• Proportion of subjects avoiding 15 letters (3 lines) of best-corrected distance visual acuity loss at 18 weeks after cataract surgery. Distribution of visual acuity changes at 18 weeks after cataract surgery [ Time Frame: 1 to 18 weeks post-cataract surgery ] [ Designated as safety issue: No ]
  
• Distribution of absolute levels of distance visual acuity at 18 weeks after cataract surgery [ Time Frame: 1 to 18 weeks post-cataract surgery ] [ Designated as safety issue: No ]
  
• Analysis of time to 15 letter improvement of best-corrected distance visual acuity through 18 weeks after cataract surgery using a 2-state stochastic model to account for events and recoveries from events [ Time Frame: 1 to 18 weeks post-cataract surgery ] [ Designated as safety issue: No ]
  

• Analysis of improvement of fluorescein leakage seen on fluorescein angiography at 18 weeks after cataract surgery [ Time Frame: pre-cataract surgery to 18 weeks post-cataract surgery ] [ Designated as safety issue: No ]
  
• Analysis of decrease in retinal thickness by OCT at 18 weeks after cataract surgery [ Time Frame: pre-cataract surgery to 18 weeks post-cataract surgery ] [ Designated as safety issue: No ]
  
• Analysis of level of diabetic retinopathy using recognized photographic grading system at 18 weeks after cataract surgery [ Time Frame: pre-cataract surgery to 18 weeks post-cataract surgery ] [ Designated as safety issue: No ]
  
• Additional changes 12 weeks after discontinuation of pegaptanib (6 months after study entry) [ Time Frame: pre-cataract surgery to 6 months post-cataract surgery ] [ Designated as safety issue: No ]
  

Macular edema occurs as a complication of cataract surgery in approximately 2% of all surgeries. In this condition, cystic, fluid-filled spaces develop in the outer plexiform layer of the retina resulting in a loss of vision. This condition is termed "Cystoid Macular Edema (CME)." In non-diabetics, the majority of such cases resolve spontaneously.

Diabetic macular edema (DME) is an important cause of visual disability among patients with diabetes. It is widely recognized that cataract surgery often triggers severe CME in patients with pre-existing DME. This exacerbation begins immediately following cataract surgery; and unlike in non-diabetics the edema is likely to be protracted and poorly responsive both to traditional treatments for CME (topical NSAIDS) and DME (laser photocoagulation).

Fluorescein angiography, a photographic test that evaluates the blood circulation in the back of the eye, has demonstrated that both CME and DME are associated with increased permeability of retinal blood vessels.

The high rates and severity of post-cataract surgery CME in diabetic patients with DME render this population ideal for the study of potential agents to reduce the rate and severity of this condition (i.e., post-cataract surgery CME). Recent studies have shown that vascular endothelial growth factor (VEGF) plays a major role in vessel permeability. Pegaptanib (Macugen) is an FDA-approved drug for wet AMD. Pegaptanib is a selective VEGF antagonist that blocks the effects of VEGF; therefore pegaptanib might decrease vessel permeability and possibly decrease the incidence and severity of CME. We plan to conduct a controlled pilot study to investigate the effects of pegaptanib (up to 3 treatments of pegaptanib given prior to cataract surgery and as often as every 6 weeks for up to 12 weeks after cataract surgery) in diabetic patients with pre-existing DME who are undergoing cataract surgery and who are, therefore, at very high risk for development of CME. Should the pilot study indicate a potential benefit of pegaptanib in this setting, a larger, fully powered clinical trial will be proposed. An effective treatment or preventive measure for post-cataract surgery macular edema in patients with diabetic retinopathy would offer benefit to a large patient population nationally that is at high risk of vision loss.