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Neha Gadaria-Rathod, Kyu-In Lee, Benyamin Ebrahim, Penny Asbell; Non-invasive objective metrics of Bulbar Hyperemia for Clinical Trials Endpoints. Invest. Ophthalmol. Vis. Sci. 2013;54(15):527.
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Bulbar hyperemia is a prominent feature of ocular irritation associated with dry eye disease (DED), infection and allergy. The aims of this study were to evaluate a modified topographer (OCULUS Keratograph 5M) as a non-invasive objective metric for evaluation of DED and ocular surface inflammation, and to evaluate its precision in grading bulbar redness and its correlation with clinician and subject grading.
An IRB approved prospective study of patients presenting with either normal eyes or external ocular disease was conducted. 39 eyes of 20 patients were evaluated for bulbar redness independently by 2 ophthalmologists (CLS1 and CLS2), by patients’ self-assessment (SS) and by the keratograph using the R-scan software. Standardized CCLRU grading scales were used to score the bulbar redness on a scale of 0-4. To establish precision of the keratograph, 2 pictures (KR1 and KR2) of the same eye were taken by the same clinician, 2 minutes apart. The repeatability of measurements was then analyzed using ANOVA and the repeatability index ‘r’. Bivariate correlation analysis was done to get the Spearman’s correlation coefficient.
The keratograph grading showed high repeatability; r=0.90, p<0.001. Both KR1 and KR2 showed high correlation with each other (r=0.93; p<0.01) and with subject scores (r1=0.63, r2=0.70, p<0.01), but variable correlation with clinical scores; clinician 1 scores (r1=0.59, r2=0.61, p<0.01); clinician 2 scores (r1=0.22, p1=0.1; r2=0.31, p=0.05).(Table 1) The clinician scores (mean=1.58+/-0.6) and subject scores(mean=2.3+/-0.7) were significantly higher as compared to the keratograph scores(mean=1.0+/-0.5) (p<0.01).
The keratograph showed high precision in measuring bulbar redness. Being an objective measure, it reduces the inherent variability of subjective assessments. Subjective assessment may overestimate redness due to normally present large blood vessels on the conjunctiva that are not indicative of inflammation. The keratograph takes into account proportion of bulbar area occupied by vessels, number of vessels and the proportion of area occupied by thin vessels and thus reduces overestimation of hyperemia. Thus this novel instrument may prove to be a non-invasive, objective biomarker of ocular surface inflammation and thus serve as an important endpoint in clinical trials of ocular surface disease.
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