Purpose:
To prospectively characterize visual field function and visual acuity in patients with a history of external beam radiation to the sino-nasal area, resulting in incidental radiation exposure to the retina.
Methods:
Inclusion criteria for this prospective study were patients with a history of sinonasal/orbital carcinoma treated with external beam radiation greater than one year ago, resulting in a dose of at least 45 Gy to at least one quadrant of one retina. On the same day, visual acuity was measured in both eyes using a standardized ETDRS chart, and Goldmann visual field testing was performed. A single technician performed each GVF test for all subjects. Five isopters (I2e, I3e, I4e, III4e, and V4e) were mapped in each eye. For each eye, a visual field score was determined by totaling the peripheral extent of the visual field in degrees on each of the 24 meridians and subtracting any scotomas. This sum was averaged across all patients and then compared to that calculated from normative data of each isopter.
Results:
Eight subjects (40 to 73 years old) were enrolled. Four subjects had a history of ethmoid sinus carcinomas, two with maxillary sinus tumors, and one with nasopharyngeal carcinoma. Sixteen eyes were incidentally irradiated, with each subject having a dose above 45 Gy in at least one retinal quadrant. The ETDRS visual acuities ranged from 70 (Snellen 20/50) to 90 (Snellen 20/10). The visual field scores for each isopter (averaged across 16 eyes) compared to normative values are shown in the table below. On average, the central isopter I2e (336.75 ± 211.8) was markedly constricted relative to the normal (837.6 ± 93.3). Isopter I3e was moderately constricted relative to the normal, and the peripheral isopters (I4e, III4e, and V4e) were essentially the same as normal.
Conclusions:
Goldmann visual field inner isopters were constricted in patients at least one year after incidental external beam radiation exposure to the retinas following treatment. While in this study, visual acuity was not found to be compromised from radiation at this early stage, the observed constriction of inner GVF isopters may represent an early sign of retinal damage.
Keywords: radiation therapy • visual fields