bluuebunny/crossref_metadata_2025 huggingface dataset:
THE EFFECT OF REDUCED VISUAL ACUITY UPON FARNSWORTH 100‐HUE TEST PERFORMANCE
Authors: Brown Lyndsay , Govan Eric , Block M. T.
Published: December 2007

Abstract The effect of artificially reduced visual acuity upon performance in the Farnsworth—Munsell 100‐hue test has been investigated in a population of 50 individuals with otherwise normal colour vision. Evidence for a significant impairment of performance at low levels of acuity has been obtained.
THE STABILITY OF THE FIXATION DISPARITY CURVE
Authors: Daum Kent M.
Published: December 2007

Abstract The fixation disparity curve has been measured over intervals of minutes, days and months. Two female adults with good binocular visual function were the subjects. The data indicate that significant shifts in the placement of the curve can take place over a period of several days. Over a period of 5 months, repeated measurement of the fixation disparity curve shows that the curve tends to keep the same form but shifts upwards or downwards on the y‐axis.
THE EFFECTS OF MODERATE DOSES OF ETHANOL ON HETEROPHORIA AND OTHER ASPECTS OF BINOCULAR VISION
Authors: Hogan Robert E. , Linfield Peter B.
Published: December 2007

Abstract It has been known for many years that ethanol has an impairing effect on binocular vision and the co‐ordination of the ocular motor balance. Various parameters were compared before and after imbibition of a moderate dosage of ethanol. The results show an increase in esophoria (or decrease in exophoria) at 6 m, with a reduction in the negative fusional ability. They also show an increase in exophoria (or decrease in esophoria) at near, with a decrease in both the AC/A ratio and near point of convergence. There was no significant effect on the amplitude of accommodation. This study raises the possibility of an ophthalmic practitioner attempting to correct a transient, ethanol‐induced ocular motor imbalance.
CHANGES IN SPATIAL RESOLUTION FOR PATTERN AND MOVEMENT DETECTION IN CLINICAL CASES
Authors: MacCana F. , Kulikowski J. J. , Bhargava S. K.
Published: December 2007

Abstract A simple and relatively fast method was used to evaluate visual performance: gratings of sinusoidal luminance profile, generated on the face of an oscilloscope, were reversed in contrast at a rate of 2 Hz. Under these conditions the patients could set separate contrast thresholds for seeing either the structure of a grating or its apparent movement. The grating resolution limit (maximum spatial frequency) for each task was determined by extrapolation from thresholds measured at several spatial frequencies. The resulting ratios of pattern/movement resolution limits (P:M) are usually between 1.6 and 2 for normals and for patients with pathalogical changes located distally (probably prior to the chiasma), On the other hand in patients suspected of multiple sclerosis the P:M ratios were reduced to below 1.3. It is considered that such results may suggest a central site for the damage, although they do not exclude pre‐chiasmal defects which may occur simultaneously during the acute stages of the disease.
FLASH AND PATTERN VEPs: EXAMPLES OF CASES OF HYSTERICAL AMBLYOPIA AND PROVOKED VISUAL IMPAIRMENT (UHTHOFF'S SIGN)
Authors: MacCANA F. , Bhargava S. K. , Kulikowski J. J.
Published: December 2007

Abstract The diagnostic application of averaged visual evoked potentials (VEPs) is illustrated in the investigation of hysterical amblyopia and multiple sclerosis. Averaged VEPs elicited either by a flash of light or a presentation of a grating lasting 100 ms were recorded from the occiput of patients. All the VEPs in hysterical amblyopia were normal. In multiple sclerosis the flash VEPs looked normal for both eyes, whereas the VEPs elicited by grating (2 and 5 c/deg) showed an increase in the latency of the first positive wave, again for both eyes. After physical exercise the VEPs from the right eye were dramatically reduced in amplitude (Uhthoff s sign).
POSSIBLE ALTERATIONS IN CORRESPONDENCE ASSOCIATED WITH ASYMMETRIC CONVERGENCE
Authors: Reading R. W.
Published: December 2007

Abstract Available nonius horopter data in asymmetric convergence has been reanalyzed by computing the binocular disparity of each horopter datum point relative to the Vieth‐Müller circle. The results of this analysis on the best available data indicate that some corresponding points do shift upon asymmetric gaze. Because such convergence postures involve different eye movement innervational patterns, it is suggested that this is the cause of these apparent alterations. Some of the remaining data showed nonsystematic changes in experimental errors, suggesting that unintentional shifts in fixation may have occurred; unintentional tactile cues (used in making the actual settings) may have been present; and sampling errors may have influenced these particular findings.
THE USE OF THE FRIEDMANN CENTRAL FIELD ANALYSER IN GENERAL OPTOMETRIC PRACTICE
Authors: Pitman C. R.
Published: December 2007

Abstract The importance of obtaining correct filter settings for the instrument with each patient is investigated in a study of 450 patients, covering the age range encountered in practice. The need for a correct procedure and proper training of any ancillary personnel is emphasized. Ten case histories are presented to illustrate the usefulness and limitations of the instrument. Current views of the relevance of field plotting in glaucoma are discussed. Comparisons between the Friedmann and other instruments are reviewed and a list is given of conditions in which the visual field should be plotted.
AN INSTRUMENT FOR MAPPING CORNEAL LIGHT‐SCATTERING CHARACTERISTICS
Authors: Lovasik J. V. , Remole A.
Published: December 2007

