Eye size in retinoblastoma: MR imaging measurements in normal and affected eyes

PURPOSE: To evaluate eye size retrospectively by using magnetic resonance (MR) imaging to measure axial length (AL), equatorial diameter (ED), and eye volume (EV) in patients with retinoblastoma and to evaluate the possible effect of retinoblastoma on eye size.

MATERIALS AND METHODS: Local ethics committee approval was obtained with waiver of informed consent. MR images of 100 patients with retinoblastoma (50 girls, 50 boys; mean age, 19 months; age range, 9 days to 68 months) were scored by one observer (AL, ED, EV, and tumor volume measurements), with a second observer reviewing all measurements. Normal eyes of patients with unilateral retinoblastoma served as controls. Interobserver measurement agreement was evaluated in a random subset of 50 eyes with use of intraclass correlation coefficients. Linear mixed model analysis was used with adjustments for age, laterality, and sex.

RESULTS: Interobserver agreement was good (intraclass correlation coefficients >or= 0.89). Eyes with retinoblastoma had significantly shorter ALs (95% confidence interval [CI]: -0.57 mm, -0.16 mm; P=.001) and EDs (95% CI: -1.01 mm, -0.66 mm; P<.001) and significantly smaller EVs (95% CI: -336 mm(3), -151 mm(3); P<.001) than normal eyes. Within patients, a significant negative relationship was found between tumor volume and EV (P<.001).

CONCLUSION: MR imaging measurements of AL, ED, and EV were significantly smaller in eyes with retinoblastoma than in normal eyes. In addition, in patients with retinoblastoma, the larger the tumor volume, the smaller the eye.