Intraocular straylight screening in medical testing centres for driver licence holders in Spain

Purpose: To test the performance of the C-quant straylight meter during the daily routine work in medical testing centres for driver license applicants and driver license holders in Spain. Methods: Altogether 914 subjects, of which 376 younger than 35 years, 428 between 35 and 60 years and 110 over 60 years were measured with the C-quant in three medical testing centres (Barcelona, Zaragoza and Palma de Mallorca) in 2006. Technicians were instructed once and the measurements were done during the daily routine work. We recorded: age, BCVA, self-reported subjective blinding at night; and from the C-quant: straylight parameter (log s), measurement quality parameters (ESD, Q) and test duration. Results: Total C-quant test duration increases slightly with age from a mean of 7 min (< 35 years) to a mean of 9 min (> 60). At first attempt, 82 % of all subjects produced reliable results (ESD < 0.12). The straylight parameter for this group was independent of ESD and ESD was independent of total test duration. The known age dependence of the straylight parameter and the weak correlation with BCVA was confirmed. The distribution of subjective blinding at night was very different between test centres. Subjects with “very strong” subjective blinding had significantly higher straylight values than subjects with “no” subjective blinding. Subjects avoiding night driving had significant higher straylight values than subjects driving at night. Conclusion: The C-quant measure is reasonable fast. Good subject instruction is important to get first attempt reliable results. Self-reported subjective blinding results depend strongly on the interviewer