning in the operating room, with luncheon delayed two hours. The connection of his later attacks with anger, worry, embarrassment, even the excitement of watching a play at the theatre, was noted again and again. In Javal's case, the attack fatal to one eye came at the culmination of an exciting electoral campaign. The other eye was stricken at the termination of the Dreyfus case, in which Javal was intensely interested. There seems to be a special liability to glaucoma among those residing at high altitudes, best explained by nerve influence. The frequency of glaucoma among Jews may be due to a small cornea, as suggested by Priestley Smith; but it is quite as reasonable to connect it with a racial excitability or nervous instability. More definite knowledge of the nervous mechanism concerned in the regulation of intra-ocular pressure and the production of glaucoma is much needed.
The influence of increased affinity of the tissues for fluid has already been referred to. That a similar obstacle to the escape of fluid from the eyeball might be due to a change of character in the fluid, is a conception that has been entertained as a working hypothesis, and much experimental and analytical work has been done to test its correctness. This work has been so slightly related to practical ophthalmology, and so contradictory in its results that alterations in the fluids can only be regarded as a possible etiologic factor. Glaucoma secondary to intra-ocular hemorrhage, operations on the lens or its capsule, or severe nutritional disturbance may be capable of such explanation.
A better grasp of the etiology of glaucoma may be attained by considering separately various types of cases; although perfectly typical cases may be rare; and cases of mixed type and etiology much more frequent.
Simple glaucoma has been recognized as closely related to atrophy of the optic nerve with deep excavation. No line of demarcation can be drawn between them, except by reserving the term of glaucoma for cases that depart from the pure type, terminating in glaucoma of some other kind, which is no more significant than the passage of a conjunctivitis into a keratitis, or an iritis into a glaucoma. Cases of simple glaucoma do run their course of many years to complete blindness, or to death, without exacerbations, inflammation, or characteristic pain. In such cases the intra-ocular tension does not rise suddenly; and it may be little or not at all elevated above the usual normal limit.
For nine years I have watched the progress of such a glaucoma in a man now aged 87, with slow development of glaucomatous cupping of the optic disc, now more than 3 D. deep. The tension has never been noted at more than Plus T (?), and when taken with the tonometer varied from 9 to 32 mm. for the worse eye, and 13 to 24 mm. for the other. Similar cases in which the tension lay within the commonly accepted normal limits have been reported recently by Bietti and Stock.
In the eye there is probably a normal equilibrium between blood pressure, tissue activity, and intra-ocular tension. This may be destroyed either by increasing the intra-ocular tension, or lowering the tissue activity, or the blood pressure. Lowered blood pressure has been suggested by Paton as an explanation of symptoms usually ascribed to vascular obstruction. Rising blood pressure may be required in old age to compensate for diminished tissue activity; and it is conceivable, under normal intra-ocular tension, that diminished nutritional activity may result in the same symptoms as are produced in other eyes by increased tension. Glaucoma is probably not so much an increase of tension as a loss of balance between intra-ocular tension and nutritional activity.
In contrast with the above are the cases marked by sudden elevations of ocular tension recurring repeatedly over long periods without permanent visual impairment. Laqueur's case continued of this character for six years, under the use of miotics, and then was cured by iridectomy, the cure remaining permanent with normal vision until his death after 30 years. Millikin has reported the case of a patient who in five years had "many hundreds" of attacks, in which vision was impaired, haloes appeared about the light, the pupil dilated, the cornea became steamy, and tension rose to plus T. 1 or plus T. 2. After iridectomy the attacks ceased, leaving no pathological cupping of the disc, full vision, and a good field. I have seen cases of this type in women under middle age, and of marked nervous instability.
A third type which will come to be more generally recognized, as the tonometer comes to be more widely used, includes cases in which there is little beside the increase of intra-ocular tension to justify their mention in a discussion on glaucoma. A patient, then aged 21, suffered three years ago from a scotoma almost central; and was first seen six months after that with a macular choroidal atrophy and abnormal pigmentation. She suffered, we afterwards concluded, from choroidal tuberculosis. A recurrence involving adjoining choroid occurred fourteen months ago. There was at the start pain, slight dilatation of the pupil, and slight general hyperemia of the globe. The tension of the eyeball rose to 60 mm., that of the fellow eye being 20 mm. Under miotics the tension fell at first but slightly. It was 55 mm. at the end of a week; but after two weeks came down to normal, 20 mm. A month later the tension rose to 28 mm., but for a year has continued normal; the eye did well under tuberculin treatment, and without any local treatment. In September of this year I had two cases of iritis in which the intra-ocular tension rose to 45 and 52 mm., respectively, and gradually returned to normal, with the cure of the iritis under atropine. In one of these cases, a lady of 70, I used atropine also in the other eye, but the tension of that eye remained normal, 22 to 24 mm., throughout. After needling the lens in young people I have seen a rise of intra-ocular tension to 50 and 60 mm., maintained for many days, with considerable general deep hyperemia, and soreness of the globe, followed by gradual return to normal tension, and no permanent impairment of vision or the visual field.
One other type may be mentioned. That of an elderly patient with marked vascular disease, often renal involvement, and distinctly impaired nutrition. There may be renal retinitis or retinal hemorrhages. The case may easily become one of hemorrhagic glaucoma. It may run a very chronic course. But it may become suddenly worse, or go on to complete blindness with pain, demanding enucleation, after some temporary perturbation, as the performance of a glaucoma operation. It is pre-eminently the kind of a case you would prefer would go to some one else.
Each of these types illustrate a distinct cause or group of causes. The first type brings us near to what may be the essential nature of glaucoma, impairment of ocular nutrition by the intra-ocular tension, which is generally elevated, but may not be above the usual normal. A special weakness in the nutrition of nerve tissue may be assumed. It would help to explain the cavernous atrophy of the optic nerve associated with simple glaucoma. The second type shows impairment of the regulative mechanism permitting rapid rise of the intra-ocular pressure. In persons of good nerve nutrition and strong recuperative power, it may exist for years without doing permanent damage. But joined to causes of the first type, lowered nutritive activity, it causes rapid and permanent loss of sight. The third group are cases associated with glaucoma only as causes. In eyes with low nutritive power, or subject to exacerbations of increased intra-ocular pressure, uveal inflammations may prove disastrous. The fourth type shows the results of the combination of the causes of the other types; with the elements of acute or slow malignancy added—the impaired circulation and lowered oxidation producing some degree of edema of the tissues that insures a fatal result.
