FEB 18, 2011
This study compared the intraocular and serum vascular endothelial growth factor (VEGF) levels of patients with acute retinal necrosis (ARN) with the levels in ocular toxoplasmosis (OT) patients. The study's authors hypothesize that the occlusive vasculitis and subsequent necrosis that occur during the early stages of ARN may be in part VEGF-driven and play a role in the development of subsequent retinal detachments and neovascularization. What they found suggests that ARN patients have strong intraocular VEGF production, a factor which may be of importance in developing future treatments for these patients.
The authors determined VEGF levels in paired aqueous and serum samples of 17 patients with ARN and 16 patients with OT. They analyzed their medical and photographic records for clinical features, in particular the presence and size of ischemic retinal areas, occurrence of complications and visual acuity.
They found that mean intraocular VEGF levels were significantly higher in ARN patients than OT patients (P = 0.005), although serum levels were not different between the two groups. Intraocular VEGF levels exceeded serum levels in eight of 17 ARN patients (47 percent) compared with one of 16 OT patients (6 percent) (P = 0.009). Patients with high intraocular VEGF had more extensive retinitis (P = 0.001) and lower visual acuity (P = 0.031) at the three-month follow-up visit.
The study's limitations include the lack of a healthy control group, use of VEGF level data from only one point in time and examination of patients at different disease stages. The authors say that greater knowledge of the role of VEGF in intraocular inflammation is needed in order to determine whether intraocular anti-VEGF medication would be useful in the treatment of ARN and other occlusive retinal vasculitides.
Despite these drawbacks, the results suggest that retinal vascular occlusions in peripheral retina and at the level of optic nerve may be at least in part VEGF-driven. The authors hypothesize that treatment of ARN patients with anti-VEGF medication may have beneficial effects on retinal and optic disc perfusion and limit the development of neovascularization. But they add that the exact physiologic role of VEGF in the eye has not yet been fully clarified, and it is not known whether high VEGF levels in ARN are a mere consequence of ischemia and severe inflammation. The role of anti-VEGF medication in combination with standard therapeutic agents in the treatment of ARN also remains to be elucidated.