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Impact of categorising keratoconus as central, paracentral, or peripheral based on pachymetry or keratometry on progression parameters

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Session Details

Session Title: Presented Poster Session: Refractive

Venue: Poster Village: Pod 3

First Author: : M.Kubrak-Kisza UK

Co Author(s): :    K. Kisza   M. Nanavaty                    

Abstract Details


To evaluate the impact of categorizing keratoconus as central, paracentral or peripheral based on pachymetry or keratometry on current progression parameters.


Sussex Eye Hospital, Brighton and Sussex University Hospital NHS Trust, Brighton, UK


52 keratoconic eyes underwent epithelial off corneal crosslinking (CXL). Keratoconus was classified as central, paracentral or peripheral based on X and Y coordinates of either thinnest local pachymetry (Group 1) or maximum keratometry (Group 2). Parameters: Kmax, ABCD, anterior, posterior and total corneal wave-front were compared between groups at 1, 3, 6 and 12 months following CXL.d on thinnest pachymetry (group 1) or Kmax (group 2).


For central cones, group 1 (43 eyes) showed decrease in Kmax, ‘A’, anterior and total corneal aberrations at 6 and 12 months. ‘C’ increased after 3 months. In groups 2 (22 eyes), Kmax and total wavefront decreased after 3 months. ‘A’ decreased at 12 months. ‘C’ increased from 3 months onwards. For paracentral cones, group 1 (7 eyes), ‘C’ and total corneal aberrations showed increase. In group 2 (20 eyes) Kmax and ‘A’ decreased after 6 months. ‘C’ showed increase after 3 months. In group 2 (10 eyes), ‘C’ changes at 1 month, posterior corneal aberrometry changed at 6 months.


Thinnest local pachymetry and maximum keratometery should not be used interchangeable when categorizing keratoconus. Although keratoconus may have very thin cornea centrally, the Kmax may not be central in all case. For majority of the parameters considered for monitoring progression, changes were noticed earlier when the keratoconus was classified based on Kmax.

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