Early grading of corneal fluorescein staining may affect diagnosis, treatment of DED
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The evaluation of dry eye disease severity and treatment success could significantly be affected by early grading of corneal fluorescein staining, according to a study published in The Ocular Surface.
“The results of this study highlight concerns about the optimum time for grading corneal fluorescein staining,” Carolyn G. Begley, OD, professor emerita at Indiana University School of Optometry, and colleagues wrote. “This is worrisome when considering the errors in grading of corneal staining that may occur in clinical studies or practice, given that there are no widely accepted standards for fluorescein dye instillation and time of observation.”
Begley and colleagues evaluated images of 68 patients with non-Sjögren’s dry eye disease (nSS DED) and 32 with Sjögren’s DED (SS DED) who received corneal fluorescein staining, then conjunctival lissamine green staining every 30 seconds for at least 5 minutes.
Two authors of the study, who are experienced clinicians, graded the de-identified images on a scale from 0 (no staining) to 5 (severe staining). Researchers than calculated the average time needed to achieve the maximum grade of staining (Gmax).
According to study results, there was a statistically significant difference in the median time to corneal fluorescein Gmax between nSS DED (2.6 minutes; lower-upper quartile: 1.3-5.3 minutes) and SS DED (3.8 minutes; lower-upper quartile: 2.6-5.4 minutes).
Further, at 30 seconds, only 15% of nSS DED and 6% of SS DED patients reached corneal fluorescein Gmax. Nearly half of nSS DED patients reached the Gmax at 2 minutes, while it took 4 minutes for half of SS DED patients to reach the Gmax, suggesting that grading corneal staining within the first minute of dye instillation “could result in under-grading large numbers” of patients, according to the authors.
Conversely, the median time to Gmax for lissamine green staining of the nasal and temporal conjunctiva for nSS DED and SS DED patients was not statistically significant. The authors wrote that assessing lissamine green conjunctival staining 1 to 2 minutes after dye instillation does not appear to result in under-grading.
“While these results apply only to the conditions used in this study, we hope it will provide a ‘wake-up’ call for standardizing the use of fluorescein in the assessment of corneal staining in clinical practice as well as in clinical trials,” Begley and colleagues concluded. “Further study of the best time to assess corneal fluorescein staining in various DED populations could be considered an opportunity to greatly improve existing techniques, which would impact both clinical practice and DED clinical trials.”
Perspective
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Grading corneal fluorescein and conjunctival lissamine green staining can vary depending on how long after instillation the grading is performed. The results from this study suggest that the time needed to reach maximal corneal fluorescein staining varied between 30 seconds and 8 minutes after instillation, depending somewhat on dry eye disease (DED) status. However, the time needed to reach maximal lissamine green staining was within the first minute after instillation. These results can help providers improve clinical practice to accurately grade staining presentations.
When using lissamine green, providers should examine the staining pattern within the first minute after instillation. This will give the most accurate presentation for proper grading. For corneal fluorescein staining, providers would benefit by carefully examining the staining pattern at several different times after instillation. The study results suggest that evaluation of corneal fluorescein staining in patients without Sjögren DED is best represented after about 2 minutes, while patients with Sjögren DED show a full staining presentation around 4 minutes after instillation. Grading corneal fluorescein staining every few minutes after initial instillation for 5 to 6 minutes could give a more accurate presentation of the true extent of corneal staining in all patients.
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Begley CG, et al. Ocul Surf. 2022;doi:10.1016/j.jtos.2022.05.003.
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