A cross-sectional study of submacular thickening in intermediate uveitis and determination of treatment threshold

The aim of this work is to refine understanding of anatomical and functional alterations in eyes with Intermediate Uveitis (IU), their natural history in mild cases not necessitating treatment and their response to treatment in severely affected eyes with macular edema.

61 consecutive patients with IU presenting over a 6-year period were prospectively recruited into the study. Two subgroups of patients with IU were identified on the basis of the need or not for systemic cortico-steroid treatment. A group of healthy volunteers was identified for determining normal average central foveal thickness (CFT) values. Statistical comparisons were sought between patient sub-groups and with the group of normal volunteers for CFT and Best Corrected Visual Acuity (BCVA) at baseline and after 6 months. In a post hoc analysis, a cut-off value of CFT for systemic treatment initiation in IU was statistically identified and its sensitivity and specificity determined.

A statistically significant difference in mean CFT at baseline was observed between patients under systemic treatment and untreated patients (p = 0.0005) as well as between untreated patients and healthy volunteers. (p < 0.001) After six months difference in CFT between the two patients subgroups was no longer significant (p = 0.699). BCVA was worse for patients under systemic treatment. No statistically significant difference could be identified between the subgroup of untreated patients and the group of healthy volunteers either at baseline or after 6 months. Correlation between LogMAR visual acuity and central retinal thickness at baseline was strong (r = 0.7436, p < 0.0001, Pearson's correlation coefficient). The cut-off value of CFT for initiating systemic treatment was determined at 215.5 μm in a post hoc analysis (sensitivity 62.5 %, specificity 96.4 %).

Subclinical retinal thickening of mildly inflamed eyes with IU can occur though bearing no functional clinical significance and spontaneously resolving within 6 months. A cut-off CFT value for treatment of macular edema in IU, in the presence of other relevant morphological features on Optical Coherence Tomography, seems to emerge from post hoc analysis of collected data demonstrating strong specificity and moderate sensitivity.