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Kinga Kranitz, Illes Kovacs, Kata Mihaltz, Gabor L. Sandor, Janos Nemeth, Zoltan Z. Nagy; Corneal Changes in Progressive Keratoconus After Cross-linking Therapy Assessed by Scheimpflug-Camera. Invest. Ophthalmol. Vis. Sci. 2012;53(14):1113.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate corneal changes after corneal cross-linking therapy (CXL) in progressive keratoconus assessed by Scheimpflug-camera.
40 eyes of 22 patients with progressive keratoconus were enrolled in the study. CXL was performed in 25 eyes (CXL group) and 15 fellow eyes with stable keratoconus served as controls.Uncorrected and best corrected distance visual acuity (UCVA, BCVA) were determined and thinnest corneal thickness (ThCT), posterior elevation of the cornea at minimum pachymetry (PE), and Holladay equivalent keratometry values (K1 and K2) were measured with Pentacam (OCULUS Optikgerate GmbH) before and 1 year after CXL. For group comparisons the Student’s t-test for paired samples was used, the most sensitive parameter of corneal changes after CXL was determined using Area Under the Receiver Operator Characteristic Curve (AUC). Multivariable general estimating equation (GEE) model analysing interactions was used to determine significant predictors of corneal changes.
After 1 year both UCVA and BCVA improved significantly in the CXL group (from 0.23±0.25 to 0.31±0.25 p<0.001 and from 0.58±0.28 to 0.72±0.19 p=0.019, respectively) while these parameters did not change in the control group (p>0.05). After 1 year we found statistically significant decrease of ThCT (from 472.53±33.18 µm to 440.53±38.67 µm; p<0.001), of PE (from 68.33±28.69 µm to 22.67±16.21 µm; p<0.001) and of keratometry values (K1: from 45.06±4.55 D to 43.51±4.67 D; p<0.001; K2: from 48.39±5.41 D to 46.71±5.67 D; p<0.001) in the CXL group, while these parameters remained stable in the control group (p>0.05). According to AUROC values, change in PE values (AUC: 0.99) proved to be the most characteristic parameter of corneal flattening after CXL followed by change in ThCT (AUC: 0.86). GEE model showed that CXL treatment (p=0.001) and initial ThCT (p=0.007) were significant predictors of posterior elevation decrease with a significant negative interaction of initial ThCT on CXL effect (p=0.005).
Posterior elevation measured by Pentacam is a sensitive parameter to monitor corneal flattening after CXL therapy. According to our results initial corneal thickness has a negative influence on the effect of CXL therapy.
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