Margareta Claesson

Corneal transplant rejection rate and severity after endothelial keratoplasty.

Purpose: To examine the corneal transplant rejection rate and the rate of graft failure subsequent to rejection in the first 2 years after endothelial keratoplasty (EK) and to compare this to background data for similar cases of penetrating keratoplasty (PK). Methods: Anonymized data from consecutive cases of EK [deep lamellar (DLEK) or Descemet stripping (DSEK)] for Fuchs corneal endothelial dystrophy or pseudophakic bullous keratopathy operated on before August 2004 were collected in 4 participating centers. The number and timing of rejection episodes and cases of subsequent graft failure were recorded, together with the time to cessation of topical steroid medication. Two-year postoperative findings were compared with background data for similar patients undergoing PK recorded in the Swedish Corneal Transplant Registry. Results: Rejection episodes were less frequent after EK than PK (P = 0.035). Fifteen (7.5%) of 199 EK cases had a rejection episode in the first 2 years after surgery versus 92 (13%) of 708 PK cases. Graft failure after rejection in EK may have been less frequent than in PK (P = 0.063), with only 1 (6.7%) case of rejection after EK versus 26 (28.3%) cases of rejection after PK proceeding to graft failure. A strong trend toward continued use of low-dose topical steroid medication was observed in the EK group. Eighty percent of EK patients were still taking topical steroid medication 2 years after surgery, whereas topical steroid medication had been ceased within a year of surgery in almost all PK patients in the comparator group. Conclusions: Corneal transplant rejection is less frequent and may be less severe after EK than after PK. It is not yet clear whether these apparent differences are simply a product of relatively prolonged postoperative topical steroid cover in EK patients.

Glare and contrast sensitivity before and after Nd:YAG laser capsulotomy

Abstract. The benefits of Nd:YAG laser capsulotomy on visual peformance were evaluated in 13 patients with after‐cataract following extracapsular cataract extraction. Besides clinical evaluation we measured: visual acuity, letter contrast sensitivity with and without the presence of a circular glare source (glare angle: 8°). Finally, the patients were asked to evaluate their subjective glare problems. In all patients, visual acuity had decreased markedly compared to measurements 2 months after cataract surgery. Before capsulotomy we observed impaired letter contrast sensitivity and increased intraocular light scatter compared to normals. Following capsulotomy, VA and contrast sensitivity both improved by a factor of 2. The subjective glare problems diminished, although most patients showed minor decreases in intraocular light scatter. The limited glare induced loss of letter contrast sensitivity, present before capsulotomy, remained after treatment. Our study indicates that after‐cataract impairs resolution and contrast sensitivity without necessarily causing a marked increase in light scatter as measured at a large angle.

Donor and recipient endothelial cell population of the transplanted human cornea: a two-dimensional imaging study.

Purpose. To elucidate the pattern of donor and recipient endothelial cell populations in transplanted human corneas and determine the degree to which donor endothelial cells survive in the graft. Methods. Thirty-six corneal grafts were collected from recipients of opposite sex to the donor, at the time of retransplantation for various indications. Cells from the endothelial side of the grafts were harvested, preserving their relative location on the endothelium. Fluorescence in situ hybridization of the sex chromosomes enabled each cell to be identified as donor- or recipient-derived. Images of the graft endothelium were assembled, to depict the pattern of cell population of the graft, and the proportion of donor cells present was estimated. Results. Endothelial cells of donor origin were found in 26 of 36 grafts (72.2%)-in one case, up to 26 years after transplantation. The proportion of donor endothelium ranged from 2% to 99%; however, there was no significant correlation of this proportion with postoperative time (P = 0.19). The mean annual rate of donor cell loss correlated negatively with the time to graft failure by endothelial decompensation (P = 0.002). Endothelial images indicated a highly variable pattern of recipient cell repopulation of the graft. A tendency toward donor cell retention in transparent, successful grafts was noted; however, this feature alone was not a reliable indicator of long-term graft transparency. Conclusions. Two-dimensional imaging of the corneal graft endothelium revealed a variable pattern and extent of donor and recipient cell population, indicating the highly dynamic nature of the corneal endothelium after transplantation.

