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V. P. Shah, K. L. Fry, S. Greenstein, P. S. Hersh; Natural History of Corneal Thickness After Corneal Collagen Crosslinking. Invest. Ophthalmol. Vis. Sci. 2010;51(13):4974.
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To investigate corneal thickness changes up to one year after corneal collagen crosslinking (CXL) for keratoconus (KC) and ectasia.
39 patients (47 eyes) underwent CXL for keratoconus or ectasia (29 and 18 eyes respectively) in a prospective, randomized controlled trial. CXL was performed using the UVX system (Peschke Meditrade GmbH) using the method of Seiler and colleagues. Forty-five control patients (46 eyes) received riboflavin only. The thinnest Pentacam pachymetry measurements at baseline, 1 month, 3 month, 6 month, and 1 year follow up visits were recorded and analyzed.
Mean initial corneal thickness was 445.32µm ± 52.97 for the treatment group. Corneal thickness decreased at 1 month (mean 416.45µm ± 52.31) and then further decreased at 3 months (mean 411.21µm ± 53.02). At 6 months, compared to 1 and 3 months, an increase in corneal thickness was observed (mean 432.30 ± 50.624). Mean corneal thickness at 6 months was significantly thicker than corneal thickness at 1 and 3 months (p<0.05). At 12 months, thickness had further increased toward baseline (mean 438.12µm ± 52.453). However, mean corneal thicknesses at 1, 3, 6, and 12 months all were significantly thinner than baseline (p<0.05). The same pattern was found for the ectasia and KC subgroups. However, in the ectasia subgroup, the 12 month corneal thickness was not statistically different from baseline. In the control group, there was no statistically significant difference (p>0.05) in corneal thickness at all follow-up visits compared to baseline.
The cornea undergoes significant change in corneal thickness during the first year after the CXL procedure. The cornea thins for the first 3 months, and begins to thicken toward baseline at 6 months. One year post-treatment corneal thickness measurements are near preoperative values. These changes in corneal thickness may be the result of anatomic and structural changes of corneal collagen fibrils such as compression of collagen fibrils, changes in corneal hydration, keratocyte apoptosis, changes in glycosaminoglycans, and other processes.
Clinical Trial: :
www.clinicaltrials.gov NCT 00647699 & NCT 00674661
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