摘要:

ABSTRACTMany methods can be used to obtain specific values for relative corneal location. This paper derives a method in which those points can be used to generate a mathematical equation which will accurately describe the patient's corneal topology. After various dimensional methods are discussed, a three-dimensional mathematical method is derived.

ISSN:0093-7002    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

ABSTRACTThe purpose of this study was to obtain a numerically accurate discrete model of the effect of front aspheric soft lenses of various asphericities on the retinal illuminance profiles within the blur circles of a model eye. A computer program was developed for a model eye based on geometrical optics. The ray density was assumed to be proportional to the flux density or illumination. Retinal illuminance profiles are calculated for several values of defocus and asphericity. These results are validated by calculations based on modulation transfer functions (MTFs), observational data from contrast sensitivity and clinical results with Cals aspheric soft lenses. The results suggest that aspheric soft lenses maximize the central illuminance of blur circles and extend the range of desensitivity to retinal defocus in the eye to 4.00 D at the largest asphericity constant investigated.

ISSN:0093-7002    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

ABSTRACTKatz described a design for a postcataract spectacle lens with two aspheric surfaces. Previously, von Rohr and Jeffree had patented designs with similar optical properties, but using steeper lens forms than the Katz design. These three design studies are compared with two aspheric spectacle lenses that have been produced commercially in order to demonstrate the differences in calculated aberrations and their significance on the practicality of a lens design.

ISSN:0093-7002    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

ABSTRACTA randomized, double-masked, placebo-controlled study was conducted to determine the effect of the prostaglandin-inhibitor naproxen on the bleb response of the corneal endothelium during hydrogel contact lens wear. Naproxen did not significantly alter the bleb response. This finding suggests that the endothelial bleb response is not prostaglandin-mediated.

ISSN:0093-7002    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

ABSTRACTFour hundred forty-seven of five hundred beginning 2nd-year optometry students responded to a survey requesting them to report the equivalent sphere of the lenses neutralizing their most ametropic eye and, if myopic, the age at which they were first prescribed lenses. The population was 20% female, 80% male, and predominately Caucasian. The mean refractive status was –2.21 D with a range from –11.00 to +5.50 D. Seventy-five percent of the respondees were myopes. There was a clear relation between final amount of myopia and the age at which corrective lenses were first prescribed. New myopes did not seek care in equal numbers at each age, but instead clustered in three groups: ages 8 to 9 years, 12 to 13 years, and 19 years. Regression characteristics were different when myopes of 0.12 to 6.00 D were segregated from the total group, suggesting different rates of change, and, by implication, different populations within the group. Females tended to become myopic earlier. There were proportionately more high myopes among the females than among the males.

ISSN:0093-7002    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

ABSTRACTIn this study, five dissimilar crossed cylinder targets were used to determine the cylindrical component of the refractive error of 30 subjects. Our purpose is to see if variations in target configuration affect the results of the test. Although there are statistical differences when targets with different configurations are used in determining astigmatism subjectively, these differences are not clinically significant if we assume that the least amount of error required for clinical significance is 0.25 D. We conclude that dissimilar crossed cylinder targets yield similar astigmatic findings clinically.

ISSN:0093-7002    

出版商:OVID    

年代:1984

数据来源: OVID

ISSN:0093-7002    

出版商:OVID    

年代:1984

数据来源: OVID

ISSN:0093-7002    

出版商:OVID    

年代:1984

数据来源: OVID

ISSN:0093-7002    

出版商:OVID    

年代:1984

数据来源: OVID

ISSN:0093-7002    

出版商:OVID    

年代:1984

数据来源: OVID