Scleral prosthesis for treatment of presbyopia and other eye disorders

Presbyopia is treated by implanting within a plurality of elongated pockets formed in the tissue of the sclera of the eye transverse to a meridian of the eye, a prosthesis having an elongated base member having an inward surface adapted to be placed against the inward wall of the pocket and having a ridge on the inward surface of the base extending along at least a major portion of the major dimension of the base. The combined effect of the implanted prostheses is to exert a radially outward traction on the sclera in the region overlying the ciliary body which expands the sclera in the affected region together with the underlying ciliary body. The expansion of the ciliary body restores the effective working distance of the ciliary muscle in the presbyopic eye and thereby increases the amplitude of accommodation. Hyperopia, primary open angle glaucoma and/or ocular hypertension can be treated by increasing the effective working distance of the ciliary muscle according to the invention.

BACKGROUND OF THE INVENTION 
1. Field of the Invention: 
This invention relates to methods of treating presbyopia, hyperopia, 
primary open angle glaucoma and ocular hypertension and more particularly 
to methods of treating these diseases by increasing the effective working 
distance of the ciliary muscle. The invention also relates to increasing 
the amplitude of accommodation of the eye by increasing the effective 
working range of the ciliary muscle. 
2. Brief Description of the Prior Art 
In order for the human eye to have clear vision of objects at different 
distances, the effective focal length of the eye must be adjusted to keep 
the image of the object focused as sharply as possible on the retina. This 
change in effective focal length is known as accommodation and is 
accomplished in the eye by varying the shape of the crystalline lens. 
Generally, in the unaccommodated emmetropic eye the curvature of the lens 
is such that distant objects are sharply imaged on the retina. In the 
unaccommodated eye near objects are not focused sharply on the retina 
because their images lie behind the retinal surface. In order to visualize 
a near object clearly, the curvature of the crystalline lens is increased, 
thereby increasing its refractive power and causing the image of the near 
object to fall on the retina. 
The change in shape of the crystalline lens is accomplished by the action 
of certain muscles and structures within the eyeball or globe of the eye. 
The lens is located in the forward part of the eye, immediately behind the 
pupil. It has the shape of a classical biconvex optical lens, i.e., it has 
a generally circular cross section having two convex refracting surfaces, 
and is located generally on the optical axis of the eye, i.e., a straight 
line drawn from the center of the cornea to the macula in the retina at 
the posterior portion of the globe. In the unaccommodated human eye the 
curvature of the posterior surface of the lens, i.e., the surface adjacent 
to the vitreous body, is somewhat greater than that of the anterior 
surface. The lens is closely surrounded by a membranous capsule that 
serves as an intermediate structure in the support and actuation of the 
lens. The lens and its capsule are suspended on the optical axis behind 
the pupil by a circular assembly of very many radially directed elastic 
fibers, the zonules, which are attached at their inner ends to the lens 
capsule and at their outer ends to the ciliary muscle, a muscular ring of 
tissue, located just within the outer supporting structure of the eye, the 
sclera. The ciliary muscle is relaxed in the unaccommodated eye and 
therefore assumes its largest diameter. According to the classical theory 
of accommodation, originating with Helmholtz, the relatively large 
diameter of the ciliary muscle in this condition causes a tension on the 
zonules which in turn pulls radially outward on the lens capsule, causing 
the equatorial diameter of the lens to increase slightly and decreasing 
the anterior-posterior dimension of the lens at the optical axis. Thus, 
the tension on the lens capsule causes the lens to assume a flattened 
state wherein the curvature of the anterior surface, and to some extent 
the posterior surface, is less than it would be in the absence of the 
tension. In this state the refractive power of the lens is relatively low 
and the eye is focused for clear vision for distant objects. 
