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Algorithm for correcting keratometric error in the estimation of corneal power in keratoconus eyes after accelerated corneal collagen cross-linking

Poster Details

First Author: V.Camps SPAIN

Co Author(s):    D. Pinero   E. Caravaca                 

Abstract Details

Purpose:

To analyze theoretically and clinically the errors associated to corneal power calculation using the keratometric approach in keratoconus eyes after accelerated corneal collagen crosslinking (CXL) surgery and to obtain a model for the estimation of an adjusted keratometric index (nkadj) minimizing such errors.

Setting:

University of Alicante (Spain)

Methods:

Potential differences (�Î�”Pc) among keratometric (Pk) and Gaussian corneal power (PcGauss) in keratoconus eyes with previous CXL were simulated. Three algorithms based on the use of nkadj for the estimation of an adjusted keratometric corneal power (Pkadj) were developed. The agreement between P(k1.3375)(keratometric power using the keratometric index of 1.3375), PcGauss and Pkadj was evaluated. This agreement and validity of the algorithm developed were investigated in 21 keratoconus eyes undergoing accelerated CXL.

Results:

Pk1.3375 overestimated corneal power between 0.3 and 3.2 D in theoretical simulations, and between 0.8 and 2.9 D in the clinical study. Mean clinical �Î�”Pc was 1.63 D (limits of agreement: 0.44 and 2.82 D). Three linear equations were defined for nkadj to be used for different ranges of r1c. In the clinical study, differences between Pkadj and PcGauss did not exceed �Â�±0.8 D and the use of nk= 1.3375 was associated to significant overestimations. No statistically differences were found between Pkadj and PcGauss (p>0.05), whereas differences between Pk1.3375 and Pkadj were statistically significant (p<0.01).

Conclusions:

The use of a single value of keratometric index for corneal power calculation in keratoconus eyes after accelerated CXL can lead to significant clinical errors. These errors can be minimized with an adjusted keratometric approach.

Financial Disclosure:

NONE

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