Cataract Grading and Classification
Many systems have been proposed for grading cataract severity, using reference photographs to evaluate the color and opacity of the crystalline lens. To be clinically useful, such a grading system must be easy to learn and reproducible, and its degree of complexity should depend on the application. For instance, a grading system used in presurgical assessment may differ from one designed to quantify small changes in lens opacification over time (eg, for use in an epidemiology study or for drug development).
Figure 5-8 Posterior subcapsular cataract (PSC). A, Clinical photograph. B, Viewed with indirect illumination. C, Schematic of PSC.
(Part A courtesy of Arlene V. Drack, MD; part C illustration by Mark Miller.)
The Lens Opacities Classification System III (LOCS III), which is widely used today, consists of a chart with 6 slit-lamp photographs used for evaluating nuclear coloration and opalescence, 5 retroillumination images used for grading cortical cataract, and 5 retroillumination photos used for evaluating PSC. A recent review suggests that although LOCS III is often used in clinical practice, it likely has little impact on the decision of when to perform cataract surgery. New systems that incorporate lens density measurements taken from anterior segment optical coherence tomography (OCT) and fundus photography and that utilize machine learning and artificial intelligence will enable researchers and clinicians to evaluate lens pathology in a standardized and objective way.
Chylack LT Jr, Wolfe JK, Singer DM, et al. The Lens Opacities Classification System III. The Longitudinal Study of Cataract Study Group. Arch Ophthalmol. 1993;111(6):831–836.
Gali HE, Sella R, Afshari NA. Cataract grading systems: a review of past and present. Curr Opin Ophthalmol. 2019;30(1):13–18.
Excerpted from BCSC 2020-2021 series: Section 11 - Lens and Cataract. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.