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Vienna 2018 Delegate Registration Programme Exhibition Virtual Exhibition Satellites 2018 Survey


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Corneal posterior surface features in keratoconus patients according to the degree of visual limitation

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Session Details

Session Title: Moderated Poster Session: Cornea

Venue: Poster Village: Pod 1

First Author: : J.AliĆ³ del Barrio SPAIN

Co Author(s): :    A. Vega-Estrada   P. Sanz Diez   J. Alio                 

Abstract Details


To describe and analyze the main features of the corneal posterior surface in normal and keratoconus patients taking into account the severity of the visual function.


Vissum, Alicante, Spain.


Retrospective, clinical study evaluating 477 eyes. All patients were classified according to the degree of the visual limitation as follows: normal group: patients with corrected visual acuity (CDVA) of 1,000 in the decimal scale; grade I, CDVA between 0,900 and 0,980; grade II, CDVA between 0,600 and 0,880; grade III, CDVA between 0,400 and 0,580; grade IV, between 0,200 and 0,380 and grade Plus, less than 0,200. All patients were evaluated using rotating Scheimpflug camera and Placido disc topographer device (Sirius system, CSO, Firenze, Italy).


Dioptric power of the posterior corneal surface increases linearly as corrected visual acuity (CDVA) deteriorates (r>0.700; p<0.001). Significant correlation was also observed between shape indices RMS/A (posterior surface irregularity) and CDVA (r=-0.750; p<0.001). Additionally, keratoconus screening indices as BCVb (posterior corneal aberrations) and KVb (posterior ectasia vertex) also showed significant correlation with the degree of visual limitation (r= -0.687; p<0.001 and r= -0.789; p<0.001, respectively).


Posterior corneal surface characteristics are closely related with the degree of visual limitation and can be correctly used for classifying the severity of keratoconus patients. Posterior surface irregularity, posterior ectasia vertex and posterior corneal aberrations are the most representative variables of visual function deterioration and are also useful to differentiate normal from mild keratoconus cases.

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