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Treating ectatic corneas

Study gives insight into benefits and drawbacks of CXL approaches

Roibeard O’hEineachain

Posted: Saturday, June 1, 2019

Corneal cross-linking (CXL) combined with intracorneal ring segments (ICRS) appears to provide ectatic corneas with greater improvements in vision than CXL alone or CXL combined with topography-guided photorefractive keratectomy (PRK). However, this approach involves a higher risk of adverse events, according to results of prospective single-centre trial presented at a Cornea Day session of the 23rd ESCRS Winter Meeting in Athens, Greece.

The study included 204 patients who underwent CXL alone, 126 who underwent CXL and intracorneal ring segment implantation (CXL-ICRS), 122 who underwent CXL with topography-guided PRK (CXL-TG-PRK) using the Dresden (Epi-on) protocol at the KEI centre from 2013 to March 2015, said Allan Slomovic MD, Cornea Surgeon, Kensington Eye Hospital (KEI), Professor of Ophthalmology, University of Toronto, Toronto, Canada.

All eyes in the study fit at least one of the following criteria: an increase in manifest cylinder greater or equal to 1.0D, an increase in steepest keratotomy equal to or greater than 1.0D and had needed glasses or contact lenses with or without evidence of topographical corneal steepening. In addition, all eyes had a corneal thickness greater than 400 microns in the treatment zone and a best-corrected visual acuity between logMAR 0.18 and 0.7.

At a follow-up of one year, the logMAR best spectacle-corrected visual acuity (BSCVA) had improved from 0.1536 to 0.0952 in the CXL alone group, a gain of around 1.2 lines. The CXL-ICRS group improved from 0.2683 to 0.1952, a gain of around 2.3 lines. The CXL-TG-PRK group improved from 0.20911 to -0.1322, a gain of around 1.7 lines. The CXL-ICRS group gained a mean of around five more letters of BSCVA than the CXL alone group (p<0.0001) and around three more letters than the CXL-TG-PRK group (p=0.0164).

The difference between the CXL-alone group and the CXL-TG-PRK group, around two letters, did not reach statistical significance.

There was a significantly greater mean reduction in K Max in the CXL-TG-PRK group (3.6924D) and the CXL-ICRS group (3.2149D) than in the CXL alone group (0.0533D) (p=0.001). However, there was no statistically significant difference between the decrease in K Max between the CXL-ICRS and the CXL-TG-PRK groups.

Adverse events in the CXL-ICRS group included one case of suture abscess, one case of corneal ulcer, seven cases of corneal scarring and four cases of extrusion. In the CXL-TG-PRK group there was one case of sterile corneal melt and this patient experienced a loss of greater than three lines of BSCVA.

Allan Slomovic: allan.slomovic@utoronto.ca