This is no complete presentation of my subject, but a selection of facts bearing on the etiology, to serve as a foundation for the discussion of those practical aspects of glaucoma which are to claim your attention through the papers and remarks of subsequent speakers.
Not one of the theories thus far propounded to explain the essential cause of increased intra-ocular tension is satisfactory. Our present day knowledge apparently ceases with a more or less incomplete understanding of the mere circumstance under which increase of tension in general depends.
The question of the source of the normal intra-ocular pressure must first be solved before any discussion of a pathological increase can be engaged in. This question primarily hinges on whether the corneo-sclera is to be regarded as an unelastic capsule with a fixed volume, or as a yielding envelope with an ever changing capacity.
Hill has satisfactorily demonstrated that, under physiological conditions, the hydrostatic pressure within the eye and the skull is identical; it rises and falls simultaneously; it is the same as the cerebral venous pressure; it is constantly varying, depending directly on the general circulation. Upon these findings Henderson based his opinion that the physiological properties of the tunica fibrosa and the skull are identical, realizing at the same time, that the rigidity of the corneo-sclera, because of its fibrous nature, is not as firm as the cranium. In accepting this belief the inference was that the cubic capacity of both coverings is fixed. Applying these conclusions to the eye, it can be said that the pressure of the fixed intra-ocular volume varies with the venous tension within the bulb, which in turn is influenced by the general circulation. Such a conception, while not strictly in accord with recognized physiological teachings, proves that the normal intra-ocular pressure is not a question of volume content, but that it is purely a question of pressure of a fixed volume within an unyielding capsule. Dr. Jackson virtually puts aside the volumetric theory with his statement, that "the balance of intra-ocular pressure is not maintained by the slight distensibility of the sclero-corneal coat." Further discussion on the inadequacy of the volumetric theory need not detain us.
It is well to recall a few anatomical features because of their bearing on the theories herein considered.
1. The angle of the anterior chamber is a true angle and not an annular sinus.
2. The meshwork of the iris angle (ligamentum pectinatum), a cellular structure at birth, undergoes a progressive and physiological fibrosis with early subsequent sclerosis, until finally it becomes a fibrous structure. The individual strands of this meshwork are more than two times as large at advanced age as at birth, consequently the alveoli of the meshwork becomes markedly reduced in size.
3. The spongy nature of this meshwork affords free access of aqueous to the venous sinus of Schlemm, thence by tributaries into the supra-choroidal space and anterior uveal venous system.
4. Fuchs's iris cripts afford direct access of aqueous to the veins of the iris.
Furthermore, two simple principles are taught by physics: Fluids are incompressible and they seek the lowest hydrostatic level. The application of these perfectly obvious principles to the eyeball makes the intra-ocular pressure the same as that within the elastic venous walls, which is the lowest circulating pressure within the bulb.
To summarize: The aqueous has direct access to the anterior uveal venous system; the physiological thickening of the strands of the meshwork of the iris angle supplies a mechanical obstruction between the anterior chamber and the venous sinus of Schlemm; intra-ocular pressure stands at the same level as the intra-venous, consequently, the hydrostatic pressure is the same on both sides of the iris angle meshwork, because the canal of Schlemm is a secondary venous system; lastly, the outflow of aqueous into the venous sinus is by diffusion, not by filtration, because the pressure is the same on both sides of the meshwork.
These facts and deductions have given rise to the present day circulatory theory of intra-ocular pressure, so we now can approach the predisposing and exciting factors which determine glaucoma.
The central fact to be borne in mind is, if the physiological pressure is vascular in origin and nature, the pathological pressure must likewise be derived from the same source.
Sclerosis of the meshwork of the iris angle is the predisposing factor because it hinders free access of aqueous into the venous sinus of Schlemm. Sclerosis alone, however, will not cause glaucoma so long as access to the iris veins can keep the intra-ocular pressure at the intra-venous level, and, too, as long as the exciting cause is absent.
The exciting cause is vascular, maintained and influenced by the general circulatory pressure. A rise of the general vascular tension alone will not cause glaucoma, because any alteration in intra-ocular pressure resulting would be purely a temporary change, easily taken care of by the extensive access of aqueous to the intra-ocular venous system. When these two factors coexist in their varying combinations, pathological increase of pressure results—in short, glaucoma.
Syphilis, rheumatism, gout, auto-intoxication and many other constitutional disorders are well recognized agencies which induce sclerosis in body tissues, so there can be little doubt that these conditions produce pathological sclerosis of the meshwork of the iris angle. Psychic disturbances, congested portal or renal system, hard mental or muscular work, etc., etc., induce increased pressure of the general circulation, and so simultaneously the intra-ocular pressure.
According to the edema theory advanced by Fischer, glaucoma is "essentially an edema of the eyeball, and for its production we must hold responsible the same circumstances which are responsible for a state of edema in any other part of the body." The magnificent experimental work of this investigator has shown that edema is nothing more or less than an increased capacity of the protein colloid tissues for water; that the most important factor leading to this increased hydration capacity is an abnormal production or accumulation of acid content, effected by those agencies which are instrumental in causing sclerosis and an increase of blood pressure.
It seems that both of these theories afford an explanation for many of the secondary pathological manifestations which characterize the intra-ocular tissues during a glaucomatous onset.
Fischer criticizes the Henderson theory on the ground that increased blood pressure alone does not lead to edema—edema is thwarted by high blood pressure. On the other hand, if Fischer believes that sclerosis of the meshwork of the iris angle is a result and not a cause of glaucoma, then it would seem that Henderson has the better of the argument. The physiological changes in this structure, which take place with advancing age, can rightfully be looked upon as a predisposing factor in glaucoma.
Dr. Jackson has presented all other phases of this part of the symposium in such a comprehensive manner that nothing further remains to be said.
In reviewing the pathology of glaucoma it seems proper to consider the various structures and tissues of the eye in logical order.
Lids and Conjunctiva. "The only change observed in these tissues is a reflex edema, excited apparently by pressure on the ciliary nerves and, probably, irritation of the vaso-motor fibers of the sympathetic."
Lachrymal Gland. Hyper secretion due to reflex irritation.
