Proliferative diabetic retinopathy (PDR; a more advanced form of the disease) is a leading cause of vision loss in patients with diabetes mellitus, resulting in 12,000 to 24,000 new cases of blindness each year in the United States.

Panretinal photocoagulation (PRP; procedure that involves use of a laser) is the standard treatment for reducing severe visual loss from PDR. However, PRP can cause permanent peripheral visual field loss and decreased night vision and may exacerbate diabetic macular edema (DME; swelling of the retina in diabetes mellitus due to leaking of fluid from blood vessels within the macula), which makes alternative treatments desirable.

When used as treatment of DME, intravitreous (in the vitreous, the fluid behind the lens in the eye) anti-vascular endothelial growth factor (VEGF) agents reduce the risk of diabetic retinopathy worsening and increase the chance of improvement, making these agents a potentially viable PDR treatment.

The researchers found that intravitreous anti-VEGF agent ranibizumab met a prespecified noninferiority (not worse than) outcome of visual acuity change at 2 years than in the PRP group. There was no statistically significant visual acuity difference between the groups at 2 years, with the authors noting that 53 percent of the PRP group received ranibizumab injections for DME.

More peripheral visual field loss occurred, more vitrectomies (removal of the gel [vitreous] from within the eyeball) were performed, and DME development was more frequent in the PRP group compared with the ranibizumab group. No systemic safety concerns with ranibizumab were identified in the prespecified major safety outcomes.

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