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Article
June 1993

The Lens Opacities Classification System III

Author Affiliations

From the Center for Clinical Cataract Research, Brigham and Women's Hospital (Drs Chylack, Wolfe, Singer, Friend, and McCarthy, and the Longitudinal Study of Cataract [LSC] Study Group) and Harvard Medical School (Drs Chylack, Wolfe, and Friend, and the LSC Study Group), Boston, Mass; Department of Preventive Medicine, State University of New York at Stony Brook (Drs Leske and Wu and the LSC Study Group), and School of Optometry, University of California, Berkeley (Drs Bullimore and Bailey).

Arch Ophthalmol. 1993;111(6):831-836. doi:10.1001/archopht.1993.01090060119035
Abstract

• Objective.  —To develop the Lens Opacities Classification System III (LOCS III) to overcome the limitations inherent in lens classification using LOCS II. These limitations include unequal intervals between standards, only one standard for color grading, use of integer grading, and wide 95% tolerance limits.

Design and Results.  —The LOCS III contains an expanded set of standards that were selected from the Longitudinal Study of Cataract slide library at the Center for Clinical Cataract Research, Boston, Mass. It consists of six slitlamp images for grading nuclear color (NC) and nuclear opalescence (NO), five retroillumination images for grading cortical cataract (C), and five retroillumination images for grading posterior subcapsular (P) cataract. Cataract severity is graded on a decimal scale, and the standards have regularly spaced intervals on a decimal scale. The 95% tolerance limits are reduced from 2.0 for each class with LOCS II to 0.7 for nuclear opalescence, 0.7 for nuclear color, 0.5 for cortical cataract, and 1.0 for posterior subcapsular cataract with the LOCS III, with excellent interobserver agreement.

Conclusion.  —The LOCS III is an improved LOCS system for grading slit-lamp and retroillumination images of age-related cataract.

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