ISSN:0002-9408    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Objective recordings of eye movements in a patient with congenital pendular nystagmus showed only tiny superimposed saccades. Also, in tracking movements and in special “variable feedback” experiments, where a normal subject would ordinarily exhibit mainly fair-sized saccades, the patient showed only markedly decreased saccades. However, these small saccades showed maximal velocities appropriate to their reduced amplitudes: thus suggesting normal “time-optimal” motor control signal shapes and a normal extra-ocular muscular system. The increase in pursuit movements seems to be a compensatory effect secondary to the basic defect in saccades.Prisms were prescribed to minimize the amplitude of the nystagmus since it had shown dependence upon angle of gaze and amount of vergence. Excellent subjective results were obtained and indicated that the sensory visual mechanism was normal.Since the efferent signal shape. the muscular system. and the afferent visual system are all normal. and the smooth pursuit system better than normal (compensatory adjustment), we suggest that the basic defect in our patient is early in the generation of intermittent control signals for saccades from the central nervous system dual mode controller.

ISSN:0002-9408    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

A mathematical model, predicting the lifting forces required to dislodge an “on K” (or near “on K”) fitted contact lens from the corneal surface, was tested in the laboratory. While the greatest force increases occurred with the addition of an initial 0.2 mm aperture. Further expansion of aperture diameter brought progress by smaller force increases.

ISSN:0002-9408    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Measurements of the threshold of stereopsis under conditions in which a difference in monocular retinal illuminance exists indicate a decrease in sensitivity. Delaying one of the two binocular images was used as a means of investigating whether or not the decrease in stereo sensitivity due to differences in monocular retinal illuminances could be equated to changes in latency. The study indicates that a pure latency hypothesis is too simple a concept to account for the results.

ISSN:0002-9408    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Previous investigations of the mechanical properties of the cornea have dealt with postmortem material which has been reported as having a delayed as well as an instantaneous component in its response to deforming forces. In the present investigation the recovery of the humanin vivocornea after deformation was measured by a photokeratoscopic method. The delayed component of the recovery was much smaller than expected on the basis of some published results for thepost-mortemmaterial.

ISSN:0002-9408    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

This study was designed to determine the corneal toricity which is transferred to the front surface of a gel contact lens as the thickness of the lens varies. Five different Griffin Hydrogel contact lenses of essentially the same dimensions, except thickness. were used. Keratometer readings and a monocular subjective refraction were taken without a lens on the eye and with each of the five lenses on an eye for each of ten subjects. In general there was a direct transfer of the corneal toricity and axis to the front surface of the gel lens regardless of lens thickness. In general, the subjective astigmatic correction was unchanged with each of the five lenses. The original corneal toricity and axis, and subjective refractive cylinder are generally not altered by the wearing of Hydrogel lenses of different thicknesses.

ISSN:0002-9408    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Fifty-three persons with healthy eyes were fitted with spherical contact lenses and monitored over a 90-day test period. Clinical tests of keratometry, central corneal clouding and subjective spectacle blur refraction with resultant visual acuity were conducted at four time intervals and those test constituted the profiles. Adaptation was judged complete for 78 eyes. The critical test was the subjective blur refraction and the resultant visual acuity. The keratometer flat meridian was also unchanged. The observation of central corneal clouding did not correlate with these findings. The remaining 23 eyes were not adapted in the 90-day test period. These eyes were identifiable as early as the first day of wear.Four profiles of adaptation were built; fast adapting eyes, slow adapting eyes, eyes with near spherical corneas and eyes with astigmatic corneas.

ISSN:0002-9408    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

This experiment tested the hypothesis that the formation of educational skills of writing and drawing are preceded before school age by development of dynamic continuously-controlled tactual, auditory, and visual tracking abilities that are based primarily on social following of movements made by others. A portable photoresistor visual tracking device was developed to measure the performances of children between 3 and 14 years of age in tracking movements made by an experimenter in forming visual figures on translucent glass plate. Results showed that there is a marked maturational increase in such social tracking ability with a plateau of development at 9 to 11 years in the age range studied. Preschool children also were found to be capable of doing social tactual and auditory speech tracking and to perform the tactual tracking with smooth uninterrupted movements never observed in the visual social tracking. Children under four years of age were shown to be able to write the alphabet dynamically tracking the form letters made by an experimenter. It was concluded that a major function of the tactual system in infancy and childhood may be to provide high-speed stabilizing feedback essential to maturation of smooth flowing movements needed in writing, drawing, and other educational maturation of smooth flowing movements needed in writing, drawing, and other, educational skills. The findings add to previous experiments showing that social visual tracking develops between six months and three years of age in relation to dynamic activity of parents and others. Years before he can reproduce static object or letter forms through drawing and writing. the preschool child can execute dynamic social tracking movements in making such patterns. Dynamic, social, feedback-controlled imitation thus constitutes a diversified form of pretraining in the maturation and learning of educational skills.

ISSN:0002-9408    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Experience with the fitting of contact lenses on children, over a period of 8 years, is reported. The children ranged in age from 6 weeks to 14 years. The conditions for which the lenses were fitted were: Bilateral and unilateral aphakia (31 cases), anisometropia (16 cases) and high myopia (21 cases). The benefits of the contact lens as an optical and corneal device in infants and children is presented.

ISSN:0002-9408    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

A foveal after-image transferred from the normal to the amblyopic eye has been used in a method treating amblyopic and eccentric fixation. The patient aligns the after-image projected by the amblyopic fovea with letters of decreasing sizes. Thus, eye aiming errors are eliminated, resulting in foveal fixation and improved visual acuity.

ISSN:0002-9408    

出版商:OVID    

年代:1972

数据来源: OVID