Ten-year follow up of graft survival and visual outcome after penetrating keratoplasty in Sweden

Purpose: To determine factors influencing graft survival and visual outcome 10 years after penetrating keratoplasty. Methods: Ten-year follow-up data were obtained from a cohort of patients that represented 20% of corneal transplants in Sweden between1996 and1998. Multiple regression analyses (logistic and linear) were performed on graft survival and visual outcome (visual acuity and astigmatism). Results: Of the initial 242 patients receiving a corneal transplant during 1996-1998, 140 were available at 10 years. The majority of patients lost to follow-up had the indication bullous keratopathy and many were deceased. Overall, 71% of transplants available for follow-up at 10 years were still functioning, with keratoconus showing the best result (88%) and bullous keratopathy the worst (48%). Complications during the first 2 postoperative years reduced the percentage of functioning grafts at 10 years from 84% to 50%. The visual acuity was influenced by indication and postoperative complications. The change in Snellen lines between preoperative and 10-year visual acuity for the individual patients also depended on indication and postoperative complications. Most of the changes occurred during the first 2 postoperative years. The astigmatism at 10 years was also affected by postoperative complications and in addition by the amount of astigmatism at 2 years. Conclusion: Graft survival and visual outcome at 10 years depended on indication and postoperative complications. Most improvement of vision occurred during the first 2 years and was predictive of the 10-year visual outcome.

Astigmatism and the Impact of Relaxing Incisions After Penetrating Keratoplasty

PURPOSE To determine the impact of relaxing incisions for correcting postoperative astigmatism following penetrating keratoplasty. METHODS Data were collected through the Swedish Corneal Transplant Register. Of the 1161 grafts with complete 2-year follow-up, 131 underwent relaxing incisions. Stepwise multiple regression was used to determine the factors that influenced the extent of astigmatism in diopters (D) (square root transformed). The change in astigmatism brought about by relaxing incisions was evaluated both by subtraction (ie, ignoring angle) and vector analysis. RESULTS The overall mean astigmatism was 4.56 D (95% confidence interval [CI]: 4.40-4.73, n = 1161). The final regression model explained only a small proportion of the overall variability of the data (< 5%). There was a slight increase in postoperative astigmatism with recipient age (P = .025), and two of the seven participating clinics achieved lower levels of astigmatism (P = .001 and P = .036, respectively). In patients who underwent relaxing incisions, astigmatism was reduced from 8.40 D (95% CI: 8.0-9.0, n = 131) to 3.80 D (95% CI: 3.5-4.3). The mean difference by subtraction was 4.50 D (95% CI: 4.0-5.0, P < .001, paired t test). Vector analysis showed the overall reduction of astigmatism due to surgery to be 7.90 D (95% CI: 7.2-8.7). Compared with grafts with no refractive surgery, a trend was noted that suggested corrected visual acuity was improved following relaxing incisions. CONCLUSIONS Relaxing incisions were found to be a safe and effective method for reducing postoperative astigmatism and may improve visual acuity.

Survival of Donor-Derived Cells in Human Corneal Transplants

PURPOSE To determine the fate of donor epithelial, stromal, and endothelial cells after corneal transplantation in humans. METHODS Fifty-two transplanted corneal buttons were explanted over a 2-year period from patients who required regrafting and had received corneas from donors of opposite sex. Fluorescence in situ hybridization of the sex chromosomes of the epithelial, stromal, and endothelial cells was performed in histologic sections prepared from each freshly explanted graft. Fluorescence microscopy was subsequently used to determine the origin of cells in the graft (donor or recipient) and to quantify the relative proportion of donor and recipient cells of each corneal cell type. RESULTS As early as 3 months after transplantation, donor epithelial cells were completely replaced by recipient epithelium in all corneal buttons examined. Donor stromal and endothelial cells, however, were found in all 52 buttons, with 4% to 95% of stromal cells and 6% to 95% of endothelial cells being of donor origin. No significant correlation between donor cell proportion and the age of the graft could be found. Donor-derived cells were found in significant numbers up to 32 years after transplantation. Eight corneas in this study were transparent, compensated grafts, and a similar long-term survival of donor stromal and endothelial cells was found in these cases. CONCLUSIONS Although donor epithelial cells are promptly replaced, a high proportion of donor stromal and endothelial cells can survive within the corneal transplant in the long-term. The proportion of surviving donor cells is highly variable; however, the source of this variability remains unknown.