When the eye is intended to be focused on a near object, the ciliary 
muscles contract. According to the classical theory, this contraction 
causes the ciliary muscle to move forward and inward, thereby relaxing the 
outward pull of the zonules on the equator of the lens capsule. This 
reduced zonular tension allows the elastic capsule of the lens to contract 
causing an increase in the antero-posterior diameter of the lens (i.e., 
the lens becomes more spherical) resulting in an increase in the optical 
power of the lens. Because of topographical differences in the thickness 
of the lens capsule, the central anterior radius of curvature decreases 
more than the central posterior radius of curvature. This is the 
accommodated condition of the eye wherein the image of near objects falls 
sharply on the retina. 
Presbyopia is the universal decrease in the amplitude of accommodation that 
is typically observed in individuals over 40 years of age. In the person 
having normal vision, i.e., having emmetropic eyes, the ability to focus 
on near objects is gradually lost, and the individual comes to need 
glasses for tasks requiring near vision, such as reading. 
According to the conventional view the amplitude of accommodation of the 
aging eye is decreased because of the loss of elasticity of the lens 
capsule and/or sclerosis of the lens with age. Consequently, even though 
the radial tension on the zonules is relaxed by contraction of the ciliary 
muscles, the lens does not assume a greater curvature. According to the 
conventional view, it is not possible by any treatment to restore the 
accommodative power to the presbyopic eye. The loss of elasticity of the 
lens and capsule is seen as irreversible, and the only solution to the 
problems presented by presbyopia is to use corrective lenses for close 
work, or bifocal lenses, if corrective lenses are also required for 
distant vision. 
Certain rings and/or segments have been used in ocular surgery for various 
purposes. Rings and/or segments of flexible and/or elastic material, 
attached or prepared in situ by fastening the ends of strips of the 
material around the posterior portion of the globe, posterior to the pars 
plana (over the underlying retina), have been used to compress the sclera 
in certain posterior regions. Supporting rings of metal, adapted to fit 
the contour of the sclera have been used as temporary supporting 
structures during surgery on the globe. However, none of these known 
devices have been used for surgical treatment of presbyopia, and none have 
been adapted to the special needs of prosthetic devices used in treating 
presbyopia. 
Accordingly, a need has continued to exist for a method of treating 
presbyopia that will increase the amplitude of accommodation of the 
presbyopic eye, thereby lessening or eliminating the need for auxiliary 
spectacle lenses to relieve the problems of presbyopia. 
SUMMARY OF THE INVENTION 
The treatment of presbyopia has now been facilitated by the prosthetic 
device of this invention which is implanted within a pocket formed in the 
sclera of the globe of the eye in the vicinity of the plane of the equator 
of the crystalline lens. The prosthetic device of the invention comprises 
a base, having an elongated planform, and a ridge extending along at least 
a major portion of the elongated planform. The prosthesis is inserted into 
the scleral pocket with the base oriented in a generally outward direction 
from the center of the globe, and the ridge directed inwardly. The 
anterior edge of the prosthesis accordingly applies an outward force on 
the anterior edge of the scleral pocket which elevates the portion of the 
sclera attached thereto and the ciliary body immediately beneath the 
sclera to increase the working distance of the ciliary muscle according to 
the theory of the inventor. 
Accordingly, it is an object of the invention to provide a treatment for 
presbyopia. 
A further object is to provide a treatment for presbyopia by increasing the 
effective working distance of the ciliary muscle in the presbyopic eye. 
A further object is to provide a treatment for presbyopia by increasing the 
radial distance between the equator of the crystalline lens and the 
ciliary body. 
A further object is to provide a treatment for presbyopia by implanting in 
the sclera a plurality of prostheses which will increase the working 
distance of the ciliary muscle 
A further object is to provide a treatment for hyperopia. 
A further object is to provide a treatment for primary open angle glaucoma. 
A further object is to provide a treatment for ocular hypertension. 
A further object is to provide a treatment for increasing the amplitude of 
accommodation of the eye. 
Further objects of the invention will become apparent from the description 
of the invention which follows.

DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS 
This invention is based on a different theory, developed by the inventor, 
which has been described in U.S. Pat. No. 5,354,331, the entire disclosure 
of which is incorporated herein by reference, regarding the cause of the 
loss of amplitude of accommodation that constitutes presbyopia. According 
to the invention, presbyopia is treated by increasing the effective 
working distance of the ciliary muscle. This is accomplished by increasing 
the distance between the ciliary muscle and the lens equator by increasing 
the diameter of the sclera in the region of the ciliary body. 
According to the invention the effective working distance of the ciliary 
muscle is increased by implanting in pockets surgically formed in the 
sclera of the eye a plurality of prostheses designed to place an outward 
traction on the sclera in the region of the ciliary body. The relevant 
anatomy of the eye for locating the scleral pockets may be seen by 
reference to FIGS. 1-4. The outermost layer of the eye 100 comprises the 
white, tough sclera 102 which encompasses most of the globe and the 
transparent cornea 104, which constitutes the anterior segment of the 
outer coat. The circular junction of the cornea and sclera is the limbus 
106. Within the globe of the eye, as illustrated in the cross-section of 
FIG. 4, the crystalline lens 108 is enclosed in a thin membranous capsule 
and is located immediately posterior to the iris 112, suspended centrally 
posterior to the pupil 114 on the optical axis of the eye. The lens 108 is 
suspended by zonules extending between the lens capsule at the equator 110 
of the lens 108 and the ciliary body 116. The ciliary body 116 lies just 
under the sclera 102 (i.e., just inwardly of the sclera 102) and is 
attached to the inner surface of the sclera 102. As may be seen in FIG. 4, 
the ciliary body 116 lies generally in a plane 130 defined by the equator 
110 of the lens 108. The plane 130 can also be extended to intersect the 
sclera 102 whereby it forms a generally circular intersection located 
about 2 millimeters posterior to the limbus 106. The external muscles 118 
of the eyeball control the movement of the eye. 
According to the invention a generally outwardly directed traction is 
exerted on the sclera in the region of the ciliary body to expand the 
sclera 102 in that region. This expansion of the sclera 102 produces a 
corresponding expansion of the attached ciliary body 116 and moves the 
ciliary body 116 outwardly away from the equator of the lens 108, 
generally in the plane 130 of the equator 110 of the lens 108. The sclera 
102 is preferably expanded approximately in the plane of the equator of 
the lens 108. However, any expansion of the sclera 102 in the region of 
the ciliary body 116, i.e., in the region of the sclera somewhat anterior 
or posterior to the plane of the equator 110 of the lens 108 is within the 
scope of the invention, provided that such expansion of the sclera 102 
moves the ciliary body 116 away from the equator 110 of the lens 108. 
Typically, the expansion of the sclera will be accomplished in the region 
from about 1.5 millimeters anterior to the plane 130 of the equator of the 
lens 108 to about 2.5 millimeters posterior to that plane, i.e., from 
about 0.5 millimeters to about 4.5 millimeters posterior to the limbus 
106. Accordingly, the anterior margin 122 of a scleral pocket 120 will be 
located in that region of the sclera. 
The prosthesis of the invention is designed to apply an outwardly directed 
traction to the sclera at the general position of the anterior margin 122 
of a scleral pocket 120. Accordingly, the prosthesis of the invention has 
a base adapted to be placed against the outer wall of the pocket 
surgically formed in the sclera. The base has an elongated planform and is 
oriented generally circumferentially with respect to the circle defined on 
the sclera by the intersection therewith of the plane 130 of the equator 
110 of the lens 108. 
The position of the prosthesis within a scleral pocket and its operation to 
expand the sclera are illustrated in FIGS. 4 and 5, showing a prosthesis 
of the type illustrated in FIGS. 6-8. 
