Experimental studies on penetrating heterokeratoplasty with human corneal grafts in monkey eyes

In nine rhesus monkeys, human corneal grafts were used for penetrating keratoplasty in one eye of each. The data were divided into three groups according to the size of grafts. Group 1 (n = 3) received 5.5-mm human corneal grafts in 5.0-mm recipient beds; group 2 (n = 3) received 6.2-mm human corneal grafts in 6.0-mm beds; and group 3 (n = 3) received 7.5-mm grafts in 7.0-mm beds. Five of nine eyes in groups 1 and 2 (55%) maintained graft clarity for more than 1 year, but only two of the three in group 1 maintained clear human corneal grafts for 32 and 36 months, respectively. However, the three grafts in the third group maintained transparency for only 4-7 months. Our findings suggest that xenogeneic corneal grafts may have a greater success rate in humans than previously believed.