摘要:

The diagnosis and monitoring of Fuchs' disease is typically based on information obtained from patient symptoms and a slitlamp examination. Although this clinical information provides a basis for diagnosis, it does not give a quantitative method for charting the progression of the disease systematically or a reliable basis for predicting the cornea's capacity to remain transparent after stress (e.g., cataract extraction). However, it is possible to quantify overall corneal hydration control by inducing corneal swelling and then monitoring the deswelling rate expressed as percent recovery per hour (PRPH). We have tested subjects with Fuchs' dystrophy and found that the PRPH provides a reasonable estimate of corneal hydration control. Unfortunately, the PRPH procedure involves considerable time and technical assistance and therefore is not convenient for clinical practice. In this report, we document the results of an initial effort to explore the relations between PRPH and six clinical measures consisting of five bio microscopic indices and a subjective synthesis of clinical information called the probability of decompensation (POD) based on these indices. PRPH was significantly related to striae (p<0.001), stromal haze (p=0.025), micro cysts (p<0.001), and the POD (p<0.001) and not significantly related to guttae (p=0.252) or Descemet's folds (p=0.185). An empirically weighted predictor of PRPH was constructed from a statistical analysis of five slitlamp assessments and age. This approach for synthesizing clinical information produced a result at least as good as that obtained from the POD summary. These results show an important link between a quantitative laboratory assessment of corneal function and a clinical evaluation of corneal status and suggest that with continued refinement, clinical assessment may provide more quantitative information on Fuch's dystrophy and other diseases that affect corneal status.

ISSN:1040-5488    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

The relation between visual functions and reading performance has been the subject of conflicting opinion over the years. The purpose of this study is 2-fold: first, to examine factors other than visual acuity, i.e., stereopsis, accommodative facility and vergence facility, which might show a greater impact on reading achievement; and second, to utilize well defined dyslexic and normal controls to ensure that the reading deficits were not caused by overt neurological, psychological, educational, or environmental factors. Thirteen normal readers and 13 dyslexics were carefully matched by rigorous quantitative criteria. The performance of both groups on tests of visual acuity and stereopsis was similar. The dyslexic readers tended to show better accommodative facility. Dyslexics performed significantly worse than the matched normal readers on a test of vergence facility. These results, in agreement with those reported by other studies, indicate that less efficient dynamic vergence facility may contribute to reading impairment, unlike other static functions such as visual acuity and stereopsis. It may be that the vergence problems of the dyslexics are related to sequential oculo-motor abnormalities. The dyslexics' vergence problems may also be partly responsible for their large number of small eye movements

ISSN:1040-5488    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

We compared the morphology of the accommodative apparatus in myopic and control chicks using light microscopy and scanning and transmission electron microscopy. Results indicate no significant difference in ciliary muscle and ciliary fold structure between control chick eyes and eyes in which at least 10 D myopia was induced by the application of a translucent goggle. Based on the assumption that sustained tonic contraction of the accommodative apparatus in the myopic eye would lead to morphological differences, we conclude that the myopic eye is not accommodating excessively during development. These results, in combination with previous findings concerning the role of accommodation in experimental myopia, strongly indicate that accommodation does not play a significant role in this type of experimental myopia in chicks.

ISSN:1040-5488    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

Corneal immune ring (CIR) appeared in the eyes of three patients who wore their extended wear contact lenses while sleeping. CIR's have not been reported as a complication associated with the wear of soft extended wear lenses. The CIR appeared within days of an episode of ulcerative keratitis with an infiltrative component. Treatment with topical antibiotic and anti inflammatory agents produced resolution of the corneal lesions. The clinical appearance of the lesions as well as the time frame involved suggest that the immune response that produced the CIR was triggered by bacterial endotoxin through the properdin-mediated complement pathway.

ISSN:1040-5488    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

An artificial tear solution containing the major types of proteins, glycoproteins, and lipids represented in human tears has been developed. The adsorption of lipids onto various hydrogel lens materials (polymacon, lidofilcon A, phemfilcon A, etafilcon A) was examined by exposing the lenses to our artificial tear solution for 18 h. The adsorbed lipids were detected using Nile red stain. The patterns of deposits obtained in vitro were similar to those obtained with human worn lenses. The Nile red stain appeared far more sensitive in detecting lipids adsorbed to hydrogel lenses than the oil red O stain. It was found that lipids adsorb to hydrogel materials quite readily either in a pure state or combined with mucin or other proteins. In view of this work more attention should be given to the role of lipids in the etiology of various contact lens wear complications.

ISSN:1040-5488    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

Patient-worn lenses (N=1058) were evaluated using both the Rudko method for deposit typing and a quantitative assay for adsorbed protein. The visible deposit typing results were compared to the values obtained by the quantitative assay. The Rudko method for deposit classification was found to be a poor quantitative measure of deposited protein. Statistical differences were found between protein levels on lenses with identical Rudko scores among the FDA lens groups. In many cases, no meaningful correlation was found between Rudko scores and protein levels for lenses within the same FDA lens group. Significant differences in the distribution of visible deposits (Rudko scores) were found among the four FDA lens groups. Significant differences were also found in the quantity of adsorbed protein among FDA lens groups.

ISSN:1040-5488    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

This paper solves the problem of finding the power of a lens which has given prismatic effect and thickness at a given point. Depending on the conditions there may be no solution or an infinity of solutions. An equation for all the solutions (when they exist) is derived. The paper makes use of matrix results that are new and that are likely to have more general application in ophthalmic optics and vision science. In particular the matrix Spof Fang and Xu is introduced

ISSN:1040-5488    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

Eleven unadapted contact lens wearers wore a high (74%) water content hydrogel lens (Permaflex, CooperVision) of oxygen transmissibility Dk/Lav14 x 10-9in one eye and a low (43%) water content hydrogel lens (Aquaflex Superthin) of Dk/Lav4 x 10-9in the other eye under open-eye conditions for 8 h. After 8 h, average corneal edema for the lower water content lens was 7.9 ± 2.6%, which was significantly more than that for the higher water content lens, 1.7 ± 1.6%. Significantly fewer corneal striae and folds were also seen in the eyes wearing the higher water content lens. Subjective ratings of lens comfort were significantly better for the higher water content lens. Low water content positive power hydrogel lenses of the thicknesses used in this study place unacceptable hypoxic stress on the cornea and therefore should not be used for all-day wear.

ISSN:1040-5488    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

A glare test based on psychophysical estimation of intraocular light scatter and using a flickering, annular glare source was evaluated. The parameters determining the accuracy of the test were studied. In particular the influence of background light and flicker frequency were investigated and optimum values for best accuracy were found. Based on these findings a versatile and simple apparatus was constructed. Forty patients with various degrees of cataract were investigated in a clinical study. Patients, who subjectively experience severe glare problems, indeed show high glare values as measured with the apparatus. No obvious relation between visual acuity and glare score was found. In comparison with glare tests using a stationary glare source the use of a flickering glare source is advantageous in terms of sensitivity and accuracy

ISSN:1040-5488    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

In the literature, there is evidence supporting the notion that visual display unit (VDU) use decreases the blink rate and possibly reduces the stability of the precorneal tear film. In this investigation the blink rate and tear stability were measured using noninvasive techniques, in relation to VDU use. In normal healthy subjects, the results show an average 5-fold drop in blink rate during VDU use but tear stability appears to be unaffected. During VDU use a significant relation was found to exist between the interval between blinks and the stability of the precorneal tear film.

ISSN:1040-5488    

出版商:OVID    

年代:1991

数据来源: OVID