Variation of choroidal thickness and vessel diameter in patients with posterior non-infectious uveitis

Background: Choroidal thickness (CTh) and choroidal vessel diameter (VD) in the Haler’s layer were evaluated as markers of inflammatory insult in non-infectious uveitis (NIU). Spectral-domain optical coherence tomography (Spectralis®, Heidelberg Engineering Inc.) scans were acquired from 23 normal subjects (39 eyes – group 1), 7 subjects with high myopia (14 eyes – group 2), and 19 patients with NIU (23 eyes – group 3). In groups 1 and 2, CTh and VD were measured at 3 different points of the same horizontal OCT scan passing through the fovea and a mean calculated. Mean CTh and VD were calculated in 2 other locations, 2 mm superior and inferior from the chosen foveal horizontal scan. In group 3, three measurements of CTh and VD were obtained within 1 mm of a horizontal scan passing through a retinal lesion; mean CTh and VD were then computed. A ratio (R) between the VD and the corresponding CTh was calculated. Results: Group 1, 2 and 3 mean age was 29.6, 29.1 and 45.9 years, respectively. Sixteen normal subjects, three myopic subjects and six NIU patients were male. Group 1 mean CTh did not differ from group 2 (261.6±45.6 vs. 260.2±50.6 µm µm; p>0.05); mean VD was marginally higher in Group 2 (159.8±32.2 vs. 163.2±33.2 µm; p>0.05). Group 3 demonstrated thinner CTh (193.6±54.6 µm) than Groups 1 and 2 (p = 0.02 and <0.001). Group 3 mean VD (123.6±37.4 µm) was also less than that in Groups 1 and 2; the difference was statistically significant only when compared to group 2, p = 0.01. R did not differ across groups (p-values >0.05), indicating that variations in CTh and VD followed the same trend. Conclusions: The study reports potential quantitative OCT-derived parameters that may be explored in future trials of non-infectious uveitis. Thinning of choroid and decrease of vessel diameter are observed in patients with chronic NIU compared to controls.