Relation of donor age to success in penetrating keratoplasty

Profile of donors and corneal tissue obtained through hospital cornea retrieval programme in a recently established eye bank of a tertiary care teaching hospital of Eastern India

Context:

There is a global need for quality eye banking practices and sensitization of primary care physicians toward corneal donation.

Aims:

To evaluate performance of a recently established eye bank (EB) and quality of corneas obtained, and identify areas of improvement during procurement and utilization of donor corneas.

Settings and Design:

This retrospective observational study is based on records of corneas collected through hospital cornea retrieval programme (HRCP) in the EB of a tertiary care institution during the first 2 years of its establishment.

Methods and Material:

Data on demographic characteristics of donors, death-preservation interval, specular microscopy parameters of corneas, indications for utilization, and reasons for non-utilization of corneas were collected.

Statistical Analysis Used:

Means, standard deviation, range, frequencies, and proportions were analyzed. Spearman's correlation coefficient and Kruskal–Wallis test were applied taking P < 0.05 as significant.

Results:

The EB retrieved 54 corneas from 27 donors with mean age 42.3 ± 24.2 years. All tissues were preserved in Cornisol®. Majority (50%) of transplantable tissues had an endothelial cell density (ECD) between 2,000 and 2,500 cells/mm². ECD decreased significantly with increasing age (Spearman's ρ -0.747, P < 0.001; Kruskal–Wallis P < 0.001). Overall utilization rate of tissues was 87.04% (47/54), and utilizable corneas (50/54, 92.6%) were mainly used for optical purposes (34/50, 68%).

Conclusions:

Successful HCRP of the recently established EB has shown considerable promise in terms of quality and utilisation of corneas. There is need for active involvement of primary care physicians in contributing to increasing voluntary eye donation through awareness, advocacy, and social mobilization.

Effect of Donor Cornea on the Surgical Outcomes of Penetrating Keratoplasty: Imported Cornea Versus Domestic Cornea

OBJECTIVES

In this study, we compared the surgical outcomes of penetrating keratoplasty using domestic and imported donor corneas.

MATERIALS AND METHODS

We retrospectively evaluated 200 eyes and 200 consecutive patients who underwent penetrating keratoplasty by using domestic and imported donor corneas between January 2013 and December 2013. The donor characteristics, preoperative clinical features, and clinical outcomes at 6, 12, 24, and 36 months were assessed.

RESULTS

No significant differences existed between the 2 groups with respect to age, sex, lateralization, and penetrating keratoplasty indication (P > .05). Donor age was lower (P = .012), the death-to-preservation time and the preservation-to-surgery time were shorter, the rate of epithelial defect was lower, and the endothelial cell count was higher in the domestic group (P < .001). The 2 groups were also similar in terms of developing persistent epithelial defect, glaucoma, keratitis, and graft survival (P > .05).

CONCLUSIONS

We observed no significant differences in clinical outcomes during and after penetrating keratoplasty surgery between imported and domestic donor corneas.

[Influence of the donor age on graft survival : Is the demographic change also important for corneal tissue donation?]

The success of corneal transplantation highly depends on the quality of the used graft. Various factors play a crucial role such as a perfect stroma without optically relevant, centrally located cloudiness or changes (e. g. scars) or an adherent Descemet membrane. One of the most important parameters is the quality of the endothelial cell layer with a sufficiently large endothelial cell count. An open question is so far whether the donor age affects corneal quality and therefore has an impact on the success of transplantation. A comprehensive review of the available literature revealed that a large amount of scientific data on the influence of donor age exist to answer this question. In a variety of studies, no significant dependence of graft quality of donor age could be detected. Rather the studies prove that graft survival depends primarily on the state of the endothelial cell layer, and postoperative endothelial cell loss must be considered as a major cause of graft failure. Extensive quality assurance procedures in tissue preparation and cornea processing in the eye banks in Germany (Europe) ensures that only corneas with tested high quality are allocated for transplantation regardless of the donor age. Against the background of an aging population, the use of grafts from older donors should not be waived.

