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Dawn Meyer, Pete S Kollbaum, Ping Situ, Carolyn G Begley, Trefford L Simpson; Within- and Between-Observer Repeatability of Real-Time and Video-Recorded Slit Lamp Measures of Contact Lens Performance. Invest. Ophthalmol. Vis. Sci. 2014;55(13):6076.
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© ARVO (1962-2015); The Authors (2016-present)
Most methods to clinically measure contact lens performance characteristics are subjective (e.g. 0-4 scale), have poor between measurement repeatability, and poor between observer repeatability. Even with attempts at creating standardized scales and concordance techniques between-measure and between-observer repeatability remain poor, forcing an increased sample size and cost of a study. The aim of the current study is to quantify the within- and between-grader repeatability of real-time and video-recorded soft contact lens performance characteristics.
In this proof of concept study 34 contact lens evaluations were graded in real-time by one observer while simultaneously recording these exams. The same observer and one other observer then used these recordings to provide grades of the lens surface wettability, surface acceptance, push-up tightness, fit acceptance and reticule/scale-based measures of horizontal and vertical lens centration, and post-blink movement on two occasions in a randomized order. Limits of agreement (LoA) were used to describe the within-observer, between-observer, and (within-observer) between-method repeatability. Coefficient of reliability (COR) was also calculated.
Within-observer repeatability was slightly better (average COR: 1.11) than between-observer (average COR: 1.64) for all measures. Between-method repeatability was only slightly higher (average COR: 1.12) than within-observer repeatability. For example, repeatability of grades of wettability and push-up tightness, and measures of vertical lens centration had better between-method repeatability (COR: 0.58, 4.68, and 0.48, respectively) than between-observer repeatability (COR: 0.86, 6.87, and 0.60, respectively).
Repeatable subjective grades and objective measures of contact lens performance are attainable from standardized video recordings. A reading center to grade standardized video captures of contact lens performance characteristics may decrease measurement variability, allowing for smaller sample sizes and improved combination of measures across multiple sites.
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