Penetrating keratoplasty for keratoconus: complications and long-term success. A series of 100 penetrating keratoplasties for keratoconus performed between 1968 abd 1986 were reviewed for long-term results. The mean follow-up was 6.1 years with a range of 4-16 years. The systemic associations and the postoperative complications were analysed. Grafting in cases associated with Down's syndrome had a higher incidence of complications. 93% of grafts remained clear and 81% achieved a final corrected visual acuity of 6/12 or better. 21% of eyes developed a homograft reaction, with 50% of rejection episodes occurring in the first year after operation. Factors associated with higher incidence of rejection included loose sutures, traumatic wound dehiscence, and grafts larger than 8.5 mm. Only three grafts with rejection episodes lost graft clarity, while rejection in the rest was successfully reversed with topical steroid therapy. No relationship was found between donor age and long-term graft clarity. 