First Author: D.Pi SPAIN
Co Author(s): V. Camps V. Mateo P. Ruiz Fortes
Purpose:
To validate clinically in a normal healthy population an algorithm to correct the error in the keratometric estimation of corneal power based on the use a variable keratometric index of refraction (nk).
Setting:
Medimar International Hospital (Oftalmar) and University of Alicante, Spain
Methods:
Corneal power was measured with a Scheimpflug photography-based system (Pentacam software version 1.14r01) in 92 healthy eyes with no previous ocular surgeries of 92 patients ranging in age from 15 to 64 years. In all cases, keratometric corneal power was also estimated by using an adjusted value of nk dependent on the anterior corneal radius (r1c): nkadj=-0.0064286 r1c +1.37688. Agreement between the Gaussian (PcGauss ) and adjusted keratometric (Pkadj) corneal power values was evaluated.
Results:
Mean difference between PcGauss and Pkadj was -0.02±0.22 D (p=0.43). A very strong and statistically significant correlation was found between both corneal powers (r=0.994, p<0.01). The range of agreement between PcGauss and Pkadj was 0.44 D, with limits of agreement of -0.46 and +0.42 D. In addition, a very strong and statistically significant correlation of the difference between PcGauss and Pkadj and the posterior corneal radius was found (r=0.96, p<0.01).
Conclusions:
The imprecision in the calculation of corneal power by using the keratometric estimation can be minimized in clinical practice by using a variable keratometric index that depends on the radius of the anterior corneal surface. The potential benefit of using this algorithm in IOL power calculation in order to optimize the refractive outcome should be also evaluated. FINANCIAL DISCLOSURE?: No
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