Evaluation of the relationship between symptomatic assessment, corneal staining and tear meniscus by image analysis

Purpose: Vital staining is one of the most widely test used to evaluate the corneal damage. The aim of this study was to assess the relationship of the corneal damage with tear meniscus height (TMH) and dry eye symptomatology. Material and methods: 530 subjects were recruited among patients of the Optometry Clinic (USC). Previously, all of them completed an OSDI questionnaire. Two videos of the ocular surface were recorded from each patient by a digital camera attached to a slit-lamp. Firstly, a video of central tear meniscus under 40x with the Tearscope device illumination was recorded. From those videos, a masked observer extracted one image and TMH was measured by using the ImageJ software. Secondly, after fluorescein instillation, the corneal surface was recorded by another experienced masked observer, who assigned a category to the corneal damaged based on the Oxford Scheme. The evaluation was stratified by corneal zones based on the CCLRU grading scales (central, superior, inferior, nasal and temporal). Results: When the sample was grouped by the corneal staining Oxford Grade, there was found a statistical difference between groups in OSDI and TMH value (ANOVA: Both p≤0.006). There was found a difference in OSDI value when corneal damage was in nasal or inferior areas (t-test; both p≤0.015), and a difference in TMH value arises when damage was in the central, nasal or inferior areas (t-test; all p≤0.013). Conclusions: There is a relationship between corneal damage grade and corneal zones with dry eye symptomatology and tear film volume.