The accuracy of IOL power calculation formulas for eyes of axial length exceeding 24.5 mm

Introduction
To compare the accuracy of different IOL power calculation formulas for eyes of axial length exceeding 24.5 mm.

Material and methods
61 patients were examined, whose ocular axial lenght ranged between 24.51 mm and 26.72 mm. Preoperatively, the IOL power for each patient was calculated using six different formulas (SRK II, SRK/T, Binkhorst, Hoffer Q, Holladay 1, and Haigis). The power of the actually implanted IOL was based on Holladay 1 formula. Visual acuity was measured using Snellen chart on the 30th postoperative day.

Results
54 patients (88.5%) achieved full visual acuity (1.0 on Snellen chart) after cataract surgery. If other power calculation formulas were used for the actual IOL, this would be achieved respectively in: SRK/T – 39 patients (63.9%), Hoffer Q – 22 patients (36.1%), Binkhorst – 21 patients (34.4%), Haigis – 7 patients (11.5%), SRK II – 5 patients (8.2%).

Conclusions
1. Holladay 1 formula is recommended for intraocular lens power calculation for eyes of axial length exceeding 24.5 mm. 2. SRK/T formula also seems to be satisfactory for these cases.