The base member 202 of the prosthesis 200 has a smooth exterior face 216 
adapted to be placed in contact with the internal surface of the outer 
wall 128 of the scleral pocket 120. The opposite, or interior, face 212 of 
the prosthesis 200 is provided with a ridge 214 extending along a 
substantial portion of the length of the base 202. This ridge bears 
against the inner wall 126 of the scleral pocket 120. Accordingly, the 
sclera 102 at the anterior margin 122 of the scleral pocket 120 is 
elevated above its original level. The attached ciliary body 116 is 
thereby also expanded away from the equator 110 of the lens 108, and the 
working distance of the ciliary muscle is increased. 
A first embodiment of the prosthesis of the invention is illustrated in 
FIGS. 6-8. FIG. 6 shows a plan view of the inner face of the prosthesis 
200 having a base 202 with an anterior edge 204, a posterior edge 206, and 
lateral ends 208 and 210. The inner face 212 is provided with a ridge 214 
extending along the length of the major dimension of the elongated base 
202. FIG. 7 shows a front elevational view of the prosthesis of FIG. 6 
showing the flat, smooth outer surface 216 of the prosthesis. FIG. 8 shows 
a side view of the prosthesis showing the outer surface 216, the ridge 214 
and a notch 218 on the inner surface 212 of the prosthesis. 
FIGS. 9-10 illustrate a prosthesis of the invention having a curved 
planform adapted to be implanted in a scleral pocket that is curved to 
match the curvature of the eyeball. The prosthesis 300 of FIGS. 9-10 has a 
generally planar base 302, curved in the plane of the base 302, having an 
anterior edge 304, a posterior edge 306, and lateral ends 308 and 310. The 
inner face 312 is provided with a ridge 314 extending along the length of 
the major dimension of the elongated curved base 302. FIG. 10 shows an 
side view of the prosthesis of FIG. 9 showing the outer face 316, the 
ridge 314 and a notch 318 on the inner face 312 of the prosthesis. The 
curvature of the base is chosen to provide at least an approximate match 
for the curvature of the adjacent structures on the surface of the sclera, 
e.g., the limbus 106, adjusted for the distance of the scleral pocket 120 
and prosthesis 300 from the limbus 106. FIG. 3 shows a front elevational 
view of an eye provide with curved scleral pockets 120 to accommodate a 
curved prosthesis 300 of the type illustrated in FIGS. 9 and 10. 
FIGS. 11-13 show an embodiment of the invention wherein the anterior 
portion is tapered from the ridge to the anterior edge. FIG. 11 shows a 
plan view of the prosthesis 400 having a base 402 with an anterior edge 
404, a posterior edge 406, and lateral ends 408 and 410. The outer face 
416 is smooth and adapted to be placed against the inner surface of the 
outer wall 128 of a scleral pocket 120. The inner face 412 is provided 
with a ridge 414 extending along the length of the major dimension of the 
elongated base 402. FIG. 12 shows a front elevational view of the 
prosthesis of FIG. 11 showing the flat, smooth outer face 412 of the 
prosthesis. FIG. 13 shows an end view of the prosthesis of FIG. 11 showing 
the outer face 412 and the ridge 414 on the inner face 412 of the 
prosthesis 400. In this embodiment the ridge 410 tapers toward the 
anterior edge 404 of the prosthesis. 
FIGS. 14-16 show a preferred embodiment of the prosthesis in which the 
ridge member includes extensions beyond the ends of the base member which 
lie on the surface of the sclera adjacent to the scleral pocket and help 
to stabilize the prosthesis. FIG. 14 shows a plan view of this embodiment 
500 having a base 502 with an anterior edge 504, a posterior edge 506, and 
lateral ends 508 and 510. The inner face 512 is provided with a ridge 514. 
