The effect of paired opposite clear corneal incisions on with-the-rule vs against-the-rule astigmatism

Session Details

Session Title: Corneal Astigmatism Assessment. Surgery Equipment

Session Date/Time: Saturday 05/09/2015 | 11:00-13:00

Paper Time: 12:22

Venue: Main Auditorium

First Author: : N.Spanou UK

Co Author(s): :    P. Chiam                    

Abstract Details

Purpose:

To determine the refractive effects of paired opposite clear corneal incisions (OCCI) on with-the-rule (WTR) and against-the-rule (ATR) astigmatisms at 1 and 6 months postoperatively.

Setting:

Leighton Hospital, Cheshire, UK

Methods:

This is a retrospective cohort study. Consecutive eyes from different patients who had OCCI for keratometric astigmatism of 1.50 to 2.50 D were included. They were divided into group A with steepest meridian at 90 ± 20; group B and group C with steepest meridian at 180 ± 20 degree. The keratome width used for group A and B was 3.2 mm and group C 3.5 mm. Keratometry by partial coherence interferometry, manifest refraction and visual acuities were measured at 1 and 6 months postoperatively.

Results:

Twenty-eight eyes were included in each group. The median of surgically induced astigmatism (SIA) magnitude at 1 month postoperatively for groups A, B and C were 1.70, 1.13 and 1.71D respectively (P<0.001). Post hoc test showed group A and C SIA's were significantly greater than group B. Six months postoperatively, the medians were 1.63, 0.85 and 1.49D (P<0.001). The change was significantly different from 1 month for group B and C (P=0.001 and P=0.006 respectively). The median uncorrected distant visual acuity was better for group A and C compared to B at 1 month (P=0.016).

Conclusions:

A paired OCCI has significantly greater refractive effect on WTR than ATR astigmatism correction. The SIA for ATR astigmatism reduces significantly more than for WTR astigmatism correction at 6 months. Collagen fibrillar orientation of the cornea are likely the main reason for this observation.

Financial Interest:

NONE