The suprachoroidal space is expandable, allowing fluids to enter and exit without disruption
The suprachoroidal space is primarily in a collapsed state under typical physiological conditions, primarily due to intraocular pressure (IOP). The suprachoroidal space plays a role in maintaining IOP via uveoscleral outflow, which is an alternative drainage route for the aqueous humor, and is a natural flow path from the front to the back of the eye.
Due to its role in maintaining IOP, the suprachoroidal space has the potential to expand and contract in response to the presence of fluid. In animal models,* the suprachoroidal space has been reported to expand to accommodate different volumes. The maximal thickness ranged from 1.7-2.8 mm, depending on injection volumes. On injection, the suprachoroidal space expands locally, then rapidly empties into the posterior region of the eye. Within an hour post-injection, IOP returns to baseline and the suprachoroidal space contracts.
*Based on studies of adult porcine and canine ex vivo eyes.
Treatments that target retina disease through the vitreous space, such as intravitreal injections, have the potential to diffuse toward nontarget regions of the eye, such as the lens and ciliary body.