The influence of concomitant glaucoma on iol power calculation accuracy

Abstract

Aim. To estimate the influence of concomitant glaucoma (including that after surgery) on IOL power calculation accuracy before phacoemulsification. Materials and methods. 413 patients were included in the study divided in 4 groups: 1st patients with cataract and no concomitant glaucoma (251 cases); 2nd patients with cataract and primary open-angle glaucoma (POAG) on medical therapy (103 cases); 3rd patients with cataract and prior trabeculectomy (42 cases); 4th patients with cataract and primary angle-closure glaucoma (PACG) on medical therapy (17 cases). In all patients, the IOL power calculation was performed using optical biometry (IOL-Master 500). 1 month after surgery, desired refraction according to Barrett Universal II Formula and real obtained refraction estimated by automatic refractometry (Topcon-8800) were compared. Results. There was no significant difference between study groups 13 in IOL power calculation accuracy (the calculation error was 0.09 0.39 D, 0.08 0.45 D, 0.03 0.49 D, for each group respectively). However, we found a higher myopic shift (0.47 0.48 D, p = 0.095) in the 4th group. Conclusion. The presence of concomitant POAG on medical therapy, same as earlier trabeculectomy, does not demand any modification of the IOL calculation algorithm. However, in PACG patients we recommend taking 0.5 D lower optical power IOLs to avoid excessive myopic refraction after phacoemulsification.