Abstract A simple inexpensive apparatus for measuring the forward light‐scattering properties of excised corneas is described. The apparatus generates a light scatter profile to indicate the angular dependence of the intensity of scattered light over a 140° angle within a time of 9 s. The potential clinical use of light scatter measurements in the detection of corneal disease and other uses for this apparatus are discussed.
DEVELOPMENT OF A CONTACT LENS FOR REFRACTING AQUATIC ANIMALS
Authors: Spielman Stanley L. , Gruber Samuel H.
Published: December 2007

Abstract Development of a new technique for refracting the eye of unwieldy and large aquatic organisms in air is presented. The technique employs a contact lens to simulate underwater conditions. Refraction is performed through a flat front surface with an ophthalmoscope or a streak retinoscope. Data from 11 carcharhinid sharks (four species) indicate that the smaller eyes of inshore species are defocused relative to the eyes of offshore species.
ULTRASOUND—A RESEARCH TOOL IN THE STUDY OF ACCOMMODATION*
Authors: Storey J. K. , Rabie E. P.
Published: December 2007

Abstract Measurements of the globe were made at different stages of accommodation with Kretz A‐mode ultrasonic equipment. A comparison between the movement of the crystalline lens in two refractive groups appeared to show that the highly myopic lens had to expand more per dioptre of accommodation; in other words, it was less efficient than the near‐emmetropic lens. Also the posterior surface of the lens appeared to move more in highly myopic eyes than in near‐emmetropic eyes.
SOCIAL ASPECTS OF VISUAL DISABILITY*
Authors: Silver Janet
Published: December 2007

Abstract Over 40 million people are estimated to be limited in the work they can do by a visual disability, most of them in the Third World. Much preventable blindness goes unchecked and even reversible blindness is untreated in countries where aphakic spectacles may cost the equivalent of a year's earnings. In the United Kingdom and other advanced countries the problems are very different. Visual disability is 100 times more likely to occur in a person over 75 than in a child. The disabled carry heavy penalties, social, financial and psychological. Society, when it is aware, tends to “look after” the disabled person, rather than provide him with the means to look after himself, but services are inadequate to meet demands.
MERIDIONAL VARIATIONS AND OTHER PROPERTIES SUGGESTING THAT ACUITY AND ORIENTATION DISCRIMINATION RELY ON DIFFERENT NEURONAL MECHANISMS *
Authors: Orban Guy A. , Vandenbussche Erik , Vogels Rufin
Published: December 2007

Abstract It has been widely reported that both grating acuity and orientation discrimination show meridional variations: performance is better for targets oriented horizontally or vertically than for those with oblique orientations. In spite of such similarities, we now present both behavioral and psychophysical evidence from tats and humans to show that grating acuity and orientation discrimination depend upon different neuronal mechanisms.
CRITICAL PERIOD PLASTICITY FOR VISUAL FUNCTION: DEFINITION IN MONOCULARLY DEPRIVED RATS USING VISUALLY EVOKED POTENTIALS *
Authors: Stafford Carole A.
Published: December 2007

Abstract VEPs were used to study the effects of visual deprivation and to define the critical period in the hooded rat. it is shown that monocular deprivation in young animals reduces both the visual acuity and the contrast sensitivity of the deprived eye and that the depth of attenuation depends upon the age at onset of deprivation. This suggests that the critical period is almost over by 6 weeks postnatally. This simple recording technique might be useful in studying amblyopic children and in defining more clearly the critical period for human vision.
AN ASYMMETRY IN THE OPTOKINETIC NYSTAGMUS RESPONSE IN NORMAL INDIVIDUALS
Authors: Thomson W. D. , Saunders J. E.
Published: December 2007

Abstract Optokinetic nystagmus (OKN) was induced by using a modified projector system to provide a moving pattern of irregular spots of light. A systematic electro‐oculographic study of horizontal and vertical OKN for a series of stimulus velocities from 10 to 100° SM was conducted on 10 healthy young subjects. It was found that the vertical responses, in particular to upward‐moving stimuli, were less well sustained at velocities above 30° s−1 than the horizontal responses. In view of these observations, care should be taken in the interpretation of OKN results clinically, and only when the response is absent in one direction or an extreme asymmetry is present should clinical significance be attached. This applies particularly for the vertical OKN responses. Clearly, the use of stimulus velocities below 40° s−1 is advised and the standard suggested by Holm‐Jensen and Peitersen [Acta oto‐lar, 88, 110–116 (1968)] of a target moving at 20°p s−1 seems a reasonable choice.
BINOCULAR BALANCE VALIDITY: A COMPARISON OF FIVE COMMON SUBJECTIVE TECHNIQUES
Authors: West Douglas , Somers William W.
Published: December 2007

Abstract For most patients, one of the last steps in the subjective determination of the refractive error is the equalization of their accommodative stimuli. Several previous authors have Mated that the preferred method of balancing is by some form of binocular stimulation, either with a Turville infinity balance or a polarizing technique [Miles, P. (1948) Am. J. Ophthal.31, 1460–1466; Morgan, M. W., Jr (1949) Am. J. Optom.26, 231–239; Goodwin. H. E. (1966) Optom. Wkly57, 28, 47–51; Grentsch, L. W. and Goodwin, H. E. (1966) Am. J. Optom.43, 658–663]. This experiment looks at a slightly different aspect: how repeatable a given technique is. We performed five common methods of balancing: vectographic, equal acuity through low plus blur, red‐green equalization, Jackson cross‐cylinder, and equal loss of acuity with plus blur. We find no significant differences in the variation of any of the techniques; they are all equally reliable. In addition, there seems to be no difference in their mean values, contrary to previous reports.
THE LATERAL CHROMATIC ABERRATION OF THE EYE
Authors: Howarth Petek Alan
Published: December 2007