Cornea. As has been shown by Priestley Smith, the cornea in glaucomatous eyes is, as a rule, smaller than in non-glaucomatous eyes, the mean of a series of measurements being 11.1 mm. horizontally and 10.3 mm. vertically in glaucomatous and 11.6 mm. horizontally and 11 mm. vertically in non-glaucomatous eyes. In cases of considerable increase of tension, particularly if the onset is sudden, the circulation of lymph in the cornea is interfered with, the anterior layers of the cornea become edematous, the spaces between the lamellae filled with albuminous fluid. Some of this fluid finds its way through Bowman's membrane, apparently by way of the minute channels which permit the passage of small nerve twigs, and enters the epithelial cell layer. The fluid finds its way between the epithelial cells in the deeper layers, apparently being taken into some of the superficial cells by imbibition. Some of the swollen surface cells open spontaneously and discharge their contents, others drop off. The process causes a roughening of the surface of the cornea and produces a faint haziness. There is another form of haziness that develops on sudden rise in tension and completely disappears on subsidence of the tension. This is due, as has been shown by V. Fleischl (Sitzungsberichle d. Weiner Akad. d. Wissensch, 1880) and others, to increased tension on the fibrillae of the cornea, a double refraction being induced. In cases of long continued increase of tension minute permanent vesicles form in the epithelial layers, particularly in the superficial portion. Anaesthesia of the cornea develops, due to pressure on the nerve fibers that are distributed to the epithelium, the compression probably occurring along the course of the long ciliary nerves, from which the corneal nerves are derived, as they pass between the choroid and the unyielding sclera (Collins & Mayou).
In advanced cases of glaucoma after the congestive period has subsided the cornea becomes somewhat condensed, the lymph spaces contracted; a condition of sclerosis obtains. Alteration in the shape of the cornea occurs only rarely in adult life. When it does occur it takes place in corneae that have suffered from keratitis. The alteration is usually in the form of ectasiae. In infancy and early youth (buphthalmia) the cornea may become uniformly enlarged and globular. Often, however, the enlargement of the cornea is irregular. Increase in tension may produce fissures in Descemet's membrane. These occur more frequently in the cornea that have suffered a change in shape, as in buphthalmos. Gaps occur in the elastic membrane which become covered by endothelium. Some cloudiness may be seen in the corneal lamellae adjacent to these fissures, in some cases due evidently to the filtration of aqueous humor through defective endothelium. Prolonged high intra-ocular tension may be accompanied, particularly in cases of secondary glaucoma, by vesicular and bullous keratitis.
In acute glaucoma the sclera appears to be edematous and slightly thickened. As the disease progresses the sclera becomes denser than normal. The oblique openings—passages for the venae vorticosae—are said to be narrowed. The openings for the passage of the anterior ciliary vessels are enlarged in many, particularly in advanced cases. Minute herniae at these openings are sometimes present. Dilatation and tortuosity of the anterior ciliary veins are due apparently to excessive flow of blood through them on account of the abnormally small amount carried off by the venae vorticosae. In the stage of degeneration, ectasae of the sclera occur most frequently near the equator of the globe. Spontaneous rupture may take place.
Anterior Chamber. The anterior chamber is shallow, as a rule. This is almost without exception in primary glaucoma in adults. In secondary glaucoma in which occlusion of Fontana's spaces occurs as a result of the deposition of fibrin or other inflammatory products the anterior chamber may be of normal depth, or deeper than normal. Very deep anterior chamber may occur in glaucoma, due to retraction of lens and iris following fibrinous or plastic exudation into the vitreous, or when it occurs in congenital glaucoma, due to enlargement of the globe.
Aqueous Humor. The aqueous humor, as has been pointed out by Uribe-Troncoso (Pathoginie du Glaucome 1903) contains a greatly increased quantity of albuminoids and inorganic salts in glaucoma. In acute glaucoma the increase of albuminoids (blood proteids) is greater than in chronic glaucoma. The aqueous humor becomes slightly turbid in acute attacks, coagulating more readily than the normal. The plastic principle contained in the aqueous is rarely sufficient to cause adhesion between the margin of the iris and the lens capsule, but the colloid nature of the aqueous, according to Troncoso, lessens its diffusibility and prevents its free passage into the lymph channels. The increase in albuminoids is a consequence of congestion and venous stasis and does not precede the attack.
Filtration Angle. The changes that occur in the filtration angle before it is encroached upon by iris tissue are sclerosis of the ligamentum pectinatum in adults to which Henderson (Trans. Ophth. Soc. U.K. Vol. xxviii) has called our attention; the accompanying sclerosis of the other tissues to the inner side of Schlemm's canal; and, in some cases, the deposition of pigmented cells derived from the iris and ciliary processes (Levinsohn) which serve to obstruct the lymph spaces. In many of the cases of acute glaucoma and almost all of the cases of chronic glaucoma of long standing the filtration angle becomes blocked by the advance of the root of the iris.
Iris. In acute glaucoma the iris is congested and thickened. It is pushed forward and may lie against the cornea at its periphery. When the attack subsides, the iris falls away from the cornea. Aside from the congestion, the primary changes that take place in the iris are indicative of paresis of the fibers of the motor oculi that supply the sphincter pupillae, and stimulation of the fibers from the sympathetic producing vasomotor spasm. The long diameter of the pupil apparently lies in the direction of the terminal vessels of the two principal branches of each long ciliary artery which form the circulus iridis major, where the vasomotor spasm would have the greatest effect in lessening the blood supply. The haziness of the cornea and slight turbidity of the aqueous contribute greatly to the apparent change in the color of the iris. In cases of simple chronic glaucoma there is but little evidence of edema of the iris. If the iris lies in contact with the sclera and cornea for some time, it becomes adherent (peripheral anterior synechia). As the disease progresses, the stroma of the iris atrophies and contracts. There is very little evidence of small-cell infiltration or the formation of cicatrical tissue. Numerous slits may develop in the iris through which the fundus of the eye may be seen (polycoria). The pigment layer does not atrophy in proportion to the stroma of the iris; by the contraction of the stroma of the pigment layer is doubled upon itself at the pupillary margin, forming a black ring of greater or less width (ectropian uveae). The iris becomes attached to the pectinate ligament and to the endothelium of Descemet's membrane. In a very few cases the closure of the angle is not complete at the apex, a small space remaining comparatively free for a long time. The adhesion of the iris to the pectinaform ligament and cornea is not uniform at all parts of the periphery; it varies in width. Portions of the iris angle may remain open while other parts are closed. Where the iris tissue lies in contact with the cornea, the stroma of the iris almost totally disappears. In some cases the iris becomes totally adherent to the cornea.
