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It has long been recognized that heredity plays a part in the aetiology of glaucoma. In open-angle glaucoma an autosomal recessive inheritance has been suggested (Waardenburg, 1949), but in the majority of families reported in which a high prevalence has been found, an autosomal dominant transmission seems apparent (Miller and Paterson, I962; Fransois, Heintz-de Bree, and Tripathi, I966; Francois and Heintz-de Bree, I966; FranSois, i966). The penetrance of the dominant gene appears, however, to be highly variable; Fransois and Heintz-de Bree (i966) noted a 98 per cent. penetrance in some families but admitted that in many others the penetrance was very low. On the other hand, Armaly, Monstavicius, and Sayegh (i968) suggested a multifactorial aetiology for the condition. A similar controversy exists in regard to the aetiology of angle-closure glaucoma. The influence of ocular dimensions in the aetiology of angle-closure glaucoma is well established (Priestley-Smith, 1883; Rosengren, I950; Tornquist, 1956; Lowe, I970; Storey and Phillips, 1971). Tomlinson and Leighton (1973) have considered the role of ocular dimensions in the heredity of angle-closure glaucoma in an attempt to define the importance ofindividual dimensions in the aetiology and heredity of the condition. Their results, which may favour a multifactorial determination, were discussed in the light of conflicting views concerning the heredity of that form of glaucoma. The influence ofocular dimensions on the aetiology ofopen-angle glaucoma is apparently not as great as it is in angle-closure glaucoma, but there is some evidence to show that the myopic eye may be particularly sensitive to raised intraocular pressure. Perkins and Jay (I960) reported that 22 per cent. of 205 patients with open-angle glaucoma over the age of 50 years were myopic; under the age of 50 the incidence of myopia was 37-8 per cent. A high incidence ofopen-angle glaucoma in myopic patients has been observed by Weekers, Lavergne, and Prijot (1958) and by Diaz-Dominguez (I96I, I966). A relationship between myopia and a high response of ocular tension to topical corticosteroids also appears to exist (Podos, Becker, and Morton, i966). T6rnquist and Broden (I958) and Tomlinson and Leighton (1972) have observed that eyes with open-angle glaucoma have significantly shallower anterior chambers than normal eyes. This may be a contributory factor to the development of open-angle glaucoma, as Francois, Rabaey, Neetens, and Evens (I958) found the reduction in anterior chamber depth to have more effect on the outflow of aqueous humour from the eye than any other factor considered. An investigation was carried out in which certain ocular dimensions were measured in patients with open-angle glaucoma and in their first-degree relatives. A similarity in these dimensions between the patients and relatives may explain an increased liability to the

Refractive errors of the eyes of six species of Microchiroptera were determined by retinoscopy. Constricted and dilated entrance pupil diameters were measured in seven species. The dimensions and curvatures of the dioptric components were obtained from frozen sections of eyes ofPhyllostomus hastatus, Carollia perspicillata andMyotis sodalis. The total effective power and theoretical depth of field of these eyes was estimated. Near points may lie between a few centimeters and a few meters for constricted and dilated pupils, respectively. The refractive errors and apparent lack of accommodation in Microchiropteran eyes are probably insignificant and do not of themselves imply poorly developed vision. The optical properties of these eyes are consistent with the hypothesis that vision is especially useful in detecting objects beyond the range of echolocation.

The data from 131 eyes operated upon by one of us (W.S.H.) for retinal detachment due to dialysis in a consecutive series of 1,352 eyes operated for retinal detachment were analyzed. Dialyses were found to be a common cause (10%) of all retinal detachment and are the most common cause (50%) of retinal detachments in children and young adults. Retinal detachment due to dialyses have very specific clinical characteristics, and they tend to behave in a predictable manner. These characteristics have been analyzed and emphasized.