Abstract Although the longitudinal chromatic aberration of the eye has been extensively studied, little data has been published on its lateral chromatic aberration. Using a reduced eye, this has been calculated for different eccentricities and wavelengths, and data are presented. The lateral chromatic aberration of the eye will cause the perceived direction of an off‐axis object or light in vary with its wavelength.
ESTIMATION OF THE STEREOSCOPIC THRESHOLD UTILIZING PERCEIVED DEPTH
Authors: Somers William W. , Hamilton Mark J.
Published: December 2007

Abstract Recent reports in the literature indicate that a random‐dot style of stereoscopic test is the most accurate method of assessing stereoscopic threshold [Cooper, J., Feldman, J. and Medlin, D. (1979) J. Am. optom. Ass.50, 821–825]. While this is undoubtedly true for those who can respond to the test, it is less so for very young, infirm or other patients who do not or cannot have the requisite attention span. This experiment finds that the amount of perceived depth seen on a test like the Titmus fly correlates very accurately with the measured stereoscopic threshold and can therefore be used as a measure of the threshold without having to employ the entire testing procedure of the random dot tests. The regression equation derived from the data is presented, as well as a table that allows a practitioner to estimate the stereoscopic threshold from the amount of perceived depth on a common stereo test: the Titmus fly.
ANALYSIS OF CLINICAL APPROXIMATION IN APPLYING PRENTICE'S RULE TO DECENTRATION OF SPHEROCYLINDER LENSES
Authors: Cobb C. H.
Published: December 2007

Abstract A common approximation for obtaining the prism induced by decentration ot spherocylinder lenses in non‐principal meridia has been compared 10 the actual prism for numerous cylinder axis orientations. The base direction predicted by the approximation shows significant variations from the actual direction when the cylinder axis is more than 20° from the horizontal or vertical direction, When there is only vertical decentration, the power error is directly proportional to the decentration and the cylinder power. Both the meridional error and the power error depend on the ratio of the sphere power to the cylinder power and on the decentration.
DISPLACEMENT THRESHOLDS FOR MOTION DETECTION UNDER CONDITIONS OF CHROMATIC ADAPTATION
Authors: Barbur John L. , Saunders John E.
Published: December 2007

Abstract— The smallest, continuous target displacement which is sufficient to cause a sensation of movement was measured under conditions of chromatic adaptation. The experiments were carried out for test target and background field wavelengths which selectively isolate the activity of the colour mechanisms of the human eye. The results show that, when target detection is largely mediated by the red or green colour mechanism, a target displacement of 2–3′ in the foveal region is sufficient to cause a reliable sensation of movement. These displacement thresholds show only a small change as a function of target contrast or background retinal illuminance level. Similar results were obtained when the colour of the test target was the same as that of the background field (e.g. green, yellow or red), when no attempt was made to isolate a single colour mechanism. Test target and background wavelengths which isolate the activity of the blue colour mechanism yield displacement thresholds in the range 5–7′ and show a stronger dependence on target contrast and background retinal illuminance level. The experiments were repeated at several eccentricities and the results show that, for a test target and background field of the same colour and under conditions which isolate the green or red spectral response mechanism, the minimum target displacement required for motion detection appears to increase in a manner similar to the centre‐width receptive‐field size of broad‐band, centre‐surround transient neurons in the rhesus monkey retina [De Monasterio and Gouras (1975) J. Physiol., Lond.251, 167–195]. In contrast, displacement thresholds obtained under conditions which isolate the blue colour mechanism do not show significant variation for target presentation locations up to 25° of visual angle. These data relate well to other psychophysical results which reveal the spatial properties of motion‐detecting mechanisms in human vision [Barbur and Ruddock (1980b) Biol. Cybernetics37, 93–98].
CRITICAL FUSION FREQUENCY IN THE CENTRAL VISUAL FIELD
Authors: Douthwaite W. A. , Halliwell J. A. , Lomas A. M. , Muk W. K. Yan , Topliss J. N.
Published: December 2007

Abstract— The critical fusion frequency (CFF) was measured across the central visual field. Stimulus parameters were adjusted to ensure an increase in CFF at the fovea. Comparison was made between the foveal and extra‐foveal CFF values. The study showed that, while the CFF may be highest at the fovea when the CFF values are generally low, stimulus parameter changes that increase the CFF result in a greater increase extra‐foveally. Ultimately, then, the CFF maximum shifts from the fovea to an extra‐foveal area. Under the experimental conditions used in the study, the maximum occurred approximately 10° from fixation.
THE RELATIONSHIP BETWEEN TONIC VERGENCE AND OCULOMOTOR STRESS INDUCED BY ETHANOL
Authors: Hogan Robert E. , Gilmartin Bernard
Published: December 2007

Abstract— Previous investigations have demonstrated an ethanol‐induced increase in distance esophoria and an increase in near exophoria, together with a decrease in negative fusional ability, the AC/A ratio and near point of convergence. The present study (N= 10) was designed to test the hypothesis that these effects are due to a biasing of vergence towards its tonic resting state when under conditions of oculomotor stress. Measurements of the parameters before and 1 hr after imbibition of a moderate dose of ethanol supported the previous findings. Darkroom measures of tonic vergence (vernier alignment) and tonic accommodation (laser optometry) were unaffected by ethanol. The study indicates that the changes in oculomotor function induced by the central inhibitory action of ethanol represent a shift towards the tonic vergence position.
THE EMPLOYMENT AND EDUCATION OF THE PARTIALLY SIGHTED IN THE PERIOD IMMEDIATELY AFTER LEAVING SPECIAL SCHOOL
Authors: Wild J. M. , Wolffe M.
Published: December 2007

