Association of visual field severity and parapapillary retinal blood flow in open-angle glaucoma

PURPOSE: To examine the association of the parapapillary blood flow parameters with severity of visual field loss (VFL) in open-angle glaucoma (OAG) patients. DESIGN: Observational clinical study. METHODS: Fifty-two patients with OAG and 30 normal subjects were studied prospectively. Parapapillary blood flow parameters were obtained for superotemporal and inferotemporal quadrants using the scanning laser Doppler flowmeter. Mean deviation score was used to determine the severity of VFL both as continuous variable and stratified by severity: no VFL (OAG A) ≤ 2dB, mild VFL (OAG B) from 2.1 to 6dB and moderate-severe VFL (OAG C) >6 dB. In the OAG patients with an abnormal Glaucoma Hemifield Test, the hemifield with a predominant VFL was determined. Linear regression analysis and analysis of covariance were used to assess the relationship between the severity of the VFL and the parapapillary blood flow parameters. The variance in mean parapapillary blood flow was assessed using standard deviation (SD) and coefficient of variation (COV). RESULTS: There was no correlation between the severity of VFL and parapapillary blood flow parameters. Variance in the mean parapapillary blood flow was significantly greater in OAG patients with VFL compared with OAG patients without VFL and normal subjects for the superotemporal quadrant (SD, P=0.04; COV, P=0.02) and the inferotemporal quadrant (SD, P<0.02; COV, P=0.02). Results for COV were confirmed for the inferotemporal quadrant in analysis of covariance after adjusting for age and intraocular pressure (F=1.60, P=0.04). CONCLUSION: The parapapillary blood flow did not correlate with VFL. However, the variance in meanparapapillary blood flow was significantly larger in OAG patients with VFL, thus suggesting vascular abnormality.