Pupil Size in the Dark in Normal Adults

Ryou, Ji Han; Kim, Hae Won; Park, Mee Gyeong; Paik, Hae Jung

Abstract

Recently refractive corneal surgery has been increasing and intraocular lens implantation is a routine procedure during cataract surgery. Many people have various activities in the evening such as night driving, thus it may be very important measuring the pupil size in the dark in determining the size of the optical zone. We measured pupil size of sixty normal adult candidates in darkness of 0, 20, 60, 100 lux and also in the bright illumination of 200 lux for comparison using near lens camera and slide film. The pupils became larger with younger age and increased darkness. Pupil Size(log mm) = 4.57 - 0.0388 X Age(year) - 0.005 X Luminance(lux). The average pupil size of all age groups were 7.0mm, 6.56mm, 5.97mm, 5.4mm sequencially in darkness and 4.77mm in brightness(200 lux). The average pupil size of 20~30 year old group who are socially active even at night was 7.18mm and 8.4mm in maximum. This has significant meaning clinically. Additionally the size of pupil became larger with increased corneal diameter and the amount of anisocoria tended to be greater with the increase of the darkness.