The impact of donor age and endothelial cell density on graft survival following penetrating keratoplasty

PURPOSE

To determine if donor age and preoperative endothelial cell density (ECD) affect corneal endothelial failure following penetrating keratoplasty (PK).

METHODS

Preoperative and postoperative data for PKs performed in the UK between April 1999 and March 2012 were analysed. Donor age was split into three groups (0-60, 61-75 and >75 years) and donor ECD was split into three groups (≤2400, 2401-2600 and >2600 cells/mm²). Cox proportional hazards regression was used to determine whether the selected subgroups of donor age and donor ECD have an impact on endothelial failure and a systematic analysis of the interaction between donor ECD and donor age was conducted. The analysis was stratified for primary corneal diagnosis (Fuchs endothelial dystrophy (FED), pseudophakic bullous keratopathy (PBK) and other) and corrected for potentially confounding factors (human leukocyte antigen matching, donor trephine diameter, deep vascularisation, the occurrence of reversible rejection episodes and receipt of systemic antiviral medication, long-term steroids or other immunosuppressive agents).

RESULTS

A total of 9415 patients, from the National Health Service Blood and Transplant UK Transplant Registry, who received their first PK for visual reasons were included in this study. The overall 5-year graft survival rate due to endothelial failure was 89%. Survival rates in recipients with FED, PBK and 'all other indications' were 95%, 83% and 89%, respectively. Our analysis shows that donor ECD did not affect outcome following corneal graft within the preselected categories, irrespective of diagnosis and after allowing for any potential confounding factors. Furthermore, HRs for each level of donor ECD, relative to >2600 cells/mm², for each combination of age group and indication, were not statistically significant.

CONCLUSIONS

We were unable to detect a significant effect of donor age, up to 90 years, and preoperative donor ECD, above the lower limit of 2200 cells/mm², on endothelial failure at 5 years following PK.

Corneal graft rejection 10 years after penetrating keratoplasty in the cornea donor study

PURPOSE

The aim of this study was to assess the effect of donor and recipient factors on corneal allograft rejection and evaluate whether a rejection event was associated with graft failure.

METHODS

One thousand ninety subjects undergoing penetrating keratoplasty for a moderate risk condition (principally Fuchs dystrophy or pseudophakic corneal edema) were followed for up to 12 years. Associations of baseline recipient and donor factors with the occurrence of a rejection event were assessed in univariate and multivariate proportional hazards models.

RESULTS

Among 651 eyes with a surviving graft at 5 years, the 10-year graft failure (±99% confidence interval) rates were 12% ± 4% among eyes with no rejection events in the first 5 years, 17% ± 12% in eyes with at least 1 probable, but no definite rejection event, and 22% ± 20% in eyes with at least 1 definite rejection event. The only baseline factor significantly associated with a higher risk of definite graft rejection was a preoperative history of glaucoma, particularly when previous glaucoma surgery had been performed and glaucoma medications were being used at the time of transplant (10-year incidence 35% ± 23% compared with 14% ± 4% in eyes with no history of glaucoma/intraocular pressure treatment, P = 0.008).

CONCLUSIONS

Patients who experienced a definite rejection event frequently developed graft failure raising important questions as to how we might change acute and long-term corneal graft management. Multivariate analysis indicated that previous use of glaucoma medications and glaucoma filtering surgery was a significant risk factor related to a definite rejection event.

The effect of donor age on corneal transplantation outcome results of the cornea donor study

OBJECTIVE

To determine whether graft survival over a 5-year follow-up period using corneal tissue from donors older than 65 is similar to graft survival using corneas from younger donors.

DESIGN

Multicenter prospective, double-masked, controlled clinical trial.

PARTICIPANTS

One thousand ninety subjects undergoing corneal transplantation for a moderate-risk condition (principally Fuchs' dystrophy or pseudophakic corneal edema); 11 subjects with ineligible diagnoses were not included.

METHODS

Forty-three participating eye banks provided corneas from donors in the age range of 12 to 75 with endothelial cell densities of 2300 to 3300 cells/mm(2), using a random approach without respect to recipient factors. The 105 participating surgeons at 80 sites were masked to information about the donor cornea including donor age. Surgery and postoperative care were performed according to the surgeons' usual routines. Subjects were observed for 5 years.

