Eyeworld

54 | EYEWORLD | WINTER 2026 R EFRACTIVE Reference 1. Fernández J, et al. Global con- sensus on the evidence-based functional classification of simul- taneous vision IOLs. J Cataract Refract Surg. 2026;52:219–222. among clinicians and researchers." IOLs were then described further in subcategories. Within the Partial-DOFi category, there are Narrowed, Enhanced, and Extended subcategories. Nar- rowed IOLs are standard monofocal IOLs, Enhanced are those that provide more DOFi than Narrowed IOLs, and Extended are those that provide still more DOFi, approaching a full range of vision but not quite. The next major category is Full-DOFi, from distance to near, with subcategories of Steep, Smooth, and Con- tinuous depending on the intermediate vision. IOLs in the Steep subcategory would provide Full-DOFi vision at distance and near with a de- crease in the intermediate. Those in the Smooth subcategory provide a smoother transition from intermediate to near. Those in the Continuous subcategory provide relatively little change in visual acuity from intermediate to near. "… the terminology needed to distinguish more clearly between optical and clinical assess- ment while remaining consistent with terms al- ready established in the scientific literature," Dr. Fernández explained. "'Depth of focus' (DOFo) has traditionally been used in an optical context, whereas the Functional Classification is based on clinical defocus curves and therefore describes the range of visual performance experienced by the patient across different viewing distances. For this reason, DOFo was retained for optical bench assessment, while 'depth of field,' or DOFi, was adopted for the clinical domain." Moving away from "range of field (ROF)" terminology to DOFi helped avoid introducing an additional term. "DOFi provides a familiar and scientifically established concept that can be directly related to the way clinicians inter- pret defocus curves: as the range of distances over which useful vision is maintained," Dr. Fernández said. "This creates a clearer and more standardized language, while immediately indicating whether we are referring to optical performance in the laboratory or functional visual performance measured clinically." Not a replacement for regulatory classification The Functional Classification and the ISO 11979-7:2024 are complementary, not com- peting. "ISO is primarily a pre-market frame- work; it asks whether an IOL meets predefined requirements for a regulatory category such as multifocal, EDOF, or full visual range under highly standardized clinical conditions," Dr. Fernández explained. "That rigor is essential for demonstrating safety and effectiveness and for reducing uncertainty at market entry, but the resulting category reflects performance within that specific regulatory framework." The Functional Classification composed by the working group asks a different question of the lens once it has been used more broad- ly, Dr. Fernández continued. "What functional continued from page 53 Diagram of the functional classification based on (1) the DOFi achieved on the monocular defocus curve with best distance correction at a visual acuity (VA) threshold of 0.2 logMAR and (2) the improvement in VA from intermediate to near (∆VA) Source: Adapted by the author of Fernández et al. and supplied for use in this article; Fernández et al. Global consensus on the evidence-based functional classification of simultaneous vision IOLs. J Cataract Refract Surg. 2026;52:219–222

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