Abstract
Abstract: :
Purpose: Recent studies reported that intravitreal or posterior sub–Tenon’s injection of triamcinolone acetonide (TA) is effective for the treatment of macular edema resulting from retinal microcirculatory disturbances such as diabetic retinopathy and retinal vein occlusion. We quantitatively evaluated retinal edema in the experimental retinal ischemia of rats with the use of optical coherence tomography (OCT). The effect of sub–Tenon’s administration of TA on the retinal edema was also studied. Methods:Transient retinal ischemia for 60 minutes was induced in male Long Evans rats (n=12) by the temporal ligation of the optic nerve. After the induction of ischemia, experimental eyes received posterior sub–Tenon’s injection of TA (2 mg). For controls, the same volume of saline was administered. At 6 hours after reperfusion, we evaluated retinal thickness using OCT. The eyes were enucleated after OCT examinations and processed for the histological evaluation. Ten µm cryosections were stained with hematoxylin and eosin and the thickness of outer to inner limiting membrane (OLM–ILM) at a distance of 1.5mm from the center of the optic nerve head was measured. Results: The retinal thickness evaluated with OCT after ischemia was increased in the vehicle treated rats (336±31 µm, P<0.0001) compared to normal rats (174±14 µm). Treatment with TA significantly reduced the post ischemic retinal edema (215±12 µm, P<0.0001 ). Histological study showed that the thickness from OLM to ILM was increased both in TA– and vehicle–treated rats. However, the thickness was significantly reduced in TA treated rats (206±11 µm, P<0.0001) compared with vehicle treated rats (267±15 µm). Conclusions: The present study demonstrated that OCT is useful to evaluate the retinal edema in rat noninvasively and that the posterior sub–Tenon’s injection of TA effectively inhibited retinal edema after ischemia.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • ischemia • retina