Impact of Best Corrected Final Visual Acuity on the Performance of Intraocular Lens Power Calculations

H John Shammas,1,2 Maya C Shammas,2 Cooper Bahr,3 Ramie Sahota,2 Brad Hall4 1From the Department of Ophthalmology, the Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA; 2Eye department, Shammas Eye Medical Center, Lynwood, CA, USA; 3Department of medicine, Drexel University College of Medicine, Philadelphia, PA, USA; 4Sengi, Penniac, NB, CanadaCorrespondence: H John Shammas, Shammas Eye Medical Eye Centers, 3510 Martin Luther King jr. Blvd., Lynwood, CA, 90262, USA, Email [email protected]: To evaluate the impact of the best-corrected final visual acuity (BCFVA) on the accuracy of intraocular lens (IOL) power calculations.Design, Setting and Methods: This is a retrospective observational study in a private practice setting, Lynwood, California, USA. We analyzed 1107 eyes undergoing standard monofocal cataract surgery, with IOL power calculated using the Barrett Universal II formula. We evaluated the Mean Prediction Error (MPE) and its standard deviation (SD), the Mean Absolute Error (MAE) and its SD and the percentage of eyes within ± 0.50D and ± 1.00D in relation to BCFVA.Results: We analyzed 4 groups with BCFVA noted in LogMAR of ≤ 0.00, 0.02– 0.10, 0.12– 0.20 and 0.22– 0.30. MPE was − 0.030± 0.321, − 0.018± 0.353, 0.015± 0.369 and 0.070± 0.421 D, respectively. MAE was 0.263± 0.186, 0.282± 0.213, 0.301± 0.214 and 0.354± 0.236 D, respectively. The percentage of eyes within ± 0.50D was 85.9%, 82.6%, 81.5% and 75.5%, respectively. A subgroup analysis of the 1005 eyes with BCFVA of 0.20 LogMAR or better resulted in an MPE of − 0.007± 0.354 D, a MAE of 0.285± 0.209 D and a percentage of eyes within ± 0.50D of 82.8%. The difference between this subgroup and the group of eyes with a BCFVA 0.22– 0.30 was statistically significant (p< 0.001).Conclusion: Better IOL power predictions were noted by limiting the study to eyes with BCFVA of 0.20 LogMAR or better.Plain Language Summary: During cataract surgery, the clouded natural lens of the eye is removed and replaced with an intraocular lens, or IOL. Prior to surgery, calculations are required to determine the power of the IOL to be inserted in the eye at the time of surgery. Many studies evaluate the accuracy of such calculations by comparing the final refraction to the predicted one. Most of these patients are seniors and some of them present with concomitant retinal problems that limit the final visual acuity. Studies usually evaluate eyes that have achieved a vision of 0.30 LogMAR (20/40) or better. Our results showed that limiting the analysis to only those eyes that have achieved 0.20 LogMAR (20/32) or better will result in a more accurate evaluation of these predictions by eliminating those cases with poorer final vision that are prone to a higher variability in the post-operative refraction.Keywords: intraocular lens power calculations, Barrett Universal II formula, post-operative visual acuity