ISSN:0093-7002    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

Stereopsis was assessed in 94 children ages 2–5 yr using random-dot stereograms (RDSs) and operant conditioning. After five traditional screening tests of stereopsis, all children were trained to perform a match-to-sample discrimination task involving RDSs with and without lateral disparity. An added feature of the operant RDS task was the availability of monocular cue-fading for children who failed initial RDS testing. The operant RDS test facilitated stereopsis-based responding more than the traditional clinical tests did. This finding is interpreted as indicating the importance of such factors as attention, motivation, and language ability in the assessment of stereopsis in young children.

ISSN:0093-7002    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

Improvements in polycarbonate material, production techniques, and scratch-resistant coatings, combined with a process-oriented design, have resulted in a precision lens series. Surface quality is comparable to that of untreated glass ophthalmic lenses. The repeatability of the process results in closely controlled axial power and off-axis performance. For most lens prescriptions, the ANSI Z80.1 optical-center specifications for prescription accuracy are maintained through a total field of view of 40 deg for an 8-mm range of center-of-rotation distances. Off-axis astigmatism is controlled for near-point seeing. The lenses are both lighter and thinner than those of crown glass. A scratch-resistant coating reduces the reflections normally associated with high-index (1.586) materials. Impact resistance exceeds that required by ANSI Z80.7 and is many times that required by ANSI Z80.1.

ISSN:0093-7002    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

To identify the surface from which the retinoscopic reflex originates, retinoscopy was performed on 305 eyes of various ages with polarized and depolarized light. The discrepancy between retinoscopic and subjective refraction measures in the two conditions shows that two fundus reflective layers contribute to retinoscopy: a specularly reflecting layer presumably at the retina/vitreous interface and a diffusely reflecting layer near the pigment epithelium. In young eyes the retina/vitreous interface predominates; the other predominates in older eyes.

ISSN:0093-7002    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

The oculomotor performance of 25 dyslexic and 1 9 normal children was evaluated to determine whether or not dyslexia involves deficits in oculomotor function or visual perception. When the children were required to follow a meaningless target or to solve pictorial tasks, the two age-matched groups could not be differentiated. When they were required to read selections commensurate with their measured reading level, the dyslexic children were markedly different on a number of parameters. It appears that the dyslexic's difficulty lies beyond visual perception, perhaps in the language area itself. The dyslexic's characteristic deficit seems to involve the integration of visual input into the language-acquisition function.

ISSN:0093-7002    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

The effective power of the crystalline lens, as well as the effective change in its power (accommodation), depends on its location with respect to the cornea and the retina. This study examines these factors in a theoretical model. The most important factor influencing effective power is shown to be anterior-chamber depth. Eyes with smaller anterior-chamber depths are more efficient in increasing the power of the eye by accommodation.

ISSN:0093-7002    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

Catastrophe theory, a recently developed area of mathematics, is used to model two aspects of visual behavior. Visual behavior measured in a patient undergoing phorometry and the visual behavior of some patients with anomalous retinal correspondence undergoing the Walraven technique are characterized as catastrophes.

ISSN:0093-7002    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

A double-pass, photoelectric, ophthalmoscopic method was used for objective study of the variation in image quality across the retina in terms of the reflected image of a fine line, the line-spread function. Radial and tangential line-spread functions have been studied with active and paralyzed accommodation at eccentricities up to 45 deg. With large pupils, the retinal image quality remained relatively constant over the central 20 deg of field and deteriorated at larger field angles. The results are discussed with respect to field curvature, peripheral acuity, and peripheral refraction.

ISSN:0093-7002    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

Subjective measures of refractive error were obtained on 530 eyes using the AO SR III Subjective Refraction System (operated by a trained secretary) and using a phoropter (operated by optometrists and optometry students) in a clinical setting. Comparison of these measures from the present study and from a previous study by Bannon leads us to conclude that the SR III instrument is capable of estimating refractive error with good agreement with conventional refractive methods. Comparison with the Acuity Systems' 6600 Auto-Refractor(tm) was also made.

ISSN:0093-7002    

出版商:OVID    

年代:1978

数据来源: OVID