Straylight values after refractive surgery: screening for ocular fitness in demanding professions

PURPOSE: To study straylight testing as a screening method for ocular fitness after refractive surgery in demanding professions and to determine the distribution of elevations in straylight as a result of refractive surgery in a non-research setting in contrast with earlier reports in research settings.

DESIGN: Cross-sectional study.

PARTICIPANTS AND CONTROLS: The refractive surgery population consisted of 373 eyes in 198 subjects with a history of refractive surgery. The reference population consisted of 402 eyes in 214 young individuals without a history of refractive surgery.

METHODS: Data were collected as part of routine testing at The Queen Astrid Military Hospital (Belgium), an independent military institution responsible for medical fitness examinations. Intraocular straylight was measured with the commercially available C-Quant instrument (Oculus Optikgeräte GmbH, Wetzlar, Germany), using the psychophysical compensation comparison (CC) method. Fellow eyes were compared to evaluate methodological aspects. The prevalence of impairment was evaluated for 2 age-independent cutoff criteria, a 2.0-fold and 3.2-fold increase, and an age-dependent cutoff criterion corresponding to an increase of 0.20 log units.

MAIN OUTCOME MEASURES: Methodological aspects such as repeatability, systematic differences, and distance to impaired scores, and prevalence of impaired straylight values after refractive surgery using proposed cutoff criteria.

RESULTS: The CC method exhibited good repeatability, and the chance of impaired scores due to variability in measurement was small. The prevalence of impaired straylight values was minimal in the reference population. In the refractive population, 9% (33/373) of values were above the factor 2.0 criterion, 2% (7/373) were above the factor 3.2 criterion, and 12% (45/373) were 0.20 log units above the age reference.

CONCLUSIONS: Straylight testing is a viable screening method for ocular fitness after refractive surgery. Patients from the general population who have undergone refractive surgery have significant elevations more frequently than surgery populations from high-quality research centers.