摘要:

The binocular depth of focus of monovision wearers was compared to the sum of the two monocularly determined depths of focus. Observers fell into three groups based upon ocular sighting dominance. Complete binocular summation of the monocular depths of focus was observed in subjects without a preferred fixating eye. Subjects who preferred to fixate with one eye had difficulty suppressing blur of that eye while the binocular target was within the depth of focus of the nonpreferred eye. A third group showed partial summation of the two monocular depths of focus. Similar patterns of accommodative response, measured objectively with the SRI optometer, were observed in subjects wearing monovision corrections. Accommodative response to sinusoidal variations in blur was controlled primarily by the dominant sighting eye. These results demonstrate the effectiveness of interocular suppression of anisometropic blur in monovision correction and the influence of ocular dominance upon this suppression process.

ISSN:0093-7002    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

Pre- and post-task measures of dark-focus (DF) were used to assess accommodative adaptation induced by a 45-s near-vision task at 33 cm. Adaptation was measured under monocular and binocular conditions for a group of 10 young emmetropic subjects (mean age 21.6 years). The accommodative response was measured objectively using an infrared optometer (Canon Autoref R-1). Post-task DF was sampled immediately after the task at 1-s intervals over a 90-s period. No significant difference in accommodative adaptation was observed between the monocular and binocular near-vision tasks. The implications of this finding are discussed with regard to the oculomotor constituents of the closed-loop accommodative response.

ISSN:0093-7002    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

We investigated the effects of the ophthalmic preservatives thimerosal and sorbic acid on the proliferation and survival of rabbit corneal epithelial cells in tissue culture. Normally, explants of corneal epithelium grow vigorously during the first 7 days in culture. With 0.004% thimerosal present in the culture medium, the normal proliferation of corneal cells is suppressed completely. When 0.1% sorbic acid is present, proliferation is delayed and the lifespan of the corneal cells is reduced. After a 1-h exposure to concentrations of thimerosal of 0.0005% or greater, virtually all corneal cells present in established cultures are killed. These results suggest that use of ophthalmic preparations containing these chemicals may affect the metabolic and proliferative capacity of the corneal epithelium adversely.

ISSN:0093-7002    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

Gas permeable (GP) lenses can flex on some eyes producing unpredictable clinical results. A method of measuring the flexibility of hard GP materials has been developed and shown to be repeatable. Materials in the form of flats rather than lenses were used. Differences between materials were found and in general a linear relation was shown to exist between maximum flexing and quoted oxygen permeability (r = 0.78, p < 0.05). It is recommended that flexibility be measured and reported in the data presented with all new GP polymers. The term “hard” rather than “rigid” in describing GP lenses is suggested.

ISSN:0093-7002    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

The directional sensitivity (DS) of the red (π5), green (π4), and blue (π1) color mechanisms was measured for both the horizontal and vertical pupil meridians, thus localizing the peak of each π-mechanism DS function within the two-dimensional pupillary aperture. In the horizontal meridian, there were greater differences among observers in DS function peak locations than there were for any one observer. Along the vertical meridian, peak location differences within observers were similar to those found in the horizontal meridian, whereas among-observer differences were much smaller. Significant differences between horizontal and vertical DS function halfwidths were also found for at least one π-mechanism of each observer. It is concluded that meridional variations exist in either the morphology or orientational distribution of foveal photore-ceptors, and that more than one alignment mechanism is responsible for photoreceptor orientation in the human fovea.

ISSN:0093-7002    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

This paper describes three sisters, triplets, age 7 years, 2 months, two of whom derive from a single ovum, the third from a second ovum. As such, they provide an opportunity to examine the relative impact of heredity on certain of their physical, developed, and acquired abilities and characteristics. In addition to a comparison of such physical traits as height, weight, refractive status, axial length, and so on, certain (developed) sensory-motor and (acquired) cognitive and language measures are reported, such as binocular status, visual and auditory analysis skills, intelligence quotient, and (expressive and receptive) language abilities. Because all three children have lived in (more or less) the same pre- and post-natal environment, we assume that whatever concordance the monozygotic (MZ) pair displays that is not shared by their dizygotic (DZ) sister is attributable to heredity. (It does not necessarily follow, however, that any discordance between the two MZ sisters or any concordance between one of them and their DZ sister is attributable to environment.)

ISSN:0093-7002    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

We report a meta-analysis of studies of the relation of vision anomalies to reading skill. Meta-analysis is a quantitative technique for combining the results of multiple studies that reduces the subjectivity of literature reviews. The results of the analysis of 34 studies of vision anomalies and reading skill that met the criteria for inclusion in the meta-analysis showed that hyperopia, exophoria at near, vertical phoria, anisometropia, and aniseikoniasre associated with below average reading performance. Myopia and esophoria and esophorla at far are associated with average and above average reading performance. Reduced visual acuity, astigmatism, esophoria at near, fuelonal convergence and divergence, strabismus, nearpoint of convergence, and stereopsis were not found to be associated with reading performance.

ISSN:0093-7002    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

Phakometry is a technique for measurement of the crystalline lens radii of curvature, usually involving photography of the Purkinje images. We have devised a system of comparison phakometry using commercially available camera equipment. This paper contains a description of the apparatus, technique, and necessary calculations. Reliability of the method is discussed.

ISSN:0093-7002    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

Twenty-three patients suffering from the progressive cone dystrophies (PCD) were evaluated retrospectively, after they had undergone treatment for low vision. All patients were able to read 1 M or smaller print with magnification, despite poor central acuity. Eighteen (78%) patients achieved their primary rehabilitation goal, and 86% of the low vision devices prescribed were used at follow-up. Photosensitivity was reported by a large number of patients. Seven patients indicated that alleviating this problem was their primary rehabilitation goal. Eight (35%) found sun filters to be helpful. Our successful experience with patients with these disorders suggests that examination for, and trial of, low vision devices is warranted.

ISSN:0093-7002    

出版商:OVID    

年代:1988

数据来源: OVID

ISSN:0093-7002    

出版商:OVID    

年代:1988

数据来源: OVID