The Effect of Donor Diabetes History on Graft Failure and Endothelial Cell Density Ten Years after Penetrating Keratoplasty

Abstract

Objective

To examine the long term effect of donor diabetes history on graft failure and endothelial cell density (ECD) after penetrating keratoplasty (PKP) in the Cornea Donor Study

Design

Multi-center prospective, double-masked, controlled clinical trial

Participants

1090 subjects undergoing PKP for a moderate risk condition, principally Fuchs’ dystrophy or pseudophakic/aphakic corneal edema (PACE), were enrolled by 105 surgeons from 80 clinical sites in the United States.

Methods

Corneas from donors 12 to 75 years old were assigned by 43 eye banks to participants without respect to recipient factors. Donor and recipient diabetes status was determined from existing medical records. Images of the central endothelium were obtained preoperatively (baseline) and at intervals for ten years postoperatively and analyzed by a central image analysis reading center to determine ECD.

Main Outcome Measure(s)

Time to graft failure (regraft or cloudy cornea for 3 consecutive months) and ECD.

Results

There was no statistically significant association of donor diabetes history with 10-year graft failure, baseline ECD, 10-year ECD or ECD values longitudinally over time in unadjusted analyses nor after adjusting for donor age and other significant covariates. The 10-year graft failure rate was 23% in the 199 cases receiving a cornea from a donor with diabetes versus 26% in the 891 cases receiving a cornea from a donor without diabetes (95% confidence interval for the difference: −10% to +6%; unadjusted p = 0.60). Baseline ECD (p=0.71), 10-year ECD (p>0.99), and changes in ECD over 10 years (p=0.86) were similar comparing donor diabetes and no-diabetes groups.

Conclusions and Relevance

The study results do not suggest an association between donor diabetes and PKP outcome. However, the assessment of donor diabetes was imprecise and based on historical data only. The increasing frequency of diabetes in the aging population in the United States affects the donor pool, thus the impact of donor diabetes on long term endothelial health after penetrating and/or endothelial keratoplasty warrants further study with more precise measures of diabetes and its complications.

Trial Registration

clinicaltrials.gov NCT00006411

Introduction

Numerous animal and human studies have suggested that the corneal endothelium is adversely affected biochemically, ^1–5 morphologically,^6–13 and functionally^{8, 13–21} by diabetes mellitus. Despite this literature, there have been virtually no studies on the effects of diabetes in cornea donors on graft outcome and cell loss following keratoplasty. In a study of organ culture stored corneas at 31°C, diabetes in the donor did not affect endothelial cell loss in storage for < 30 days compared with non-diabetic donor tissue²². Some medical directors and surgeons are reluctant to use donor corneas from diabetic donors particularly when associated with complications from diabetes (e.g, laser or anti-vascular-endothelial-growth-factor-treated retinopathy, peripheral vascular disease) and/or lower endothelial cell density (ECD) around the minimum ECD of 2000 cells/mm² associated with significant polymegathism and pleomorphism. However, no studies to our knowledge have examined the effect of diabetes determined historically in donor corneas stored at 4°C.

The dearth of information on diabetes in the donor has occurred in part because the Medical Standards and Procedures Manual of the Eye Bank Association of America (EBAA) does not require tracking of diabetes as a separate category contributing to donor death.²³ Instead, each eye bank and its medical director determine what data are recorded from the donor’s medical history, including diabetes and complications associated with this disease (retinopathy, nephropathy, neuropathy, vascular disease). In this regard, scanning a write-in field for any comments regarding diabetes utilizing the Midwire software of Midwest Eye-Banks for 5 eye banks in 2013, 6,704 out of 22,105 eyes retrieved (30%) were from donors with diabetes, having an average age of 62 (personal communication, Michael O’Keefe). Of these 22,105 eyes, 13,164 (60%) were suitable for transplant with a comparable percentage between the donors with and without diabetes. Of the 13,164 suitable donors, 3,757 donors with diabetes (29%) were used for keratoplasty, either penetrating or endothelial. This figure is consistent with the Centers for Disease Control and Prevention (CDC) report that 26% of people ≥65 years of age in 2012 had diabetes.²⁴ Given the tremendous growth of diabetes in the population, morphologic and functional data suggesting that the diabetic corneal endothelium is abnormal, it is incumbent upon the fields of eye banking and corneal surgery to determine if our patients are at increased risk of graft failure when receiving corneas from donors with diabetes. To address this issue, we utilized the dataset from the Cornea Donor Study (CDS) to evaluate the effect of the donor’s diabetes status on graft outcome and on central corneal endothelial cell density (ECD) at baseline and longitudinally over 10 years.

