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

, 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.

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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.