Purpose: To determine whether retrobulbar blood flow (RBF) velocities are predictive of conversion to glaucoma.
Methods: A total of 262 glaucoma suspects were prospectively selected. Participants had normal visual field, increased intraocular pressure, and glaucomatous optic disc appearance at baseline. Topographic analysis of the optic nerve head was performed using a confocal laser scanning ophthalmoscope and the blood flow velocity of retrobulbar vessels was measured by color Doppler imaging. Conversion to glaucoma was assessed according to the changes in the color-coded Moorfields Regression Analysis (MRA) classification of the confocal laser scanning system during a 48-month follow-up period. Survival curves and hazard ratios (HRs) for the association between RBF parameters and conversion to glaucoma were calculated.
Results: End-diastolic velocity and mean velocity in the ophthalmic artery were reduced in subjects that converted to glaucoma based on MRA (36 individuals, 13.7%), while resistivity (RI) and pulsatility indices were increased in the same vessel. Patients with RI values lower than 0.75 in the ophthalmic artery had a survival rate (MRA-converters versus nonconverters) of 93.9%, whereas individuals with RI values greater than 0.75 had a survival rate of 81.7% (HR = 3.306; P = 0.002).
Conclusions: Abnormal RBF velocities measured by color Doppler ultrasound may be a risk factor for conversion to glaucoma. An RI value higher than 0.75 in the ophthalmic artery was associated with the development of glaucoma.