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Antioxidants enhance ocular perfusion in OAG, study shows
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Taking specific antioxidants for at least 1 month significantly increases blood supply within the retinal and retrobulbar vascular beds, with potential protective effects on retinal ganglion cells in patients with open angle glaucoma.
In a double-masked, prospective study, 45 patients with open-angle glaucoma (OAG) were randomized to receive either placebo or a specific dietary supplement formula (Optic Nerve Formula, ScienceBased Health) containing omega-3 fatty acids, vitamins, minerals and ginkgo biloba. After 4 weeks of four-times-daily administration, patients in the antioxidant group showed significant increase in peak systolic velocity and/or diastolic blood flow velocity in all the retrobulbar blood vessels. Vascular resistance in the central retinal artery and nasal posterior ciliary artery was significantly reduced.
“In agreement with previous findings, our results indicate that the supplementation of certain antioxidants may increase blood supply to the orbit and within retinal capillary beds following 4 weeks administration,” the authors wrote. “Our data suggest oral antioxidant supplementation may decrease vascular resistance over a longer period of time than previous trials investigated.”
By improving ocular blood flow and, therefore, cell oxygenation and nutrition, this combination of nutraceuticals could help prevent retinal ganglion cell death in patients with OAG, they said.
“Theoretically, a healthy and stable ocular circulation may provide some amount of protection to retinal ganglion cells,” the authors wrote, and concluded by advocating further studies to assess the long-term effects of antioxidants on structural and functional disease progression. – by Michela Cimberle
Disclosure: Harris is a consultant to Stemnion, Biolight, Nano Retina, AdOM, ScienceBased Health, Isarna Therapeutics and Ono Pharmaceuticals and holds an ownership interest in AdOM, Nano Retina and Oxymap.
Perspective
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Derek MacDonald, OD, FAAO
Elevated IOP is inarguably a strong risk factor for glaucoma. However, most individuals with untreated ocular hypertension won’t develop manifest disease, at least one of every two diagnosed with open-angle glaucoma present with statistically normal IOP, and post-diagnosis progression can occur despite pressures that appear to be well controlled … so, what gives?
A number of additional risk factors for glaucoma have been identified, many related to impaired ocular blood flow. Systemic hypotension and vascular dysregulation compromise ocular perfusion, which exacerbates glaucomatous optic neuropathy and visual field loss. While lowering IOP and elevating blood pressure both increase ocular perfusion pressure, the former is obviously more feasible than the latter.
In demonstrating that dietary antioxidants including ginkgo and bilberry increase blood flow velocity and decrease vascular resistance, Harris and colleagues inform our management of patients progressing at relatively low IOP, who may also benefit from two things:
--dosing systemic blood pressure medications in the morning rather than evening and
--lowering IOP with medications that increase ocular blood flow (prostaglandin analogues and carbonic anhydrase inhibitors).
While reducing IOP remains the cornerstone of glaucoma treatment, clinicians are wise to remember that it’s no longer the only stone.
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