MAIN OUTCOME MEASURES

Graft failure, defined as a regraft or a cloudy cornea that was sufficiently opaque as to compromise vision for a minimum of 3 consecutive months.

RESULTS

The 5-year cumulative probability of graft survival was 86% in both the <66.0 donor age group and the >/=66.0 donor age group (difference = 0%, upper limit of 1-sided 95% confidence interval = 4%). In a statistical model with donor age as a continuous variable, there was no significant relationship between donor age and outcome (P = 0.11). Three graft failures were due to primary donor failure, 8 to uncorrectable refractive error, 48 to graft rejection, 46 to endothelial decompensation (23 of which had a prior, resolved episode of probable or definite graft rejection), and 30 to other causes. Distributions of the causes of graft failure did not differ between donor age groups.

CONCLUSIONS

Five-year graft survivals for cornea transplants at moderate risk for failure are similar using corneas from donors >/= 66.0 years and donors < 66.0. Surgeons and patients now have evidence that corneas comparable in quality to those used in this study from donors through age 75 are suitable for transplantation.

Donor age as a predictor of cornea transplant success

BACKGROUND

The purpose of this study was to examine the association between donor age and cornea transplant success.

METHODS

This retrospective cohort study comprised 116 patients who had cornea transplants performed for the first time. The primary analysis was performed to evaluate the time to graft failure as a function of donor age. Donor age was divided into 3 categories: (1) continuous, (2) younger than 65 versus 65 years and older, and (3) younger than 60 versus older than 70 years. We controlled for other variables that may affect graft outcome by multivariate modeling. The primary outcome was graft failure.

RESULTS

No statistically significant association was found between time to failure and donor age [adjusted hazard ratio: 1.004 (p = 0.68) for continuous age, 1.18 (p = 0.68) for age < 65 vs. > or = 65 years, and 2.10 (p = 0.089) for age < 60 vs. > 70 years]. However, with all model-building strategies, our results demonstrated that all hazard ratios calculated were greater than 1.00 for the older versus the younger aged groups.

INTERPRETATION

The influence of donor age on success of cornea transplants remains unresolved. Large, multicentre prospective cohort studies and randomized trials are needed to decisively determine the impact of donor age on cornea transplant success.

The New Zealand National Eye Bank Study 1991-2003

PURPOSE

To evaluate donor demographics and source, donor tissue processing and storage, biologic contamination, and the utilization and distribution of corneal tissue procured by the New Zealand National Eye Bank.

METHODS

As part of a prospective longitudinal study, the electronic records of the NZNEB for the 13-year period 1991-2003 were analyzed for each year with respect to donor demographics, donor source and cause of death, death-to-preservation interval, storage methods, endothelial assessment, biologic contamination, corneal tissue utilization, and distribution.

RESULTS

During the study period, 3221 corneas were retrieved from 1628 donors (69.8% male, 30.2% female), with the mean age of donors 59.4 years (SD 18.3 years) and range 4 to 95 years. No significant correlation was identified between donor age group (using 10-year intervals) and the proportion of corneas suitable for transplantation. Donors were procured from the Coroner's service (67.6%), public hospitals, (23.5%) and multiorgan donors (7.1%). The most common causes of donor death were cardiovascular disease, trauma, and cerebrovascular disease. Average storage duration increased from 3.5 to 11.8 days when organ culture replaced hypothermic storage in 1992. Biologic contamination occurred in 5% of all donor corneas. The most common bacterial and fungal isolates were coagulase-negative staphylococci and Candida spp, respectively. A significant decrease in contamination rate over the years of the study was identified. Overall, 79.4% of corneal tissue procured was used for corneal transplantation (75.8% for penetrating keratoplasty, 2.1% for lamellar keratoplasty, and 1.5% for unspecified transplants), and 21.6% was discarded. Most common reasons for discarding tissue were biologic contamination, abnormal serology, and failed endothelial assessment.

CONCLUSION

Analysis of the NZNEB database provides valuable information in relation to eye banking and corneal transplantation in New Zealand. Significant trends were identified in donor demographics, donor procurement source, improved donor tissue processing and storage, decreased biologic contamination, and increased utilization of corneal tissue.

