QUANTIFICATION OF LACRIMAL FUNCTION AFTER D-SHAPED FIELD IRRADIATION FOR RETINOBLASTOMA

To study the quantitative effects of megavoltage external beam irradia tion in a D-shaped field in patients with retinoblastoma, biomicroscop y was performed in 61 patients and tear function tests (Schirmer-lacto ferrin and lysozyme tests) on 45 eyes in 34 irradiated patients. The r esults were compared with those obtained in 25 non-irradiated control eyes. The Schirmer test was significantly diminished (p<0.001) in irra diated eyes, as were the lactoferrin and lysozyme values (p<0.001). A mild to severe keratitis was found in 17 of the 61 patients (28%). A s ignificant correlation (p<0.005) was found between the severe keratiti s and the mean Schirmer values; the mean lactoferrin and lysozyme valu es were diminished in all patients but did not correlate significantly with the corneal abnormalities. These quantitative data, obtained in patients treated for retinoblastoma, affirm the qualitative data found in patients irradiated for other reasons such as orbital or sinus tum ours. Irradiation for retinoblastoma is not a harmless treatment and s erious late side effects have to be considered.