Conjunctival and Scleral Thicknesses with and without Conjunctival Ultraviolet Autofluorescence

Purpose : Ultraviolet autofluorescence (UVAF) is a clinical technique used to visualise conjunctival changes thought to be due to excessive sunlight exposure and so is considered to be an outdoor sunlight biomarker with UV damage and myopia applications. We performed an experimental observation study aimed to measure the conjunctival and scleral thicknesses in participants with and without conjunctival UVAF to better understand the underlying tissues changes.Methods : Conjunctival UVAF photographs (Nikon D90, 375 nm LEDs) and anterior OCT volume scans (Heidelberg, Spectralis) of the right eye were taken on 42 participants with healthy eyes aged between 19 and 43 years of age. The participants were classified according to the presence or absence of UVAF on the temporal and nasal conjunctivas of the right eye, resulting in 4 groups (Table 1).The OCT images of the temporal conjunctiva were exported and analysed with a previously reported semi-automated procedure using custom written software. From these segmentations, tissue thicknesses were determined for the conjunctival epithelium, conjunctival stroma and sclera for the 21 horizontal line scans analysed between 0 to 4 mm from the scleral spur.Results : Significant differences in thickness for all 3 tissues were observed with the presence of UVAF with a thinner conjunctival epithelium, thicker conjunctival stroma and thicker sclera (ANOVA p Conclusions : The conjunctival epithelium, conjunctival stroma and sclera all had significant changes in tissue thickness with the presence of UVAF. A significant difference in temporal conjunctival stromal thickness was observed when the presence of both nasal and temporal UVAF was considered, suggesting that the tissue may be thickening before UVAF is visible. This may help to further understand the sunlight-related damage to this tissue.