Cornea procurement from very old donors: post organ culture cornea outcome and recipient graft outcome

AIM

To study the suitability of corneas from very old donors for graft after banking and their clinical and endothelial outcomes in recipients.

METHODS

419 corneas stored in organ culture were divided into group 1, donors under 85 years (330 corneas) and group 2, "very old" donors aged 85 years and over (89 corneas). Endothelial cell density (ECD) before and after organ culture, discard rate before and after storage, and clinical and endothelial outcomes of the 196 penetrating keratoplasties (PKP) (158 in group 1 and 38 in group 2) were compared in a prospective longitudinal study.

RESULTS

Initial ECD was lower in group 2 than in group 1 and elimination for low ECD was more frequent in group 2 (respectively 38% v 20.2%, p=0.001). At the end of storage, because very old corneas lost fewer ECs than younger ones (respectively 4.2% v 9.5%, p=0.022), ECD was comparable between the two groups. The corneas of very old donors had a poorer macroscopic appearance at procurement and during surgery. Despite this, in grafted patients, overall graft survival in groups 1 and 2 (respectively 87.4% v 80.6%, p=0.197), visual acuity, and ECD did not differ at completion of the study (mean follow up 25 months).

CONCLUSION

This study suggests that endothelial cell count during banking ensures that functional and cellular results of PKPs are not dramatically influenced by very old donor age. Considering Europe's ageing population, the very elderly should not be deemed off limits for corneal procurement.

Risk factors for corneal graft failure and rejection in penetrating keratoplasty

PURPOSE

To evaluate risk factors for graft failure and allograft rejection after penetrating keratoplasty (PK).

METHODS

We retrospectively studied clinical results of PKs in terms of graft survival and rejection-free graft survival rates. PKs were done on 271 eyes between 1987 and 1997. Clinical results were analyzed by Kaplan-Meier's life table method and the log-rank test. Relative risks and adjusted survival probabilities for each value of the factor were compared with the risk for a specified reference value.

RESULTS

The overall rates of graft survival and rejection-free graft survival in 10 years after PK were 79.3% and 77.9%, respectively. Higher relative risk of graft failure was associated with corneal vascularization (relative risk for within one quadrant = 1.67, two quadrants = 2.37, three or more quadrants = 3.39), regraft (relative risk for one failed previously graft = 2.08, two or more failed previously graft = 2.65), aphakia (relative risk = 2.17) or pseudophakia (relative risk = 3.02), presence of anterior synechia (relative risk = 2.91), presence of posterior synechia (relative risk = 2.56), long (more than 85 minutes) operation time (relative risk = 2.20), and older (more than 50 years) recipient age (relative risk = 2.38). Higher relative risk of rejection was associated with corneal vascularization (relative risk for within one quadrant = 2.35, two quadrants = 2.03, three or more quadrants = 2.63), long (more than 85 minutes) operation time (relative risk = 1.47), and younger (less than 60 years) donor age (relative risk = 2.10). There was no association between graft failure or allograft rejection and graft size or suture technique, respectively.

CONCLUSION

The risk factors for graft failure after PK were corneal vascularization, regraft, aphakia or pseudophakia, presence of anterior synechia, presence of posterior synechia, long operation time, and older recipient age. The risk factors after PK for allograft rejection were corneal vascularization, long operation time, and younger donor age.

The profile of repeated corneal transplantation

PURPOSE

To evaluate the primary indications for corneal transplantation in patients with repeated keratoplasties, graft survival, the causes and risk factors for failure.

SETTING

Tertiary referral care center.

DESIGN

Retrospective, noncomparative case series.

METHODS

Charts of all patients who underwent repeated corneal transplantation between 1985 and 1998 were reviewed. Eighty patients underwent repeated corneal transplantation, of which six underwent repeated corneal transplantation in both eyes, totaling 86 eyes. A total of 208 keratoplasties were performed in this group; 86 primary and 122 repeated keratoplasties. The most common primary indications for corneal transplantation were vascularized corneal scar in 31 of the 86 eyes (36%), followed by pseudophakic and aphakic bullous keratopathy (PBK, ABK). Of the repeated transplants, 55 eyes (64%) had one repeated graft, 27 eyes (31.4%) had two repeated grafts, three (3.5%) had three repeated grafts, and one (1.2%) had four repeated transplants.

