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Cross-linking improves visual acuity, reduces higher-order aberrations at 2 years
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Collagen cross-linking provided good long-term visual, refractive and topographic outcomes in eyes treated for progressive keratoconus, a study found.
The prospective case series included 42 eyes of 32 patients with progressive keratoconus and a mean age of 22.4 years. Bilateral surgery was performed on 11 patients. The mean interval between diagnosis and treatment was 2.2 years.
Uncorrected and corrected distance visual acuity, refraction, topography and corneal aberrations were evaluated at baseline and 6, 12 and 24 months after surgery.
Uncorrected distance visual acuity, corrected distance visual acuity and spherical equivalent improved significantly 2 years after treatment (P < .001, P < .001 and P = .048, respectively).
Apical keratometry, differential keratometry and central keratometry decreased significantly from baseline (P < .001, P = .031 and P = .003, respectively).
Coma, trefoil, secondary astigmatism, quatrefoil, secondary coma and secondary trefoil also decreased significantly (P = .016, P = .018, P < .001, P = .031, P < 001, P = .001, respectively).
There was no significant correlation between changes in corneal higher-order aberrations and improvements to visual acuity. Only the reduction in apical keratometry correlated with improvement in corrected distance visual acuity.
Disclosure: The study authors have no relevant financial disclosures.
Perspective
Back to TopA. John Kanellopoulos, MD
This study on topographic and corneal wavefront and refractive outcomes 2 years after collagen cross-linking for progressive keratoconus by Ramon Ghanem and associates is quite an interesting one.
The investigators found, as has been published extensively in the past, that with a quite lengthy follow-up of 2 years, collagen cross-linking was effective in improving uncorrected and corrected visual acuity, possibly due to the improvement of topographic metrics and, most importantly, higher-order aberrations, notably coma, in these eyes with progressive keratoconus. They speculated that a significant reduction was observed mainly in apical keratometry, and this was directly correlated with visual acuity.
The clinical perspective here is that collagen cross-linking has for many years and with this study again established itself as a very significant tool in stabilizing ectasia. What we have found, collectively as ophthalmologists, is that there is some remarkable improvement in some of the topographic and topometric parameters of the cornea, which also translates to improvement in corneal higher-order aberrations.
Many people describe these as “disease regression.” In my opinion, this is not disease regression. This is a refractive effect that collagen cross-linking has on these corneas, a very crude refractive effect that collagen cross-linking has on these corneas, which has advantageous results in reducing the corneal deformity.
We are at the moment where the study of this refractive effect can be used in a customized way to achieve even more significant changes to the parameters that matter the most, which is the parameters of topographic and topometric symmetry that improve corrected visual acuity, and why not uncorrected visual acuity as well?
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