To study the transparent rate of corneal graft and its influencing factors after optical penetrating keratoplasty(PKP). METHODS: A retrospective study was done to 97 cases (105 eyes) in Qingdao Eye Hospital between January 2004 and December 2005 who had accepted optical PKP for keratoconus, corneal stroma dystrophy, corneal leukoma caused in ocular trauma or infection, herpes simplex keratitis(HSK),corneal endothelial function decompensation and so on. Best-corrected visual acuity(BCVA) of preoperative and postoperative, graft clarity, allograft reactions, final postoperative visual acuity and complications leading to graft opacity were reviewed and statistically analyzed. RESULTS: The transparent rate of corneal graft were respectively 89.8% after 1 year, 83.7% after 2 years, 78.3% after 3 years, 67.1% after 4 years, and 63.6% after 5 years. The best graft clarity was in eyes with an original diagnosis of keratoconus (94.1%) and the worst was in eyes with corneal endothelial function decompensation (14.3%) at postoperative 5 years. The BCVA after PKP was between 0.05 and 1.0, keratoconus accounted for the largest proportion(72.5%) of whom achieved 0.8 or better, and corneal endothelial function decompensation accounted for the smallest proportion(6.3%).Graft immunological rejection and corneal allograft endothelial function decompensation were the leading causes of allografts opacity . CONCLUSION: The transparent rate of corneal graft decreases year by year stably after optical PKP. There is no significant difference between adjoining two years. There are differences in the transparent rate of corneal graft from different primary diseases. The result of kereatoconus is better than others. Graft immunological rejection and corneal allograft endothelial function decompensation are the leading causes of allografts opacity.