Abstract— Initial results are reported of a major study undertaken to determine factors which could be used to predict employment success of partially‐sighted school leavers. The sample involved 355 individuals from 13 schools for the partially sighted taken from three successive final academic years and followed up 1 year after leaving school. Questionnaire techniques were used, the response rate being 85.6%. Analysis revealed that 55.6% sought or experienced employment and 44.4% undertook further education. Eighty‐seven per cent of those seeking employment obtained jobs alongside the normally sighted. Only 12 leavers remained totally unemployed. Forty‐seven per cent were still in their initial employment.
A BASIC COMPUTER PROGRAM FOR ANALYSIS OF THE FARNSWORTH 100‐HUE TEST
Authors: Crabbe M. James C. , Mengher Lakhbir Singh
Published: December 2007

Abstract— A computer program in BASIC has been written which will compute all scores for the Farnsworth 100‐hue test, and plot them in the appropriate colour on a polar co‐ordinate graph. Hard copy can be obtained on a dot‐matrix printer. The program is simple to use, and considerably curtails the analysis time for this test, as well as eliminating possible computational errors.
A COMPARISON OF DIFFERENT MODELS OF EXTRAOCULAR MUSCLE COOPERATION
Authors: Clement R. A.
Published: December 2007

Abstract— Different assumptions about the way in which the extraocular muscles act have been evaluated by comparing a set of models of extraocular muscle cooperation, each of which differ by just one assumption, against clinical data from patients with isolated nerve palsies.
INTER‐RELATIONSHIPS BETWEEN BRITISH DRIVERS‘ VISUAL ABILITIES, AGE AND ROAD ACCIDENT HISTORIES
Authors: Davison Peter A.
Published: December 2007

Abstract— Statistical analysis is described of data on 1000 British drivers' accident histories and their performance on a vision screening instrument. Significant positive associations are evident between various accident variables and tests of hyperphoria, right eye visual acuity, left eye acuity and binocular acuity. The clustering of associations is strongest for older drivers. The significance of hyperphoria has received little attention previously.

The age‐related associations with accidents parallel the decline with age of other visual abilities. Statutory re‐testing of drivers' vision at about the age of 50 is recommended.
VISUAL STANDARDS FOR DRIVING
Authors: Charman W. N.
Published: December 2007

Abstract— The visual standards for drivers set by a selection of countries across the world are reviewed. It is found that there is little unanimity in what constitutes an “adequate” standard of vision for drivers of either private or public vehicles, or in the testing procedures employed.
EFFECT OF INSTRUCTION AND HIGHER LEVEL CONTROL ON THE ACCOMMODATIVE RESPONSE SPATIAL FREQUENCY PROFILE
Authors: Ciuffreda K. J. , Hokoda S. C.
Published: December 2007

Abstract— Although the spatial frequency dependence of accommodation is well established, characteristics of the accommodative response profile may vary significantly, thus supporting opposing theories of accommodation control. We demonstrate the pronounced influence of instruction and higher level control on such accommodation profiles. The results suggest that extreme care be taken in the methodological considerations of such experiments, as well as the need for additional systematic investigation of these factors in accommodation studies.
A PRACTICAL GUIDE FOR COLOUR‐VISION EXAMINATION: REPORT OF THE STANDARDIZATION COMMITTEE OF THE INTERNATIONAL RESEARCH GROUP ON COLOUR‐VISION DEFICIENCIES*
Authors: Birch Jennifer
Published: December 2007

Abstract— There are different types and degrees of colour deficiency and some types of defect occur more frequently than others. Several different techniques are used for examining colour vision and many different tests are available commercially. Clinical tests have three aims: to screen for colour deficiency, to diagnose or classify the type of defect and to grade the severity of the defect. Individual tests do not fulfil all three aims and a test battery is recommended for any detailed colour‐vision examination or for giving occupational advice.

This paper provides information about congenital and acquired colour‐vision defects and lists the principal colour‐vision tests. Standardized test methods and viewing conditions are described. The efficiency of each test, for screening, diagnosis and grading is indicated and appropriate test batteries are recommended for different testing requirements.
ACCOMMODATION FOR FLICKERING STIMULI
Authors: Owens D. A. , Wolfe J. M.
Published: December 2007

Abstract— A laser optometer was used to measure accommodative responses of three observers for sinusoidal gratings presented in Maxwellian view at optical distances ranging from 0 to 4 dioptres. Contrast of the stimuli was modulated spatially at 1.0, 4.2 and 6.5 cycles deg.‐1 (cpd), and temporally at six frequencies ranging from 3.0 to 40 Hz. Accommodation was consistently more accurate for the 4.2 cpd than for either the 1.0 or 6.5 cpd gratings. Furthermore, accommodative responsiveness for the 4.2 cpd was not affected by temporal modulation, while that for the other spatial frequencies improved monotonically as a function of temporal frequency. These results reinforce earlier reports that accommodation is most responsive for contrast of intermediate spatial frequencies and they indicate that stimulus flicker generally degrades accommodation for spatial contrast.
CONJUNCTIVAL CYTOLOGY IN HARD AND SOFT CONTACT LENS WEAR
Authors: Hirji N. K. , Scott J. , Sabell A. G.
Published: December 2007

Abstract— The conjunctival cytological profiles of asymptomatic healthy contact lens wearers are described. An impression biopsy technique (5 h after insertion of contact lenses) was used. Significantly higher cell counts (neutrophils and lymphocytes) were found amongst the soft lens wearers, biopsies compared to hard lens wearers' biopsies or control subjects' biopsies.

