Severe dry-eye syndrome following external beam irradiation.
OBJECTIVE
There are limited data in the literature on the probability of dry-eye complications according to radiotherapy dose. This study investigates the risk of radiation-induced severe dry-eye syndrome in patients in whom an entire orbit was exposed to fractionated external beam irradiation.


METHODS
Between October 1964 and May 1989, 33 patients with extracranial head and neck tumors received irradiation of an entire orbit. Most patients were treated with 60Co. The dose to the lacrimal apparatus was calculated at a depth of 1 cm from the anterior skin surface, the approximate depth of the major lacrimal gland. The end point of the study was severe dry-eye syndrome sufficient to produce visual loss secondary to corneal opacification, ulceration, or vascularization.


RESULTS
Twenty patients developed severe dry-eye syndrome. All 17 patients who received doses > or = 57 Gy developed severe dry-eye syndrome. Three (19%) of 16 patients who received doses < or = 45 Gy developed severe dry-eye syndrome; injuries in the latter group were much slower to develop (4 to 11 years) than in the higher dose group, in whom corneal vascularization and opacification were usually pronounced within 9-10 months. There were no data for the range of doses between 45.01 and 56.99 Gy. The data did not suggest an increased risk of severe dry-eye syndrome with increasing age.


CONCLUSIONS
Data from the current series and the literature are combined to construct a sigmoid dose response curve. The incidence of injury increases from 0% reported after doses < or = 30 Gy to 100% after doses > or = 57 Gy.
Parsons
J T
JT
Department of Radiation Oncology, University of Florida College of Medicine, Gainesville.
Bova
F J
FJ
Fitzgerald
C R
CR
Mendenhall
W M
WM
Million
R R
RR
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D004307:Dose-Response Relationship, Radiation; D015352:Dry Eye Syndromes / Q000209:etiology*; D005260:Female; D006258:Head and Neck Neoplasms / Q000532:radiotherapy; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011832:Radiation Injuries / Q000209:etiology*; D011878:Radiotherapy / Q000009:adverse effects*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D014786:Vision Disorders / Q000209:etiology