Clinical outcome of repeat penetrating keratoplasty.

Purpose: To compare the clinical outcome of regrafts with first grafts. Methods: Two-year outcome data were obtained from the Swedish Cornea Transplant Register for patients undergoing penetrating keratoplasty between 2001 and 2008. Only data from the 3 centers with follow-up return rates >75% were included. The survival and visual outcome of regrafts with the original diagnoses of keratoconus, Fuchs endothelial dystrophy (FED), or bullous keratopathy (BK) were compared with first grafts for the same diagnoses by univariate and logistic regression methods. Results: For keratoconus, the failure rate increased 3-fold in regrafts compared with first grafts (ie, 17% vs. 6%; P = 0.002) and doubled in FED regrafts (33% vs. 15%; P = 0.001). In BK, the failure rate was already high in first grafts, and the increase in failure of regrafts was minimal (P = 0.9). Visual acuity was also worse in regrafts compared with first grafts, mainly in the keratoconus and FED patients. In the keratoconus group, visual acuity with preferred correction was ≥0.5 in 69% of first grafts compared with only 55% in regrafts (P = 001). In FED, 52% of first grafts but only 19% of regrafts achieved visual acuity ≥0.5 (P = 0.001). The visual outcome of regrafts in BK was poor but little different from first grafts where fewer than 20% achieved visual acuity ≥0.5. Conclusions: This analysis confirmed the poorer survival of regrafts where the original indication was keratoconus or FED. In addition, visual outcome was also worse than in the first grafts. However, the outcomes of regrafts in BK were similar to first grafts.

Corneal oedema after cataract surgery: predisposing factors and corneal graft outcome

Purpose:  Pseudophakic bullous keratopathy (PBK) is one of the main indications for corneal transplantation. Graft survival and visual outcome in this group are often poorer than for other indications. The aim of this study was to find risk factors for developing corneal oedema after cataract surgery and factors that influence the subsequent survival of the graft and the visual outcome.

Corneal grafts at St John Eye Hospital, Jerusalem, January 2001–November 2002

Aim: To compare a cohort of corneal graft patients in east Jerusalem with one in Sweden, concerning diagnosis, sex, patient age, preoperative visual acuity in both eyes, and type of operation. Methods: Standard forms developed for the Swedish Corneal Transplant Register were used for data collection at the time of operation. Results: In east Jerusalem, keratoconus accounted for 51% of the grafts compared with only 27% in Sweden and the male:female ratio was reversed. There were very few patients with endothelial disease. The Palestinian patients had overall worse visual acuity both in the eye to be operated and the fellow eye compared with patients in Sweden. Conclusion: Significant differences were found between the Palestinian and Swedish cohorts in the distribution of indications for transplantation and preoperative visual acuity.

National Corneal Transplant Registries

National corneal transplant registries collect and analyze observational, longitudinal data and report outcomes on large numbers of patients across multiple transplant centres. Registry data are valuable for monitoring activity and outcomes, including rare events such as primary graft failure, and for showing the uptake of new surgical techniques. While randomized controlled trials (RCT) are considered to provide the highest level of evidence for comparative studies, the strict inclusion and exclusion criteria make generalization of the results and translation into routine practice at times uncertain. The greater heterogeneity of patient characteristics in registries provides a perhaps more realistic picture of expected outcomes. The same is true of carefully conducted single-centre case series, which can often provide benchmark data, but do not necessarily reflect the outcomes in routine practice in multiple centres. National registries provide an important source of information that contributes, along with RCTs, single-centre studies, expert opinion and meta-analyses, to a better understanding of corneal transplant outcomes.