New straylight issues in treatment of the eye

Abstract

AbstractPurpose Straylight exerts its deleterious effect on visual function by reducing the sensitivity of the retina for whatever visual task the retina must perform: face recognition, movement detection, color discrimination etc. It can be expected that patients suffering from a retinal condition will be handicapped by straylight twice as much. To assess retinal condition in a non‐confounded way, flicker sensitivity has been proposed. Such a test was developed on the C‐Quant. Moreover, the test serves to assess whether a paptient has sufficient flicker sensitivity for the normal straylight test itself.Methods Visual field lay‐out was identical, as well as the subject's 2AFC task, but the peripheral annulus was silent, as well as one of the two half fields in the center. The other half flield flickered at 8 Hz, with modulation depth according an adaptive staircase procedure. Outcome measure is logTCS (temporal contrast sensitivity). An uncertainty parameter (Unc) was included. Population test was performed in science fair settings on 400 subjects. Moreover in the laboratory 2 subjects were extensively tested to check whether optical defects, mimicked with trial lenses and scatter filters, affected the TCS outcome.Results Repeated measures standard deviation was 0.11 log units for the reference group using as reliability criterion unc<0.15. Normal values for logTCS were around 2 (threshold 1%) with some dependence on age (range 6‐85 years). Test outcome did not change upon a ten‐fold (optical) deterioration in visual acuity or straylight.Conclusion The test has adequate sensitivity to check a subject's capability to perform straylight assessment. The unc reliability criterion secures sufficient precision, also for assessment of retinal sensitivity loss. Commercial interest