It is postulated that conjunctival cytological examination may reveal early, subclinical, cytotoxic effects attributable to the preservatives and chelating agents in soft contact lens care systems.
THE INCREASE IN CONVERGENCE INADEQUACY WITH AGE
Authors: Pickwell L. D.
Published: December 2007

Abstract— This short note looks at convergence insufficiency in a sample of patients from optometric practice in relation to the patient's age. It is found that the percentage of patients with convergence insufficiency increases slightly up to the age of 55–60 years and then there is a more marked increase from about 25% at 55 years to over 60% in the aged patients. This finding is compared with the increase in physiological exophoria for near vision with age and it is concluded that an additional factor other than age must account for the marked increase in the incidence of convergence insufficiency over the age of 60 years. In view of previous work, it is clear that deterioration in general health is the main additional factor.
ORTHOPTIC EFFECTS ON ACCOMMODATION AND RELATED VISUAL FUNCTIONS IN AN ADULT ALTERNATING ESOTROPE
Authors: Schnider C. M. , Ciuffreda K. J. , Selenow A.
Published: December 2007

Abstract— Orthoptic therapy was instituted in an adult, alternating esotrope with asthenopia who exhibited inaccurate static accommodative responses with adequate, clinically determined, accommodative facility. During and following therapy the patient showed considerable improvement in accommodative accuracy and related visual functions, such as contrast sensitivity, in the absence of any change in strabismic deviation. This case provides the first laboratory documentation of orthoptic effects on accommodation in an adult strabismic.
ACCOMMODATIVE VERGENCE AND RELATED FINDINGS FOR A NIGERIAN POPULATION
Authors: Kragha I. K. O. K.
Published: December 2007

Abstract— Using clinical data, normative values of accommodative vergence and related tests are presented and compared to previously published data.

The results are highly variable. The ‘phorias are the most variable tests while positive relative accommodation (PRA) and the recovery values on the whole have moderate variability. Negative relative accommodation (NRA), pupil size, break and blur findings on average exhibit low variation.
THE TECHNICAL PROBLEMS OF PRODUCING PHOTOGRAPHIC PRINTS FOR THE MEASUREMENT OF HUMAN CONTRAST THRESHOLDS
Authors: Verbaken J. H. , Jacobs R. J.
Published: December 2007

Abstract— Whilst most optometrists today are aware of the need for a practical method of measuring the contrast sensitivity function (CSF), cost and length of testing have usually precluded this measurement. As the Arden Grating Test is a screening test for normal CSF, and since many patients with low vision cannot see any of its gratings, there is a need for a test with an extended contrast range which is calibrated to allow quantitative measurement of contrast thresholds in the clinic. This paper discusses the problems associated with the use of the photographic process to manufacture such a test. A series of stimuli covering a wide range of contrasts were manufactured photographically and evaluated photometrically and psychophysically to validate the photographic process. The results show that the photographic techniques can be controlled sufficiently to enable the manufacture of stimuli of the required contrasts and that, at low contrasts where calibration is inaccurate or impossible, the contrasts produced are linearly related to exposure. The results also show that the illumination and observation conditions need to be accurately controlled for the plate contrast to be unaffected by veiling glare.
A REVIEW OF THE ROLE OF SYMPATHETIC INNERVATION OF THE CILIARY MUSCLE IN OCULAR ACCOMMODATION
Authors: Gilmartin B.
Published: December 2007

Although it is well established that autonomic control of ocular accommodation is predominantly parasympathetic, many investigators have, over the last 150 years, proposed that a supplementary sympathetic innervation should be considered. Particular attention is directed in this review to previous literature providing anatomical, physiological and pharmacological evidence for dual innervation of the ciliary muscle. Clinical and psychological evidence is shown to be equivocal. A review of recent laser optometry studies of tonic (“dark‐focus”) resting positions of accommodation indicates that the inhibitory nature of sympathetic innervation suggested by the majority of previous studies can be further defined with respect to specific adrenergic receptors. The implications of dual innervation relating to ocular accommodation during sustained near‐vision tasks is discussed.
VERGENCE INSTABILITIES AND THE LONGITUDINAL HOROPTER
Authors: Reading R. W.
Published: December 2007

The method of averaging was applied to the results of repeated measures of the longitudinal horopter for four subjects classified as binocularly normal and one anisometropic amblyope. The results produced a refined horopter locus and suggested that the so‐called Vieth‐Mueller circle is an adequate describer of the empirical longitudinal horopter, except in those cases involving uncorrected aniseikonia.
THE EFFECT OF PERIMETRIC STIMULATION ON EVOKED POTENTIAL DISTRIBUTION ‐ A THEORETICAL MODEL
Authors: Drasdo N.
Published: December 2007

Abstract— A schematic cortical projection of the human visual field is combined with the concept of dipole planar generators to provide a theoretical model of the scalp distribution of evoked potentials from visual field stimuli. The computations illustrate the importance of gyral surfaces as the principal generators of recorded evoked potentials. Taking several zones of the visual field projection on the striate area as an example, the model is used to produce horizontal profiles of evoked potential amplitude. This indicates the limitation and possibilities of mapping the cortical projections in man and relating these to perimetric findings.
THE ELUCIDATION AND USE OF THE EFFECT OF NEAR FIXATION IN CONGENITAL NYSTAGMUS
Authors: Dickinson Christine M.
Published: December 2007

