Simultaneous evaluation of iris area and subfoveal choroidal thickness in Fuchs uveitis syndrome

Abstract

Background/aims: To simultaneously evaluate iris area (IA) and subfoveal choroidal thickness (SFCT) in eyes with Fuchs Uveitis Syndrome (FUS).

Methods: We prospectively recruited a case series of patients with FUS at our institution, simultaneously measuring IA with anterior segment spectral domain optical coherence tomography (SD-OCT) and SFCT with enhanced depth imaging optical coherence tomography (EDI-OCT). Iris images were analyzed by ImageJ software. We tested the differences in intereye IA and SFCT with the healthy eye (HE) using the Wilcoxon test, and clinical interpretation was controlled by intraclass correlation coefficient (ICC) between two masked specialists.

Results: Sixteen patients with unilateral FUS were included. Six were female, and the age range was 37 to 67 (median age 48 years, IQR 41-60). ICC of 98.9%, with a lower confidence interval of 97%. Eyes with FUS had a significant thinning of the total iris median area (p < 0.002), restricted to the temporal and nasal areas compared to the HE (p < 0.01 and < 0.001, respectively). SFCT was also significantly thinner compared to the HE (p < 0.0001). A low correlation was found between iris and choroidal thinning in FUS eyes (r_s = 0.21; p = 0.4).

Conclusions: This study found reduced iris area and subfoveal choroidal thickness in eyes with FUS compared to the normal fellow eye.

Keywords: Choroidal thickness; Fuchs uveitis syndrome; Inter-eye differences; Iris area; Optical coherence tomography.

Fig. 1

1a. Clinical image of the normal right eye (RE). 1b. Clinical image of Fuchs uveitis syndrome (FUS) left eye (LE) with pronounced iris atrophy. 1c. AS-OCT of RE with normal thickness iris (643mm²). 1d. Affected LE with a marked decrease in iris stroma thickness (507mm²), images were taken making a 3 mm cut from the pupillary edge to the base of the iris. (Technique proposed by Invernizzi [7]). Dotted white line is the iris area. 1e. RE Spectral domain EDI-OCT in the healthy eye; red line measures choroidal thickness on the subfoveal central position (SFCT), as the distance from the outer border of Bruch’s membrane to the inner surface of the sclera [10] with a normal choroidal thickness (506 μm). 1f. LE with FUS, showing a significant decrease in choroidal thickness measured with the red line (248 μm)