MAIN OUTCOME MEASURES

Final visual outcome and clarity of corneal graft.

RESULTS

At the end of the follow-up period, 44 of the 86 eyes (51%) had clear grafts, but only 39.5% had good visual outcome. The mean survival periods of the repeated transplants decreased gradually with the number of regrafting procedures, from 14.3 to 8.7 months. The mean survival period was longer for patients with ABK, PBK, and secondary glaucoma, and shorter for patients who experienced graft ulcer or surface disorders. Graft failure was unrelated to graft size, but was associated with vascularization (P = 0.025), additional surgical procedures (P < 0.0001), and postoperative complications (P < 0.0001). There was a constant tendency for decrease in visual acuity with time. Final visual acuity was 20/20 to 20/40 in 13 of the 86 eyes (15%), 20/80 to 20/200 in 23 eyes (27%), and less than 20/200 in 50 eyes (58%). The most common complication was immune rejection, which occurred in 65 of the 208 transplants (31%), followed by secondary glaucoma in 48 eyes (23%) and cataract in 19 eyes (9%). Graft survival decreased remarkably after the third and forth regrafts, to 25% and 0%, respectively, compared with the first and second regrafts, 37% and 43%, respectively.

CONCLUSIONS

"High-risk" preoperative conditions, postoperative complications, and the need for additional surgical interventions may decrease graft survival. Close follow-up, extended use of antiinflammatory, antiviral, and immunosuppressive drugs, and avoiding additional surgical interventions as much as possible may decrease graft failure and the need for repeated keratoplasties.

The past twenty-five years in eye banking

PURPOSE

This review of milestones and challenges in eye banking describes efforts made by dedicated eye bankers to ensure the quality and quantity of corneal tissue for corneal blind patients over the last 25 years.

METHODS

This account is the result of the recollection of the author, discussions with eye bankers, and a review of the literature, public documents, and Eye Bank Association of America (EBAA) records.

RESULTS

A measure of the success of eye banking is the fact that corneal transplant surgery is now scheduled as an elective procedure. Corneal tissue has also enjoyed a stellar safety record. This is due in part to the establishment of comprehensive medical standards by the EBAA, the accreditation of eye banks, and the training and certification of eye bank technicians.

CONCLUSION

Advancements in eye banking over the last 25 years have improved the quality of life of several hundred thousand corneal blind persons in this country. More efforts must be made in the future to eliminate corneal blindness internationally.

Donor organ cultured corneal tissue selection before penetrating keratoplasty

AIMS

Donor organ cultured corneal tissue selection before penetrating keratoplasty is carried out by taking into account different variables. The objective was to identify preoperative variables which are significantly and independently associated with transplant outcome and should effectively be taken into account before transplantation.

METHODS

231 consecutive penetrating keratoplasties were prospectively studied using organ cultured tissue. Morphometric analysis of the donor corneal endothelium was performed before transplantation. Graft survival and endothelial cell density, during the second year following transplantation, were studied both at a univariate and multivariate level.

RESULTS

Recipient age, recipient rejection status, and preoperative diagnosis significantly influenced graft survival. Graft survival was higher when using corneal tissue from donors older than 80 years. Postoperative endothelial density decreased with preservation time and coefficient of variation after preservation. It increased with endothelial cell density after preservation and deswelling time, and correlated with preoperative diagnosis.

CONCLUSION

Organ cultured corneas with endothelial cell density after preservation < 2000 cells/mm2, and high coefficient of variation, may be discarded before transplantation. Corneas should be preserved for less than 3 weeks, and allowed to deswell before transplantation for 2 or 3 days rather than 1 day.

The effects of donor age on the outcome of penetrating keratoplasty in adults

OBJECTIVE

The purpose of the study is to determine whether there is a higher incidence of complications in adult patients receiving corneas from pediatric donors compared to those receiving corneas from adult donors.