The ends 508 and 510 of the base 502 extend slightly beyond the ends of 
the ridge 514. Accordingly, the ends 508 and 510 of the base 502 will 
extend beyond the ends of the pocket 120 and lie on the surface of the 
sclera 102. FIG. 15 shows a front elevational view of the prosthesis of 
FIG. 14 showing the flat, smooth outer face 516 of the prosthesis and the 
ends 508 and 510 of the base 502 extending beyond the ends of the ridge 
514. FIG. 16a shows an end view of the prosthesis of FIG. 14 showing the 
smooth outer face 516 and the ridge 514 on the inner face 512 of the base 
502, as well as a notch 518. FIG. 16b shows and end view of an alternate 
embodiment of the prosthesis 500 wherein the base 502 does not taper all 
the way to the posterior edge 506. Evidently, the thickness of the 
posterior edge 506 may vary from a relatively sharp posterior edge as 
shown in FIG. 16a to a relatively thick posterior edge as shown in FIG. 
16b, or even thicker if it is advantageous. 
FIGS. 17-20 illustrate an embodiment of the prosthesis that is hollow and 
made from a plastic or elastomeric material and filled with a liquid. FIG. 
17 shows a plan view of this embodiment 600 having a base 602 with an 
anterior edge 604, a posterior edge 606, and lateral ends 608 and 610. The 
inner face 612 is smoothly rounded and rises to a crest 614 that serves to 
support the prosthesis on the inner wall 126 of the scleral pocket 120 in 
the same way as the ridge member of other embodiments of the invention. 
FIG. 18 shows a front elevational view of the prosthesis of FIG. 17 
showing the flat, smooth outer face 616 of the prosthesis. FIG. 19 shows a 
cross section of the prosthesis of FIG. 17 taken along the line 19--19. 
The cross-section shows the flexible wall 612 of the prosthesis as well as 
the flat outer face 616, and the crest 614. The cross section also shows 
the filling liquid 620. FIG. 20 shows an end view of the prosthesis of 
FIG. 17 showing the outer face 616 and the crest or ridge 614 on the inner 
face 612 of the prosthesis 600. The hollow prosthesis is filled with 
liquid, typically by injecting the liquid through an end 608 or 610. The 
prosthesis may be filled with more or less liquid in order to adjust the 
thickness between the outer face 616 and the crest or ridge 614 to provide 
more or less traction on the sclera at the anterior margin 122 of the 
scleral pocket or belt loop 120. 
FIGS. 21-23 illustrate an embodiment of the invention generally similar to 
that shown in FIGS. 6-8, having, however, a base in which the inner face 
of the prosthesis is curved to provide an approximate match to the 
curvature of the globe. FIG. 21 shows a plan view of the inner face of the 
prosthesis 700 having a base 702 with an anterior edge 704, a posterior 
edge 706, and lateral ends 708 and 710. The inner face 712 is provided 
with a ridge 714 extending along the length of the major dimension of the 
elongated base 716. FIG. 22 shows a front elevational view of the 
prosthesis of FIG. 21 showing the curved, smooth outer surface 716 of the 
prosthesis. FIG. 23 shows an end view of the prosthesis showing the outer 
surface 716, the ridge 714 and a notch 718 on the curved inner surface 712 
of the prosthesis. 
A preferred embodiment of the scleral prosthesis is that shown in FIGS. 9 
and 10, wherein the anterior rim 304 and the posterior rim 306 are both 
generally circular arcs. The taper in the diameter of the segment is 
preferably selected in an individual case to fit the globe in the region 
of the ciliary body. Accordingly, different sizes of segments will be 
provided wherein the radius of curvature of the anterior rim ranges from 
about 7.0 to about 10 millimeters in 0.50 millimeter increments. 
Accordingly, a preferred segment has a typical internal circular radius of 
curvature at its anterior portion of about 7.76 millimeters, at the 
position of the ridge of about 8.21 millimeters, and at the posterior rim 
of about 8.91 millimeters. The preferred segment has outer radius of 
curvature at its anterior portion of 8.02 millimeters, at its mid portion 
8.47 millimeters, and at its base 8.94 millimeters. These measurements 
will vary depending on the size of the eye, the amount of rigidity 
required, and the strength of the material from which the segment is made. 
The preferred anterior chord length of the segment is 5 millimeters. The 
axial width of the segment will typically be about 2 millimeters. 
