Abstract
Purpose:
Sustained drug, gene, and/or stem cell therapy of the ocular posterior segment would be beneficial for many common ocular diseases. The purpose of this study was to evaluate the tolerability and toxicity of a promising sustained drug delivery vehicle, pentablock co-polymer (PBC), injected into the suprachoroidal space (SCS) in the normal rabbit eye.
Methods:
New Zealand White rabbits were tranquilized and injected with 100 uL of a thermosensitive PBC OD and 100 uL BSS OS into the SCS using a purpose-designed, rabbit-specific, 31-gauge microneedle. Hackett-McDonald ocular irritation scoring, intraocular pressure (IOP) and pachymetry were performed prior to, and at 1, 3, 7, 14, 21, and 28 days after injection. Scotopic electroretinography (ERG) was performed prior to injection and at 7 and 28 days later. Twenty-eight days after injection, the rabbits were euthanized and eyes collected for histopathology.
Results:
SCS injection of PBC was performed without difficulty, resistance, or adverse reaction. The rabbits remained comfortable throughout the study and at no time was intraocular inflammation observed. Mild conjunctival hyperemia and swelling (chemosis) was observed in both eyes 24 hours after the injections and the mean inflammatory scores peaked 3 days after the injection (mean cumulative score of 3.5 +/- 1.29) OD. No significant differences in IOP, corneal thickness, or scotopic B-wave amplitude (ERG) were observed between OD and OS throughout the study. Histopathology revealed PBC in the SCS superiorly, but no evidence of inflammation or tissue degeneration.
Conclusions:
After SCS injection of PBC, no adverse reaction, intraocular inflammation or significant differences in IOP, corneal thickness, or scotopic B-wave amplitude (ERG) was observed. These results warrant further evaluation of this promising drug delivery vehicle for treatment of the ocular posterior segment via the SCS.