A review of 38 cases of ischemic optic neuropathy (ION) is given. All the patients exhibited typical signs of papilledema with rapid transition to optic nerve atrophy and nerve fiber bundle defects in the visual field. General examination revealed increased diastolic blood pressure in 17 cases, as well as other signs of arteriosclerosis. Biopsy of the temporal artery showed in 11 cases only arteriosclerotic changes; in 12 cases the ESR was accelerated in the first hour. The dreaded arteritis temporalis could be etiologically almost completely eliminated on the basis of these findings. The term of ‘vascular opticopathy’ is proposed for this hypertensive arteriosclerotic form of ION. Our review shows moreover the following facts: the prevalence of males in the 6th and 7th decade of age; the prevalence of hypermetropic or emmetropic eyes (only 3 myopic among 50 eyes); retention of usable vision in two thirds of the unilateral and in one half only of the bilateral cases. The latter show a parallelity in the course and outcome of the diseases in both eyes.

A brief review of the major psychological refractory period (PRP) theories reveals that they have lost their original objective, i.e., to explain human information processing under rapid sequential stimulation. Conventional data interpretation has restricted attention to delay of reaction times as a result of interstimulus interval (ISI) variation. This form of data interpretation fails to capture important performance aspects under double-stimulation, e.g., the phenomenon that stimulus complexity affects the processing rate. Effects of stimulus rate and complexity are better analyzed in terms of reaction times as well as interresponse intervals (IRI). If this is done, behavioral phenomena emerge that cannot be explained within the frame of any of the existing PRP theories. To account for these newly revealed phenomena a processing interrupt model is introduced which is based on three major hypotheses: single-channel processor, additive stages, and perceptual interrupt facility.

Averaged evoked cortical potentials were investigated as a function of the on- and off-set of patterned light (white polka-dots on black background) and the density and sharpness of contours. Six adult human subjects viewed patterned stimuli which were illuminated once every 1.3 sec for 600 msec. Contour density and sharpness was varied by varying the size and distance between polka-dots (0–35 min of arc) and induced refractive error (0–5 diopters). Analyses of variance indicated that dot-size and between-dot-distance significantly influenced the amplitude of early and late components of evoked responses to both the on-and off-set of pattern (P < 0.01). In general, response amplitude progressively decreased as a function of decreased distance between elements and increased refractive error. The results were discussed in terms of lateral inhibition and the size of receptive field centers of on- and off-center cells in the visual system of animals.

A CAUSE of false scotoma is deserving of presentation because the potential frequency of the type of scotoma is greater than the combined incidence of all other types and because false scotoma simulates a genuine scotoma so closely that it may be misleading. At the University of Michigan eye clinic we use a 10-mm. white circle for a fixation target at 1 meter on the black campimeter screen; and when searching for central scotomas we not infrequently move the appropriately sized object out from this central target until the patient says that he sees it. With this method, however, a central scotoma almost invariably appears under cycloplegia in patients with uncorrected ametropia. The intensity of this scotoma depends on the degree of ametropia and is essentially unchanged by changes in illumination, ranging from ordinary indoor lighting to very subdued light. If there is no associated macular or other pathologic change

Aim: To study accommodation in relation to different refractive errors, amblyopia and to measure the anatomical changes in the accommodating eye Materials and methods: We studied the amplitude of accommodation (AA) in 150 patients in the age group 11 – 30 years which included emmetropes, myopes, hypermetropes and hypermetropic amblyopes using the Royal Air Force (RAF) rule. The anterior chamber depth (ACD), axial length (AxL) and lens thickness (LT) changes during accommodation were measured using an A-scan. Myopes and hypermetropes were further divided based on the amount of refractive error : < 2D, 2 -4D and > 4D. Results: Corrected low myopes had the highest accommodation amplitude (p < 0.05) followed by emmetropes. Corrected hypermetropes were found to have the lowest amplitude of accommodation (p < 0.05). The amblyopic eye had a significantly low AA compared to the non-amblyopic eye (p < 0.05). ACD decreased (p < 0.05) and LT increased (p < 0.05) during accommodation. The AxL increase was maximum in myopes (p < 0.05) followed by hypermetropes but the change was not significant in hypermetropes (p > 0.05). Conclusion: The amblyopic eye has low amplitudes of accommodation proving the benefit of near adds in amblyopic patients. Prolonged near work might induce myopia in susceptible eyes by increasing the axial length. Key words: accommodation, refractive error, amblyopia, biometric changes DOI: http://dx.doi.org/10.3126/nepjoph.v3i2.5267 Nepal J Ophthalmol 2011; 3(2): 146-150

