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Endri Angjeli, Keith Jeffrey Lane, Michael Watson, John David Rodriguez, George W Ousler; Clinical and Regulatory Implications of Fluorescein Staining Scores With and Without the Yellow Low Pass Filter. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):336.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate fluorescein staining of the cornea in the presence and absence of a yellow low pass filter, and to discuss how simple variations in technique have implications on the significance of staining in clinical practice and in the context of clinical trials.
Eighteen dry eye subjects were defined by the presence of dry eye symptoms and a minimum score of 2 in one region using the Ora Calibra TM staining scale and technique. Sodium fluorescein was instilled in a precisely controlled manner and graded at strict time points. Each eye was graded under blue light followed by grading with a yellow filter. The time between grading cycles was approximately 15 seconds. The inferior and central corneal regions were graded individually from a total of 36 eyes yielding 72 graded regions. These no-filter grades were then averaged at each filter grade category.
The mean central staining score was 0.15 ± 0.35 without the filter and 1.13 ± 0.89 with the filter (p<0.000); the mean inferior staining score was 1.03 ± 1.08 without the filter and 2.33 ± 0.73 with the filter (p<0.000). This represents a 0.98 score increase for the central region and a 1.3 score increase for the inferior region, both of which are considered clinically relevant differences. The one 4 score was graded equally with and without the filter.
Clinicians do not normally use a yellow pass filter when grading fluorescein staining, however, clinical trial protocols typically require this more sensitive and precise technique. This study demonstrated great differences in scores in the lower end of the scale when using a filter, making comparisons of clinical trial data with ‘real world clinic data’ difficult. This finding has multiple implications: 1) that normal subjects might show staining if the technique is sensitive enough; 2) that clinicians might miss dry eye diagnoses if not using a filter when grading staining, and conversely, if using a filter, might falsely diagnose normal subjects with dry eye staining; and 3) that if staining is assessed with a filter, treatment-related total clearing of staining (i.e., a score of 0 after treatment) might not be feasible as an FDA-recommended dry eye clinical endpoint.
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