Abstract— It has frequently been reported that the spontaneous ocular oscillation in congenital nystagmats is less intense for near viewing than during distance fixation. The reason for this effect was sought, and the influences of monocular adduction, convergence and accommodation acting separately and synergistically were assessed. The frequent assumption that nystagmus intensity (amplitude and frequency) is determined by convergence angle (either symmetrical or asymmetrical) was confirmed, and it was found that binocular viewing was not necessary. An identical effect on nystagmus intensity could be created for distance fixation by the use of base‐out prisms, and these were prescribed for constant wear in two congenital idiopathic nystagmats. Although nystagmus intensity was constantly reduced, no concomitant increase in binocular contrast sensitivity or Snellen visual acuity occurred.
BINOCULAR VISION: ITS INFLUENCE ON THE DEVELOPMENT OF VISUAL AND POSTURAL REFLEX EYE MOVEMENTS*
Authors: Westall Carol A.
Published: December 2007

Abstract— The time course for the development of binocular vision is similar to the time course for the development of mature, symmetrical, monocular optokinetic nystagmus in response to movements of the visual field in the nasalward or temporalward direction. If binocular vision does not develop normally, then the monocular optokinetic response remains immature, or asymmetric. This paper examines the connection between the development of symmetrical OKN and binocular vision, and relates how disturbances in visual development affect the ability of postural reflex eye movements to adapt to changes in the visual environment.
A LONGITUDINAL STUDY OF THE AGE DEPENDENCE OF HUMAN OCULAR REFRACTION—II. PREDICTION OF FUTURE TRENDS IN MEDIUM AND HIGH MYOPIA BY MEANS OF CLUSTER ANALYSIS
Authors: Saunders Harold
Published: December 2007

Abstracts— A sample population of myopes with an initial correction of 2 DS or more is extracted from the longitudinal sample of ametropes reported by Saunders (1986). The myopes are partitioned by means of cluster analysis and, as a result, three distinct groups of myopes are identified. The time/regression equations which best describe the groups are stated. It is concluded that meaningful long‐term prognosis of medium and high myopes is unlikely and that reasonable prediction of short‐term trends requires at least two consecutive refraction data to determine the group allocation of a myope.
THE EFFECT OF PRISMATIC SPECTACLE AND CONTACT LENS CORRECTIONS ON OCULAR ROTATION
Authors: Obstfeld Henri
Published: December 2007

Abstracts— The effect of prismatic spectacle corrections on ocular rotation for different object distances is determined and evaluated.

The same principles are applied for a correction fitted on the eye, that is, a contact lens correction. The latter must be considered as a thick lens system. The effects of different types of prismatic contact lenses on ocular rotation are considered. Assuming the contact lens to remain stationary and the eye behind the lens to rotate, it is shown that the theoretical effect on ocular rotation of prismatic contact lenses is practically equal to their prismatic effect in air. The effect for high‐powered contact lenses is discussed.
ORIGINS OF COLOUR VISION STANDARDS WITHIN THE TRANSPORT INDUSTRY
Authors: Vingrys Algis J. , Cole Barry L.
Published: December 2007

Abstract— Colour vision standards should reflect changes in our understanding of the nature of these defects as well as technological advances that place less importance upon the visual senses of the human operator. Therefore it is suggested that visual standards be subject to routine reviews in order to assess their suitability for modern. work environments. This paper gives a chronological account of the introduction of colour vision standards by several national transport authorities and identifies historical reasons that led to their implementation. It is concluded that the same factors that gave rise to the adoption of early colour vision standards are still relevant for modern transport systems. However the recent deployment of automatic or semi‐automatic control or navigational systems has substantially altered man's role from being the primary source of information input to one of a monitoring process. This has generated a good deal of debate and uncertainty regarding the level of responsibility that a human operator has for the control of modern transport vehicles. Nevertheless, it is argued that in the absence of complete automation some type of visual standard is needed whenever visual judgements must be made by human observers.
EFFECT OF IMPOSED RETINAL IMAGE MOVEMENTS ON COLOUR VISION AT A HETEROCHROMATIC BOUNDARY IN A STABILIZED RETINAL IMAGE
Authors: Fisher J. A. Foley , Ditchburn R. W.
Published: December 2007

Abstract— A stabilized image, including a straight‐line boundary between two areas of different colour was displayed. Movements normal to itself were imposed on this boundary while other boundaries remained stabilized. Broad band filters giving red, yellow, green and blue were used in various pairs. Step movements, pulse movements and oscillatory movements (including sinusoidal, triangular and square wave forms) were applied in turn. Threshold movements to give perception of hue were measured for steps and pulses and signal/photon‐noise ratios were calculated for a red/blue boundary. The ratio was found to be constant at a value of about 20 when the retinal illuminance (ER) varied between 5 td and 60 td. When ER was increased (up to 2000 td) the ratio increased rapidly. None of the colour appearances produced by moving the boundary exactly matched the corresponding appearances in an unstabilized image, though the nearest matches were obtained with oscillatory movements of frequency 2 Hz and displacement greater than 5.
EFFECT OF DEFOCUS ON VISUAL FIELD MEASUREMENT
Authors: Atchison David A.
Published: December 2007

