PURPOSE: To evaluate the impact of macular edema on visual acuity and visual field sensitivity in uveitis. DESIGN: This study utilized baseline data from the Multicenter Uveitis Steroid Treatment (MUST) Trial, a randomized, parallel treatment clinical trial comparing alternative treatments for intermediate, posterior and panuveitis. PATIENTS & METHODS: 255 patients (481 eyes with uveitis) recruited at 23 subspecialty centers. Visual acuity, optical coherence tomography and Humphrey 24-2 visual field testing. RESULTS: Macular edema was associated with impaired visual acuity (p < 0.01). Different phenotypes of macular edema were associated with different degrees of visual impairment: cystoid changes without retinal thickening were associated with moderately impaired visual acuity (-5 ETDRS letters), but visual acuity was worse in eyes with retinal thickening (-13 letters) and with both cysts and thickening (-19 letters). Uveitis sufficient to satisfy the study's inclusion criteria was associated with impaired visual field sensitivity, but eyes with macular edema had even worse visual field sensitivity (p < 0.01). CONCLUSIONS: The observation that macular edema substantially reduces visual function suggests macular edema itself is an important endpoint to study in the treatment of uveitis. As uveitis and macular edema both impair visual field sensitivity as measured by Humphrey 24-2 perimetry, both should be considered when evaluating patients with uveitis and raised intraocular pressure for glaucoma.