Abstract
Purpose: :
The suprachoroidal space (SCS) is a potential site for drug delivery to the posterior segment of the eye. The anterior SCS is readily available via a minimally invasive partial sclerotomy. The purpose of this study was to determine if local injection of a drug-like liquid latex into the anterior SCS can effectively distribute to the ocular posterior segment.
Methods: :
Eight fresh canine and 8 porcine cadaver eyes were injected with liquid latex through a 2 mm scleral incision into the SCS, 5 mm posterior to the superior limbus. Latex was injected through a 27 gauge cannula that was placed 1-2 mm into the SCS through the scleral incision. Latex was injected until reflux through the scleral incision occurred, resulting in an injection of 1 to 2 ml of latex. Globes were fixed in 10% formalin and sectioned either sagittally (n=4 of each species) or in quadrants (i.e., flat mount) after removal of the anterior segment (n=4 of each species). The retina and choroid were removed, exposing the latex in the SCS and sclera. High-resolution digital photos of the eyes were analyzed using Photoshop and ImageJ software (NIH) to determine overall percent distribution of latex to the ocular posterior segment.
Results: :
In canine eyes, latex distributed to a mean (±SD) 39.9±5.2% of the area of the SCS in sagittal cut sections and 46.8±13.1 % of the eyes sectioned in quadrants. In porcine eyes, latex distributed to a mean 54.8±15.4% of SCS in sagittal cut sections and 42.1±4.3% of the eyes sectioned in quadrants. There were no significant differences between species or sectioning technique in area of distribution. Latex reached the SCS adjacent to the area centralis (i.e., macula) in 9 of 16 (56%) eyes.
Conclusions: :
A single injection into the anterior SCS resulted in distribution of drug - like liquid latex to nearly 50% of the ocular posterior segment in 2 large animal species commonly used for retinal research. These results suggest that a single injection of a drug into the anterior SCS can reach a high percentage of the posterior ocular tissues including the macular area. Therefore, further development of anterior SCS injections for macular disease and other diseases of the posterior segment of the eye is warranted.
Keywords: macula/fovea • choroid • drug toxicity/drug effects