Direct injection of drugs to back of eye shows potential

Clearside Biomedical presented human and animal study data showing the benefits of directly injecting medication into the eye's posterior suprachoroidal space (SCS) at the Association for Research in Vision and Ophthalmology (ARVO) 2014 annual meeting in Orlando, FL.

One study in two African green monkeys found that injecting up to 100 mL of sodium fluorescein into the SCS, the area located between the protective outer layer of the eye known as the sclera and the vascular choroid, which contains blood vessels and supplies oxygen to the retina, produced fewer complications than intravitreal injections. "Intravitreal fluorescein injection contributed to significant intraocular fluorescein signal in the vitreous, serving as a positive control to substantiate the SCS placement of the microneedle injections," the study's research abstract says. A 650-millimeter microneedle was used to access the SCS.

Other studies found that SCS injections of various compounds were well tolerated in rabbits and did not increase intraocular pressure compared to intravitreal injections.

Using four donated enucleated human globes from two recently deceased donors, Clearside researchers found that suprachoroidal delivery can be confirmed visually using ultrasound biomicroscopy because the images revealed an increase in scleral thickness of about 3 millimeters postinjection.

Clearside's website says the current delivery methods have limitations. Topical drops applied to the eye's surface do not always reach the retina in sufficient quantities, and intravitreal injections are invasive and can lead to side effects such as cataract formation.

Also featured in FierceDrugDelivery are the advances made in ophthalmology by Envisia Therapeutics, as presented at the ARVO conference.

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