Abstract
Purpose: :
Prosthetic corneas offer an alternative to donor tissue for patients at high risk for graft failure. The AlphaCor Keratoprosthesis is one such device and its composition offers biointegration into the host cornea. The purpose of this study is to describe the clinical outcomes of eight patients who underwent AlphaCor device implantation at a single center.
Methods: :
Between 8/30/04 and 5/15/08, eight AlphaCor devices were placed in patients considered to be high risk keratoplasty candidates. The mean age at the time of surgery was 60 years (range 27-80 years). The mean number of keratoplasties per patient prior to AlphaCor placement was 3.25 per patient. Preoperative best corrected visual acuity (BCVA) ranged from HM at 3 feet to 20/250. Three of eight patients (37.5%) had Type I surgery using a limbal pocket incision with a Gundersen conjunctival flap. Three of eight patients (37.5%) had Type II surgery using a temporal clear cornea pocket incision. Two of eight patients (25%) had Type III surgery using a keratoplasty wound pocket incision.
Results: :
Six of eight patients (75%) have active device retention. In six active patients, two patients have BCVA of 20/40 or better whereas four have vision of 20/200 or worse (range 20/20 to CF at 1 foot). Pre-existing end stage glaucomatous optic neuropathy is the reason for poor vision in three of the four poorest seeing eyes. Stromal melting occurred in three patients despite use of Medroxyprogesterone topically. Of these, two were successfully treated with a lamellar onlay keratoplasty. Retroprosthetic membrane formation occurred in four of eight patients (50%). Two of these occurred in patients with Type I surgery and two occurred in patients with Type II surgery. No retroprosthetic membranes occurred with Type III surgery.
Conclusions: :
The device retention rate in this study is superior to that in the reported literature. Type III surgery may lead to less retroprosthetic membrane formation. Performance of Stage II surgery followed by use of a piggyback contact lens fitting system is required for best visual performance in eyes with excellent visual potential.
Keywords: cornea: clinical science • transplantation