Introduction: Uncorrected refractive error is an important cause of childhood blindness and visual impairment. Objective : To describe the patterns of refractive errors among children attending the outpatient clinic at the Department of Pediatric Ophthalmology, Lumbini Eye Institute, Bhairahawa, Nepal. Subjects and methods: Records of 133 children with refractive errors aged 5 - 15 years from both the urban and rural areas of Nepal and the adjacent territory of India attending the hospital between September and November 2010 were examined for patterns of refractive errors. The SPSS statistical software was used to perform data analysis. Results: The commonest type of refractive error among the children was astigmatism (47 %) followed by myopia (34 %) and hyperopia (15 %). The refractive error was more prevalent among children of both the genders of age group 11-15 years as compared to their younger counterparts (RR = 1.22, 95 % CI = 0.66 – 2.25). The refractive error was more common (70 %) in the rural than the urban children (26 %). The rural females had a higher (38 %) prevalence of myopia than urban females (18 %). Among the children with refractive errors, only 57 % were using spectacles at the initial presentation. Conclusions: Astigmatism is the commonest type of refractive error among the children of age 5 - 15 years followed by hypermetropia and myopia. Refractive error remains uncorrected in a significant number of children. DOI: http://dx.doi.org/10.3126/nepjoph.v4i1.5858 NEPJOPH 2012; 4(1): 90-95

Introduction: Refractive errors are a major cause of visual impairment in the population. Purpose: To find the pattern of refractive errors among patients evaluated in a tertiary care hospital in the western region of Nepal. Materials and methods: The present hospital-based retrospective study was conducted in the Department of Ophthalmology of the Manipal Teaching Hospital, situated in Pokhara, Nepal. Patients who had refractive error of at least 0.5 D (dioptre) were included for the study. Results: During the study period, 15,410 patients attended the outpatient department and 10.8% of the patients were identified as having refractive error. The age of the patients in the present study ranged between 5 - 90 years. Myopia was the commonest refractive error followed by hypermetropia. There was no difference in the frequency of the type of refractive errors when they were defined using right the eye, the left eye or both the eyes. Males predominated among myopics and females predominated among hypermetropics. The majority of spherical errors was less than or equal to 2 D. Astigmatic power above 1D was rarely seen with hypermetropic astigmatism and was seen in around 13 % with myopic astigmatism. "Astigmatism against the rule" was more common than "astigmatism with the rule", irrespective of age. Conclusion: Refractive errors progressively shift along myopia up to the third decade and change to hypermetropia till the seventh decade. Hyperopic shift in the refractive error in young adults should be well noted while planning any refractive surgery in younger patients with myopia. Keywords : myopia; hypermetropia; astigmatism; ethnicities; age DOI: 10.3126/nepjoph.v2i2.3714 Nep J Oph 2010;2(2) 87-96

