Abstract
Abstract: :
Purpose: Measurement of retinal straylight is a functional measure providing information about the optical quality of the human eye in relation to deterioration due to aging of the lens and cataract, refractive surgery, corneal abnormalities, etc. In this study the technique of retinal straylight measurement based on the direct compensation method was evaluated and compared to glare testing. Methods: The study concentrated on measures for the visual capacity of elderly drivers and drivers with cataract. The widespread implementation of such measures depends on the availability of a measurement technique, that is proven to be reproducible, valid and resistant to fraud. The technique has to be able to discriminate between ‘normal' and ‘impaired' subjects and provide information about visual capacity that is not provided by visual acuity alone. The measurement techniques that are currently available, have been insufficiently investigated, regarding these aspects. As test devices for measurement of glare sensitivity and straylight were used the Nyktotest and Mesotest as well as the Straylight Meter. A new version of the Straylight Meter, to facilitate large–scale and clinical routine implementation was developed. Three groups of subjects were included: 1) 40 Young subjects without any eye disease; 2) 37 Elderly subjects without any eye disease and 3) 35 Subjects with (early) cataract in at least one eye. All subjects underwent a battery of glare and straylight tests, as well as measurement of visual acuity, contrast sensitivity, refraction, eye colour and objective assessment of cataract. (LOCS III classification). Subjects filled out a questionnaire on self perceived disability during driving. Results: AUC values of the ROC curves differed by 0.1–0.2 in favor of the Straylight Meters, the new straylight meter being superior. Repeatability, discriminative ability, resistance to fraud and added value were all on the level that should be required from a test for driver licensing. Conclusions: Glare testing showed to be a relatively erratic measurement, especially if the glare effect was considerd per se (as difference between with and without glare). Retinal straylight measurement could be achieved with a measurement accuracy of 0.06 log units, to be compared to differences in the population of 1 log unit. Retinal straylight measurement now holds promise for routine clinical evaluation of the optical quality of the human eye in relation to deteriorations such as due to aging of the lens and cataract, refractive surgery, corneal abnormalities, etc.
Keywords: optical properties • aging: visual performance • refractive surgery: optical quality