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Illes Kovacs, Kinga Kranitz, Andrea Gyenes, Gábor László Sándor, Eva Juhasz, Lorant Dienes, Janos Nemeth, Zoltan Nagy, Cornea study group; Assessment the long term effect of corneal cross-linking therapy on corneal ectasia in progressive keratoconus. Invest. Ophthalmol. Vis. Sci. 2013;54(15):5275.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate stabilizing effect of cross-linking (CXL) therapy on corneal ectasia in progressive keratoconus with Scheimpflug imaging.
In this prospective study corneal CXL was performed in 22 progressive keratoconus eyes (CXL group) and 28 clinically non-progressive keratoconus eyes served as controls (control group). Anterior keratometry readings at the steepest meridian (Ks), thinnest corneal thickness (ThCT) and posterior elevation values at the thinnest point of the cornea (PE) were measured using Scheimpflug-camera at baseline and 12-25 months after enrolment. Cox proportional regression model was used to evaluate long term effect of CXL on keratoconus progression taken into account the within-subject fluctuations of measurements.
At baseline, higher Ks (CXL: 49.87±3.62 D vs. control: 46.76±3.25 D; p=0.002), higher PE (CXL: 27.05±17.13 µm vs. control: 14.36±12.54 µm; p=.006) and lower ThCT values (CXL: 461.52±24.43 µm vs. control: 497.64±31.68 µm; p<0.001) showed more advanced keratoconus cases in the CXL group compared to controls. During the follow up, there was no significant change in mean keratometry values compared to baseline in the CXL group (48.51 ± 3.64 D; p>0.05) and only 2 of 22 cases showed progression in keratometry values beyond within-subject fluctuation. In the control group marginally significant increase was measured in mean keratometry (46.90 ± 3.33 D; p=0.06) and keratometry values increased beyond within-subject fluctuation in 11 of 28 cases. The Cox model showed, that after CXL treatment the ratio of further keratometry progression was 0.09 (95% CL: 0.02 - 0.57; p=0.01) compared to controls after adjustment for initial ThCT.
CXL decreased the incidence of progression in advanced keratoconus by 91% after a long term follow-up independently from initial corneal pachymetry. Steep keratometry is a sensitive parameter to monitor stabilizing effect of corneal cross-linking therapy.
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