Functional Optical Balance (FOB) is a novel personalized strategy for intraocular lens (IOL) selection in cataract surgery, designed to reconcile the trade-off between optical quality and spectacle independence. FOB is a core concept aiming to maximize visual performance by treating the two eyes as a synergistic pair. One eye (often the dominant eye) is optimized for pristine optical quality (typically distance vision with a high-contrast monofocal or low-add IOL). In contrast, the fellow eye is optimized for extended depth of focus and pseudoaccommodation (using an extended depth-of-focus or multifocal/trifocal IOL) to reduce dependence on glasses. This review introduces the rationale and theoretical basis for FOB, including the interplay of depth of focus and optical aberrations, binocular summation, ocular dominance, and neuroadaptation. We discuss the clinical implementation of FOB: how the first-eye results guide the second-eye IOL choice in a tailored “mix-and-match” approach, as well as practical workflow considerations such as patient selection, ocular measurements, and decision algorithms. We also review current evidence from the literature on asymmetric IOL combinations (e.g., monofocal plus multifocal, or EDOF plus trifocal), highlighting visual outcomes, patient satisfaction, and remaining evidence gaps. Overall, FOB represents a paradigm shift toward binocular, patient-customized refractive planning. Early clinical reports suggest it can deliver a continuous range of vision without significantly compromising visual quality, though careful patient counseling and case selection are essential. Future directions include the integration of advanced diagnostics, artificial intelligence-driven IOL planning tools, and adaptive optics simulations to refine this personalized approach further. The promise of FOB is to improve cataract surgery outcomes by achieving an optimal balance: one that provides each patient with excellent visual quality and functional vision across distances, tailored to their lifestyle and expectations.
Amaral et al. (Fri,) studied this question.