Ciliary Body and Chorioid. In acute glaucoma there is congestion of the entire uveal tract, the congestion partaking more of a venous stasis than of an active or arterial congestion. The vessels of the ciliary process, which are larger and more tortuous in adults of advanced years than in the young, become enormously distended, causing almost complete obliteration of the perilental space. They press against the root of the iris and the equator of the lens, forcing them forward. There is edema of the ureal tract, apparently from transudation of serum. Many small, and sometimes rather large hemorrhages may occur. There is but little small cell infiltration, indicating almost total absence of what is ordinarily recognized as true inflammation. It is probable that the secretion from the glandular zone of the ciliary body is increased.
On subsidence of the congestion, as after miotics or iridectomy, the tissues may return to very nearly a normal condition. The iris recedes from contact with the ligamentum pectinatum and cornea and the filtration angle is again open. In some cases the iris becomes adherent to the head of the ciliary processes and, when atrophy of the ciliary body occurs, is drawn backward at the base of the iris by the receding tissues. If the hypertension persists or is repeated at varying periods, a slow atrophy of the uveal tract sets in. Eventually the ciliary body becomes very much reduced in thickness, is flattened out, the ciliary processes reduced in size and the blood vessels disappear or are reduced much in caliber. Those that persist possess walls that are much thickened. This is particularly true of hemorrhagic glaucoma.
In advanced absolute glaucoma the chorioid may become reduced to a very thin membrane consisting of connective tissue and pigmented cells, scarcely distinguishable even by moderate powers of the microscope. Atrophy is marked in the vicinity of the venae vorticosae. Czermak and Birnbacher describe proliferation of the endothelium of the large veins with contraction and obliteration of their lumen.
Optic Nerve and Retina. In the acute form the retina and optic nerve present the same condition that is present in the vascular tunic; namely, that of venous stasis with the consequent edema. Frequently minute hemorrhages occur in the retina, particularly in violent acute attacks. Cupping of the discs slowly develops, causing more or less stretching of the nerve fibers over the edge of the cup. The gradual diminution of the field of vision is due in greater part to death of peripheral nervous elements of the retina, those parts of the field farthest removed from the large arterial trunks suffering first. The arrangement of the arteries at the disc, passing out as they do from the nasal side, of necessity make the vessels that pass to the temporal part of the retina longest and of less caliber. These vessels and their terminals are first to suffer marked diminution in size; death of the perceptive elements supplied with nutrition by these vessels follows. For this reason the nasal part of the field of vision is more often the first to disappear. In congestive (inflammatory) glaucoma, the typical field of vision shows most marked contraction on the nasal side. The disturbance of the nutrition of the retina accounts in greater part for the various forms of visual field met with.
Death of all of the perceptive elements of the retina eventually occurs. The loss of nutrition is apparently not the whole cause of blindness. Atrophy of the nerve fibers follows death of retinal neurons, but atrophy of some of the nerve fibers may be, and probably is, due to the pressure and traction exerted upon them at the margin of the disc. It is probable that too much importance has been given to this mode of interference with the nerve fibers. However, the change in the position of the lamina cribrosa must exert a deleterious effect, particularly on those fibers which pass through the peripheral meshes, the shape of which must necessarily be much distorted. In glaucoma simplex, which is largely devoid of marked congestive periods (acute attacks), a surprisingly high degree of acuity of vision may exist with a deep excavation and pale nerve. Careful studies of the retinal vessels in glaucoma (Verhoeff Arch. of Ophth. XLII. p. 145; Opin. Soc. Francaise d'Ophth. 1908) disclose the fact that an increase in the elastic tissue and connective tissue elements occurs in some cases, also proliferation of the endothelial cells, which serve to irregularly narrow and, in some instances, obliterate the lumen of the vessel. Arteries and veins are both affected. Hyaline degeneration of the media also occurs. The process is not uniform.
Glaucomatous Cup. The excavation of the disc progresses slowly and is due in part to stretching the fibers of the lamina cribrosa pressing this structure outward, and partly to atrophy and disappearance of the nerve tissue and much of the vascular tissues in the nerve head. The displacement backward of the lamina cribrosa may cause that structure to lie behind the outer surface of the sclera. Atrophy and cystic degeneration of the nerve trunk follows destruction of retinal neurons and cupping of the disc. Neuroglia remains in part. Connective tissue elements increase in the optic nerve as the nerve fibers disappear.
Glaucomatous Ring. The development of the pale circle which surrounds the disc, particularly in glaucomatous eyes, is due to a very slight recession of the pigment layer of the retina and of the margin of the chorioid at this point with some atrophy, apparently consequent on the beginning retraction of the lamina cribrosa and slightly increased pressure of the nerve fiber layer on the underlying tissues at the margin of the disc. This permits the sclera to show through a very little at this part. In some eyes in which there is a beginning sclero-chorioiditis posterior, the condition is very similar to that presented by the glaucomatous ring.
Field of Vision. The two pathological processes that operate to destroy the function of the retina suffice to produce scotomata in the field of vision of varying shapes. The typical glaucomatous field in the acute cases shows a defect most pronounced to the nasal side. As has been shown by Bjeraum, the blind spot corresponding with the optic disc is enlarged in glaucoma, a relative scotoma often connecting it with the blind nasal portion of the field either above or below the horizontal meridian (Straub). The field in a simple glaucoma is apt to approach concentric limitation; namely, more like the field in simple atrophy. This is consistent with the fact that simple glaucoma in many cases possesses the characteristics of glaucoma plus atrophy of the optic nerve.
Vitreous. During the acute attack, the vitreous may become slightly turbid by transudation of serum from the vessel of the ciliary body and the chorioid and may become filled with fibrin. In some chronic cases in which absolute glaucoma is reached the development of small blood vessels in convoluted loops springing from the vessels of the discs has been observed. Any process that increases the volume of the contents of the vitreous chamber, as hemorrhage, neoplasm, profuse serous or plastic exudation, may by pushing iris and lens forward produce an attack of acute glaucoma.
Buphthalmos. Reis (Graefe's Arch. f. Ophth. V. LX. 1905) states that there is always obliteration of the anterior scleral venous channels (Schlemm's canal) in buphthalmos. Seefelder (Graefe's Arch. V. LXIII. 1906) mentions the abnormal position and abnormal narrowing of Schlemm's canal and the imperfect and insufficient differentiation of the cornea-scleral junction. In all of the cases in which the eye has been examined microscopically obliteration of Schlemm's canal has been reported. This is thought to be a defect in development. Magitot (Ann. d'Oculis CXLVII) suggests that injury to mesoderm which pushes itself between the ectoderm and anterior surface of the lens would account for the failure in development of Schlemm's canal. The changes that occur in the tissues of the eye appear to be largely due to the stretching consequent on the more or less uniform distentions of the globe as a result of hypertension.
