摘要:

An optometer is described that provides an electrical signal proportional to the amount of movement of the anterior surface of the crystalline lens. Dynamic recordings of this movement were made on a number of subjects tracking predictable (periodic) and nonpredictable target step movements. Histograms of the reaction times definitely show that the accommodation system can reduce its delay time when presented with a predictable stimulus. Typical accommodative reaction times are compared to those published by other authors in the literature.The change of anterior chamber depth lens curvature, and pupil diameter are related to accommodative target distance by a photographic method and help to provide a clearer understanding of accommodative lens changes.

ISSN:0002-9408    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

When a bi-prism is used to split a field into two parts a dark line is seen at the dihedral edge. This can be demonstrated to be due to an imperfect edge. This can be avoided by using a mirror to split the field. A different kind of artifact can arise when the source is made conjugate to the pupil instead of the retina. Other sources of trouble are axial chromatic aberration, lateral chromatic dispersion and diffraction. These variables can be controlled to produce an acceptable bipartite pattern for beterochromatic luminance matches and testing the sensitivity to differences in chromaticity.

ISSN:0002-9408    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Of 47 eyes of 25 patients fitted with the GriffinNaturalens, all but two eyes attained 20/20 or 20/15 visual acuity in spite of up to – 2.25 D of uncorrected astigmatism. Astigmatism on the front surface of the soft lens, as measured by the keratometer, showed a close relationship to corneal astigmatism without the lens, indicating that the lens conforms almost perfectly to the corneal toricity. A similar relationship was found between subjectively determined astigmatism with the lens in place and without the lens. When fitting a patient with significant astigmatism with soft contact lenses. the practitioner should be aware that blurring of vision and symptoms of asthenopia may result, even though the patient attains 20/20 visual acuity in the refracting room.

ISSN:0002-9408    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Thirty patients were given two pairs of spectacles and requested to state a preference. These spectacles were identical in every respect except that the cylinder was located on the rear surface of the lenses for one pair and the front surface for the other. There was no significant difference in the patient's choice of plus or minus cylinder form. There was a tendency, however, for patients who wore spectacles constantly to prefer the same lens form that they had worn previously.

ISSN:0002-9408    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

The relative radiant power and luminous power spectra of the emission from a commercially available red highway flare are reported.

ISSN:0002-9408    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Eccentric fixation may be measured in prism diopters in amblyopic eyes by means of a simple device. A pinhole slightly eccentric to the geometric center of a circular disc is used: as the disc rotates the observer observes entoptically a filmy pattern of his retinal vasculature. The method has been tested on 240 eyes and a high degree of correlation was found between the amount of eccentric fixation and the decrement in acuity.

ISSN:0002-9408    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

When a small diaphragm is placed at the back focal plane of the photokeratoscope, a differential equation which can determine the corneal topology in one plane is obtained. The solution of the differential equation results in a more accurate description of corneal topology than previous methods. The solution of the equation requires computer programs.For each keratoscope ring of a variable coordinate a and a fixed coordinate b, a differential equation is obtained. One differential equation characteristic of the corneal surface was sought. For the discret values are the polynomial function a1= a(y) was substituted. The numerical precision was demonstrated to be exact enough for practical purposes. Experimental errors had a minor influence on keralogram evaluation. Results were corrected for corneal misalignment. Corrections for defocusing require very precise measurement of the smallest ring image diameter. When the corneal vertex-position was aligned with an accuracy of 0.2 mm, the accuracy of measurement at the corneal periphery was better than 0.02 mm.

ISSN:0002-9408    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Star-tracing performance of 31 fourth graders, 14 boys and 17 girls, were measured and analyzed with respect to sex difference and eye-hand preferential difference for boys and girls separately. Results showed significant sex difference but not eye-hand preferential difference, meaning that the boys are superior to the girls in eye-hand coordination and that the so-called laterality or dominance has no effect on such performance.

ISSN:0002-9408    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

This paper contains a brief analysis of the problems involved in measuring near point acuity levels of preschool children, and the methods presently available for this measurement. A new near point acuity test card for these children is proposed, along with a summary of the factors considered in its design.

ISSN:0002-9408    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

The author discusses his experience over the past three years with 80 patients for whom he prescribed Omnifocals. He points out five major areas where problems can occur and offers his solutions. Despite these problems, the many advantages outweigh the disadvantages: and he concludes that the Omnifocal is an excellent lens when properly prescribed for selected patients.

ISSN:0002-9408    

出版商:OVID    

年代:1972

数据来源: OVID