Abstract
Purpose: :
To evaluate the effect of high dose niacin (nicotinic acid) with or without topical prednisolone acetate on the course of nonischemic central, hemiretinal and branch retinal vein occlusions.
Methods: :
A prospective, nonrandomized pilot study of nicotinic acid as a possible vasodilator, with or without a topical steroid for reduction of macular edema, was undertaken in patients with nonischemic retinal vein occlusions. Thirty–five consecutive patients with worsening central (25), hemiretinal (5) or branch (5) retinal vein occlusions were placed on lipid lowering doses of nicotinic acid (target dose 500mg TID, range 1–2 grams/day) under an internist's supervision. Prednisolone acetate eye drops were used QID in the affected eye of 19 of the subjects. They were followed with sequential examinations, OCT and fundus photos. Major outcome measures were changes in vision, vascular congestion, amount of hemorrhage and macular edema.
Results: :
Over time, usually a few months, retinal hemorrhages subsided, as did vascular congestion and macular edema in many, but not all patients. Some patients improved on nicotinic acid alone, whereas others only improved after the addition of the topical steroid. Vision improved subjectively in the form of a sense of expanded field as hemorrhages resolved. This was followed in most eyes with improved visual acuity as macular edema subsided. In several instances, inadvertent withdrawal of either nicotinic acid or topical steroid drops was followed by deterioration, which resolved after restoring treatment, suggesting reversibility of effect.
Conclusions: :
Nicotinic acid, alone or sometimes combined with topical prednisolone acetate drops, was associated with clinical improvement in nonischemic CRVO, HRVO and BRVO. Most eyes showed improved visual acuity, which persisted over time. Nicotinic acid induces vasodilation by means of a prostaglandin mediated release of nitric oxide, a potent vasodilator. It has been shown by others to be capable of increasing the thickness of the choroid in the dose used in this study. Perhaps the vasodilation effect contributes to earlier collateral vessel formation. Dilation of the choroid might also improve outer retinal oxygenation, thereby allowing for autoregulatory constriction of the retinal circulation, thus better balancing retinal vascular inflow with the capacity of a compromised venous outflow system. The topical steroid, perhaps in part by systemic absorption and posterior recirculation, appears to hasten the resolution of macular edema, compared to the use of nicotinic acid alone.
Keywords: vascular occlusion/vascular occlusive disease • retina • blood supply