The influence of implant design on accuracy of postoperative refraction

Abstract

Purpose To assess the degree of accuracy of postoperative refraction that may be achieved with modern techniques and a new lens of modern design. Methods Five hundred eyes underwent refraction at one week and one month following phacoemulsification and implantation of the Centerflex™ lens (Rayner Intraocular Lenses Ltd style 570H). Results were compared with the target that had been computerised at the time of surgery, using the Hoffer Q formula for axial lengths less than 22.0 mm, the SRK-T for lengths greater than 24.5 mm and a mean of the two formulae for lengths between 22.0 and 24.5 mm. Statistical analysis used Fisher's exact and one way ANOVA tests. Results At one month 97% of refractions were within 1.0 D spherical equivalent (SE) of target and 81% within 0.5 SE. The mean absolute error was 0.37 ± 0.39 SD. 75.8% of all eyes achieved 6/12 unaided and 88.6% achieved 6/9 with correction. In only 1.2% the refraction between one week and one month had altered by 0.5 D or more. Conclusions The Centerflex™ when combined with modern methods of power calculation, can be associated with a high degree of accuracy in postoperative refraction.