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Franz Prager, Gerald Schmidinger; 12-months Results Of Riboflavin/ultraviolet A Corneal Collagen Cross-linking (CXL) For Keratoconus In Patients With Thin Corneas. Invest. Ophthalmol. Vis. Sci. 2011;52(14):5199.
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To evaluate the efficacy and safety of riboflavin/ultraviolet A corneal collagen cross-linking in patients with progressive keratoconus and thin corneas.
In a prospective, clinical trial, 19 eyes of 15 patients with progressive keratoconus and corneas thinner than 400 µm after epithelial removal underwent corneal cross-linking (CXL) between January 2009 and September 2010. All CXL treatments included corneal abrasion under topical anaesthesia with subsequent installation of isotonic riboflavin 0,1 % solution in 20% dextran for 30 minutes. Since the corneal thickness was less than 400 µm, riboflavin in a hypotonic solution was used in all patients to swell the cornea. Afterwards, UV A irradiation (3 mW/cm2) was started while isotonic riboflavin solution was continuously administered every 2 minutes for a total of 30 minutes. Patients were seen 1 month, 3 months, 6 months and 12 months after treatment. Examinations during follow-up included best corrected visual acuity testing in snellen, endothelial cell count (Noncon ROBO-CA, Konan-Keeler, Kobe, Japan), optical pachymetry, corneal topography and surface aberrometry (Pentacam®, Oculus, Wetzlar, Germany; Keratron Scout, Optikon 2000 SpA, Rome, Italy) as well as documentation of potential haze formation and any adverse events.
Mean age was 26 years. Mean follow-up period for all patients was 6,1 months. Mean visual acuity increased from 20/40+1 at baseline to 20/30+2 after 12 months (+ 10 letters, p=0.001). The mean endothelial cell density decreased slightly, but not statistically significant, from 2621 cells/mm2 at baseline to 2460 cells/mm2 after 12 months (-6%, p=0.365). Mean spherical equivalent decreased from -4,7 diopters (D) to -3 D after 12 months (-1,7 D) and mean astigmatism stayed stable at +4,1 D after 12 months (+/- 0 D). Mean central corneal thickness decreased from 444 µm at baseline to 416 µm after 12 months (- 28 µm, p=0.09). Topographic mean K reduction was -2,62 D after 12 months of follow-up. Temporary mild haze was reported in 37% of patients one month after CXL, but disappeared progressively.
Hypotonic riboflavin solution is a useful method to treat patients with progressive keratokonus and already thin corneas. Treatment results were comparable to results from standard treatments. Despite swelling of the cornea, the thinner corneas are at higher risk for endothelial damage, although no significant reduction in endothelial cell count was observed.
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