The scleral prosthesis of the invention is made of a material that is 
sufficiently rigid to exert a force on the sclera sufficient to produce 
the radial expansion required by the method of the invention and that is 
physiologically acceptable for long-term implantation or contact with the 
ocular tissues. Such materials are well-known in the surgical art and 
include suitable metals, ceramics, and synthetic resins. Suitable metals 
include titanium, gold, platinum, stainless steel, tantalum and various 
surgically acceptable alloys, and the like. Suitable ceramics may include 
crystalline and vitreous materials such as porcelain, alumina, silica, 
silicon carbide, high-strength glasses and the like. Suitable synthetic 
materials include physiologically inert materials such as poly(methyl 
methacrylate), polyethylene, polypropylene, poly(tetrafluoroethylene), 
polycarbonate, silicone resins and the like. The prosthesis may also be 
made of composite materials incorporating a synthetic resin or other 
matrix reinforced with fibers of high strength material such as glass 
fibers, boron fibers or the like. Thus, the segment may be made of 
glass-fiber-reinforced epoxy resin, carbon fiber-reinforced epoxy resin, 
carbon fiber-reinforced carbon (carbon-carbon), or the like. The segment 
may be made of a semi-rigid exterior and a liquid or gel filled interior 
so that the internal and external dimensions can be altered by injecting 
various amounts of liquid: water, saline, or silicone oil; or various 
amounts of a gel: silicone, collagen, or gelatin. The semi-rigid exterior 
may be made of any of the already listed materials. A preferred material 
for the entire segment is surgical grade poly(methyl methacrylate). 
The scleral prosthesis of the invention may be manufactured by any 
conventional technique appropriate to the material used, such as 
machining, injection molding, heat molding, compression molding and the 
like. 
The scleral prosthesis may be foldable to facilitate insertion into a 
scleral belt loop or made in a plurality of parts so that it can be 
assembled prior to use or may be installed separately to form a complete 
prosthesis. 
In practicing the method of the invention, the surgeon locates the proper 
region of the sclera to be expanded by measuring a distance of preferably 
2.0 millimeters posterior of the limbus. At 2.5 millimeters clockwise and 
counterclockwise from each of the 45.degree. meridians of the eye, and 2 
millimeters posterior to the limbus, partial scleral thickness radial 
incisions, i.e., antero-posterior incisions, are made which are 2 
millimeters long and 350 microns deep. Using a lamella blade the sclera is 
dissected until the partial thickness incisions are connected so that four 
scleral pockets or belt loops are made which have an anterior length of 5 
millimeters, and a length extending generally axially of the eye of 2 
millimeters. Thus, each pocket or belt loop is preferably centered over 
the 45.degree. meridian of the eye. A prosthesis is then inserted in each 
of the four scleral belt loops. This produces symmetrical scleral 
expansion which will produce the desired result of increasing the 
effective working distance of the ciliary muscle. 
The location of the prostheses of the invention when implanted in the eye 
is illustrated in FIGS. 1-4. FIG. 1 is an isometric view of an eye 100 
having a globe 102 with the relevant exterior anatomical parts indicated 
as discussed above. 
FIGS. 2 and 3 show front elevational views of an eye 100 showing the 
scleral pockets 120 formed at approximately the 45.degree. meridians of 
the eye, i.e., approximately halfway between the vertical and horizontal 
meridians of the globe. This location is preferred because it avoids 
interference with structures of the eye that are located generally on the 
vertical and horizontal meridians. FIG. 3 shows the use of curved scleral 
pockets 120 to permit the use of curved prostheses of the type illustrated 
in FIGS. 9 and 10. FIG. 2 shows the use of straight scleral pockets 120. 
Such straight pockets are somewhat simpler to prepare surgically. For many 
patients the use of straight prostheses can provide adequate treatment of 
their presbyopia. 
FIG. 4 shows a cross-section of the eye, taken along the line 4--4 in FIG. 
