Optic disc morphometry correlated with confocal laser scanning Doppler flowmetry measurements in normal-pressure glaucoma

PURPOSE: To examine the relationship between morphologic optic disc parameters and hemodynamic parameters as measured by confocal laser scanning Doppler flowmetry in patients with normal-pressure glaucoma. METHODS: The study included 91 eyes of 54 patients with normal-pressure glaucoma (mean age: 57.7 +/- 9.8 years), and 136 eyes of 77 age-adjusted normal controls. Color stereo optic disc photographs were morphometrically examined, and confocal laser scanning flowmetry (Heidelberg Retinal Flowmeter) in the neuroretinal rim inside of the optic disc, and in the retina close to the temporal and nasal border of the optic nerve head was performed. RESULTS: Mean confocal laser scanning flowmetric measurements in the neuroretinal rim, temporal parapapillary retina, and nasal parapapillary retina were significantly (P<0.03) lower in the normal-pressure glaucoma group than in the age-adjusted control group. Correspondingly, mean confocal laser scanning flowmetric measurements within the neuroretinal rim decreased significantly, with relatively low correlation coefficients, decreasing neuroretinal rim area (P = 0.016; correlation coefficient r2 = 0.026), and increasing mean visual field defect (P = 0.011; r2 = 0.029). Measurements were statistically independent of alpha zone (P = 0.38; r2 = 0.004) and beta zone (P = 0.57; r2 = 0.002) of parapapillary atrophy. CONCLUSIONS: Confocal laser scanning flowmetric measurements within the neuroretinal rim were lower in eyes with normal-pressure glaucoma than in age-matched normal eyes. Confocal laser scanning flowmetric measurements decrease with increasing glaucomatous optic nerve damage. There is, however, a marked variability preventing a clear relationship between stage of glaucoma and decrease in confocal laser scanning flowmetric measurements. The correlation between parapapillary atrophy and confocal laser scanning flowmetric measurements is not statistically significant in normal-pressure glaucoma.