• Mean change from pre-PRP best corrected visual acuity (BCVA) at 3 months as expressed as an Early Treatment Diabetic Retinopathy Study (ETDRS) score (number of letters correctly read.)
  

• Mean change from pre-PRP Optical Coherence Tomography (OCT) in central foveal thickness and macular volume as assessed by OCT at 1, 2 and 3 months.
  
• Percentage of patients that maintain pre-PRP visual acuity at the 3 month time point
  
• Change between baseline and each efficacy outcome assessment in best-corrected ETDRS visual acuity score (e.g. mean visual acuity score)
  
• Change in the hyperfluorescence of the macula as assessed by 2 readers blinded to the 2 arms of the study.
  
• Injection-related events including severe uveitis, infectious endophthalmitis, non-infectious endophthalmitis, retinal detachment, and vitreous hemorrhage.
  

Levels of VEGF are elevated in eyes wth Diabetic Macular Edema and the expression of VEGF was found to be elevated temporarily following the photocoagulation of human Retinal Pigment Epithelial (RPE) cells. Ranibizumab (Lucentis TM, Genentech) is an anti-VEGF antibody shown to have properties to prevent macular edema. We hypothesize that VEGF inhibition can effectively treat PRP-induced macular edema, thereby minimizing post-PRP vision loss.

Subjects who meet eligibility criteria will be randomized to either ranibizumab 0.5mg or observation at a ratio of 2:1. All subjects will be followed for 90 days for safety and efficacy assessments. There is no placebo or sham arm of this trial.