Diagnosis of Photokeratitis by Tear Ferning Using a Novel Set of SK Grading Criteria in a UVB-Induced Mouse Model

Purpose: Current ocular surface diagnostic methods may not totally meet and imple-ment the clinical demands for early and precise treatments. The tear ferning (TF) test has been known as a quick, simple, and inexpensive procedure. This study aimed to validate the TF test as an alternative method for early determination of photokeratitis status. Methods: The tear sample was collected from the UVB-induced photokeratitis eyes and processed for TF formation. The TF patterns were graded by both the Masmali and a Sophie-Kevin (SK) grading criteria, a new set of criteria modified from the Masmali grading, for differential diagnoses. In addition, the TF test results were correlated with three clinical ocular surface indicators, including tear volume (TV), tear film break-up time (TBUT), and cornea staining, to evaluate the diagnostic capacity. Results: Differential diagnosis between the normal and the photokeratitis status was achieved by the TF test. The SK grading reflected earlier photokeratitis status than the Masmali grading criteria. The TF results were strongly correlated with the three clinical ocular surface indicators, particularly for the TBUT and cornea staining. Conclusions: The TF test was proven to have a capacity to distinguish photokeratitis from the normal status at an early stage by using the SK grading criteria. It is therefore potentially useful for photokeratitis diagnosis in the clinical settings. Translational Relevance: The TF test may fulfill the demands of precise and early diagnosis to facilitate in time the intervention for photokeratitis.