Topography-Guided Photorefractive Keratectomy For Correction Of Irregular Astigmatism Following Penetrating Keratoplasty

Penetrating keratoplasty (PKP) may result in high and irregular astigmatism. Treatment options such as contact lenses may not be well tolerated requiring techniques such as relieving incision and wedge resection.

The purpose of this study was to evaluate the efficacy and safety of Topography-Guided Photorefractive Keratectomy (TG-PRK) to correct irregular astigmatism following PKP.

A total of 185 eyes were operated on at a laser refractive clinic in Vancouver, Canada.

Retrospective cohort study of 185 eyes that underwent TG-PRK for irregular astigmatism post-PKP. Only those eyes with 12 months of follow-up data were included for evaluation in this study.

Analysed outcomes included preoperative and postoperative uncorrected distance visual acuity (UDVA), best corrected visual acuity (CDVA), manifest refraction, and topographic cylinder. 

Postoperatively, 61 (33%) eyes had an UDVA better than 20/40 at 12 months.

Three (1.6%) eyes had a recorded UDVA better than 20/40 at 12 months.

Twenty-five percent of eyes gained experienced 2 lines of improvement on the Snellen Chart.

Ten percent of eyes lost 2 lines of vision on the Snellen Chart from incomplete treatment, haze, or cataracts, however, no eyes in our study required specialty contact lenses for funtional vision post-operatively. 

Trans-epithelial TG-PRK is a surface procedure that avoids more invasive techniques such as wedge resection and relieving incisions for post-penetrating keratoplasty. TG-PRK may improve irregular astigmatism postoperatively and improve both UDVA and CDVA with promising efficacy and safety. This may be an alternative to current surgical management for post-PKP irregular astigmatism and reduce the need for specialty contact lenses.