Application of fluorescein angiography in retinoblastoma.

Although a slight dilatation of the retinal capillaries is the only significant fluorescein angiographic finding in retinoblastoma when the tumor is less than 0.5 disk diameter in size, microaneurysms become distinct in the tumor after it attains a size of 1 disk diameter. As growth of the tumor progresses, blood vessels within the tumor become thicker and permeability increases; eventually neovascularization occurs. When the tumor exceeds 3 disk diameters in size, the feeder arteries and drainage veins become dilated and tortuous. With healing of the retinoblastoma, light fluorescent stains and thick vessels are no longer demonstrable and the dye is visible in the sclera during later periods. A recurrent tumor is visible as a white fluffy mass in which the fluorescent dye accumulates. Occasionally a thick vessel stemming from the scar can be detected in a recurrent tumor.