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Evaluation of sequential wavefront-guided PRK using high definition aberrometer after corneal collagen cross-linking in Keratoconic eyes

Poster Details

First Author: M.Shafik Shaheen EGYPT

Co Author(s):    H. Ezz Eldin   A. Ghanem                 

Abstract Details


The aim of this work was to evaluate visual improvement after wavefront-guided (WFG) Photorefractive keratectomy (PRK) using the high definition aberrometer iDesign System for treatment planning of keratoconic eyes that underwent crosslinking (CXL) at least one year before the laser vision correction (LVC) treatment.


Horus vision Correction Center, Alexandria, Egypt.


Prospective interventional study including 24 eyes with Grade I or II keratoconus according to the Amsler-krumeich classification that were crosslinked at least one year before the LVC surgery. WFG PRK with Mytomicin C was performed using the iDesign System to create the ablation profile and the Star S4IR excimer laser platform to execute the ablation. The maximum ablation depth was planned to not exceed 50 microns. Uncorrected visual acuity (UCVA), manifest refraction, best corrected visual acuity (BCVA), full Pentacam study, Wavefront data acquisition and contrast sensitivity evaluation was performed Preoperatively, 3 months and 6 months after LVC.


24 keratoconic eyes from 16 patients with a significantly aberrated post CXL corneas were operated and completed the 6 months visit. Mean preoperative spherical equivalent was -3.43 ±1.85D and decreased to - 0.41±0.76D at 6 months postoperative visit (p=0.01). There was a significant improvements (with p≤ 0.10) in UDVA logMAR from (0.89±0.41) to (0.16±0.08), BCVA logMAR from (0.62±0.25) to (0.13±0.09), cylinder from (-3.68D±1.04) to (-1.27D±0.77) Contrast Sensitivity significantly improved for all spatial frequencies above 6 cycle/º (p=0.01). HOA RMS (µm) and primary coma RMS improved from (1.35±0.72) to (0.62±0.38) and (0.33±0.27) to (0.15±0.13) (p = 0.01) respectively. All cornea irregularity indices showed decrease in their values although were insignificant.


Before the introduction of high definition aberrometers for planning LVC, many keratoconic eyes could not benefit from a WFG procedure because the aberrometer could not measure their high aberrations. The results of this study show that the treatment of crosslinked keratoconic eyes with WFG PRK is safe and effective to improve the visual function of these type of patients. This is because that we can manage ametropia correction, decreasing the value of HOA that degrade vision especially coma and target a more regular corneal surface.

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