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Cross-linking appears to halt progression of keratoconus for at least 7 years
Improvements were seen in topographic and wavefront parameters over the long term.
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Corneal collagen cross-linking improved visual acuity and prevented the progression of keratoconus for up to 7 years, according to a long-term study investigating the procedure, with no serious complications and no eyes requiring re-treatment.
“All eyes were stable 7 years following cross-linking, and between 1 and 5 years, there were continued improvements in corneal shape with K-max reduced and coma improved. Importantly, there were no sight-threatening complications out to 7 to 8 years,” David P.S. O’Brart, MD, FRCS, FRCOphth, the corresponding author, told Ocular Surgery News.
O’Brart said there is still a lack of cross-linking studies with more than 5 years of follow-up.
Study details
The prospective study, published in the American Journal of Ophthalmology, included 36 eyes of 36 patients who underwent epithelium-off corneal collagen cross-linking 6 to 8 years previously. Mean age at the time of cross-linking was 27.4 years. Mean follow-up was 7 years.
One eye of each patient was selected for analysis. The contralateral eye underwent cross-linking 18 to 95 months after the first eye in 11 patients. The initially untreated eyes had a mean follow-up of 68 months and served as controls.
“There were a number of patients that underwent treatment in only one eye, with the contralateral eyes undergoing cross-linking only if they showed progression during the follow-up period,” O’Brart said.
An epithelial spatula was used to remove a 9-mm area of central epithelium. Five drops of riboflavin 0.1% in dextran 20% were instilled and reapplied 5 minutes later. Ultraviolet light exposure occurred 10 minutes after riboflavin instillation.
Long-term outcomes
Mean Snellen equivalent uncorrected distance visual acuity improved from 0.32 preoperatively to 0.41 at 1 year, 0.39 at 5 years and 0.46 at 7 years. The improvement in uncorrected distance visual acuity was statistically significant at 5 years (P < .005) and 7 years (P < .0005) compared with baseline.
Mean corrected distance visual acuity improved from 0.85 preoperatively to 0.96 at 1 year (P < .02), 0.92 at 5 years (P < .04) and 0.96 at 7 years (P < .0001).
Mean spherical equivalent refractive error increased from –1.39 D preoperatively to –0.61 D at 7 years; the 0.78 D hyperopic shift from before surgery was statistically significant (P < .005).
Root mean square, coma and secondary astigmatism decreased significantly from before surgery to 7 years after surgery (P < .0005, P < .0005, P < .005, respectively).
Mean simulated topographic keratometry decreased by 0.74 D and mean maximum keratometry decreased by 0.91 D (both P < .0001) at 7 years.
The decreases in mean simulated topographic astigmatism and mean central corneal thickness were not significant at 7 years.
None of the 36 study eyes showed evidence of progression at 7 years.
“Approximately 25% of the contralateral eyes that weren’t treated progressed, whereas none of the eyes that we treated showed any evidence of progression,” O’Brart said.
Investigators plan to conduct a follow-up study with 10-year data, O’Brart said. – by Matt Hasson
- Reference:
- O’Brart DPS, et al. Am J Ophthalmol. 2015;doi:10.1016/j.ajo.2015.08.023.
- For more information:
- David P.S. O’Brart, MD, FRCS, FRCOphth, can be reached at Department of Ophthalmology, St Thomas’ Hospital, London, United Kingdom; email: davidobrart@aol.com.
Disclosure: O’Brart reports no relevant financial disclosures.