摘要:

The tear-turnover rate of 68 normal human subjects (age range 15–63 yr) was determined using a slit lamp modified to serve as a fluorophotometer. Tear volume and tear secretion, computed from tear-turnover rate, had mean values of 8.47 μl and 1.78 μl/min, respectively. Analysis of the results shows a decrease in tear production with age. The mean tear-flow rate was 1.55 μl/min in subjects aged 15–39 and 0.95 Zμl/min in subjects aged 40–63. This fluorophotometer is adaptable to a clinical setting and may prove useful in diagnosis and treatment of anomalies of tear production.

ISSN:0093-7002    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

Sensitivity to blur detection was measured for 30 optometric patients by having them match the clarity (or blur) of the target words at the test endpoint with 1 of an identical set of photographically defocused words. The group showed considerable variance in their blur scores which approached a normal distribution. Some clinical implications are discussed.

ISSN:0093-7002    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

When a hydrogel lens is placed on the eye, its power may change because of flexing of the lens. The correcting power of the lens when on the eye can be calculated by assuming that the lens flexes to the shape of the underlying cornea. Actual measurements of the correcting power of a Hydrocurve lens on the eye were not in agreement with the calculated values. Assuming that the front and back surfaces of the lens flex by the same amount, the presence of a fluid lens between the hydrogel lens and the cornea would account for this discrepancy. For minus lenses of moderate and high power, it was found that the change in power was in the direction of more plus; for low minus and all plus lenses, the change was in the direction of more minus. Under the conditions of the present investigation, correcting power measured with the lens on the eye was in agreement with the calculated value for regular-thickness Hydrocurve lenses of −2.00 D and thin lenses of –0.75 D. This is interpreted to mean that lenses of these powers conform to the shape of the cornea so that the fluid lens is thin and piano. The clinical implications are discussed.

ISSN:0093-7002    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

The steady-state, monocular accommodation response to sinusoidal grating targets was assessed as a function of the spatial frequency of the grating and its vergence at the eye, using a laser optometer. At all levels of accommodative stimulus, the response was found to be dependent on grating frequency. At very low frequencies, the response was often substantially in error and was closely related to the accommodation exercised by the observer when viewing an empty field. At higher frequencies, the response became more accurate. Possible models for accommodative strategies underlying the experimental results are discussed. A model involving dynamic evaluation of the changes in retinal-image modulation produced by accommodation fluctuations accounts for many features of the observations.

ISSN:0093-7002    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

The visible-light transmission of various Bausch & Lomb Soflens(r) contact lenses and Hydrocurve(tm) contact lenses was measured with a Perkin-Elmer model 202 UV spectrophotometer. The light transmission for both types of lenses ranged from 96–99%, and was almost constant over the visible spectrum. Neither the power, the thickness, nor the posterior apical radius of the lenses had a significant effect on the amount of light they transmitted.

ISSN:0093-7002    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

In the hands of a trained user, the topographic pachometer proves to be an instrument of acceptable clinical precision (standard deviation = 0.006 mm). An examination of corneal thinning during waking hours revealed a rate of thinning which was greatest upon lid opening and which declined uniformly throughout the day (p = 0.01). An investigation into menstrually related change in corneal thickness revealed that at least 122 subjects would be required to investigate this change on an acceptable statistical basis (p = 0.05).

ISSN:0093-7002    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

The EOG ratio is an established clinical test of retinal function. Since its development by Arden and coworkers in 1962, it has been thought of as simply a rod-mediated response. Using scotopically matched red and blue lights, we found a 24% larger response to the red light than to the blue light, establishing that a cone contribution exists in the EOG ratio of normal subjects.

ISSN:0093-7002    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

Air Force laser safety standards are developed from laser-exposure data obtained in studies using experimental animals and from biomathematical modeling procedures. Interpretation of research data and predictive modeling calculations are enhanced by knowledge of the temperature values of the tissue absorption sites. Corneal temperature values for the normal, the anesthetized, and the laser-injured Dutch belted rabbit are presented and compared with values obtained in other studies. The corneal temperatures were measured by infrared radiometry.

ISSN:0093-7002    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

Examination of some 6000 Navajo children in their schools in the Shiprock, New Mexico area between 1975 and 1977 yielded an overall prevalence of trachoma of 2.4%. The prevalence was highest for high schoolers (3.8%) and lowest for pre-schoolers (2.3%). These prevalences are lower than those found (6.0%) for Navajo schoolchildren in the Gallup, New Mexico area 8–9 yr previously.

ISSN:0093-7002    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

Although patients with frank goiter are less commonly seen in optometric offices than they were 20 years ago, there are still numerous patients with visual problems associated with endocrine dysfunction who consult optometrists. A review of the ocular signs, and symptoms, following Werner's classification, is presented.

ISSN:0093-7002    

出版商:OVID    

年代:1978

数据来源: OVID