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Reproducibility of the OQUAL grid cataract grading system in an African setting.

Bhatt S, Bekele F, Murdoch I

Aim: There is no universal grading system for age-related cataracts. ‘Lens Opacities Classification System III’ (LOCS III), the current gold standard, requires lengthy training, is not time or costeffective and can have poor patient cooperation. These challenges are compounded in resource poor settings. In this study, we explore the OQUAL™ grid as a potential lens grading system compared to the gold standard to overcome these constraints. Method: Pensioners aged over 49 years in Mekelle, Ethiopia were offered a free eye examination and involved in the study if a cataractous lens was present. The degree of crystalline lens opacity was graded using LOCS III and the OQUAL™ grid. Bland-Altman plots were constructed to investigate agreement between both methods of cataract assessment. Results: Bland-Altman plots demonstrated good agreement between both both methods for pure nuclear sclerotic (NS) cataracts. There was weak agreement between both methods for other lens opacity with no systematic bias. A significant association with visual acuity was demonstrated with both OQUAL™ (Chi2=79.0 p=0.019) and a composite LOCS score (Chi2=73.7 p=0.004). Conclusion: This study confirms the OQUAL™ method bears comparison with LOCS III in predicting visual acuity and good agreement exists between the methods when assessing pure NS cataracts which are regarded as difficult to diagnose and grade. The OQUAL™ system detects severe cataracts with worse visual acuities, it is portable, simple, objective, cheap and requires a shorter training period than LOCS III. This allows for large-scale screening, case-finding or research to be conducted in a time and cost effective manner as OQUAL™ can be utilized by a technician on a largescale.