2, showing the placement of the prosthesis of the invention relative to 
the significant anatomical structures of the eye. This figure shows the 
general configuration of the scleral pockets 120 and the prostheses 200 of 
the type illustrated in FIGS. 6-8 in a preferred embodiment. The anterior 
margins 122 of the scleral pockets or belt loops 120 are located 
approximately in the plane 130 of the equator 110 of the lens 108. The 
ridge 210 of the prosthesis causes the anterior portion of the pocket to 
be expanded somewhat more than the posterior portion. This places the 
sclera at the anterior margin of the pocket under a radial tension and 
causes it to expand somewhat from its normal diameter at that position. 
This scleral expansion draws with it the underlying ciliary body 116 and 
causes the ciliary body to be drawn away from the equator 110 of the lens 
108. Accordingly, the expansion of the ciliary body 116 operates to 
increase the working distance of the ciliary muscle and restore, at least 
in part, the ability of the eye to accommodate for clear focusing on 
objects at different distances. FIG. 5 shows an enlarged portion of one of 
the scleral pockets 120 with adjacent anatomical structures. It shows the 
relation of the scleral pocket 120 to the underlying structures and its 
location just posterior to the equator of the lens 108 and overlying the 
ciliary body 116. 
The method of the invention which increases the amplitude of accommodation 
may also be of benefit in treatment of hyperopia in certain patients. Some 
youthful hyperopes can achieve relatively normal vision by compensating 
for their hyperopia through the natural accommodative ability of the eye. 
However, as this ability declines with age, they find that it becomes more 
difficult to attain normal vision by this process, and they begin to 
experience headaches and other symptoms, even at an age somewhat less than 
usual for the onset of presbyopia. Evidently, increasing the amplitude of 
accommodation by the method of this invention would be useful in restoring 
the ability of these patients to compensate for their hyperopia. 
The method of this invention also has utility in the treatment of primary 
open-angle glaucoma, which shows a correlation with age in certain 
individuals. It has been found that, in general, intraocular pressure 
(IOP) exhibits a linear increase with increasing age. (Armaly, M. F., On 
the distribution of applanation pressure I. Statistical features and the 
effect of age, sex, and family history of glaucoma, Archives of 
Ophthalmology, Vol. 73, pp. 11-18 (1965)). Among the general population is 
found a group of individuals who develop abnormally high intraocular 
pressures as a result of primary open angle glaucoma, a disease which is 
one of the most prevalent causes of blindness in the world. According to 
the theory of this invention, the linear increase in IOP with age is a 
direct result of the decrease in distance between the lens equator and the 
ciliary muscle and the resulting linear decrease in the effective pull of 
the ciliary muscle. Since the ciliary muscle inserts into the trabecular 
meshwork, the decrease in pull will decrease the size of the trabeculum 
and/or the drainage pores and result in a linear increase of intraocular 
pressure with age. In this view, the patients who develop primary open 
angle glaucoma may have a congenital predilection to narrower pores, 
protein deposition in the pores, and/or a smaller trabecular meshwork, so 
that when the ability of the ciliary muscle to exert force declines, after 
the age of 40 or thereabouts, they tend to develop excessively elevated 
IOP. 
The method of the invention which increases the effective working distance 
of the ciliary muscle, and thereby increases the force that it can exert 
when it contracts, restores the level of force which the ciliary muscle 
exerts on the trabecular meshwork to a value characteristic of a more 
youthful eye. In this way it is expected that the tendency of an eye that 
is disposed to develop primary open angle glaucoma as it ages would be 
overcome and the onset of this disease would be prevented or at least 
postponed. 
The invention having now been fully described, it should be understood that 
it may be embodied in other specific forms or variations without departing 
from its spirit or essential characteristics. Accordingly, the embodiments 
described above are to be considered in all respects as illustrative and 
not restrictive, the scope of the invention being indicated by the 
appended claims rather than the foregoing description, and all changes 
which come within the meaning and range of equivalency of the claims are 
intended to be embraced therein.