Photostress Recovery Time among Commercial Drivers in Kano Metropolis, Kano State, Nigeria

Abstract

Driving being a vision dependent task requires the drivers to have good vision. The essence of driver’s license is therefore contingent upon meeting visual standards for public safety. This study aimed at determining the photostress recovery time (PSRT) of commercial drivers of Kano metropolis. A prospective analytical cross-sectional study was conducted on 134 purposively sampled commercial drivers who have clear ocular media. Prior to the testing each subject were given 5 minutes to adapt to ambient illumination. The pre-bleach distant visual acuity of each eye was determined with the Snellen’s distance visual acuity chart. With one eye occluded, the other eye was dazzled for 10 seconds, measured by a stopwatch, with the light of a pen torch held at 2cm from the eye. The time required in seconds to read at least, three optotypes on the line directly above the baseline acuity was recorded as the PSRT. The 20-29 years age group recorded the least mean PSRT (12.2 seconds) for both eyes, while the 60-70 years category has the highest mean PSRT (41.8 and 41.1 seconds) for right and left eye respectively. Age associated significantly (p<0.05) with mean PSRT. The observed mean PSRT with glare sensitivity was statistically significant (p<0.05). Positive association between PSRT in relation to age and disability glare were found. This emphasizes the need to introduce photostress test as a requirement for issuance and renewal of driving license especially for older and visually impaired people.