Ischaemic retinopathies may lead to neovascular glaucoma (NVG) due to the growth of blood vessels on the iris surface and anterior chamber angle. Vascular endothelial growth factor (VEGF) is the most studied angiogenic peptide in ischaemic retinal diseases and NVG (Tripathi et al. 1998; Michels et al. 2005). Intravitreal injection of bevacizumab, an anti-VEGF agent, for the treatment of neovascular diseases has shown encouraging results (Michels et al. 2005; Spaide & Fisher 2006). We report the effects of an intravitreal injection of 1.5 mg bevacizumab (Avastin; Genentech, Inc., San Francisco, CA, USA) on iris and angle neovascularization in a patient with NVG secondary to diabetic retinopathy.
A 69-year-old white woman presented with decreased visual acuity in both eyes of 1 year's duration and severe pain in the right eye for 1 day. The patient reported a history of diabetes and systemic hypertension of at least 20 years' duration. Visual acuity was hand motion in the right eye and light perception in the left. Slit-lamp examination demonstrated 8 clock hours of iris neovascularization in the right eye. Intraocular pressure (IOP) was 40 mmHg in the right eye and 14 mmHg in the left. Gonioscopy demonstrated 10 clock hours of angle neovascularization without synechiae in the right eye. Indirect ophthalmoscopy showed vitreous haemorrhage associated with retinal neovascularization in both eyes. Vitreous haemorrhage precluded the application of panretinal laser photocoagulation in either eye. The patient was treated with timolol and brimonidine, both b.i.d. in the right eye, and acetazolamide (750 mg/day). One day after presentation, IOP was 23 mmHg in the right eye. The patient was offered pars plana vitrectomy with endophotocoagulation in the right eye. The patient declined surgery and was offered an off-label intravitreal bevacizumab injection in the right eye. After extensive discussion, the patient gave written informed consent for off-label intravitreal bevacizumab injection (1.5 mg) in the right eye.
One day after intravitreal injection of bevacizumab, the pain in the right eye had resolved, and examination demonstrated partial regression of the iris and angle neovascularization. One week later, iris fluorescein angiography demonstrated complete regression of the iris and angle neovascularization and absence of fluorescein leakage (Fig. 1). Gonioscopy demonstrated complete regression of the iris and angle neovascularization (Fig. 2). These findings have been stable for 8 weeks post-treatment, and the IOP at 8 weeks post-injection was 19 mmHg with the same medications. Vitreous haemorrhage has cleared substantially and there is no leakage from retinal new vessels on fluorescein angiography. The last noted visual acuity in the right eye was counting fingers at 3 metres.
The standard treatment of NVG associated with ischaemic retinopathy includes retinal ablation (Sivak-Callcott et al. 2001). Although retinal ablation has an efficacy of about 85% using cryosurgery or laser surgery, NVG has been reported to persist in 1.6% of treated eyes (Fernandez-Vigo et al. 1997). A pharmacological treatment directed against the angiogenic stimulus for neovascularization may represent an alternative or an adjunctive treatment for ischaemic retinal diseases. In fact, promising results have been reported recently for intravitreal bevacizumab in iris neovascularization (Avery 2006; Davidorf et al. 2006).
The current case demonstrates that intravitreal bevacizumab injection may be associated with rapid regression of iris and angle neovascularization in the setting of NVG associated with diabetic retinopathy. A single injection was associated with medically controlled IOP for at least 8 weeks.
Although only a single bevacizumab injection was administered in this case, repeated injection(s) may be needed for longer-term treatment. Intravitreal bevacizumab injections may represent a useful alternative treatment for patients with NVG in whom inadequate visualization precludes treatment by retinal photocoagulation.