Topographic, keratometric, refractive and wavefront changes attributable to epithelial removal in keratoconus

Session Details

Session Title: Keratoconus

Session Date/Time: Monday 16/09/2019 | 14:00-16:00

Paper Time: 15:06

Venue: Free Paper Forum: Podium 2

First Author: : M.Ziaei UK

Co Author(s): :    A. Gokul   H. Vallera   D. Patel   C. McGhee                    

Abstract Details

Purpose:

To compare the topographic, keratometric, refractive and aberrometric features of the corneal epithelium and Bowman layer in eyes with moderate to severe keratoconus before and after epithelial debridement.

Setting:

Tertiary referral centre

Methods:

Prospective interventional case series at a University hospital tertiary referral centre. Corneal topographic, keratometeric, refractive and wavefront variables were measured in patients with keratoconus undergoing corneal collagen crosslinking – immediately before and after epithelial debridement using a third-generation combined corneal topographer, autorefractor and aberrometer.

Results:

The study comprised 30 eyes of 30 patients. Following epithelial debridement, there were significant changes in anterior axial average keratometry in the 3rd central mm ring (+0.81D) and 5.0 central mm ring (+0.36D), asphericity (-0.64) and spherical equivalent (-1.37D). The mean difference in the magnitude of epithelium-induced astigmatism in the 3rd, and 5th central millimeter rings was 0.44 ± 3.20 D × 8 and 0.43 ± 2.75 D × 21 (positive cylinder) respectively. Corneal astigmatism shifted toward the against-the-rule orientation after epithelial debridement. There were no significant changes in any corneal higher order aberration parameter following epithelial debridement.

Conclusions:

In eyes with moderate to severe keratoconus, the topography of Bowman layer was significantly steeper than that of the epithelium. Epithelial debridement increased the magnitude of anterior corneal keratometry and prolateness and tended to increase myopia and against-the-rule astigmatism. Our data support the notion that the corneal epithelium smooths underlying Bowman layer irregularity in keratoconus.

Financial Disclosure:

None