Relation of Corneal Astigmatism with Various Corneal Image Quality Parameters in a Large Cohort of Naïve Corneas

• Main Authors: Omar Yousif M, Elkitkat RS, Abdelsadek Alaarag N, Shams A, Gharieb HM
• Format: Article
• Language: English
• Published: Dove Medical Press 2020-08-01
• Series: Clinical Ophthalmology
• Subjects: sirius topographer; corneal astigmatism; corneal image quality; higher order aberrations; customized versus optimized laser corne-al ablation
• Online Access: https://www.dovepress.com/relation-of-corneal-astigmatism-with-various-corneal-image-quality-par-peer-reviewed-article-OPTH

Mohamed Omar Yousif,1,2 Rania Serag Elkitkat,1,3 Noha Abdelsadek Alaarag,1 Abdelrhman Shams,1 Hesham Mohamed Gharieb1,4 1Faculty of Medicine, Ain Shams University, Cairo, Egypt; 2Maadi Eye Subspecialty Center, Cairo, Egypt; 3Al Watani Eye Hospitals, Cairo, Egypt; 4Research and Development Department, Eye World Hospital, Giza, EgyptCorrespondence: Abdelrhman Shams Cairo, EgyptTel [phone]Email [e-mail]: To investigate the relationship between corneal astigmatism and corneal image quality parameters (i.e., root mean square [RMS] of some major corneal higher order aberrations [HOAs] “namely RMS of coma aberrations, RMS of trefoil aberrations, and RMS of spherical aberration [RMS-SA]” and Strehl ratio [SR] of point spread function [PSF]) by using the Sirius topographer (CSO Italia, Florence, Italy).Patients and Methods: This cross-sectional study used the Sirius topographer to evaluate the naïve corneas of right eyes (n = 1,356). The study included three groups which were based on the mean anterior corneal astigmatism value (group 1, < 1 D; group 2, 1– 2 D; and group 3, > 2 D).Results: The corneal astigmatism showed statistically significant (yet narrow clinical) differences among the groups regarding all the examined parameters (P< 0.001), except for the RMS-SA (which was statistically insignificant among the three groups). Correlation coefficients were weak between the corneal astigmatism and HOAs (correlation coefficient “r” not reaching 0.2 with any of the evaluated HOAs).Conclusion: Significant differences existed among the astigmatic groups regarding corneal HOAs, but the mean values were very close. The deduced relations between corneal astigmatism and corneal image quality parameters had limited clinical relevance. Thus, the corneal astigmatism should be evaluated separately from corneal image quality parameters, either when deciding between refractive correction modalities (customized versus optimized ablation techniques) or when evaluating corneal image quality of a naïve cornea.Keywords: Sirius topographer, corneal astigmatism, corneal image quality, higher order aberrations (HOAs), customized versus optimized laser corneal ablation