DESIGN

The design is a follow-up of two matched cohorts.

PARTICIPANTS

The outcome of penetrating keratoplasty in 29 adult patients (age 20 years of age and older) receiving pediatric donor corneas (range, 0-5 years) was compared to that of 29 control patients matched for recipient age and diagnosis who received adult donor corneas (range, 40-70 years).

INTERVENTION

Chart review was performed.

MAIN OUTCOME MEASURES

Graft rejection, postoperative keratometry, postoperative refractive cylinder, postoperative intraocular pressure, and graft failure due to rejection were measured.

RESULTS

One or more allograft reactions occurred in 11 (37.9%) of 29 patients who received pediatric donor corneas compared to 2 (6.9%) of 29 patients who received adult donor corneas (P = 0.005, chi-square). There were a total of 20 rejection episodes in patients receiving pediatric donor corneas compared to a total of 5 rejection episodes in patients receiving adult donor corneas. The average postoperative keratometry was 46.1 diopters for the pediatric donor group and 44.0 diopters for the adult donor group (P = 0.03). There was no statistically significant difference in average refractive cylinder (P = 1.0), intraocular pressure (P = 0.26), or the incidence of graft failure due to rejection (P = 1.0) between the two groups. The average follow-up time for clear grafts was 58.3 months in the pediatric donor group and 59.9 months in the adult donor group.

CONCLUSIONS

The incidence of allograft reactions and the postoperative corneal curvature is greater in adult eyes undergoing penetrating keratoplasty with young donor corneas compared to those undergoing penetrating keratoplasty with older donor corneas. There was no difference in the incidence of graft failure due to rejection between the two groups.

Good visual result following early penetrating keratoplasty for Peters' anomaly

Visual results following penetrating keratoplasty for congenital corneal opacities have been generally disappointing, prompting many ophthalmologists to recommend no surgery for congenital, monocular corneal opacities. A 14-day-old boy had a penetrating keratoplasty performed for unilateral Peters' anomaly and microcornea. Visual acuity 49 months after surgery was 20/40 and peripheral fusion was present. Early surgery with early suture removal, amblyopia therapy, frequent clinical examinations, and motivated, well-informed parents were important factors in obtaining a good visual result.

Factors predictive of corneal graft survival. Report from the Australian Corneal Graft Registry

Risk factors for graft failure after penetrating keratoplasty were investigated in 961 patients from records collected prospectively by the Australian Corneal Graft Registry. The most common cause of graft failure was irreversible rejection. A multivariate proportional hazards regression analysis indicated that the key predictors of graft failure were: an indication for graft other than keratoconus or corneal dystrophy; a failed previous graft (ipsilateral eye); aphakia; inflammation at the time of graft; presence of an anterior chamber or iris-clip intraocular lens; graft size outside the range of 7.0 to 7.9 mm diameter; and corneal vascularization occurring in the postoperative period.

Corneal transplantation--immunologically privileged status

Despite the relatively high success rate and the word 'immunologically privileged site', it has been known that a corneal graft can induce an allograft rejection reaction. This is especially true in the rat where orthotopic penetrating corneal grafts in certain strain combinations are rejected even when transplanted in avascular bed. Reliable microsurgical techniques, together with the availability of inbred or congenic strains and a rapidly developing knowledge of its major histocompatibility complex (MHC) and immune system in general, have made the rat a prime species in which to study the immunological events after corneal grafting. This review describes recent progress in understanding the immunological mechanisms behind corneal graft rejection. The topics discussed include the rat MHC (RT1) antigens and their distribution in the cornea; different responder status in fully allogeneic strain combinations, including the importance of multiple non-MHC antigens; and the role of antigen-presenting cells (APCs) in corneal graft rejection.

Effect of donor cornea preservation in tissue culture and in McCarey-Kaufmann medium on corneal graft rejection and visual acuity

In a retrospective study the rate of rejection and clouding of the donor cornea for other reasons was investigated in 230 penetrating keratoplasties performed between 1984-1986. Donor corneas were stored in McCarey-Kaufmann Medium (MK) at 4 degrees C or in a modified Minimal Essential Medium (MEM) at 31 degrees C. No statistical differences in rejection rate, cloudiness due to other causes or visual acuity was found between MEM- and MK-stored donor corneas.