Materials and Methods

Complete details of the CDS and Specular Microscopy Ancillary Study (SMAS) protocols have been previously reported^25–27; pertinent aspects are described here briefly. The CDS is registered as a clinical trial through the Clinical Trials Registry of the National Institutes of Health (NCT00006411) and information is publically available (http://www.clinicaltrials.gov, accessed 05/16/13). The study protocol was approved by the institutional review board at each investigational site, and individual participants gave written informed consent to participate in the study. Eligible donor corneas met EBAA standards for human corneal transplantation. Assigned corneas were from donors 12 to 75 years old with an eye bank measured central ECD between 2300 and3300 cells/mm². The eye bank reported at the time of collection whether or not the donor had a history of diabetes, but no information regarding type, duration, medications, metabolic control, complications, or obesity was captured.

Between January 2000 and August 2002, 1090 eligible patients (median age 72 years, quartiles 65, 76 years) at 80 sites had a PKP for Fuchs’ dystrophy (62%), pseudophakic/aphakic corneal edema (PACE) (34%; 93% pseudophakic and 7% aphakic) or another corneal endothelial disorder (4%). Similar to the donor diabetes information, the presence of recipient diabetes was recorded, but type, duration, medications, metabolic control, complications or obesity were not captured. Clinical investigators and participants were masked to all characteristics of the donor cornea including age, diabetes history and ECD. Preoperative management, surgical technique, and postoperative care, including prescription of medications, were provided according to each investigator’s routine. The minimum follow-up visit schedule included visits at 6 months, 1 year and then annually for 10 to 12 years for those participants who did not require a regraft. Graft clarity was assessed at each visit. The definition of graft failure, based on the definition used in the Collaborative Corneal Transplantation Studies (CCTS)²⁸, was a regraft or, in the absence of regraft, a cloudy cornea in which there was loss of central graft clarity sufficient to compromise vision for a minimum of three consecutive months.

A subset of the CDS participants also consented to participate in the SMAS.^{29, 30} Baseline preoperative donor images and postoperative recipient images obtained at the 6-month and annual follow-up visits were evaluated for quality and ECD by a central reading center, the Cornea Image Analysis Reading Center (CIARC; formerly the Specular Microscopy Reading Center) at Case Western Reserve University and University Hospitals Eye Institute, using a variable frame analysis method. Details of CIARC procedures have been previously described for donor and post-operative images^29–32, including reader training and certification, image quality grading, image calibration, variable frame analysis for ECD determination, and adjudication procedures for image quality and ECD determination.

Statistical Methods

Cumulative probabilities of graft failure (subsequently referred to as “graft failure rates”) at 10 years along with 95% confidence intervals were calculated using the Kaplan-Meier method. Univariate comparisons of the 10 year graft failure rate were performed using a normal approximation with the standard error estimated using Greenwood’s formula. Multivariate analysis was performed using the Cox proportional hazards model adjusting for donor age and donor race as possible confounders (both p<0.10). The proportional hazards assumption was assessed using a Kolmogorov-type supremum test^{33, 34} with 1000 simulated patterns. This assumption was violated for donor age, so the baseline hazard function was stratified by donor age. Effect modifications of donor diabetes history on graft failure were assessed for recipient diagnosis, recipient diabetes history, recipient age, donor age, donor race and baseline ECD.

Cross-sectional regression models were used to assess the association of donor diabetes history with ECD at baseline and at 10-years. All 1090 subjects were included in the analysis of baseline ECD while only 176 subjects with a surviving graft and a gradable image at 10 years were included in the analysis of 10-year ECD. For cases in which the baseline donor specular endothelial image was not analyzed by the CIARC (N=432), the ECD determined by the eye bank was used. Baseline analysis investigated possible effect modification of donor diabetes by recipient diagnosis, recipient diabetes history, recipient age, donor age and donor race. Corresponding subgroup analyses were not performed on the 10 year ECD data due to the small sample size (N=176).

To assess the association of donor diabetes history with ECD during follow-up with measurements taken at 6 months, 1, 2, 3, 4, 5, 7/8 and 10 years, a fixed effects longitudinal model was fit by restricted maximum likelihood (REML) using an unstructured covariance matrix to account for correlated data. Analysis was restricted to images taken prior to graft failure and included 2344 images from 591 subjects. Therefore, both the 10-year and the longitudinal analyses were conditional on graft survival since only the images obtained prior to graft failure were included. Longitudinal analysis investigated possible effect modifications of donor diabetes by recipient diagnosis, recipient diabetes history, recipient age, donor age and donor race.

