Outcome Measures: The primary outcome is the change in excess central macular thickening as measured by OCT in response to interferon gamma-1b as compared with baseline. Secondary efficacy outcomes include changes in macular volume as measured by OCT, visual acuity, intraocular pressure, and intraocular inflammation as graded upon slit lamp examination. Secondary safety outcomes include ocular surface irritation assessed by fluorescein staining of the cornea and conjunctiva to assess toxicity changes in subjective ocular pain assessments as compared to baseline, number and severity of systemic and ocular toxicities and adverse events and the proportion of participants with a visual loss of greater than or equal to 15 ETDRS letters.