Assessment of Preoperative Risk Factors for Post-LASIK Ectasia Development

Abstract

Mohamed Tarek El-Naggar,1 Rania Serag Elkitkat,2– 5 Hossam El-din Ziada,6 Louise Pellegrino Gomes Esporcatte,7– 9 Renato Ambrósio Jr7– 11 1Refractive Surgery Unit, Ophthalmology Department, Research Institute of Ophthalmology, Giza, Egypt; 2Ophthalmology Department, Faculty of Medicine, Ain Shams University, Cairo, Egypt; 3Watany Eye Hospital, Cairo, Egypt; 4Watany Research and Development Center, Cairo, Egypt; 5Ophthalmology Department, Modern University for Technology and Information, Cairo, Egypt; 6Cornea and Refractive Surgery Unit, Ophthalmology Department, Faculty of Medicine, AL-Azhar University, Cairo, Egypt; 7Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil; 8Instituto de Olhos Renato Ambrósio, Rio de Janeiro, Brazil; 9Department of Ophthalmology, Federal University of São Paulo, São Paulo, Brazil; 10Brazilian Study Group of Artificial Intelligence and Corneal Analysis - BrAIN, Rio de Janeiro & Maceió, Brazil; 11Department of Ophthalmology, Federal University of the State of Rio de Janeiro (UNIRIO), Rio de Janeiro, BrazilCorrespondence: Mohamed Tarek El-Naggar, Email [email protected]: To evaluate preoperative risk factors (mainly those related to corneal topography/tomography) for post-LASIK ectasia development.Methods: A retrospective case review for post-LASIK ectasia for myopia or myopic astigmatism. The evaluated data included preoperative subjective refraction, method of flap creation, and topometric/tomographic parameters from Oculus Pentacam, including subjective curvature pattern, topometric, elevation, and pachymetric indices from the Belin Ambrosio display “BAD”, and the Pentacam Random Forest Index (PRFI). Moreover, preoperative ectasia detection indices were calculated (including Percentage of Tissue Altered “PTA” index, Randleman Ectasia Risk Score System “ERSS”, and Navarro Index for Corneal Ectasia “NICE”).Results: Twenty-four eyes of 15 patients were enrolled. Concerning the risk factors, age was lower than 25 in 19 eyes (79%); flaps were created using a microkeratome in 17 eyes (70.8%); thinnest pachymetry was lower than 510μm in eight eyes (33%); total deviation from BAD was higher than 1.6 in 50%; Ambrósio’s relational thickness (ART) max was lower than 340 in 45.83%; PTA index was higher than 40% in 16%; ERSS was more than 3 points in 62.5%; NICE was higher than 8 points in three eyes (12.5%); PRFI index was more than 0.125 in 87.5%; two eyes (8%) had no identifiable risk factors.Conclusion: Current ectasia risk assessment criteria were insufficient for detecting a relatively large number of cases. There is an unequivocal need for more information, which may be derived from biomechanical assessment and epithelial thickness mapping. Novel corneal tomography indices derived from artificial intelligence may increase accuracy in characterizing ectasia susceptibility.Keywords: cornea ectasia, preoperative ectasia risk assessment, LASIK screening, Pentaca