PURPOSE: To evaluate the efficacy of a Thermoplastic Polyurethane/Poly L-Lactide-Co-DL-Lactide (TPU/PLDLA) polymer blend containing cyclosporine (CsA) for the treatment of keratoconjunctivitis sicca (KCS) in dogs. METHODS: Seventeen dogs (twenty-seven eyes total) with KCS, previously unresponsive to topical CsA or experiencing treatment challenges, received a subconjunctival implant of a TPU/PLDLA-CsA blend. Follow-up visits assessed tear production (STT-1), conjunctival hyperemia, corneal pathology, and ocular discharge at 1-, 3-, 6-, and 9 months post-implantation. RESULTS: The implant was well-tolerated. Conjunctival hyperemia was significantly reduced through 3 months post-implant, whereas ocular discharge showed a significant reduction by 9 months post-implant. STT-1 levels increased in 19 eyes (no significant results when data were analyzed collectively), while three eyes showed no improvement. Two dogs with prior stem cell therapy did not experience increased STT-1 levels. CONCLUSION: The TPU/PLDLA-CsA implant shows potential as an alternative to conventional topical CsA treatment for canine KCS, providing sustained release and reducing the need for frequent drug applications. The implant was generally well-tolerated, with observed improvements in tear production and inflammation reduction. Sedation was used for implantation, making the procedure less invasive compared to the general anesthesia required for some other implants. However, further studies with larger sample sizes and extended follow-up are required to confirm its long-term efficacy and safety, as well as to refine dosing and implantation protocols for optimal therapeutic outcomes.
Padjasek et al. (Tue,) studied this question.