In Vivo Effects of Prostaglandin Analogues Application by Topical Drops or Retrobulbar Injections on the Orbital Fat of a Rat Model

Purpose: To assess the in vivo effects of bimatoprost 0.03% (Lumigan®) on the orbital fat in a rat model. Methods: Twenty rats were randomly divided into two groups: bimatoprost was administrated to the right eye by topical drops (group 1) or retrobulbar injection (group 2), and saline was administrated to the left eye by similar administration routes (controls). Four weeks later, all rats were sedated and euthanized, both orbits exenterated, and thin sections through the intraconal orbital fat were obtained. Results: Average adipocyte cell count was significantly lower in the bimatoprost treated orbits (drops or retrobulbar injection, 29.5 vs. 67.5 cells per slide in the control globes, p=0.046). Fat cells were not detected in 9/20 (45%) bimatoprost treated orbits     . Conclusions: Orbits treated with bimatoprost by drops or retrobulbar injection demonstrated significant decrease in adipocytes cell count compared with controls. Bimatoprost could be an effective treatment for inactive thyroid eye disease.