Sixty corneal buttons excised from patients who developed pseudophakic bullous keratopathy after anterior chamber or iris-supported intraocular lens implantation were studied morphologically and statistically. The mean age of patients was 72.5 +/- 11.6 years. The mean interval between intraocular lens implantation and keratoplasty was 5.1 +/- 2.2 years. Degeneration and conversion of endothelial cells, abnormal proliferation of posterior collagenous layer, and edema of stroma and epithelium were noticed morphologically. Twenty-nine of the 60 specimens showed a surviving endothelial cell area of less than 50%. In these specimens a significant increase in the thickness of the central stroma was recognized compared with the other 31 specimens. The number of keratocytes in the 29 specimens had decreased significantly compared with the control. A linear regression study showed a significant relationship between the thickness of the stroma and the number of keratocytes. The keratocyte density decreased predominantly in the posterior part of the stroma.