Effect of vitrectomy with intrasurgical regulation of intraocular pressure in a rabbit model of central retinal artery occlusion

Retinal stroke: research models, targets and experimental drugs

INTRODUCTION

Retinal artery occlusion (RAO), often caused by a microembolus and resulting in inner retinal ischemia, could be considered as the retinal analog to cerebral stroke. Although several therapeutic targets have been suggested in animal models of retinal ischemia and several potential treatments have been evaluated on small series of patients, central retinal artery occlusion (CRAO) is still rarely treatable in clinical practice.

AREAS COVERED

Here, we review several animal models of RAO, including increased intraocular pressure, laser, vasoconstriction, embolization and clamp. We also review the pathogenic mechanisms that contribute to cell death cascades during ischemia, and the therapeutic strategies targeting these events. These strategies aim to restore blood flow by fibrinolysis, increase the oxygen or glucose supply, decrease the energy demands, restrict ionic leak fluxes or reduce the detrimental effects of glutamate, calcium and free radicals. The current literature suggests that tPA treatment could be effective for CRAO.

EXPERT OPINION

Eye care professionals must make a rapid and accurate diagnosis and immediately refer patients with acute retinal stroke to specialized centers. CRAO management should also be facilitated by developing local networks to encourage collaboration among ophthalmologists, retina specialists and stroke neurologists.

Vitrectomy and manipulation of intraocular and arterial pressures for the treatment of nonarteritic central retinal artery occlusion

The purpose of this study is to describe a surgical technique and report the functional outcome of treating nonarteritic central retinal artery occlusion (CRAO) in 2 eyes of two consecutive male patients. Two males (A) and (B) presented 6 days and few hours, respectively, after symptom onset with the clinical features typical of CRAO, including sudden severe deterioration of vision to counting fingers and a cherry-red spot in the left and right fovea, respectively. While A had been on recent treatment for hypertension and hyperlipidemia, B had no significant medical history. Both patients underwent surgery, A, 9 days, and B, <15 h after symptom onset. Surgery involved a vitrectomy, lowering of intraocular pressure (<3 mmHg), and gradual increase of arterial pressure to 165/100 mmHg (through the slow injection of intravenous adrenaline). Intraoperatively, this resulted in immediate perfusion and visible dilation of the blood-filled central retinal artery (CRA) and retinal arteriolar network and dilatation of the central retinal vein. The final vision settled to 6/60 in A and 6/36+1 in B. Although preoperative macular infarction persisted in both eyes as demonstrated by optical coherence tomography angiography, both patients claim a convincing subjective visual benefit. The procedure appeared to have positively changed the natural history of the disease in both eyes. Vitrectomy with the manipulation of intraocular and arterial pressures significantly increases ocular perfusion along the entire CRA, which can dislodge CRA thrombo-emboli and has the potential to restore retinal perfusion and improve visual outcome if undertaken before irreversible retina damage. This is a relatively straightforward technique and should join the list of surgical techniques for treating CRAO.