Abstract

SO.14.09

Fluorescein angiography in glaucoma

Niklas Plange
Augenklinik, Universitätsklinikum Aachen, Aachen

Since the late sixties, fluorescein angiographic studies have been performed to detect pathologies in retinal and optic nerve head blood flow in glaucoma. Capillary non-perfusion namely fluorescein filling defects of the optic nerve head and fluorescein leakage revealing increased vascular permeability may be detected. Retinal filling times, e.g. arteriovenous passage times have been shown to be prolonged suggesting impaired retinal circulation.
Fluorescein filling defects of the optic nerve head correspond to areas of capillary non-perfusion or drop-out. Filling defects are linked to visual field defects in glaucoma and to the morphological disc damage, i.e. neuroretinal rim loss. As a diagnostic parameter, a sensitivity of about 60% at a specificity >95% may be reached.
Late-phase fluorescein leakage of the optic nerve head indicates increased vascular permeability and may be seen in up to 30% of glaucoma patients. Fluorescein leakage may be a hint to endothelial dysfunction as the fluorescein dye does not permeate the intact blood retinal barrier in healthy subjects. The cause of the leakage phenomenon and the effect on ocular blood flow is not understood. It has been speculated that late staining of the optic disc might reflect the damage caused by increased intraocular pressure or indicate a disease of the blood vessels themselves.
Retinal transit times (e.g. arteriovenous passage time) are based on the change of intensity levels in the fluorescence at certain region of interests at the posterior pole. Retinal transit times have been shown to be longer in glaucoma patients compared to controls. However, a considerable overlap of the dynamic blood flow parameters is apparent between glaucoma patients and healthy subjects limiting the diagnostic power for an individual patient. Arteriovenous passage times are correlated to systemic blood pressure and ocular perfusion pressure in glaucoma, but not in healthy subjects. This might be a hint to disturbed retinal blood flow regulation in these patients.
In conclusion, fluorescein angiography characterises the vascular damage in glaucoma revealing fluorescein filling defects and fluorescein leakage of the optic disc, and longer retinal transit times. Prospective longitudinal studies are missing to evaluate the impact of fluorescein angiographic findings in glaucoma as marker for future progression.

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