Abstract— Defocus increased visual field contrast thresholds for stimuli equal to or smaller than Goldmann perimeter target III (26 min arc diameter). Beyond 30° ‐40° from the centre of the visual field, defocus had little effect on contrast thresholds. For accurate clinical perimetry, ametropia and presbyopia should be corrected for small targets (≤ target III) within 30° ‐40° of fixation with either a spectacle lens (if required power less than ± 10 D) or a contact lens. Larger stimuli are little affected by defocus. Outside this central 30° ‐40° field, correction with contact lenses should be provided if fixation is poor due to ametropia. Scotomata for which no cause is evident should be further investigated to find whether they have a refractive basis.
AN AVERAGING METHOD FOR THE INTERPRETATION OF THE FARNSWORTH‐MUNSELL 100‐HUE TEST—II. COLOUR VISION DEFECTS ACQUIRED IN DIABETIC RETINOPATHY
Authors: Birch Jennifer , Dain S. J.
Published: December 2007

Abstract— The Farnsworth‐Munsell 100‐Hue test is frequently used to assess acquired colour vision defects. In diabetic retinopathy the acquired defect is a mild or severe type III (Tritan) defect which may be coupled with poor overall hue discrimination. In consequence, error scores are often high and the 100‐Hue polar diagram is difficult to interpret. In this study the averaging method of analysis proposed by Dain and Birch is used to examine 120 100‐Hue plots obtained by patients with proliferative diabetic retinopathy. These plots have either moderate (150–300) or high error scores (>300). The method of analysis is found to be effective in determining whether a Tritan defect is present or not.
A COMPARATIVE STUDY IN THE USE OF CLOSED‐CIRCUIT TELEVISION READING MACHINES AND OPTICAL AIDS BY PATIENTS WITH RETINITIS PIGMENTOSA AND MACULOPATHY
Authors: Ehrlich Daniel
Published: December 2007

Abstract— Patients with retinitis pigmentosa (RP) who have insufficient vision to benefit from optical low vision aids are frequently helped by the closed‐circuit television (CCTV) reading machines. RP patients' use of the CCTV is compared with that of patients with maculopathy (i.e. a group with a central scotoma only, is compared to a group which also has additional peripheral field loss), and with that of a “normal” control group. The performance of people with RP is improved by using white print on a black background, while macular degeneration subjects have no significant preference. Speed limits appear to be a function of restrictions imposed by the machine. Both groups frequently read faster with “optical aids”.
AN IMPROVED METHOD FOR USING THE DTL FIBRE IN ELECTRORETINOGRAPHY
Authors: Thompson D. A. , Drasdo N.
Published: December 2007

Abstract— An improved method using DTL fibre for electroretinography is described. The DTL fibre is comfortable and easy to apply. Corneal anaesthesia is unnecessary. The DTL fibre does not interfere with the retinal image and has been used successfully to record both pattern and flash electroretinograms from subjects of all ages.
CURRENT CONCEPTS OF THE ACTIONS OF THE EXTRAOCULAR MUSCLES AND THE INTERPRETATION OF OCULOMOTILITY TESTS*
Authors: Clement R. A. , Boylan C.
Published: December 2007

Abstract— Contrasting views on the actions of the extraocular muscles are discussed. The contributions made by clinicians are compared to those made by investigators with a background in physical science. It is shown that a clear understanding of the mechanics of the extraocular muscles can be used to increase the efficiency of oculomotility tests.
NEAR VISION STRESS: VERGENCE ADAPTATION AND ACCOMMODATIVE FATIGUE*
Authors: Ehrlich David L.
Published: December 2007

Abstract— Changes in the visual system following prolonged near work were investigated. Fifteen young, normal subjects undertook a severe, two hour long, binocular near visual task at 20 cm without any breaks. Fusional stress was assessed by near ‘phoria change. Refractive change was measured with an auto‐refractometer to investigate whether transient myopia occurred and its subsequent recovery. The near task caused vergence adaptation which was primarily due to the fusional stress of the task (accounting for 67% of its variance). The ’phoria change was to a lesser extent (40%) dependent on the accommodative “stress” of the task. Fatigue of the accommodative system resulted in increased accommodative innervation to maintain the same accurate response. Increased innervation can continue after the task on subsequent distance viewing, resulting in transient myopia (mean 0.29 DS). This transient myopia was found to be due to a transient regression of the far point towards the subject's tonic accommodation level. This can be accounted for by a shift of the tonic level as well as an increased bias towards the pre‐task tonic level.
BINOCULAR CONTRAST DETECTION WITH UNEQUAL MONOCULAR ILLUMINANCE*
Authors: Gilchrist Jim , Pardhan Shahina
Published: December 2007

Abstract— Binocular summation was measured in eight normal subjects by means of psychometric functions for contrast detection. An average 47% increase in binocular over monocular performance was obtained. Our data agreed with the simple summation model of Signal Detection Theory (Legge, 1984). Binocular psychometric functions were also measured when the sensitivity of one eye was decreased by means of a 1.0 neutral density (ND) filter. We found that binocular detectability in this case was reduced to below that of the better eye. This binocular inhibition was seen in all subjects. The slope of a contrast detection function gives a measure of the rate of change in detectability with contrast. If the slopes of two functions are equal, then the difference in detectability between these functions remains constant for all the contrast values used. When the slopes of the measured functions were analysed, no significant differences were found under any of the testing conditions. This indicates that the magnitude of summation (with equal monocular sensitivities), and of inhibition (with unequal monocular sensitivities), remains constant across the range of stimulus contrasts. The clinical implications of binocular inhibition are discussed.
SCREENING FOR RETINOPATHY OF PREMATURITY*
Authors: Linfield P. B. , Davies J. G.
Published: December 2007

