Офтальмохирургия (Jan 2016)
Calculating the A-constant for flexible «reverse» IOL
Abstract
Purpose. To determine an A-constant for flexible «reverse» IOL and other IOL constants using the IOL-master.Material ant method. Optical results of cataract phacoemulsification with the implantation of a flexible «reverse» IOL were evaluated. The clinical group included 74 patients with high myopia. All patients underwent the phacoemulsification with the implantation of a flexible «reverse» IOL (with the 25° angle of inclination of haptic elements to the optical part). The mean patient’s age was 52.5±5 years, and the follow-up was 3 to 5 years. Corneal optical power and clinical refraction were measured using the standard keratorefractometers and the IOLmaster. The axial length of eyes was measured by ultrasound biometry and optical coherent method (IOL-master). Several formulas for IOL power calculation were used preoperatively – MICOF, SRK/T, Holladay, Hoffer with the theoretically determined A-constant (121.2).Results. Using statistical analysis of optical results a new value of A-constant for the flexible «reverse» IOL was obtained, it equals 120±0.2.Conclusion. New values of SE, ACD, pACD constants were obtained from the standard A-constant. They show an evidence of effectiveness of «reverse» IOL design features namely, the increase of the distance between the plane of the IOL optics and the apex of the cornea compared with other IOL designs that allows to take a natural anatomical and topographical position in the posterior capsule of the lens.
