Abstract
Purpose: :
To assess the histopathological appearance of retina, choroid and sclera following suprachoroidal injection of Triamcinolone Acetonide (TA, Triesence, Alcon Laboratories) and balanced salt solution in live pigmented rabbits.
Methods: :
Ten Dutch-belted rabbits weighing 4-6 lbs. were used in accordance with ARVO’s Statement for the Use of Animals in Ophthalmic and Visual Research. Eyes received single 100uL injections of 2mg TA (n=9) or balanced salt solution (n=9) using a single hollow metal microneedle in the superior temporal quadrant. Injection location was 5mm posterior to the limbus. Eyes were enucleated immediately (n=6), after 1 day (n=6), or after 7 days (n=6). Two eyes were used as negative controls. After enucleation, eyes were fixed in 2.5% Glutaraldehyde. Circular sections (4mm in diameter) were cut from the area between injection site and optic nerve, embedded in resin and stained using toluidine blue.
Results: :
Sections from all eyes were examined for inflammation, atrophy, necrosis, edema, enlargement of the suprachoroidal space, choroidal hemorrhage or any other abnormality. No inflammation, atrophy, necrosis, edema, hemorrhage or scarring was found in any of the injected eyes, or in the normal controls. In about one-third of tissue samples, an abnormal separation was observed in the area of the suprachoroidal space. Normal-appearing parallel thin septae were visible within this enlarged suprachoroidal space, without cellular infiltration or evidence of hemorrhage. Two TA-injected samples contained an amorphous, acellular, nonstaining material within the enlarged suprachoroidal space, believed to represent triamcinolone collections. The retina retained normal appearance in all tissue samples.
Conclusions: :
This histological study of in vivo suprachoroidal injections shows that triamcinolone acetonide or balanced salt solution can be injected into living rabbit eyes without causing an immediate or short-term inflammatory response or choroidal hemorrhage. These two materials, injected using a hollow metal microneedle, did not cause any significant disruptions in tissue organization or appearance through seven days post-injection.
Keywords: choroid • injection • corticosteroids