Abstract
Aim To assess the impact of posterior corneal asphericity on postoperative astigmatism. Methods We included retrospectively 70 eyes of 70 patients that underwent cataract surgery. We included data of the Q value, Kmax, K1, K2, astigmatism AL, and ACD. We performed a vectorial analysis to calculate the astigmatic vectors. Results Seventy eyes were evaluated. 40 eyes were of females (58%) and 30 of males (42%). The average cohort age was 73 ± 8.9 years. Axial length (AL) was 23.5 ± 0.9, anterior chamber depth (ACD) was 3.13 ± 0.3, and the average posterior Q value was −0.35 ± 0.2. The only significant predictive variable for the correction index (CI) was the posterior Q value (r = 0.24, p < 0.05) and for the surgically induced astigmatism (SIA) (β = 0.34, r = 0.58, p < 0.05). Conclusion Posterior corneal surface asphericity significantly influences the surgically induced astigmatism and the overcorrection for cataract patients after Lucidis EDOF IOL implantation.
Highlights
Introduction eQ value serves as a key parameter reflecting the corneal asphericity and optical properties including power of refraction, spherical aberration, and aberration variability.A negative Q value denotes a prolate structure of the cornea, while a positive value is consistent with an oblate form [1]
Corneal asphericity may be a possible source of errors in power calculations. is implies that IOL power calculation can be refined by taking asphericity into account and including measurements of both corneal surfaces [3]
For surgically induced astigmatism (SIA) as the dependent value, posterior Q value adjusted for confounders had a significant effect (β 0.34, r 0.58, p < 0.05)
Summary
A negative Q value denotes a prolate structure of the cornea, while a positive value is consistent with an oblate form [1]. Both anterior and posterior corneal asphericities do not have any correlation to each other, with the latter presenting a more aspherical shift with age [2]. Is implies that (intraocular lens) IOL power calculation can be refined by taking asphericity into account and including measurements of both corneal surfaces [3]. The posterior asphericity of the cornea has received less or almost no attention in the analysis of potential factors leading to IOL refraction calculation errors
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