Identifying a Clinically Meaningful Threshold for Change in Macular Edema in Patients with Uveitis

Abstract

Purpose: : Optical coherence tomography (OCT) has become the gold standard for evaluating macular edema (ME). However, the threshold of change of retinal thickness (RT) that is clinically meaningful has yet to be identified. We sought to determine the threshold best able to predict clinically meaningful changes in visual acuity in the Multicenter Uveitis Steroid Treatment (MUST) Trial.

Methods: : RT was measured at the central subfield with time domain OCT and visual acuity (VA) was measured with logarithmic (ETDRS) visual acuity charts at enrollment and six months. Participants were classified as having ME if the RT was > 260µm. The association between percentage change in RT and clinically meaningful VA thresholds (>5 , >10 letters or ≥15 letters) was evaluated.

Results: : In the 75 eyes with ME at enrollment, a 20% improvement was optimal for predicting greater than 10-letter changes in visual acuity with a sensitivity of 75% and a specificity of 78%. Those with a 20% or greater reduction in retinal thickness had a mean 10.9 letter improvement (95% CI: 6.5 to 15.3) as compared to a -0.5 letter change (95% CI: -4.1 to 3.3) in visual acuity for those without a 20% reduction (p < 0.01).

Conclusions: : In addition to being above the level of measurement uncertainty, a 20% change in RT in patients with ME appears to be the optimal threshold for predicting clinically important changes in VA and may be considered as an outcome for clinical trials of treatments for uveitic macular edema.

Clinical Trial: : http://www.clinicaltrials.gov NCT00132691

Keywords: uveitis-clinical/animal model • clinical (human) or epidemiologic studies: systems/equipment/techniques • imaging/image analysis: clinical