K 299
Determination of the contrast sensitivity curve using a new computer vision test
K.-J. Hartung, W. Haase
Introduction: Contrast sensitivity as a partial function of the human visual sense provides the ophthalmologist with information on the detection of rougher structures with less differences in luminance. That ability is not covered by the conventional determination of visual acuity by means of optotypes.
Method: There is presented a new automatic method (CompuVist / firm Rodenstock) for contrast sensitivity measurement that offers the variable-sized optotypes in various contrast levels on a computer monitor in a randomised manner. The method strictly complies with the requirements set out in DIN 58220. Using that new method, 81 eyes of normal-sighted adults of age ranges of 20-30 and 60-80 years were examined for the purpose of standardisation. Separate normal-value curves were established for both age ranges. The normal-value curves were represented by means of the medians resistant against outliers and the respective 5 % and 95 % percentiles shown in box plots. In order to assess the validity of CompuVist, there were performed comparison measurements of 54 eyes by means of a conventional contrast sensitivity measurement using eye charts according to Pelli-Robson.
Results: For both age groups, there resulted characteristic normal-value curves as they are known from the physiologic literature. However, no practical method for the clinical routine had been available before. The age-dependence of contract sensitivity was statistically proven. The analysis of the comparison measurements showed a random error-corrected correspondence of up to 96 %.
Discussion: CompuVist allows for an examiner-independent standardised measuring process, offers randomised optotypes in a virtually unlimited variety of contrast and vision levels, allows to maintain the outside test conditions and moreover is easy to handle and requires little time. Thus, it is a valuable diagnostic addition to the everyday clinical work. With its help and using the normal-value curves established here, the ophthalmologist can determine by a few quick measurements whether or not the individual contrast sensitivity has changed.
University Eye Clinic of Hamburg, Department for Pleoptics and Orthoptics, Martinistrasse 52, D-20246 Hamburg