Effect of a cyclosporine A delivery system in corneal transplantation

To test the immunosuppressive effect of cyclosporine (Cs) in a polymer placed in the anterior chamber of corneal allograft recipients.

Wistar inbred rats with vascularized corneas were recipients of corneal allografts from Sprague-Dawley donor rats. Rats underwent penetrating keratoplasty and were divided randomly into four groups: untreated control animals (UCA); Cs-polymer anterior chamber recipients (CPA); co-polymer subconjunctival recipients (CPS); and Cs-olive oil drop recipients (COO). Grafts were examined by slit lamp every 3 days and clinical conditions were scored. Cs concentration in the aqueous humor was assayed at 1, 2, and 4 weeks. At 1, 2 and 4 weeks after transplantation, the operated eyes were collected for histopathological evaluation of the grafts.

The median survival time of the allografts was 8.2 +/- 1.48 days for the UCA group, 11.4 +/- 2.50 days for the CPS group, and 17.0 +/- 2.00 days for the CPA group. There was a statistically significant difference (P < 0.05) between survival time of the allografts in the animals of the CPA group compared to the other groups of graft recipients. Significantly higher concentrations of Cs were found in the eyes given an anterior chamber implant of Cs-polymer, compared to other treatment groups or untreated rats. A transient inflammatory response in the anterior chamber was observed in the CPA group.

Cs-polymer placed in the anterior chamber significantly prolongs corneal allograft survival time in a high risk corneal graft rejection model. This intraocular delivery system may be a valuable adjunct for the suppression of immune graft rejection.