The use of conjunctival ultraviolet autofluorescence (CUVAF) as a biomarker of time spent outdoors.

PURPOSE: Conjunctival ultraviolet autofluorescence (CUVAF) has been used in previous Southern Hemisphere myopia research as a marker for time spent outdoors. The validity of CUVAF as an indicator of time spent outdoors is yet to be explored in the Northern Hemisphere. It is unclear if CUVAF represents damage attributed to UV exposure or dry eye. This cross-sectional study investigated the association between CUVAF measures, self-reported time spent outdoors and measures of dry eye. METHODS: Participants were recruited from University staff and students (n = 50, 19-64 years; mean 41). None were using topical ocular medications (with the exception of dry eye treatments). Sun exposure and dry eye questionnaires (Ocular Surface Disease Index and McMonnies) were completed by the participant. Dryness was also assessed using slit lamp biomicroscopy and invasive tear break up time. Images of the temporal and nasal conjunctiva from the right and left eye were captured using a bespoke photography system. The total CUVAF area, average CUVAF pixel intensity per mm(2) and total CUVAF pixel intensity were analysed using MATLAB R2013a (The MathWorks Inc). RESULTS: Of the 50 participants, 42% were classified as having dry eye. Self-reported sunglasses use was negatively associated with all CUVAF measures (Kruskal Wallis total CUVAF area, p = 0.04, ptrend  = 0.03, average CUVAF pixel intensity p = 0.02, ptrend  = 0.02, total CUVAF pixel intensity: p = 0.04, ptrend  = 0.02). Time spent outdoors was positively associated with all CUVAF measures (Spearman's correlation coefficients, total CUVAF area: r = 0.37, p = 0.01, average CUVAF pixel intensity: r = 0.36, p = 0.01, total CUVAF pixel intensity: r = 0.37, p = 0.01) and remained significant when sunglasses use was controlled for (partial correlation, total CUVAF area: r = 0.32, p = 0.03, average CUVAF pixel intensity: r = 0.39, p = 0.01, total CUVAF pixel intensity: r = 0.39, p = 0.03). Neither CUVAF area nor intensity measures were associated with any dry eye measure (Ocular Surface Disease Index: all p ≥ 0.41, corneal staining: all p ≥ 0.38, McMonnies: all r ≤ 0.09 all p ≥ 0.52, slit lamp biomicroscopy: all r ≤ 0.20 all p ≥ 0.17, invasive tear break up time: all r ≤ -0.07 all p ≥ 0.31). CONCLUSIONS: CUVAF area and intensity were not associated with clinical measures of dry eye. Greater CUVAF area and intensity were associated with wearing sunglasses less frequently and spending more time outdoors. If sunglass wear is accounted for, CUVAF may be a useful biomarker of time spent outdoors in future myopia studies.

Clinical judgement of near pupil responses provides a useful indicator of focusing ability in children with cerebral palsy.

Accommodation is often reduced in cerebral palsy (CP). Knowledge about accommodative facility is valuable when investigating a child's visual needs and developing strategies for education. With normal accommodation, changing focus from distance to near results in pupil constriction. We compared quality of near pupil responses (NPR) with objective measures of accommodative function obtained with dynamic retinoscopy (DR) to investigate the utility of NPR in indicating accommodative facility. NPR and accommodative function of 90 children with CP (56 males, 34 females; median age 11y, range 4-18y) were assessed. A total of 93% of participants had spastic CP (71.3% bilateral involvement, 28.7% hemiplegia). The severity of motor impairment ranged from very mild (n=7) to severe (no independent walking, n=28). NPR was classified subjectively as normal, reduced, or absent and compared with DR measures of accommodative response. A total of 9.8% of pupil responses were judged absent, 25.6% reduced, and 64.6% normal. Participants with reduced or absent pupil responses demonstrated significantly poorer levels of accommodation with DR (one-way analysis of variance p<0.01). Sensitivity and specificity of NPR in identifying participants with reduced accommodation were 83% (95% confidence interval [CI] 65.5-92.4%) and 72% (95% CI 58.4-82.0%) respectively. NPR provides a rapid, useful indicator of accommodative function in children with CP.