3rd Generation Formulas and Intraocular Lens Calculation with IOLMaster®. Refractive Results in 101 Eyes and Relationship with Axial Length

Abstract

Introduction: Intraocular lens calculation has become one of the main aspects of cataract surgery. An accurate lens calculation is an important factor for patient satisfaction and quality of life. The purpose of our study is to evaluate which formula (SRK II, HofferQ, Holladay 1 and SRK-T) was nearer to the final refraction after cataract surgery, using the IOLMaster®. Material and Methods: 101 eyes of 78 cataract patients were evaluated. The expected refraction with the intraocular lens used in each patient was calculated with the different formulas and compared to the patient refraction one month after surgery. We obtained data retrospectively from 23 eyes with axial length inferior to 22 mm, 62 eyes with axial length between 22 and 26 mm and 16 eyes with axial length superior to 26 mm. Results: The mean refraction after cataract surgery for all patients was -0.277 diopters (D) ± 0.94. Hoffer Q performed better for eyes with axial length inferior to 22 mm with a mean absolut error (difference between lens calculation and final refraction) of 0.4957 D ± 0.396. For eyes with axial length between 22 and 26 mm SRK-T performed better with a mean absolut error of 0.4515 D ± 0.323 and for eyes with axial length superior to 26 mm SRK-T performed better with a mean absolut error of 0.5538 D ± 0.333. We did not find statistical difference in the comparison between 3º generation formulas, we found statistical significance comparing HofferQ and SRKII in the “inferior to 22 mm” group and SRK-T and SRKII in “between 22 and 26 mm” group. Conclusions: All third generation formulas can be used to calculate intraocular lens, we recommend using HofferQ in axial length inferior to 22 mm and using SRK-T in axial length superior to 22 mm.

Keywords

• biometry
• formula
• cataract
• refraction