Effect of prisms on visual acuity, contrast sensitivity and nystagmus in patients with albinism.

Aim: To investigate the effect of using base-out prisms on nystagmus, visual acuity and contrast sensitivity in patients with albinism.

Methods: In this interventional study, patients with albinism who had nystagmus were enrolled. A comprehensive eye exam was conducted, which included refraction, assessment of far and near vision acuity, and contrast sensitivity measurements. To check for the nystagmus, a videonystagmography was used. The tests were carried out in three modes: without any correction, with optical correction, and with correction using base-out prisms in three different powers, including 4, 6, and 8 prism diopters.

Results: Totally 23 patients with average age of 28.65±12.13 were examined. It was found that the use of optical correction and optical correction with prisms resulted in a statistically significant improvement in both far (at least: P<0.006) and near visual acuity (at least: P<0.001 except for prism 8; P<0.02). In addition, contrast sensitivity significantly improved at all low and medium frequencies except for correction with prism 8 in frequency 1.5 (at least: P<0.01 except for prism 4, frequency 6; P=0.04). no significant improvement was observed in the evaluation of nystagmus characteristics.

Conclusion: Optical correction with a prism can improve visual acuity and some spatial frequencies, but failed to improve nystagmus parameters.