Cornea. This portion of the fibrous membrane is enlarged, globous or flattened, irregularly thinned, particularly at the periphery, where it may be as thin as tissue paper, nebulous because of the stretching of its fibers principally, but in some degree (differing in different cases) to edema of the epithelial layer. Fissures occur in Descemet's membrane.
Anterior Chamber. This is very deep in the greater number of cases. However, this rule has many exceptions.
The vascular tunic may be congested in young infants, but atrophy soon develops and may reach an extreme degree. The sclera ordinarily becomes quite thin throughout, but may retain almost a normal thickness at the equator of the globe and posteriorly. Posterior sclera ectasae may develop. The iris, as a rule, hangs free from the cornea, often tremulous because of retraction of the lens beyond the iris plane. In some cases the iris is partly or totally adherent to the posterior surface of the cornea.
The vascular membrane (iris, ciliary body and chorioid) and the retina become atrophic, the atrophy varying in degree in various parts. Detachment of the retina may occur, often preceded by or accompanied by subretinal hemorrhage. The optic disc becomes deeply cupped and the tissues of the optic disc and optic nerve extremely atrophied. The crystalline lens may become cataractous and shrunken. Spontaneous rupture of the suspensory ligament with consequent subluxation of the lens may follow.
1. Those that cause a partial or complete closure of the lymph spaces and Schlemm's canal by cicatrical contraction, as in sclero-keratitis.
2. Those that cause obstruction to the lymph spaces at the filtration angle by the deposition of fibrin or cellular elements, as in iritis, hemorrhage into the anterior chamber, etc.
3. Those that cause obstruction of the filtration angle by advancement of the iris and lens, as occurs when the volume of the contents of the vitreous chamber is increased, as from retinal or chorioidal hemorrhage or neoplasm.
The various changes are so numerous that they need not be described further here. The ultimate changes due to high tension resemble those already described.
I would like to emphasize one of the newer features of the pathologic anatomy of glaucoma, one which has received too little attention in this country: the lacunar or cavernous atrophy of the optic nerve.
The name accurately describes the condition. Tiny clear spaces form in the lamina cribrosa and in front and behind it in the nerve tissue. Their exact nature is unknown. Usually they are entirely empty, often they are traversed by fine glial fibers. They seem to be in no relation to the blood vessels. Adjoining lacunae are supposed to fuse to form larger cavernae and these finally merge and constitute the final glaucoma cup. The lamina may then bridge across the space like a cord, or lie back against the end of the nerve trunk.
Schnabel considered all glaucoma cups to be formed in this way, independent of tension. His views were strongly supported by Elschnig, but as vigorously opposed by others. Axenfeld cites the fact that the glaucoma cup may disappear after operation. (I myself have seen a cup of 7 D. reduced to 1 D. in the course of a year after the tension had been lowered from 62 to 12.) Stock found the same lacunae in eight cases of myopia. The last extended study of the subject was made by E. v. Hippel, who found lacunae in 20 of 33 cases (60 per cent); enough certainly to make one look for them carefully in every case. He publishes a large number of excellent photo-micrographs, but none more typical than one I have in my possession.
I have been especially interested in this subject because I have met with a complete and total glaucoma cup, with the typical (ampulliform) undermining of the scleral ring, in a pair of eyes without increased tension. The (Schiotz) tonometer was used daily for 70 consecutive days and never registered more than 12-14 mm. Hg. The man had been blinded by wood alcohol. At the time I could find no other report in the literature, but overlooked a publication by Lewin and Guillery. Friedenberg has since reported cases of the same nature.
If other conditions than increased tension can produce a typical (ampulliform) glaucomatous excavation of the disc, why may not the cavernous atrophy and cup in glaucoma be due in part at least to similar processes, possibly in the nature of a toxic oedema of the nerve, either in association with tension or independent of it, as contended for by Schnabel?
1. Myosis produced by means of solutions of various drugs, a myosis followed by reduction of intra-ocular tension.
2. Reduction of tension by means of various mechanical measures, notably massage, vibration massage and suction massage, and by means of electricity and diathermy.
3. Indirect reduction of intra-ocular tension, accomplished by lowering general vascular pressure.
4. Reduction of ocular tension by stimulation of osmosis, of lymphagog activity, of absorption of edema, and of capillary contractility, and by decreasing affinity of ocular colloids for water.
1. The Myotics. Of these, eserin (physostigmin) and pilocarpin, with their respective salts, the sulphate and the salicylate in the first instance, and the hydrochlorid and the nitrate in the second, are well established in favor and efficiency. Personally, it has always seemed to me that the salicylate of eserin is preferable to the sulphate, but I have not persuaded myself that the nitrate of pilocarpin possesses material advantages over the hydrochlorid, although some authors prefer it. With arecalin, the alkaloid of the Betel nut, I have no experience, nor have I used its mixture with eserin, recommended by Merck as more potent than either of the drugs in separate solution.
The substance isophysostigmin, found with eserin in Calabar bean, according to Ogiu, exceeds in its myotic activity the sulphate of eserin, i. e., 1/80 of a grain of the drug is equal to 1/60 of a grain of the sulphate of eserin, but it is certainly not less irritating than physostigmin, and according to Stephenson's researches, is more so, and in this sense has no superiority over the usual alkaloid. In general terms, it may be said that the time has not arrived to make a preachment "on the passing of eserin and pilocarpin."
Physiologic Action. Concerning the ocular, physiologic action of the two chief alkaloids respectively of Calabar Bean and of Jaborandi, there still exists difference of opinion. It has always been easy to attribute the myotic action of these drugs, or at least, of eserin, to their stimulant action on the peripheral ends of the oculo-motor, thus causing sphincter contraction, and to a depressing action on the sympathetic fibers, thus causing removal of the action of the dilatator of the iris. But complete experimental proof of such action is wanting, and it is probable that myosis follows a direct stimulation of the sphincter muscle fibers, aided, perhaps, by contraction of the iris vessels, although the last named effect is denied by so competent an authority as Hobart Hare.
