BJOPHTHALMOL202481 267..270

Aim To determine the effects of pupil size on uncorrected visual acuity (UCVA) in astigmatic eyes. Methods The authors examined 20 normal eyes of 20 healthy volunteers (age 26.764.9 years (mean6SD); 8 men, 12 women). After fully correcting cycloplegic refraction, the authors created with-the-rule and against-the-rule astigmatism of 1, 2, and 3 dioptres (D) in each eye, and then assessed UCVA using artificial pupils (1 to 5 mm) in these astigmatic eyes. Measurements were performed three times, and the mean value was used for statistical analysis. Results In eyes with with-the-rule astigmatism of 1, 2 and 3 D, logMAR UCVA was 0.0460. 08, 0.0960. 09 and 0.1660.16 for 1 mm pupils, 0.0160. 09, 0.1260. 15 and 0.3360. 24 for 2 mm pupils, 0.0260. 09, 0.2060. 19 and 0.4660. 30 for 3 mm pupils, 0.0260. 08, 0.2460. 20 and 0.4860. 21 for 4 mm pupils, and 0.0860.10, 0.3360. 18 and 0.5360. 22 for 5 mm pupils, respectively. The variance of the data was statistically significant (p1⁄40.03 for 1 D, p<0.001 for 2 D, p<0.001 for 3 D, analysis of variance). Similar results were obtained in eyes with against-the-rule astigmatism. Conclusions Both the amount of astigmatism and the pupil size can affect UCVA in astigmatic eyes. It is suggested that not only the amount of astigmatism but also the pupil size should be taken into consideration for acquiring better visual performance in astigmatic eyes. INTRODUCTION Since astigmatic errors can lead to both a decrease in uncorrected visual acuity (UCVA) and deterioration of quality of vision, reducing this pre-existing astigmatism and acquiring good visual outcomes are two essentials for minimising spectacle dependence and maximising subsequent patient satisfaction. Several surgical options for the correction of astigmatism have been advocated, such as laser in situ keratomileusis, photorefractive keratectomy, astigmatic keratotomy using limbal or corneal relaxing incisions, the use of a toric phakic or pseudophakic intraocular lens, and other excimer laser refractive procedures. At present, we merely consider the amount of astigmatism as well as the axis of astigmatism for these surgical approaches. However, it is known that pupil size plays an important role in the refractive outcomes of the surgical procedure. To our knowledge, the effects of pupil diameter on visual performance in astigmatic eyes have not been investigated so far and still remain unclear. The purpose of this study is to prospectively evaluate the effects of pupil size on visual acuity in eyes with astigmatism. MATERIALS AND METHODS Twenty eyes of 20 healthy volunteers (eight men and 12 women; ages 26.764.9 years (mean age6SD; range, from 22 to 37 years old)) who had no ophthalmic diseases other than refractive errors were enrolled in this prospective study. The manifest refraction (spherical equivalent) was 1.6962. 20 dioptres (D) (range 6.25 to 0.75 D). The manifest refractive cylinder was 0.1160. 25 D (range 0.75 to 0.00 D). Corneal and ocular higherorder aberrations (HOAs) determined using HartmanneShack aberrometry (KR-9000, Topcon, Tokyo, Japan) were 0.0660. 02 mm (range 0.04 to 0.10 mm), and 0.1060. 02 mm (range 0.05 to 0.16 mm) for a 4 mm pupil, respectively. Eyes with keratoconus were excluded from the study by using the keratoconus screening test of Placido disk videokeratography (TMS-2, Tomey, Nagoya, Japan). Informed consent was obtained from all volunteers in accordance with institutional guidelines, according to the tenets of the Declaration of Helsinki. After corneal anaesthesia was obtained using one drop of oxybuprocaine (Benoxil; Santen, Osaka, Japan), cycloplegia was achieved with three drops of 1% cyclopentolate hydrochloride (Cyplegin; Santen), spaced 5 min apart. 7 Autorefraction (ARK-700A; Nidek, Gamagori, Japan) was undertaken at least 30 min after the third administration of cyclopentolate hydrochloride and only if the pupillary light reflex was absent. After fully correcting cycloplegic refraction, we produced with-the-rule (WTR) (axis 908) and against-the-rule (ATR) (axis 08) astigmatism of 1, 2 and 3 D in each eye. We assessed UCVA using artificial pupils (1 to 5 mm) in these eyes. Only right eyes were tested. We carried out this measurement three times, and the average value was used for the analysis. All statistical analyses were performed using SPSS. Repeated-measures analysis of variance (ANOVA), followed by the Dunnett post hoc test for multiple comparisons, was used to compare the differences between groups with different pupil sizes. The results are expressed as mean6SD, and a p value of <0.05 was considered statistically significant. RESULTS In eyes with a WTR astigmatism of 1 D, logMAR UCVA was 0.0460. 08, 0.0160. 09, 0.0260. 09, 0.0260. 08 and 0.0860.10, for 1, 2, 3, 4 and 5 mm pupils, respectively (figure 1). The variance of the data was statistically significant (p1⁄40.03, ANOVA). Multiple comparisons demonstrated a significant Department of Ophthalmology, University of Kitasato School of Medicine, Kanagawa, Japan Department of Orthoptics and Visual Science, School of Allied Health Sciences, University of Kitasato, Kanagawa, Japan