Abstract
Purpose: :
To test the hypothesis that anastrozole (an aromatase inhbitor [AI], which blocks estrogen synthesis) causes heightened vitreo-retinal traction at the fovea.
Methods: :
Retinal thickness measurements were obtained along a 5-mm horizontal line scan through the fovea, using the Stratus OCT. Data were obtained for 3 groups of subjects: breast cancer survivors using (1) anastrozole or (2) tamoxifen as adjuvant endocrine therapy following successful treatment for early-stage breast cancer, and (3) healthy control subjects not using any hormonal medication. All subjects were under 70 years old and amenorrheic or post-menopausal, and all subjects were considered to have healthy eyes according to conventional criteria. For comparing the foveal shapes of different subjects, we shifted each subject’s retinal thickness data horizontally so that the locus of minimal thickness was superimposed for all subjects. This normalization process enabled us to measure nasal/temporal foveal shape asymmetries, which were evaluated at 10-micron (µm) steps above the plane corresponding to the locus of minimal thickness. The Stratus OCT images were used for identifying eyes with posterior vitreous detachments (PVDs).
Results: :
For subjects without PVDs, usable OCT horizontal line scan data were obtained for 17 anastrozole users, 18 tamoxifen users and 23 control subjects. At 70 µm above the foveal minimum, the nasal-temporal foveal asymmetry was significantly greater for anastrozole users than for tamoxifen users and also for control subjects. For the anastrozole users, the distance to the foveal slope on the nasal side exceeded the distance to the foveal slope on the temporal side by +69 µm on average. The corresponding values were negative for each of the other 2 groups. Both between-group differences remained significant at 60 µm above the foveal minimum. The differences between anastrozole users and control subjects remained significant down to a height of 40 µm, and the effect for anastrozole users appeared to be restricted to the temporal side of the fovea. In addition, the nasal-temporal foveal asymmetry at a height of 70 µm was significantly greater for anastrozole users with PVDs than without PVDs.
Conclusions: :
Anastrozole causes vitreo-retinal traction that pulls the temporal side of the foveal slope in the direction of the optic nerve head. This measurable degree of traction probably is a consequence of pronounced estrogen depletion.
Keywords: drug toxicity/drug effects • macula/fovea • oncology