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A screening method designed for administration by lay personnel is evaluated and compared to Modified Clinical Technique screening results for a screening of 1600 elementary school children.

Measurements of the refractive errors in 55 strabismic patients--one eye with visual acuity of 0.8 or better and the other with reduced vision, 0.4 or less due to amblyopia, and performed at roughly two-year intervals during growth and development to approximately age 25 years--showed that the eye with normal visual acuity was significantly more myopic with age, whereas there was no appreciable change in the average refractive error of the amblyopic eye. Both eyes of a control group of patients of similar age having normal distant vision and orthophoria were more myopic with age. In this group there was an insignificant difference in the change in refractive error of one eye compared with its fellow during comparable periods of time.

New techniques for recording evoked potentials to sensory stimulation have led to applications with both theoretical and practical implications. Evoked potentials can be used as a diagnostic tool in some pathological conditions, as well as shedding light on the mechanisms by which sensory information is processed in the brain.

Spot diagrams are computer generated by skew ray tracing for a model of the human eye which is corrected by means of a contact lens and spectacle lens. An examination of the images of a point source of light at 0 degrees and 20 degrees off the optical axis of the eye-lens system are shown. For the correction of aphakia, the performance of the contact lens is shown to be superior in off-axis optical performance.

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