A study was made to check the reliability of dynamic retinoscopy findings in a modification of the bell retinoscopy technique. The study was to compare findings between two examiners, the authors. Selected subjects in the test sample were retested to determine if the retinoscopy techniques were a variable. One examiner was measuring the light shadow edge of the beam with rather large sweeps of the instrument. The other was measuring the very center of the beam with very small, rapid sweeps of the instrument. The retest data confirm that the technique differences could account for at least 3.50 D difference at the 40 cm test distance. Retinoscopy is one of the basic optometric test procedures for objectively evaluating the optical status of a patient. All of the optometry schools in the United States emphasize both the theoretical and applied aspects of this test procedure in their curricula. Yet some men in optometric practices view retinoscopy findings with doubts and reservation. Many optometrists express a lack of confidence in their ability to interpret the results of dynamic skiametry, particularly the techniques commonly referred to as “book retinoscopy” and “dangle bell retinoscopy.” They question the reliability of these techniques. One of the more disturbing elements of these private “confessions” is that the doubters are often the most competent and thorough clinicians. The present study was carried out to determine the reliability of modified bell retinoscopy findings. We tested the same subjects, using presumably the same procedures and identical instruments, under the same conditions. The tests were modifications of the bell retinoscopy procedure. The data revealed that the findings of the two optometrists were not the same, despite the standard conditions. It was then hypothesized that the different results were due to variation of retinoscopy procedures of the examiners. Additional testing did show that there were two significant test factors not initially recognized. These were: 1) what area of the reflex examiner was looking at during the administration; 2) how he moved his instrument during the procedure. test Description The test target was a chrome-plated sphere, one-half inch in diameter. It was attached to an anodized aluminum rod, 3/16” in diameter. This target works well for two reasons. First it enables the subject to report clarity, while maintaining its desired three-dimensionality. Second, a sphere maintains a constancy of shape when seen from any vantage point. Therefore, the spherical target allows the subject to be more aware of the spatial changes directly related to the retinoscopy procedure. The subject, then, is not distracted by any change in target shape. Fig. 1 presents the equipment diagram. The test target (T) was suspended in a clamp holder so that it moved parallel to the carrier track and floor, and could be adjusted to the subject’s eye level. The Correspondence regarding this article should be emailed to dmaino@covd.org or sent to Dominick M. Maino, OD, MEd, Illinois College of Optometry, 3241 S. Michigan Ave., Chicago, IL 60616. All statements are the author’s personal opinions and may not reflect the opinions of the College of Optometrists in Vision Development, Optometry & Vision Development or any institution or organization to which the author may be affiliated OVD is indexed in the Directory of Open Access Journals. Online access is available at http://www.covd.org.

Objectives: Refractive errors are the one of the most common visual disorders found worldwide in school going children and it is also one of the causes of blindness. It can easily be prevented, if timely proper measures are taken. In Kathmandu valley and Mechi Zone of Nepal, the distribution of refractive errors was found to be very high. No records are available from the Western part of Nepal. Considering the importance of the refractive errors the present study had been undertaken in Pokhara city. Materials and methods: Nine hundred and sixty four subjects (474 boys, 490 girls) were selected between age groups 10 to 19 years from six schools representing different region of Pokhara. After Preliminary examination: on acuity of vision with Snellen's and Jaeger's charts, the subjects were referred to the Manipal Teaching Hospital, Pokhara for confirmation of the refractive errors. Results: Sixty two schools children (6.43%), out of 964 had refractive errors. Myopia was found to be most common (4.05%). The refractive errors were found more in Private school children (9.29%) than Government school children (4.23%), which is statistically significant (P < 0.05). More boys (7.59%) were found to have suffered from refractive errors than girls (5.31%). Further, children with vegetarian diet (10.52%) had greater number of refractive errors than non-vegetarian diet children (6.17%). Conclusion: In the present study, percentage distribution of myopia was found to be higher (4.05%) than the hyperopia (1.24%) and astigmatism (1.14%). Interestingly, in the present study the refractive errors were found significantly higher in Private schools children than Government schools because the children who read in Private schools have higher socioeconomic status; spend more time in home work, watching Television and Computer as compared to government schools children. These near activities of the eyes causes stress on eyes of the children and might be one of the causes of developing myopia. Key words: Refractive errors, Nepal, Myopia, Hyperopia doi: 10.3126/kumj.v7i1.1769 Kathmandu University Medical Journal (2009), Vol. 7, No. 1, Issue 25, 67-72