Insights into scleral violaceous hue in anterior scleritis: anterior segment optical coherence tomography evaluation.

Purpose: To determine the scleral thickness of inactive scleritis characterized by a violaceous hue (violaceous sclera) using anterior segment optical coherence tomography (AS-OCT).

Methods: Retrospective observational case series of patients with inactive unilateral anterior scleritis featuring a violaceous hue. Mean scleral thickness was measured by AS-OCT in violaceous areas and compared with the same region in the contralateral unaffected eye. Measurements were performed by two masked graders.

Results: Nine patients with median age of 52 ± 12.8 years were assessed. Eight patients were female. Rheumatoid arthritis and history of treated latent tuberculosis (33.3%) were the most common causes of anterior scleritis. Mean scleral thickness was 582.93 ± 124.03 µm and 648.59 ± 103.61 µm for violaceous sclera and the corresponding unaffected areas of the contralateral eye, respectively (mean difference = -65.65 µm, 95% CI: -143.73 to 12.42, p = 0.0885). The mean image contrast percentage of scleral hyperreflectivity as assessed by image conversion in an area of violaceous hue was 65.07 µm ± 6.49 µm compared to 42.70 µm ± 5.46 µm of unaffected areas (mean difference = 22.37 µm, 95% CI: 14.72 µm to 30.03 µm, p = 0.0001).

Conclusion: Using AS-OCT, the thicknesses of violaceous sclerae were not significantly thinner than the contralateral unaffected areas, despite a mean difference of approximately 65 microns. The increased scleral hyperreflectivity observed in the violaceous sclera may suggest collagen remodeling in these areas. Such remodeling could play a role in the sclera reflecting violaceous hues while still preventing direct visualization of the underlying choroid.