Impairment of autoregulation of optic nerve head blood flow during vitreous surgery in patients with hypertension and hyperlipidemia.

PURPOSE: To examine whether hypertension (HTN) and hyperlipidemia (HL) affect autoregulation of optic nerve head (ONH) blood flow during vitrectomy.

DESIGN: Cohort study.

METHODS: Seventeen eyes from 17 subjects with HTN and HL and 19 eyes from 19 control subjects without systemic disorders underwent vitrectomy for the treatment of epiretinal membrane or macular hole. Following standard 25-gauge microincision vitrectomy, the mean blur rate (MBR), which is an index of relative ONH blood flow, in the vascular area (vascular MBR) and MBR in the tissue area (tissue MBR) were measured using laser speckle flowgraphy. Measurements were conducted before and 5 and 10 min after an approximately 15-mmHg rise in intraocular pressure (IOP). Both parameters represent relative values of ONH blood flow (%, compared to baseline). The recovery rate of blood flow to the ONH was calculated using the following equation: (MBR at 10 min - MBR at 5 min)/(MBR at baseline - MBR at 5 min).

RESULTS: Ocular perfusion pressure in all subjects was reduced both 5 and 10 min after the increase in IOP. Vascular MBR in subjects with HTN and HL (75.5 ± 14.8) was significantly lower than that in control subjects (86.7 ± 12.1) 10 min after IOP elevation (P = 0.019). The recovery rate of vascular blood flow was significantly lower in the HTN and HL groups than in the control group (P = 0.002).

CONCLUSIONS: Our results suggest that HTN and HL impair autoregulation in the vascular component of ONH blood flow during vitrectomy.