Abstract
Abstract: :
Purpose: Tamoxifen is a selective estrogen receptor modulator used as adjuvant therapy for early–stage breast cancer. Tamoxifen can block swelling–activated chloride channels, and it occasionally causes clinically evident swelling at the optic–nerve–head (ONH). Scanning laser ophthalmoscopes now are available for quantifying the topography of the ONH. This study used the Heidelberg Retina Tomograph (HRT) to determine whether tamoxifen use often leads to measurable ONH swelling in eyes with excellent visual acuity. Methods: We tested 48 tamoxifen users who met stringent eligibility criteria, including a) no eye disease, b) 20/20 or better visual acuity in the test eye (and 20/25 or better in the other), c) no high myopia, and d) age 40–69 years. We also tested 50 women not using hormonal medication. All tamoxifen users had been treated for early–stage breast cancer but otherwise appeared healthy. Data were compared across 3 subject groups (25 short–term tamoxifen users {< 2 years}, 23 long term tamoxifen users {>2 years, < 5 years}, and 50 control subjects) for each of the following 3 measures: cup volume (CV), cup area (CA), and maximum cup depth (MCD). To compare ONH values between subject groups, we used non–parametric ANOVAS followed by post–hoc comparisons with Fisher’s Least Significant Difference. To help interpret the results, we have also begun to test women (9 thus far) who have used the aromatase inhibitor Arimidex as adjuvant therapy for < 2 years for early–stage breast cancer. Results: The CV, CA, and MCD indices all were significantly less (p=.017, p=.017, and p=.035) for the short–term tamoxifen users than for each of the other 2 subject–groups. The median values for the short–term users were 25%, 43%, and 73% of the corresponding values of control subjects for CV, CA, and MCD, respectively. The effects were essentially the same when restricted to post–menopausal subjects only. There was no suggestion whatsoever of ONH swelling among Arimidex users. Conclusions: Tamoxifen use often leads to measurable ONH swelling in eyes with excellent visual acuity. Devices such as the HRT may be valuable tools for monitoring tamoxifen–induced intraocular change.
Keywords: drug toxicity/drug effects • optic disc • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)