Central Foveal Thickness Cut-off Value Identified for Corticosteroid Treatment in Intermediate Uveitis

Intermediate uveitis (IU) is characterized by bilateral intraocular inflammation primarily in the vitreous and pars plana. IU comprises approximately 10% of all uveitis cases. It usually affects younger patients and is the second most common type of uveitis in children.

Most patients with IU do not appear to have any underlying disease. However, IU is sometimes associated with systemic diseases such as cat-scratch fever, Lyme disease, multiple sclerosis, and sarcoidosis. IU also occurs as an idiopathic disease, which is characterized by snow-banking or snowballs in the vitreous.

Common manifestations of IU include retinal vasculitis that mainly involves the venous branches as well as cystoid macular edema (CME), which occurs in 30% to 60% of cases and is the principal cause of permanent vision loss in IU patients. Early detection and treatment of CME is therefore critical for preserving vision in these patients.

Optical coherence tomography (OCT) has been used extensively to diagnose macular edema in patients with ocular inflammation, including those with IU, and has identified several predictors of visual outcome and response to treatment. However, one possible predictor that remained unevaluated in IU was subclinical macular thickening.

To determine the clinical significance of subclinical macular thickening in IU, an investigative team recruited 61 consecutive patients diagnosed with IU during a 6-year period at the Jules-Gonin Eye Hospital at the University of Lausanne in Lausanne, Switzerland.

In this prospective study, two subgroups of patients were identified on the basis of whether or not they needed systemic corticosteroid treatment. OCT was then used to measure central foveal thickness (CFT) in these subgroups as well as in a group of healthy volunteers (n = 27). CFT and best-corrected visual acuity (BCVA) in each group were then compared at baseline and after 6 months.

At baseline, the investigators found significant differences in mean CFT between patients treated with systemic corticosteroids and untreated patients (p = 0.0005) as well as between untreated patients and healthy volunteers (p < 0.001). They also found a strong correlation between BCVA and CFT at baseline (r = 0.743, p < 0.0001).

However, after 6 months, the difference in CFT between the two patient subgroups was no longer significant (p = 0.699), although BCVA was worse in those receiving systemic corticosteroid treatment. No statistically significant difference in BCVA was found between the subgroup of untreated patients and the group of healthy volunteers either at baseline or after 6 months.

In the treated patients who were available for the 6-month follow-up visit, mean CFT decreased to a significant degree from 325 μm ± 122 μm to 209 μm ± 86 μm (n = 25, p = 0.0004), and mean BCVA improved slightly but significantly from 0.222 ± 0.249 to 0.087 ± 0.125 (p = 0.0075). However, in untreated patients, neither CFT nor BCVA changed to a statistically significant degree from baseline after 6 months. As a result of these findings, the investigators concluded that, in mildly inflamed eyes with IU, subclinical retinal thickening can occur without affecting visual function.

In a post hoc statistical analysis, the CFT cut-off value for initiating mic corticosteroid treatment in patients with IU was determined to be 215.5 μm. The sensitivity of this value was found to be 62.5%, and its specificity was found to be 96.4%.