ISSN:1040-5488    

出版商:OVID    

年代:1990

数据来源: OVID

ISSN:1040-5488    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

ABSTRACTAn understanding of the spectral composition of sunlight is necessary if the effects of human exposure and protection criteria are to be meaningful. Also provided is a brief review of data for the ultraviolet UV solar spectrum in space and on earth that have been related to ocular damage. In addition, the effects of increases and decreases in the levels of ozone on the amount of ultraviolet radiation (UVR) reaching earth are presented. It is shown that enough UVR is encountered on earth to cause ocular damage and the damage will increase significantly as the levels of ozone decrease.

ISSN:1040-5488    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

ABSTRACTThe primate cornea was examined ultrastructurally subsequent to ultraviolet radiation (UVR) (300 nm) exposures of 0.08 and 0.225 J/cm2. The lower exposure caused significant, but incomplete, destruction of the epithelium and mild edema of the posterior stroma. The higher exposure resulted in complete destruction of the epithelium, significant stromal swelling, and some decomposition of endothelial cells. Widespread intracellular edema of the endothelium was also noted with the higher exposure. The ultrastructural examination subsequent to these UVR exposures also helps to explain why UV-induced keratitis is so painful. The 0.08 J/cm2exposure left the epithelial and subepithelial-stromal nerve plexuses intact, whereas the 0.225 J/cm2exposure destroyed the epithelial axons but spared the subepithelial ones. These results suggest that the pain associated with UV keratitis results from the combined effect of epithelial cell loss and sparing of the subepithelial axons.

ISSN:1040-5488    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

ABSTRACTThis paper reports on the 17-year development of the current Z80.3 Sunglass Standard. The dioptric tolerances of +0.125 to −0.25 D power, 0.125 D astigmatism, 0.25δ prism, and 0.18 D power imbalance are based on research by optometry's leaders. The traffic signal and luminous transmittance requirements are the result of study of the literature and original research. There has been much misunderstanding regarding the UV transmittance specifications. They too were exhaustively researched and discussed. That work is reviewed in detail. New equations for calculating exposures are presented with sample spectra. Graphic evaluations of severe risk exposures are presented. They show that based on the accepted criteria, for reasonable assumptions the Standard offers a 10x margin of safety. Studies of retinal risk indicate the Standard provides ample protection. Some criteria need further study. Potential problems are based on the fact that some sunglasses are too dark for driving and that use of ordinary sunglasses for sports provides inadequate protection from injuries.

ISSN:1040-5488    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

ABSTRACTThe recent public concern regarding sunglass protection from UV energy has sparked a significant debate among those in the research community and industry. This debate grows out of concern for the known effects of UV energy in producing or contributing to eye effects such as keratitis, cataract formation, and retinal damage. The ANSI Z80.3 Standard addresses itself to this issue by setting levels of UV energy that are permitted to be transmitted in various labeling categories for over-the-counter sunlenses. One important issue is that the ANSI Standard does not provide for an absolute block of UV energy in any category of these lenses. Because the technology to provide this sort of total UV block is currently available, it is argued that there should be at least one category of lens that is fully protective in the UV range.

ISSN:1040-5488    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

ABSTRACTOptical materials that are available to the practitioner for protection of the eye against hazardous exposure to ultraviolet radiation (UVR) are discussed. Principles of protection, procedures for calculating safe ocular exposure duration, and transmittance curves of commonly prescribed spectacle lenses, contact lenses, and intraocular lenses are discussed. Suggestions are made to assist the practitioner in providing adequate protection for the patient.

ISSN:1040-5488    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

ABSTRACTChanges in tonic accommodation and tonic vergence were studied as a function of stimulus duration and time after near fixation. Thirteen visually normal young adults each participated in experimental sessions comprising each of 12 combinations of stimulus type (accommodative or vergence) and stimulus duration (0.25, 0.5, 1, 2, 4, or 8 min). During each session, measurements were made of either tonic accommodation or tonic vergence 30 s before stimulus onset and at 0.5, 2, 4, 6, 8, 10, 12, and 14 min after stimulus offset. The stimulus (a high contrast reduced Snellen visual acuity chart) was viewed monocularly at the accommodative nearpoint and binocularly through pinholes at the fusional nearpoint on the accommodative and vergence sessions, respectively. For tonic accommodation, stimulus duration had no significant effect on either the magnitude of the aftereffect or its rate of decay. For tonic vergence however, the aftereffect was larger and had a slower rate of decay as stimulus duration increased. The results suggest that the adaptive mechanisms within the two systems have different time constants.

ISSN:1040-5488    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

A three-dimensional optometer (TDO), which can measure simultaneously three major ocular functions in a working environment, was used to measure the visual responses of human subjects viewing: (1) actual artworks and (2) corrugation presented by moving random dots on a cathode ray tube (CRT). Measurements were performed in natural viewing conditions on two emmetropic females. Both subjects demonstrated distinct accommodative responses for the stimuli presented at a fixed distance. The results indicate that the accommodation generally shifts in accord with changes of perceived distance. The usefulness of the TDO was demonstrated in these experiments.

ISSN:1040-5488    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

With the large number of factors that contribute to the “position of rest“ or fusion-free posture, it might be expected that heterophoria would be normally distributed. Data from a large sample of symptom-free subjects (N=925) show that this is not so. Furthermore, the difference in the prism adaptation response in orthophoria, esophoria, and exophoria suggests that the presence of heterophoria in normal subjects is due to the partial saturation of prism adaptation.

ISSN:1040-5488    

出版商:OVID    

年代:1990

数据来源: OVID