摘要:

Equivalent oxygen (E.O.P.) responses, using a mammalian corneal model, were measured for open- and closed-eye conditions, and with and without the presence of a silicone. a standard thickness HEMA, and an ultrathin HEMA contact lens. Under open-eye conditions, the silicone lens even with a center thickness of 0.25 mm, diminished the E.O.P. response insignificantly compared to the no-lens condition. The ultrathin HEMA lens (0.06-mm center thickness) produced a response approximately three times superior to that of the standard thickness HEMA lens. Under closed-eye conditions, only the silicone lens, however, caused the cornea to respond within the Polse-Mandel zone.

ISSN:0093-7002    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

The population of a large Canadian institution providing rehabilitative and health care for the mentally retarded received oculo-visual assessments in an optometric clinic established in the hospital by the University of Waterloo, School of Optometry. The ocuiar and visual anomalies of 1242 residents nave been compiled and analyzed. This paper reports the results and discusses their implications. The size of the sample makes the data useful in planning vision care delivery to the mentally retarded. Comparisons are made to similar data obtained from a concurrent study of a community, sample and to studies from vision literature.

ISSN:0093-7002    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

Contrast thresholds with sine wave grids, spatial frequency thresholds and border enhancement spread were measured while the amount of scattering in the retinal image was varied. Narrow-angle scattering similar to that produced by the cornea and crystalline lens was generated by specially designed filters. The purpose was to assess the effectivity of these widely different responses as measures of small order scattering effects. As noted by other investigators, spatial frequency thresholds proved insensitive to small amounts of scattering. On the other hand, contrast thresholds for high frequency targets and border enhancement spread both showed significant changes with small amounts of scattering. Of these two criteria, border enhancement proved to be the more consistent scattering index.

ISSN:0093-7002    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

To estimate the potential for ozone (O3) effects on the human visual system in flight. O3concentrations in Boeing 747–100 cockpits were measured during routine flights between London and the United States. From a review of previous reports, it appears that O3may have both beneficial and harmful effects but thai further studies of the visual system responses to O3are needed before the present findings of 0.030 parts per million (ppm) mean O3, 0.200 ppm maximum O3, and 0.261 ppm-hours average cumulative O3exposure can be effectively evaluated. Unexpectedly high O3, concentrations were encountered at altitudes below 18,000 feet and, at times, the O3concentration was observed to decrease as flight level was increased. The clinical, operational, and policy implications of these findings are discussed.

ISSN:0093-7002    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

Transmittance filters with selected dominant wavelengths, when placed in the light path between the light source of a retinoscope and the retinoscopist's eye, make possible a clinical measurement of the chromatic aberration of an eye. This kind of retinoscopy (chromoretinoscopy) also determines the approximate wavelength in focus in the retinal plane, when an eye is fixating an object at some distance. For laboratory purposes, these measurements can be considerably refined when a high intensity monochromator is used as the retinoscope's light source and care is taken to fix the subject's accommodation.

ISSN:0093-7002    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

It has been noted clinically that hard resin lenses mounted in rimmed frames exhibited bitoricity. The manufacturers of optyl plastic frames claim thai the molecular structure of optyl eliminates the bitoric effect. This study involves “clocking” hard resin lenses mounted in frames fashioned of optyl, zylonite plastic, and metal mountings to test this hypothesis. The results are important because of the increasing use of optical CR 39 plastic in the fabrication of eyewear.

ISSN:0093-7002    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

Fitting contact lenses for extended wear requires special lenses and sophisticated skills on the part of the fitter. Problems which may occur involve oxygen transmission, protein accumulation, neovascularization, conjunctival papillae and hyperemia, and corneal swelling. The need to keep the lenses clean and for frequent reexamination of the ocular tissues puts more demand on both the practitioner and the patient. The practitioner who fits extended wear lenses needs adequate instrumentation and the skill and time to care for the patient. He must also be easily accessible to the patient.

ISSN:0093-7002    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

Visual screening tests were done on 61 individuals with various types of genetic skeletal dysplasias to determine which, if any, refractive errors are associated with each type. In individuals with achondroplasia, refractive error distribution was approximately that expected from its distribution in the general population. However, there was a significantly higher than expected frequency of strabismus in achondroplasts. A tendency to myopia was noted in diastrophic dysplasia and in those individuals with spondyloepiphyseal dysplasia.

ISSN:0093-7002    

出版商:OVID    

年代:1980

数据来源: OVID

ISSN:0093-7002    

出版商:OVID    

年代:1980

数据来源: OVID

ISSN:0093-7002    

出版商:OVID    

年代:1980

数据来源: OVID