Materials and Methods: Anterior segment optical coherence tomography (AS-OCT) were performed for sixteen unilateral FUS patients after an ophtalmological examinaton. The iris area was calculated by marking 3 mm from the pupil edge at 3 and 9 o?clock positions. Schlemm?s canal length and area were calculated using the device?s calipers. All patients underwent corneal tomography.

Results: The average age of patients was 43.8±11.3 years. In eyes affected by FUS, there was no significant difference in nasal and temporal iris area, measuring 1.086±0.054 mm² and 0.999±0.059 mm² (p=0.11 and p=0.49). The nasal and temporal Schlemm?s canal lengths in affected eyes were 245.4±24.2 ?m and 241.3±20.5 ?m, and nasal and temporal Schlemm?s canal areas were 0.006±0.001 mm² and 0.006±0.001 mm², with no significant difference compared to unaffected eyes (p=0.58, p=0.16, p=0.79, and p=0.64, respectively). Subgroup analysis based on the presence of glaucoma and heterochromia also revealed no significant differences. Corneal tomography parameters were also found similar between the eyes (p>0.05 for all).

Conclusion: Our study found similar iris area measurements between affected and unaffected eyes. These results support that iris stromal thickness measured by AS-OCT is not sensitive enough to distinguish affected eye from unaffected eye in unilateral FUS. Remarkably, the histological changes in the Schlemm?s canal anatomy, reported in patients with glaucoma in past studies, are not detected in glaucomatous eyes affected by FUS. Keywords : Fuchs uveitis syndrome, heterochromia, iris area, corneal tomography, Schlemm canal