Amount of astigmatism and pupil size affect UCVA

Pupil size and the amount of astigmatism affect uncorrected visual acuity (UCVA) in astigmatic eyes, according to an investigation published by the British Journal of Ophthalmology.

Dr Kazutaka Kamiya et al., Department of Ophthalmology, University of Kitasato School of Medicine, Kanagawa, Japan, studied 20 healthy eyes of 20 volunteers. With-the-rule and against-the-rule astigmatism were created after cycloplegic refraction was fully treated. UCVA was measured using artificial pupils of 1 to 5 mm in each eye. To perform a statistical analysis the clinicians used the mean value of three measurements.

Eyes with with-the-rule astigmatism of 1, 2 and 3 D, logMAR UCVA was 0.04±0.08, 0.09±0.09 and 0.16±0.16 for pupils of 1 mm, −0.01±0.09, 0.12±0.15 and 0.33±0.24 for 2 mm pupils, 0.02±0.09, 0.20±0.19 and 0.46±0.30 for 3 mm pupils, 0.02±0.08, 0.24±0.20 and 0.48±0.21 for 4 mm pupils, and 0.08±0.10, 0.33±0.18 and 0.53±0.22 for 5 mm pupils, respectively. Eyes with against-the-rule astigmatism achieved similar results.

The findings advise that, as well as the amount of astigmatism, pupil size should also be considered when improving visual performance in astigmatic eyes.