PURPOSE: Permeability ( @entity63247 ) to @entity941 (F) is a characteristic of the barrier function of the corneal epithelium. The repeatability of several in vivo fluorophotometric methods used to measure permeability in @entity1 remains largely undocumented. This study examines the repeatability of a method based on topical instillation of a single drop of F for the quantitative assessment of @entity63247 . METHODS: Nine healthy subjects with no history of @entity2194 provided 1 (n = 1), 2 (n = 1), or 3 (n = 7) repeated measurements of each eye at successive visits. After making 3 baseline fluorescence scans centrally through the tear film and cornea, 2 microliters of 0.35% F were instilled and 10 fluorescence scans were obtained at approximately 2-minute intervals immediately after instillation. Subsequently, the eyes were rinsed three times with nonpreserved saline and four additional scans were performed. RESULTS: @entity63247 was calculated by dividing the baseline-corrected postrinse stromal fluorescence by the time integral of the tear film fluorescence calculated over the 20-minute exposure period. After applying a logarithmic transformation to the @entity63247 estimates, a mixed-model analysis was used to assess measurement repeatability. On the @entity63247 scale, there is an estimated 95% chance that a second measurement could be as much as 2.88 times higher or 0.35 times lower than a first measurement. CONCLUSIONS: This substantial variability between repeated measurements indicates that the single-drop procedure is unreliable for monitoring individual @entity1 changes. However, with careful sample size planning, this technique can be used in population-based research to compare differences in treatment effects between groups of subjects.

Measurement of corneal epithelial permeability to XXXX . A repeatability study.

@entity1 :: ('9606', 'Species') :: ['humans', 'patient'] @entity2194 :: ('MESH:D005128', 'Disease') :: ['ocular disease'] @entity63247 :: ('5132', 'Gene') :: ['Pdc'] @entity941 :: ('MESH:D019793', 'Chemical') :: ['sodium fluorescein']
@entity941 :: (MESH:D019793,Chemical) :: ['fluorescein']
