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Yannis M. Paulus, Michael W. Gaynon, Janet D. Leath, Sam E. Mansour; High Dose Oral Niacin as a treatment for Retinal Vein Occlusions. Invest. Ophthalmol. Vis. Sci. 2012;53(14):5192.
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Niacin (nicotinic acid, Vitamin B3) is a potent systemic vasodilator used to treat hyperlipidemia. Niacin induces vasodilation through prostaglandin-mediated release of nitric oxide. Niacin 500 mg given orally has been shown to increase choroidal blood volume by 39% at 30 minutes. The effects of high dose oral niacin in central, hemi, and branch retinal vein occlusions is examined.
A prospective, nonrandomized pilot study at a single institution of niacin with or without topical steroid was conducted in patients with retinal vein occlusions from 1998 to 2010. Patients were excluded for gout, high uric acid, or pregnancy. Sixty one consecutive patients were included, including 42 CRVO, 8 HRVO, and 11 BRVO. All patients were placed on niacin (target dose 500mg po tid). Prednisolone acetate 1% ophthalmic qid for reduction of macular edema was administered in half of the patients. Baseline characteristics were gathered, including sex, race, age, prior therapy, comorbidities, duration of retinal vascular occlusion, baseline visual acuity, and type of vascular occlusion. The primary outcome measurement was the mean change in visual acuity at 1 year. Secondary outcomes included mean change in central macular thickness on Optical Coherence Tomography, percent requiring panretinal photocoagulation, and percent requiring anti-VEGF therapy. Adverse events were evaluated. Patients were compared with a similar cohort of patients in the same period who refused therapy or withdrew from therapy early (9 patients) along with literature controls.
By 1 year, retinal hemorrhages subsided as did vascular congestion. Visual acuity improved on average in both patients receiving niacin alone and niacin in combination with prednisolone acetate. Central macular thickness also improved over the year. In some cases, withdrawal of niacin or prednisolone was followed by deterioration of visual acuity and macular edema, suggesting reversibility of effect.
Niacin, alone or in combination with topical prednisolone acetate, was associated with improvement in visual acuity and central macular thickness in patients with vascular occlusions. Utilizing the Young-Laplace Equation, we postulate that vasodilation in retinal vascular occlusions could accelerate collateral shunt vessel formation. Niacin-induced vasodilation could contribute to early collateral formation, increased choroidal circulation, and improved oxygenation. A larger, randomized, placebo-controlled multicenter clinical trial is needed.
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