Optimization of the calculation of the toric IOL optical power in patients with cataract and changed cornea

    Adstract

    Optimization of the calculation of the toric IOL optical power in patients with cataract and changed cornea

    N.I. Senchenko, O.I. Rozanova, M.A. Shanturova, O.P. Mischenko, T.N. Iureva

    The Irkutsk Branch of the S. Fyodorov Eye Microsurgery Federal State Institution, Irkutsk;
The Irkutsk State Medical Academy of Postgraduate Medical Education, Irkutsk;
The Irkutsk State Medical University, Irkutsk

    

    Purpose. To study the effectiveness of astigmatism correction in patients with cataract and corneal changes based on modified approaches to the calculation of toric IOL optical power.

    Material and methods. The results of toric IOLs implantation (model Acrysof IQ Toric and Rayner T-Flex) were analyzed in 86 patients (121 eyes) with cataract and an altered corneal topography (keratectasia of various origins, scarring, etc.).

    The optical properties of the cornea were examined using the complex tomographic Pentacam scanner and Refractive software, Holladay EKR Detail Report and Fourier – Analysis.

    Depending on the method of calculation of toric IOL optical power the patients were divided into 2 groups. In the group 1 (30 patients, 47 eyes), the corneal topography data of refractive properties of the cornea along the main meridians in a 4.5mm zone were took into account. In the group 2 (56 patients, 74 eyes) the optical corneal parameters, including the optical profile and regular astigmatism, were investigated in the actual area, distinguishing by the position of the apex of the cornea and pupil diaphragmatic function.

    The results were evaluated 1 year after surgery on the basis of residual refractive spherical and cylindrical components, visual acuity, efficiency ratio (the ratio of indicators of uncorrected visual acuity (UCVA) after surgery and best corrected visual acuity (BCVA) before surgery).

    Results. In the standard approach for the optical power calculation of toric IOL the residual astigmatism within 0.75-1.0D was noted in 27.6% of cases (13 eyes), within 1.25D or more – in 17.0% of cases (8 eyes) 12 months after surgery. In case of the modified calculation procedure of IOL power taking into account the actual zone the frequency of differences between the calculated and achieved refraction was smaller: residual astigmatism 0.75-1.0D occurred in 18.9% of cases (14 eyes), 1.25D or more – in 9.4% of cases (7 eyes). The coefficient of efficiency in the patients of the group 2 was 20% higher than in patients of the group 1.

    Conclusion. The proposed approach to the choice of toric IOL power in patients with cataract and altered cornea using the Pentacam corneal topography data in the actual zone, is a highly efficient and predictable.

    Key words: toric IOL, calculation of IOL optical power, astigmatism, cataract.

    

    No author has a financial or proprietary interest in any material or method mentioned.