An analysis of corneal endothelial and graft survival in pseudophakic bullous keratopathy

Abstract

PBK has become an important complication of cataract surgery and a leading indication for keratoplasty. While there are many potential causative factors, erroneous concepts of IOL positioning and design appear to have led to PBK with many iris-supported and anterior chamber lens styles. Underlying host endothelial abnormalities are an important risk factor with posterior chamber lenses. Previous studies of keratoplasty for PBK have shown variable early results in terms of graft clarity and visual rehabilitation. Specular microscopy and life-table survival analysis have been infrequently used to study endothelial and graft survival after keratoplasty. This study combined these techniques to evaluate several approaches to the original IOL at PKP for PBK. Four-hundred sixty-nine patients having PKP for PBK between 1976 and 1986 were studied in five retrospective cohorts on the basis of whether their IOL was retained, removed, or exchanged. Specular microscopy was performed prospectively on 390 patients. Survival analysis showed overall failure in 20% of IOL-removed, 24% of IOL-retained, and 16% of IOL-exchanged grafts, without significant differences. Within the retained group, however, graft failure rate for posterior chamber IOLs (6%) was significantly less than for anterior chamber (34%) and iris-supported (29%) lenses. With lens exchange, the failure rate was 8% for sutured posterior chamber lenses, 5% for one-piece anterior chamber lenses, and 24% for closed-loop anterior chamber lenses. Graft failure rates exceeded rejection rates for retained iris-supported and anterior chamber lenses, and exchanges for closed-loop anterior chamber lenses, suggesting nonimmunologic causes. The survival curve for all groups combined showed cumulative survival of 93% at 1 year, decreasing to 62% by 6 years. Survival was lowest for retained anterior chamber and iris-supported lenses and exchanged closed-loop anterior chamber lenses. Visual acuity results were best for retained posterior chamber IOL eyes and exchange for one-piece anterior chamber IOLs. Exchange for one-piece anterior chamber IOLs gave significantly better visual acuity than exchange for sutured posterior chamber IOLs. There was not a significant relationship between duration of corneal edema prior to PKP and visual outcome, refuting earlier findings. Cystoid macular edema was related to poor vision in 62% of those with visual acuity of less than 20/40 and in 36% of all patients. Specular microscopy findings at 1 year were predictive of longer term survival results. The least cell loss was for retained and exchanged posterior chamber lenses and exchange for one-piece anterior chamber lenses.(ABSTRACT TRUNCATED AT 400 WORDS)