The effect of external eye irradiation on choroidal circulation.
BACKGROUND
The effect of external beam radiation therapy (teletherapy) on the choroidal circulation is poorly known. Eyes irradiated with teletherapy represent a good model to study, without confounding factors, the pathophysiologic and clinical aspects of radiation-induced chorioretinal damage. This study used fluorescein and indocyanine green choroidal angiography to investigate the late effects of external eye irradiation on the choroidal circulation.


METHODS
Fluorescein angiography and indocyanine green choroidal videoangiography were performed on patients with radiation retinopathy because of external eye irradiation for orbital and paranasal sinus malignancies. Patients were divided into two groups according to the treatment field (anterior unilateral or bilateral).


RESULTS
Indocyanine green angiograms showed areas of choriocapillaris hypoperfusion in all eyes-unilateral or bilateral irradiation-affected by radiation retinopathy. Late indocyanine green choroidal staining was found in five eyes (28%) of the patients who received unilateral anterior irradiation. In the same group, nine eyes (52%) had signs of choroidal precapillary occlusion and four eyes (23%) had rubeosis iridis without retinal neovascularization. One case of subfoveal choroidal neovascularization was documented in the bilateral irradiation group.


CONCLUSIONS
Radiation side effects are not limited to the retinal vessels but also involve choroidal circulation. The damage to the choroid is primarily vascular, and its clinical aspects depend on the treatment fields. Anterior irradiation may be a critical factor for the appearance of unusual rubeosis iridis and neovascular glaucoma.
Midena
E
E
Institute of Ophthalmology, University of Padova, Italy.
Segato
T
T
Valenti
M
M
Degli Angeli
C
C
Bertoja
E
E
Piermarocchi
S
S
D000293:Adolescent; D000328:Adult; D000368:Aged; D002829:Choroid / Q000098:blood supply*; D005260:Female; D005451:Fluorescein Angiography; D005654:Fundus Oculi; D006801:Humans; D007208:Indocyanine Green; D008297:Male; D008833:Microcirculation / Q000502:physiology / Q000528:radiation effects*; D008875:Middle Aged; D009303:Nasopharyngeal Neoplasms / Q000532:radiotherapy*; D009918:Orbital Neoplasms / Q000532:radiotherapy*; D010255:Paranasal Sinus Neoplasms / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000209:etiology* / Q000503:physiopathology; D011867:Radioisotope Teletherapy / Q000009:adverse effects*; D012039:Regional Blood Flow / Q000502:physiology / Q000528:radiation effects; D012160:Retina / Q000528:radiation effects
D007208:Indocyanine Green