Quantitative analysis of the iris surface smoothness by spectral domain optical coherence tomography in Fuchs uveitis

Purpose To demonstrate the value of “smoothness index” as a novel tool for quantitative analysis of iris surface findings in unilateral Fuchs’ uveitis (FU). Methods In this observational study, both phakic eyes from patients with the diagnosis of unilateral FU were enrolled. All eyes underwent a complete ophthalmic examination and anterior segment optical coherence tomography(AS-OCT). The images were extracted and exported to the ImageJ software for calculating the “smoothness index (SI)”. The SI was defined as ratio of length of the straight line connecting the most peripheral and the most central points of anterior iris surface to actual length of this boundary. Results Forty eyes from 20 patients with unilateral FU were enrolled. Mean age of patients was 40±10 years. Mean overall SI was 0.876± 0.030 in eyes with FU that was significantly more than fellow control eyes (0.841± 0.041). (p=0.005) The mean temporal and nasal SI were 0.878± 0.035 and 0.874± 0.033 in eyes with FU, compared to 0.843± 0.041 and 0.838± 0.047 in control fellow eyes, respectively. (p = 0.008 and p = 0.009, respectively) Conclusion Iris “smoothness index” is a novel index to quantitatively document diffuse smoothness of iris anterior surface in eyes with FU. This index may facilitate diagnosis of subtle iris atrophic changes in these eyes, especially when heterochromia is absent.