Abstract— The results of a prospective study of low birthweight infants (< 1500 g) identifies those at risk of retinopathy of prematurity (R.O.P.) as being ≤ 1250 g birthweight or ≤ 30 weeks post‐conceptional age (P.C.A.). In these infants the incidence of R.O.P. was 60% (14% grades 3 or 4). in the remainder the overall incidence of R.O.P. was 24%, exclusively grades 1 or 2. Onset of R.O.P. consistently presented at a mean age of 35 weeks P.C.A. (SD 2.25). Routine retinal examination of all infants ≤ 1250 g birthweight or ≤ 30 weeks gestation is recommended between 33 and 37 weeks P.C.A.
MOVEMENT IN DECLINE? OSCILLATORY MOVEMENT DISPLACEMENT THRESHOLDS INCREASE WITH AGEING*
Authors: Buckingham Terry , Whitaker David , Banford Denise
Published: December 2007

Abstract— Displacement thresholds for continuous oscillatory movement were determined for ten subjects in each of three age groups—20–23, 40–55 and 60–80 years. Oscillation frequencies of 1, 2, 3, 5, 8, 13 and 20 Hz were used, all subjects having a corrected visual acuity of 6/5. A randomized block factorial design of analysis of variance revealed significant effects of both temporal frequency of oscillation (F6,189= 4.10, p < 0.001)and age (F2,189= 46.98, p≪ 0.001). The deterioration in movement sensitivity occurs equally at both high and low temporal frequencies—no significant interaction effects being revealed (F12,189= 0.45, p= not significant). The frequency effects are ascribed to underlying mechanisms mediating movement perception. Reasons for decreased movement sensitivity with increasing age are discussed.
THEORY AND EVIDENCE FOR A CLINICAL HYPERACUITY TEST*
Authors: Whitaker David , Buckingham Terry
Published: December 2007

Abstract— An accurate assessment of the integrity of the visual system behind opaque ocular media is of vital clinical significance, especially with regard to surgical intervention. Several techniques which are currently available to assist in this task are considered with regard to their value. Theoretical considerations indicate that hyperacuities, by virtue of their resistance to optical image degradation, should constitute ideal candidates to perform the above evaluation. Hyperacuity studies involving cataract simulation support this view, as does the clinical data which is presently available. Further work should reveal an optimum hyperacuity configuration or a battery of hyperacuity tests and establish their clinical merit.
THE MARTON LECTURE: OCULAR MANIFESTATIONS OF SYSTEMIC MEDICATION
Authors: Gilmartin B.
Published: December 2007

Abstract— The probability of ocular adverse reactions to systemic medication is low but when a reaction does occur it is often associated with one or more special factors relating to the condition being treated, to the patient, and to the nature of the drug itself. Nevertheless the role of the optometrist in the monitoring, detection and reporting of adverse reactions is important and is recognized by the College reporting scheme. A selection of the type of reactions that may be encountered in general optometric practice is reviewed. The reactions range from the relatively innocuous anticholinergic effects of the benzodiazepine tranquillizers to the more serious corneal, lens and retinal changes that may be associated with the corticosteroids, phenothiazines and chloroquine.

The Marton lecture was delivered to the 33rd Northern Optical Congress, Bowness‐on‐Windermere, on 27 September 1986.
IMPAIRMENT OF CONTRAST DISCRIMINATION IN AMBLYOPIC EYES
Authors: Ciuffreda Kenneth J. , Fisher S. Kay
Published: December 2007

Abstract— A successive two‐alternative, forced‐choice procedure incorporating a double‐interleaved staircase was used to measure monocular contrast discrimination in strabismic and/or anisometropic amblyopes, strabismics without amblyopia, and normals. Standard contrast was 25%, with comparison contrasts starting at 10 and 40%. Spatial frequencies were 0.5, 2.0, and either 4.0 or 8.0 c deg‐1. The amblyopic eye consistently required more contrast than the fellow dominant eye for the task. Results in each eye of the normals and strabismics without amblyopia were similar and normal. The findings clearly demonstrate impairment of contrast discrimination in amblyopic eyes, presumably due to early abnormal visual experience. Such impairment could contribute to the increased steady‐state accommodative error found in amblyopic eyes.
CHANGES OF OSCILLATORY POTENTIALS OF THE ERG IN DIABETIC RETINOPATHY
Authors: Moschos M. , Panagakis E. , Angelopoulos A.
Published: December 2007

Abstract— Disturbances of the oscillatory potentials of the ERG are examined in diabetic patients with and without vascular lesions of the retina. More specifically, the changes of the oscillatory potentials are investigated in relation to the manifestation and evolution of diabetic retinopathy and neovascularization of the optic disk and the retina. Particular stress is laid on the direct relation between the disturbances of the oscillatory potentials and the occurrence of neovascularization, as well as on the prognostic significance of these disturbances.
EYE DISEASES IN NORTHERN NIGERIA: PREVALENCE, AGE AND SEX DIFFERENCES
Authors: Kragha I. K. O. K.
Published: December 2007

Abstract— This study presents the prevalence, age, and sex differences of eye diseases in northern Nigeria using the records of 1677 eye hospital patients. The most common eye diseases are cataract, refractive error and presbyopia, and diseases of the conjunctiva and sclera. There are no significant age and sex differences in the prevalence of most eye conditions.