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Method of corneal optical zone diameter calculation and its influence on postsurgical aberration rate

Poster Details

First Author: E.Solodkova RUSSIA

Co Author(s):    E. Blinkova              

Abstract Details


to evaluate impact of individual corneal optical zone diameter on higher-order aberration (HOA) rate after myopic LASIK.


The S.N. Fyodorov Eye Microsurgery Federal State Institution, Volgograd Branch


a prospective case study of 113 patients, set to three groups according to myopia degree, was performed. Diameter of scotopic pupil was measured, post-LASIK corneal optical zone diameter was determined keratotopographycally. Study of spherical aberrations and coma, as well as RMS registration was made within the estimated optical zone prior to and after LASIK. Estimated optical zone diameter (OZR) was calculated according to the formulae: OZR=Dpup Ṫ APD/(APD – AC), where OZR – corneal optical zone diameter, Dpup – scotopic pupil diameter, APD - anterior-posterior dimension, AC – anterior chamber. Follow-up period equaled 3 months.


mean value of spherical aberration within OZR measured post-surgically averaged 0,33ḟ0,03 in the I group, 0,45ḟ0,03 (a 2,14-fold increase) in the II group, 0,58ḟ0,02 (a 2,8-fold increase) in the III group (p<0,05). Post-LASIK coma values within OZR amounted to 0,3ḟ0,04 in the I group (decrease by 1,6 times in comparison to the preoperative degree), to 0,23ḟ0,01 in the II group (a 1,4-fold increase), to 0,22ḟ0,01 in the III group (a 1,2-fold increase) (p<0,05). RMS findings after wave-front LASIK within OZR equaled 0,85ḟ0,06 in the I group, 0,76ḟ0,14 in the II group, 1,68ḟ0,16 in the III group (p<0,05).


it was found that LASIK tends to induce increase in spherical aberration values in cases of moderate and high myopia. However, there was noted a decrease in mean square deviation within the corneal optical zone diameter, calculated according to the proposed formulae.

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