Exactly how the myotics reduce intra-ocular tension is not definitely proven. Usually it is taught that because of the myosis the base of the iris wedged in the angle of the anterior chamber is loosened and withdrawn, precisely as a fold in a coat is straightened by a tug on the fabric beneath it. Experiments, however, for example, by E. E. Henderson, have shown that the rate of filtration in an eye with artificially raised pressure is considerably larger when it is under the influence of eserin than it is when under the influence of atropin; that is by the contraction of the pupil the iris-surface filtration is increased and consequently the pressure is reduced. We all know that Thomas Henderson maintains that the results of iridectomy are beneficial because the raw edges of the coloboma, which do not cicatrize, permit access of the aqueous to the iris veins, and that myotics, inasmuch as they contract the pupil, open the iris crypts and therefore act, less efficiently, perhaps, but act none the less like an iridectomy. The normal intra-ocular pressure is uninfluenced by myotics because this pressure represents the lowest circulatory pressure in the eye, and further contact between aqueous and veins cannot reduce it below this level, another point which is made by Thomas Henderson in support of his contention.
The clinical fact remains that either by mechanical means, as it were, in the liberation of a plugged filtering angle, or by the increasing of iris-surface filtration, the myotics markedly reduce the abnormal intra-ocular pressure.
Methods of Administration and Indications. With the methods of administration of the myotics we are all so familiar that time need not be wasted in their reiteration, except to refer to a few practical points. In acute glaucoma, and every one knows that in this disease their action is often prompt and sometimes curative, eserin in a strength of one to four grains to the ounce may be instilled with sufficient frequency to establish myosis, and its action in this respect is enhanced if the congestion of the eye is lowered by measures to which I shall refer later. There is a good deal of clinical evidence to indicate that in this type of glaucoma, as well as in the so-called sub-acute varieties, myotic activity is increased by a mixture of pilocarpin and eserin in the same solution, exactly as a mixture of arecalin and eserin is more potent than either of the drugs in separate solution.
Prior to the happy advent of technically correctly placed filtering cicatrices, a large number of surgeons depended almost exclusively on the use of myotics in so-called simple, chronic or non-inflammatory glaucoma. This is not the place to introduce a discussion of the comparative value of iridectomy and myotic treatment in simple glaucoma as based upon statistical records. We must wait now for a sufficient period of time and then compare the value of myotic treatment with that of operations by means of which satisfactory filtration is produced. We are somewhat in the position that general surgeons occupied when aseptic methods first became prevalent. We do not usually compare the statistics of early aseptic days with those of the pre-antiseptic period, and I do not think we ought to compare the statistics of myotic treatment with ordinary iridectomy any longer, but that we should wait until we can make a comparison between the results of prolonged myosis and those of an improved modern technic which establishes a permanent filtration. In the meantime the patients who will not or cannot submit to operation must be reckoned with. Doubtless many patients with chronic glaucoma can be satisfactorily managed with myotic treatment, although personally I have always advocated operation when this could be performed, but it cannot always be performed. This rule should guide us, namely, to begin with a comparatively weak solution of the selected drug, for example, as Posey has advocated a tenth of a grain of salicylate of eserin to the ounce, and the strength gradually increased so that at the end of some months the patient is using a solution 1 grain to the ounce; or if the pilocarpin is preferred, solutions in double these strengths. It is my own belief, and that of many who have studied this subject, that if, without eserin irritation, a myosis can be maintained, and if the treatment can be begun early enough, the chances of preserving vision and the field of vision are good. I believe that the two most important instillations during the twenty-four hours of the number necessary to maintain this myosis are on retiring and if possible in the very early morning, some time between two and four o'clock. Most patients can be taught to wake themselves at the proper period of time, and are little inconvenienced by this disturbance of their sleep. I believe that eserin irritation is most successfully avoided, not by preparations of the myotics in combination with the antiseptics, for example, tricresol, which has been so much advocated, but by ordering very small quantities of the solution, insisting that it shall be frequently renewed and sterilized at each preparation, and that a half an hour after its instillation, during the day time at least, the eye shall be thoroughly flushed with some mild antiseptic solution, for example, boric acid and sodium chlorid. Whether the action of the eserin on the choroidal circulation, which is maintained by Wahlfours, aids in this favorable action of the myotics remains to be proved. It has been maintained by this author and by others who have followed him.
The great trouble with myotic treatment is not its lack of efficiency, but the difficulty of carrying it out successfully on ambulant patients, even in the better walks of life. It is hard successfully to maintain in a patient with chronic glaucoma what I may call an eserin life, just as it is hard to maintain in a person with an enlarged prostate a catheter life and escape infection, resulting, if it occurs, in the one instance in a difficult and stubborn conjunctivitis, and in the other in a cystitis. Still, we are obliged to use myotics, and the way to employ them to the patients' best advantage, I have ventured to repeat in spite of the universal familiarity with the methods. Perhaps we may reach that happy day when, especially with improved tonometric methods, increased skill in measuring the rate of filtration and better instruments for determining the light sense, we can anticipate the advent of glaucoma and get ahead of the ocular and visual deterioration which increased tension produces, by performing preventive operations which shall aid nature's filtration channels in the establishment of an artificial one. But increased tension is not the whole story of glaucoma, and a filtering cicatrix is not the last word in surgical therapeutics, and there is much to learn.
2. Reduction of tension by means of various mechanical measures, notably massage, and by means of electricity and diathermy. Massage is of ancient lineage. In general terms, in so far as ocular massage is concerned, it may be applied to the eye with the finger tips (ordinary massage), by means of various instruments (vibration massage), and with the help of certain suction cups (suction massage, which is indeed a form of vibratory massage). Many authors are satisfied with their results without the employment of any instrument, and prefer simple massage with the tip of the finger to any form of the instrumental variety, to quote the words of Casey Wood. At one time in my career I experimented very extensively with massage, not alone for the purpose of reducing intra-ocular tension, but in various diseases of the lid and cornea, and taught a trained nurse, who herself had a nebulous cornea, to make what I may call a specialty of this particular therapeutic procedure. She became exceedingly skillful and was quite faithful. We believed that the best results were obtained in a seance of two or three minutes, the finger tip being used over the lid, and the surface of the cornea lubricated with a drop of pure olive oil, although in glaucoma the addition of the oil is not necessary. Four movements were utilized, the first a stroking movement in lines radiating from the central pressure, very much as the spokes of a wheel radiate from the hub, second a circular movement, third a pressure movement, a little dipping motion, so that the cornea was slightly depressed, and finally, a gentle tapping movement, precisely the same, except that it was a diminutive one, as the tapping movement that the Swedish masseur makes. Usually each movement occupied from a half to one minute, according to the results desired. I agree with Casey Wood that such a technic furnishes just as good results as any one with the aid of an instrument.