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.

Effect of donor parameters on primary graft failure and the recovery of acuity after keratoplasty

A retrospective evaluation was made of 983 penetrating corneal grafts. Donor corneas stored in either K-Sol or McCarey-Kaufman media had a significantly greater rate of primary graft failure (about 2%) than those kept in moist chamber storage (0%). Selected subgroups of 50 corneas from each storage system were studied to determine the time taken to reach a postoperative acuity of 6/12. No significant correlation was found between this time and either the duration of storage of donor corneas or the age of donor. A significant delay in recovery of visual acuity was found with increasing age of recipient. The increased average time from donor death to surgery for K-Sol (56 hours) and McCarey-Kaufman (40 hours) corneas compared with moist chamber corneas (15 hours) facilitated the scheduling of surgery at the cost of increased chance of primary graft failure.

Effect of factors unrelated to tissue matching on corneal transplant endothelial rejection

We examined 348 consecutive adult recipients of a corneal transplant for clinical signs of an endothelial rejection episode in a single-center follow-up study. The variables studied included primary diagnosis, number of previous corneal transplants, previous transplant failures from rejection episodes, transplant size, recipient corneal vascularization, donor age, recipient age and sex, past blood transfusions, and number of pregnancies. Five important risk factors were identified: primary diagnosis of herpetic, interstitial, or traumatic keratitis; transplant size 8 mm and larger; more than one previous corneal transplant; recipients younger than 60 years of age; and the presence of recipient corneal vascularization. This information will serve eventually for analyzing the effect of donor recipient tissue matching on corneal transplant rejection.

Corneal preservation

Significant advances in corneal preservation have been made over the past decade. The introduction of chondroitin sulfate-containing media for use at 4 degrees C allows storage of corneas for up to ten days prior to transplantation. Organ culture techniques have also been improved with the addition of chondroitin sulfate. There has been an increase in our understanding of preservation using McCarey-Kaufman medium. Studies have been published that compare these methods and help the clinician decide which method to use based on objective data. Also, our understanding of existing methods of evaluating endothelial viability has increased and new methods have been developed. Finally, the acquired immunodeficiency syndrome is having an increasing effect on eye-banking and the supply of donor corneas.

The preoperative assessment of the corneal endothelium

The ability of the cornea to maintain its transparency after surgery depends primarily upon the integrity of the corneal endothelium and in corneal grafting this is important for both donor and recipient eyes. The corneal endothelium may be significantly affected in various conditions of the anterior segment, especially if these exist over a considerable period of time. These conditions include superficial keratopathy, long-term contact lens wear, cornea guttata and low-grade anterior uveitis, especially chronic cyclitis which may be almost imperceptible clinically. The suitability of such corneas for use as donor material as well as the response of the eyes to anterior segment surgery can be assessed by specular microscopy and this may become even more important in the future as long-term contact lens wearers become more numerous in the community.

The influence of donor age and post mortem time on corneal graft survival and thickness when employing banked donor material (A five-year follow-up)

Sixty-three consecutive corneal transplantations employing banked donor material were grouped according to donor age and post mortem time, respectively, and followed at regular controls for 5 years. Twenty-six cases (38% belonging to a risk group i.e. had earlier had corneal transplantation(s) and/or vascularized corneas) with a mean donor age of 55.8 years were compared with 37 cases (35% at risk) with a mean donor age of 75.7 years. The five-year graft survival was 72.0% in the first group and 86.3% in the second group, however, the difference was statistically insignificant. In 27 cases (26% at risk) with a mean post mortem time of 17.4 h a five-year graft survival of 81.0% was found compared with 80.3% for 36 cases (44% at risk) with a mean post mortem time of 40.5 hours. No difference in graft thickness was demonstrated between any of the groups, and in all cases with surviving grafts normal values for corneal thickness were achieved. It is concluded that neither donor age nor post mortem time are limiting factors when selecting donor material for organ culture and corneal grafting.

