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V. K. Malhotra, A. J. Kanellopoulos; Long Term Comparison of Sequential vs. Same-Day Simultaneous Collagen Cross-Linking and Topography-Guided PRK for Treatment of Keratoconus. Invest. Ophthalmol. Vis. Sci. 2010;51(13):4967.
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© ARVO (1962-2015); The Authors (2016-present)
To examine the long term safety and efficacy of corneal cross-linking(CXL) and topography-guided PRK(TgPRK) in keratoconus patients in two different sequences and timings: CXL followed at least 6 months later by TgPRK (Group A), and sequential CXL and TgPRK performed on the same day(Group B).
A retrospective study was performed to evaluate sequential versus simultaneous corneal cross-linking and TgPRK. A total of 325 keratoconus eyes were treated and evaluated. 127 eyes (group A) had TgPRK at least 6 months following CXL, and 198 eyes (group B) had TgPRK first with CXL immediately afterward (simultaneous procedure). Mean follow-up was 36 (+/- 18) months (24 to 68). The groups were examined for statistical differences in pre-post changes in uncorrected & best-corrected visual acuity in logMAR values, mean radial spherical error, refraction, keratometry, topography, central corneal thickness (CCT), endothelial cell count (ECC), corneal haze grades, and ectatic progression.
Group A: At most recent follow-up, the mean uncorrected visual acuity improved from logMAR 0.9 (+/- 0.3) to 0.49 (+/- 0.25) and best-corrected visual acuity improved from 0.41 (+/- 0.25) to 0.16 (+/- 0.22). Mean spherical equivalent reduction (SER) was 2.5 D (+/- 1.2D). Mean haze score was 1.2 (+/- 0.5) and mean keratometry reduction was 2.75 D (+/- 1.3D).Group B: At most recent follow-up, mean uncorrected visual acuity improved from 0.96 (+/-0.2) to 0.3 (+/-0.2), and mean best-corrected visual acuity improved from 0.39 (+/- 0.3) to 0.11 (+/-0.16). Mean SER was 3.2 D (+/-1.4D) and mean haze score was 0.5 (+/-0.3). Mean keratometry reduction was 3.5 D (+/- 1.3). ECC was unchanged (p<0.05) in both groups. Group B had greater improvement in mean uncorrected visual acuity and best-corrected visual acuity, as well as a greater reduction in mean SER and mean keratometry. Mean corneal haze grade was also lower in Group B. All comparisons were statistically significant(p<0.05 for all comparisons). All analyses were performed using two-tailed, paired t-tests.
Same-day simultaneous TgPRK and CXL appears to be superior to sequential procedures of CXL preceeding TgPRK in the visual rehabilitation of progressing keratoconus.
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