Correction of astigmatism, especially if oblique, may improve visual outcomes

This investigational simulation study conducted in Japan examined whether leaving patients with uncorrected astigmatism after refractive surgery has a significant impact on their visual acuity and reading performance. The authors found that eyes with greater uncorrected astigmatism and eyes with uncorrected oblique astigmatism had lower visual acuity and reading performance. They conclude that correcting pre-existing astigmatism may be necessary in order to achieve excellent visual outcomes, especially in eyes with oblique astigmatism.

Published in the August issue of the Journal of Cataract & Refractive Surgery, the study was conducted in 38 healthy volunteers (38 eyes) with no ophthalmic disease other than refractive errors. They underwent correction of cycloplegic refraction with a 3.0 mm artificial pupil, followed by production of with-the-rule (WTR), against-the-rule (ATR) and oblique astigmatism of 1 D, 2 D and 3D using trial lenses. Distance visual acuity and reading performance were assessed under these conditions.

Distance visual acuity and reading performance decreased significantly with increasing astigmatism (P < 0.001). Distance visual acuity, reading acuity, and maximum reading speed with uncorrected astigmatism were significantly affected by axis orientation at each diopter of astigmatism (P < 0.05, 1.0 D and 2.0 D; P < 0.001, 3.0 D).

All parameters showed significantly better values in eyes with WTR or ATR astigmatism than in eyes with oblique astigmatism at each diopter (P < 0.05); there were no significant differences between eyes with WTR astigmatism and those with ATR astigmatism.