A review of ocular blood flow measurement techniques

Several major eye diseases may be characterized by deficits in ocular blood flow. Maintaining adequate nutrient delivery to the choroid, retina, and o ptic nerve head may prevent cellular damage and loss, complementing efforts to provide neuroprotection. The ability to quantify deficits in ocular blo od flow has increased in recent years with the introduction of several new techniques. 1) Scanning laser ophthalmoscopic fluorescein angiography allow s the measurement of bulk retinal flow and macular capillary transit rates. 2) Scanning laser ophthalmoscopic indocyanine green angiography measures c horoidal perfusion in selected areas near the optic nerve head and macula. 3) Confocal scanning laser Doppler flowmetry permits quantitation of retina l capillary perfusion. 4) Color Doppler ultrasound imaging measures flow ve locities in the ophthalmic, central retinal, and short posterior ciliary ar teries. While these techniques represent a major advance, significant issue s regarding blood flow and ocular disease remain. First, the hemodynamic ch aracteristics of the disease state need further definition. Second, the blo od flow effects of current and future treatments must be established. Third , improvements in ocular blood flow techniques are required, both to increa se anatomic precision and to allow non-invasive measurements during times o f potential ischemic risk such as sleep. These developments could enhance p revention, diagnosis, and treatment of several major eye diseases.