Hierarchy of prognostic factors for corneal allograft survival

The results of analyses of 1218 consecutive corneal transplants performed in a single centre reveal that the most important prognostic factors for corneal allograft survival are recipient corneal vascularisation, graft diameter, HLA-A and B matching especially for high risk patients, organ culture storage of donor corneas prior to transplantation and donor age.

Long-term changes in corneal endothelium following penetrating keratoplasty. A specular microscopic study

One hundred clear corneal grafts with a minimum follow-up of 10 years and average follow-up of 17.4 years were studied with specular microscopy. Central and peripheral graft endothelial cell counts as well as central corneal thickness measurements were done and these were correlated with the following parameters: diagnostic subgroups; donor age; graft age (follow-up time); and the postoperative clinical course. The average central endothelial cell counts for the entire series was 684 cells/mm2. Peripheral cell counts were performed in 78 eyes and averaged 749 cells/mm2. Central corneal thickness was measured in 80 eyes and averaged 0.49 mm. There were no statistically significant differences in central or peripheral cell counts when analyzing donor age, graft age, or postoperative course. When cell counts were examined among the diagnostic subgroups, those in the hereditary stromal dystrophy subgroup had a significantly lower cell density when compared to those in the keratoconus subgroup.

Variables in McCarey-Kaufman corneal storage. Their effect on corneal graft success

The results of 297 penetrating keratoplasties performed over a four-year period were reviewed retrospectively and correlated with eyebank data to determine the effect of the following corneal storage variables on corneal graft clarity: (1) donor age; (2) death-to-preservation interval; (3) death-to-surgery interval; and (4) eyebank grading of donor corneal tissue. The death-to-preservation interval (including a group of corneas preserved 12-19 hours after death) and death-to-surgery interval up to four days had no effect on corneal graft success. Transplants performed with corneas from younger donors had a higher likelihood of success than grafts from older donors (less than 35 years vs greater than 35 years, P less than 0.01; less than 50 years vs greater than 50 years, P less than 0.005). Transplants using tissue rated excellent or good by the eyebank were more successful than those using tissue rated fair (P less than 0.005). In both instances, these results were most apparent in patients believed to have a good prognosis for graft success. Thirteen cases (4.3%) of primary donor failure were identified. None of the corneal storage variables studied could be correlated with primary donor failure.

The prognosis for keratoplasty in keratoconus

The long-term results in 326 eyes grafted for phakic keratoconus by the same surgeon were reviewed. All consecutive grafts performed for this disease with a minimum of five-year follow-up were included in the study. The mean follow-up was 11.3 years, with a range of 5 to 34 years. Ninety percent of grafts remained clear, 3% were nebulous but retained 20/40 vision, and 7% failed. Donor age was available for 188 of the 326 grafts. No relationship was found between donor age and long-term graft clarity even when older (more than 70 years) donor tissue was used. The visual acuity was measured with the patient's preferred optical device worn daily. Seventy-three percent of eyes achieved 20/40 or better vision after their initial graft.

Endothelial morphology in long-term keratoconus corneal transplants

Endothelial morphology was studied in 55 long-term keratoconus grafts. Photographs were taken with a Zeiss non-contact endothelial lens and analyzed with a Zeiss MOP-3 digital analyzer. Donor ages were known in 39 cases. Statistical analysis was carried out correlating endothelial cell count with several parameters, including recipient age and cell form as expressed by the coefficient of variation. Cell counts varied from 502 to 1708 cells/mm2. No correlation between cell counts and donor age was found. Recipient age had an unexpected significance as a predictor of endothelial cell survival in that cell counts decreased as recipient age increased despite donor age. As the grafts aged, more cell pleomorphism was found as expressed by the coefficient of variation.

Complications of keratoplasty

The complications of keratoplasty have been greatly reduced in recent years by virtue of finer instrumentation, microsurgery, new drugs to minimize postoperative complications, and improved methods of donor cornea preversation. A 49-year-old woman, following uncomplicated keratoplasty with donor material from a patient who had died of a slow virus disease, developed the same condition and died 18 months later. Until more evidence is available, donor material from individuals dying of obscure chronic central nervous system disorders should be used with extreme caution.