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Michael w Belin, Jimena Carolina Siordia; Effect of Epithelial Removal on the Corneal Curvature in Keratoconic Eyes prior to Crosslinking. Invest. Ophthalmol. Vis. Sci. 2016;57(12):2889.
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© 2017 Association for Research in Vision and Ophthalmology.
To evaluate epithelial masking on keratoconic corneas and determine how anterior and posterior curvature is altered by epithelial thinning.
22 eyes of 22 patients with mild to moderate keratoconus scheduled for corneal collagen crosslinking were imaged with the Pentacam HR prior to and immediately following epithelial removal. Pre and post epithelial removal anterior and posterior radius of curvature (ARC, PRC respectively) from the central 6.0 mm zone and corneal thickness at the thinnest point were recorded.
Pre-operative ARC averaged 7.55 +/- 0.33 mm. Post removal values were 7.42 +/- 0.39, representing a significant change of -0.12 +/- 0.10 mm (p < .001). Pre-operative PRC averaged 6.03 +/- 0.24 mm. Post removal values were 6.02 +/- 0.24 mm, representing a non significant change of -0.01 +/- 0.04 (p=0.28). Pre-operative pachymetry at the thinnest point averaged 510 +/- 37 um and post removal 483 +/- 34 um. The change in corneal thickness at the thinnest point was significant with an average of 24.5 +/- 11/6 um (p<.001). A larger change in ARC was associated with a smaller pachymetric changes (r=0.50, p=0.018).
Epithelial thickness varies in mild to moderate keratoconus eyes with more thinning being correlated with disease severity. ARC changes were inversely related to corneal thickness change suggesting a greater masking effect. the degree of posterior ectasia greatly exceeded anterior ectasia with or without the effect of the corneal epithial masking.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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