Referring particularly to the reduction of intra-ocular tension, many surgeons have been impressed with the value of various instruments. Thus, Ohm, who has worked particularly in the reduction of the increased tension of secondary glaucoma, for example, after discussion of lamellar cataract, advocates the Piesbergen instrument, which makes 3,000 vibrations a minute, and is applied over the closed lids. I think the instrument best known is the one introduced by Malakow. For this purpose the point of an Edison electric pen is armed with a small ivory ball, and the vibration rate varies from 200 to several thousand a minute, the rapidly revolving ball being passed over the closed lids, in some instances directly upon the cornea itself. I am frankly afraid of these vibrating machines, and again make a plea for the finger tip, just as I am afraid of a Von Hippel trephine, and prefer one which is rotated with the fingers.
A special investigation of pressure massage according to the method of Domec has been made by Paul Knapp of Basel. This, as you know, consists in applying the thumb to the cornea through the closed lids, and making repeated pressures upon it at the rate or 60 to 100 a minute. He checked his results with the tonometer after 200, 500 and 1,000 pressures, and found that even in normal eyeballs such massage was followed by a fall of intra-ocular tension, the average being nearly 9 mm. after a thousand pressures. Within three-quarters of an hour the tension returns to the normal. In acute glaucoma such massage is not available, but it is of assistance in encouraging a reduction of the intra-ocular tension and keeping it at a normal grade after operative work, particularly after a filtering cicatrix has been made, as was well shown by Weeks in his study of glaucomatous eyes operated upon by the Lagrange method. It is interesting to remember that Paul Knapp, in the course of this investigation, observed reduction of the tension after the use of holocain.
Another method of reducing the intra-ocular tension is by the suction method, which consists in the use of certain cups from which the air is exhausted by means of a suction apparatus. Domec uses an elliptical eye cup, the concave margins of which fit closely about the globe. The air is exhausted with each respiration of the patient and from 50 to 200 tractions are made at each sitting. Domec is of the opinion that this method succeeds in two ways, namely, in producing analgesia by traction on the ciliary nerves, and in reducing intra-ocular tension.
Unfortunately, it is difficult for regular physicians to make reference to massage of the eyeball lest their words should be misquoted by irregular practitioners who employ this method, selling various instruments to trusting patients, and attributing to this simple and often beneficial procedure all sorts of marvelous influences. Doubtless all of us have seen eyes utterly ruined because the patient has trusted to the advertisements of these people, and has continued to use some foolish little suction pump, when what his eye needed was operative procedure or skilled therapeutics.
If I should sum up my opinion of massage in the reduction of intra-ocular tension, I would say that it is useful in enhancing the action of myotics, and particularly useful, as Domec, Knapp, Ohm, Weeks and many others have shown, after the filtering angle has been opened by a proper operative procedure. It seems to me that it is distinctly our duty to inform patients that it is no panacea, and that they must never trust themselves in the hands of irregular practitioners who pretend to cure all ocular ills with massage.
Electricity. The credit of first using high frequency currents in the treatment of glaucoma belongs to Truc, Imbert and Marques, and Roure's experiments indicate that this current suitably applied appears to have an influence not only in reducing the arterial tension, but also the ocular tension. Thus, in an interesting series of experiments he has been able to reduce an arterial pressure of 200 mm. to 140 mm., and an ocular tension of plus 2 to the normal after eighteen applications of the high frequency current. The current is applied for ten to fifteen minutes at a time twice a week. Some surgeons, for example, Wuerdemann, have suggested the use of electricity combined with massage, and have apparently achieved satisfactory results.
The constant current has also been much employed for the purpose of reducing intra-ocular tension. Coleman quotes Le Prince's observations, who applies the negative pole to the eye and the positive pole to the neck, gradually passing a current of 30 to 40 ma. during a quarter of an hour, and who reports notable diminution of tension. Coleman points out that in his own experience he has not found any patient who would willingly tolerate more than 19 ma. of current with an ordinary sized electrode, although he grants that it is possible that Le Prince used a very large electrode. Unfortunately he does not mention its size. Ziegler of my own city, who has studied most scientifically and intelligently the use of electricity in diseases of the eye, announces this rule: The positive pole should be used in all inflammatory processes of the eye, glaucoma excepted, and with this rule Coleman agrees. Now, although the negative pole is a stimulant and therefore not generally indicated in inflammation, as Coleman points out, the object in view is to diminish the density of the ocular capsule and its tension, hence the negative rather than the positive pole should be used, inasmuch as the former, according to him, while it is a sedative, hardens tissue and would tend to increase intra-ocular tension by diminishing excretion. Moreover, in chronic glaucoma the ordinary inflammatory processes are not present, indeed, primary acute glaucoma itself is not an inflammation.
I have no personal experience in the use of the constant current with negative pole application to the eye in the reduction of increased intra-ocular tension, but quote for our general benefit the opinions of those who have employed it. I have always been very frankly pessimistic in regard to the therapeutic value of electricity in ocular disorders. Perhaps I am wrong; I am willing to be enlightened. There seems little doubt that Truc and Imbert's observations that high frequency currents can temporarily reduce intra-ocular tension is correct, that they are able to relieve the pain of primary and of secondary glaucoma would seem to be proved by many observations, some of which I have myself made, and other very accurate and excellent ones have been made by Risley in Philadelphia.
A word might be said in regard to diathermy. According to Zahn, the method of applying diathermy to the human eye is to take a layer of cotton wool 1 cm. thick soaked in a 2 per cent solution of sodium chlorid, which is applied close to the outside of the lids. On this is put an electrode 15 cm. in size with a large indifferent electrode applied to the back of the neck. It is not germane to the subject to name the various ocular diseases which were treated in this manner, but Clausnizer has made an investigation of the influence of diathermy on intra-ocular tension. In a number of diseases, for example, iridocyclitis, the method produced distinct rise of pressure. In one, a patient with secondary glaucoma, prior to the diathermic application the tension was 371/2 mm., after the passage of the current it had fallen to 28 mm., but the next morning the tension rose to 45 mm. In a patient with chronic glaucoma no definite alteration of tension could be found. This observation is mentioned, not because it puts us in possession of a valuable therapeutic measure, but largely because it is a good example of how in this disease it is wise to investigate any method which furnishes a hope of relief.
