PHYSIOLOGICAL INFLUENCE ON OCULAR PHOTOMETRY - A REVIEW

During the development of the ocular photometer (OPM) since 1983, we h ave considered several physical and physiological factors that could p otentially influence the measurement and its results. Attention has be en given to respiratory, circulatory, and intraocular pressure provoca tions, and numerous publications document the influences or lack there of. Most recently, the authors conducted a simple reproducibility stud y with only 1 observer and 1 subject. Measurement of the same 2 retina l sites during a 3-week period yielded no statistically significant di fferences, even under relatively extreme temperature conditions. Thus, changes in readings with the OPM may be considered due to variations within the eye, such as cataract. Thus, increase in lens density may b e directly and correctly expressed by dual-site measurement of retinal brightness, resulting in the contrast transfer ratio.