8 EyeWorld Asia-Pacific | December 2024 by Graham Barrett, MD IOL Formulae With deep respect and affection for David’s ethics as an individual and surgeon, I will offer a consideration and comparison of LALs to IOL Formulae which considers precision and perfection of outcomes, as well as any additional effort, expense and safety involved. Firstly, I should note the LAL project’s inception in 1996— whereas Formulae have progressively evolved and achieved significantly greater prediction accuracy than those available when this project was initially conceived. Let’s focus first on outcomes. At present there are relatively few published studies on the refractive outcomes of patients who have had a light adjustable lens implanted. I have listed the outcomes in terms of the number of eyes achieving within 0.5 D of predicted outcomes. Most studies include normal eyes with no history of previous refractive surgery eyes as displayed in the green columns. Other studies focus on eyes with previous refractive surgery as displayed in the orange columns when available, and the published results are quite variable. The outcomes in normal eyes vary from 80% in the paper published by Villegas to 100% in the paper by Folden and co-authors. The 12-month study by Moshirfar with 89% is similar to the outcomes in the FDA study of 92% within 0.5D of the intended outcome. The outcomes in eyes with a history of previous refractive surgery are even more variable ranging from 55% in the Moshifar study to 100% within 0.5D in the Folden study. A recent study by Ferguson and co-authors which only considered eyes with previous refractive surgery reported 86% within 0.5 D. These results are excellent but it is certainly feasible to achieve similar outcomes with precision biometry and formulae. In my own patients, the percentage of eyes achieving an outcome within 0.5 D is consistently in the 90% range both for sphere and cylinder. Similar results have been published by others for example the study in 545 eyes published by Dr Chung and others in 2021 where 90% had a prediction error with 0.5 D. I am sure David achieves similar outcomes with normal eyes and that is why LAL is often recommended for patients who have had previous refractive surgery. 100 80 60 40 20 0 Haigis SRK/T Holladay II BUII IOL Formulae Outcomes - Normal 90% 86% 85% 83% Comparative prediction accuracy between total keratometry and conventional keratometry cataract surgery with refractive multifocal intraocular lens implantation. Source: Graham Barrett, MD Ho Seok Chung, Jae Lim Chung, Young Jun Kim, Hun Lee, Jae Yong Kim and Hungwon Tchah Sci Rep. 2021; 11: 19234 100 80 60 40 20 0 Moshirfar et al Folden et al Villegas et al Fegurson et al FDA Light Adjustable Lens (LAL) Outcomes 89% 55% 100% 100% 80% 92% 86% Post Refractive Normal Source: Graham Barrett, MD FEATURE Pathways to Precision and Perfection – Light Adjustable Lens (LAL) vs. IOL Formulae
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