In a few instances endeavor has been made to reduce the intra-ocular tension, or at least to relieve glaucomatous symptoms, by galvanism of the cervical sympathetic, for example, by placing one electrode along the whole length of this nerve in the neck and one on the back of the neck on the opposite side, 15 to 20 ma. of current being used. Good results have been reported by an observer named Allard. I confess that I am entirely faithless in regard to any results that may be reached in this manner. It is possible that as the positive pole is a sedative, if there were any influence, the influence of sedation would be present, but certainly it has over and over again been experimentally proved that irritation of the cervical sympathetic quite rapidly produces elevation of intra-ocular tension of 2 to 4 mm. In some experimental work the primary elevation of intra-ocular tension was followed by a secondary drop.
3. Indirect reduction of increased intra-ocular tension brought about by lowering general vascular pressure. Much has been written in regard to the association between increased vascular pressure and increased intra-ocular pressure. It is not my province to analyze observations often contradictory and not infrequently inaccurate. This much seems to be established: First, that at corresponding ages there is usually a higher average blood pressure in glaucomatous subjects than there is in non-glaucomatous subjects; second, that arteriosclerosis and therefore usually increased blood pressure, with all its concomitant conditions, is correctly classified as an exciting cause of glaucoma; and third, that the regulation of this increased blood pressure is part of the advantageous management of increased intra-ocular pressure, although it may be too much to say, as Gilbert has, that blood pressure and intra-ocular pressure rise and fall together. It may be true, as Thomas Henderson says, that the intra-ocular pressure is influenced by changes in the general arterial or general venous pressures, whereby a rise in general arterial pressure induces a proportionate rise in the intra-ocular pressure, but it would seem that future investigations must confirm this statement before it can be entirely accepted, as well as his further statement that the effect of an increased general venous pressure is a direct one, producing millimeter for millimeter a corresponding increase in the intra-ocular pressure.
Now, it goes without saying, if these data are correct, or even only partly correct, that part of the treatment of the increased intra-ocular pressure state must be constitutional in that the vascular pressures should be lowered in order that the beneficial effect of their relationship to the intra-ocular pressure shall be established. It is further a great mistake to drive down a high arterial pressure simply because that exists. In other words, it is often necessary from the general standpoint that a certain amount of plus pressure shall remain if the patient's general well-being is to be maintained. There must always be a differential diagnosis between plus pressure and what may be called over plus pressure. That is to say, a man may be perfectly comfortable and properly need, for example, a pressure of 160 or 165 mm., which is above the physiologic limit, but which is a plus pressure, while some disturbance in his general life may add to that 10, 15 or 20 mm. more of pressure, which is then the over plus amount. This over plus amount may be in association with a rise of intra-ocular pressure, and must be eliminated if the latter is to be controlled by a non-operative procedure, or, indeed, by an operative one.
It is no easy matter to determine the presence of increased venous pressure, although there are tolerably accurate instrumental technics, and yet, as Henderson points out, it is just this increased general venous pressure which is often detrimental. Therefore the perfunctory use of such drugs as nitrite of amyl and the other nitrites may not be in the least indicated when, for example, the venous pressure depends upon inability of the right heart to perform its functions, and the drug needed may, for example, be digitalis. Far better than pressure-reducing drugs like nitrite of amyl, urgently indicated in some instances and for some purposes, is the regulation of life and the restoration to their normality of the metabolic processes, the elimination of the worry which is usually the exciting agent that brings about the over plus pressure, which may have as one of its expressions an acute rise of intra-ocular tension. I believe that in the management of a case of glaucoma, whether it be chronic or chronic with sub-acute exacerbations, the greatest care with the aid of an expert clinician must be exercised to find out exactly what mean pressure of the arterial and venous system best conforms with the patient's general welfare, and I am bitterly opposed, and I think with right, to the sudden reduction of tensions, except in emergencies, without a perfect understanding of the facts I have ventured to indicate. This does not for a moment mean that prior, for example, to operative work it is not necessary to get rid by means of drugs of an over plus tension, for surely the elimination of such an over plus tension may be the means of preventing, for example, an intra-ocular hemorrhage, and in this emergency we must not lose sight of Gilbert's recent investigation, who has found that blood withdrawn to the extent of 8 grams to each kilogram of the body weight always produces lowering of the intra-ocular tension, appearing in six to eight hours and lasting to the next day in simple glaucoma, and in inflammatory glaucoma commencing the day after the venesection and lasting two to three days. It is not necessary for me to point out the value of free purgation and diaphoresis in this respect.
In most instances the successful maintenance of a glaucomatous life, exclusive of operative interference, in addition to sustained myosis, demands the investigation of the patient's metabolism, which must be kept at the normal standard, the removal of the evil effects of auto-infection, as we are wont to call it, and especially the elimination of the cause which is responsible for the over plus tension of the arteries and of the veins. This is best secured by just such regulation of life as has been referred to, aided when necessary by the ordinary drugs which the patient's condition indicate, and the success of all treatments, be they operative or non-operative, is enhanced if such a happy state of affairs can be brought about.
I am firmly convinced that every glaucomatous patient, and I now refer to those who are the subjects of chronic progressive glaucoma, should be carefully studied from the general standpoint by the oculist with the aid of an expert internist, just as I am convinced that the modern expert internist should not study his cases of cardio-vascular disease without the help of the oculist. Perhaps I am going a little far afield, but in justification of my statement I want to quote the opinion of Dr. Hobart Hare, one of America's most expert clinicians, on blood pressure, because it seems to me much harm has been done by the more or less brutal knocking down of blood pressure simply because blood pressure above the normal existed. "Concerning the matter of high blood pressure," writes Hare, "independent of cerebral lesions, the longer I study the matter the more convinced I am that this blood pressure is devised by nature to compensate for fibroid changes in peripheral vessels, in order that tissues which would otherwise be cut off from adequate blood supply may receive plenty of blood, and I consider it one of the most vital points to ascertain whether a pressure is what may be called the patient's pathological norm, that is, the pressure which is required in the face of vascular changes, or whether this pressure is in excess of his pathological norm. If it is in excess, measures directed to bring it to the pathological norm should be instituted, but if the pressure found proves to be the pathological norm it is a bitter mistake to lower it, be the pressure what it may. If it is lowered below the pathological norm, all manner of disturbed cardiac action, etc., may result. There is no more reason for reducing a blood pressure below his pathological norm than there is for reducing it below his physiological norm. The adjustment of a man's blood pressure to his pathological norm often has to be as correctly done as the adjustment of a watch which is losing or gaining time."

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