Back calculated total preoperative corneal astigmatism to assess the accuracy of keratometric astigmatism selected for an individual actual zone
Year: 2026
Type: article
Study design: Observational Study
Abstract: Purpose. To compare the back calculated total preoperative corneal astigmatism with the measured one, in accordance with an individually selected and fixed zone. Material and methods. Back calculation of the total preoperative corneal astigmatism was performed in 56 patient (56 eyes) after phacoemulsification with toric IOL implantation, using data from postoperative manifest refraction converted to the cornea plane, toricity of IOLs converted to the cornea plane and surgically induced corneal astigmatism. Using vector analysis, a comparison of the back calculated astigmatism with the one measured before the surgery in an individually selected and fixed (3 mm) zone was performed. Results. Vector analysis showed a significantly smaller difference between calculated and measured astigmatism in the individual actual zone in comparison with astigmatism in a fixed 3 mm zone: 0.57 and 0.83 D, respectively (p=0.01). The centroid values were also lower when using the individual zone (0.14 vs 0.32). Conclusions. The astigmatism selected according to the described principles of the individual actual zone most accurately reflects the “true” preoperative total corneal astigmatism and allows to improve the accuracy of the calculation of the toric IOL. Keywords: corneal astigmatism, toric IOLs, back calculation of the astigmatism, actual keratometry zone
Authors: S.V. Shukhaev, A.V. Molodkin, O.B. Ivanova
Language: English
Subfield: Ophthalmology
Field: Medicine
Domain: Health Sciences
Open Access status: diamond
OpenAlex ID: W7212484153