Contact lens opacity grading system (CLOGS)

Grading and classification systems have been used in contact lens research for many years, despite a lack ofstandardisation. A new system for classifying the type of contact lens deposit and assessing its extent is presented. It makes use of five standard photographs for direct comparison purposes and allows decimal interpolation between grades. A further five photographs are included to allow differential identification of artefacts, scratches and spot deposits. This paper presents both intraobserver (coefficients of repeatability ±0.79, ±0.79 and ±0.76; Pearson correlation coefficients 0.94, p<0.0001, 0.92, p <0.0001 and 0.91, p<0.0001) and interobserver repeatability (coefficients of repeatability ±1.13, ±1.09 and ±1.22; Pearson correlation coefficients 0.86, p<0.0001, 0.90, p<0.0001 and 0.84, p<0.0001) results derived from three observers which demonstrate the reproducible nature of assessments when using this system. We therefore recommend this system for use in longitudinal studies, such as efficacy trials of contact lens care systems and clinical procedures involving contact lens deposits.