All the ECD models were adjusted for possible confounding with donor age and donor race by including these factors whenever p<0.10. The 10-year and the longitudinal model were also adjusted for baseline ECD. QQ-plots revealed that the ECD values were not normally distributed; therefore, in all of the models, rank scores transformed to have a normal distribution (van der Waerden scores) were used as the dependent variable.^{29, 30} Continuous covariates in the models were also transformed in the same manner.

For all multivariate models (graft failure and ECD), missing values for covariates were treated as a separate category for discrete variables and a missing value indicator was added for continuous variables. All reported p-values are two-sided. Statistical analyses were conducted using SAS version 9.3 software (SAS Institute Inc., Cary, NC).

Results

Baseline Characteristics

Among the 1090 cases, 199 (18%) received a cornea from a donor with a history of diabetes while 891 (82%) did not. As expected, a history of diabetes was more likely in older donors (91% of donors with a history or diabetes were at least 50 years of age versus 76% of donors who did not have a history of diabetes; Table 1). Primary cause of death also varied somewhat by diabetes status, reflecting this age difference, with higher cardiac and stroke death occurrence in the diabetic donor group. Other donor factors including procurement, and slit-lamp characteristics were well balanced between donor diabetes history groups (Table 2).

Table 1.

Donor Factors by Donor Diabetes History (N=1090)

Donor Factors	Donor Diabetes History
	No N=891		Yes N=199
	N	%	N	%
Age (years)
<50	218	24%	18	9%
50 – <66	376	42%	95	48%
≥66	297	33%	86	43%
mean ± SD		57 ± 15		62 ± 10
Gender
Female	302	34%	72	36%
Male	589	66%	127	64%
Race
White	840	94%	184	92%
African-American	31	3%	10	5%
Hispanic	10	1%	1	<1%
Asian	3	<1%	0	0
Other	7	<1%	4	2%
Cause of Death
Cardio/Stroke	512	57%	147	74%
Cancer	185	21%	22	11%
Trauma	90	10%	6	3%
Respiratory	59	7%	19	10%
Other	45	5%	5	3%
ABO/Rh Match to Recipient
Missing	147	16%	30	15%
Yes	400	45%	94	47%
No	344	39%	75	38%
Gender Match to Recipient
Both Female	198	22%	44	22%
Both Male	220	25%	41	21%
No Match	473	53%	114	57%
Type of Tissue Retrieval
Enucleation	179	20%	39	20%
In situ	712	80%	160	80%
Tissue Refrigerated
No	209	23%	46	23%
Yes	682	77%	153	77%
Time from Death to Preservation (hours)
<4	166	19%	29	15%
4 – <8	473	53%	105	53%
8 – <10	128	14%	41	21%
≥10	124	14%	24	12%
Time from Death to Surgery
≤4 days	609	68%	134	67%
>4 days	282	32%	65	33%

Table 2.

Donor Cornea Factors by Donor Diabetes History (N=1090)

Donor Cornea Characteristics	Donor Diabetes History
	No N=891		Yes N=199
	N	%	N	%
Baseline ECD (cells/mm2)
<2500	260	29%	58	29%
2500 – <2700	211	24%	59	30%
2700 – <3000	302	34%	59	30%
≥3000	118	13%	23	12%
median (quartiles)	2671 (2462, 2874)		2618 (2445, 2864)
Polymorphism/Polymegathism
None	781	88%	170	85%
Mild/moderate	110	12%	29	15%
Endothelial Cell Damage-Central
None	889	>99%	198	>99%
Mild	2	<1%	1	<1%
Endothelial Cell Damage-Diffuse
None	859	96%	195	98%
Mild/moderate	32	4%	4	2%
Endothelial Cell Damage-Peripheral
None	847	95%	191	96%
Mild	44	5%	8	4%
Epithelium Defects
Clear and intact	434	49%	91	46%
Defects on ≤50%	457	51%	108	54%
Epithelium Haze
None	589	66%	144	72%
Mild	266	30%	49	25%
Moderate/severe	36	4%	6	3%
Epithelium-Exposure
None	180	20%	29	15%
Mild	545	61%	116	58%
Moderate/severe	166	19%	54	27%
Stromal Edema
None	664	75%	153	77%
Mild/moderate	227	25%	46	23%
Stromal Arcus
None	319	36%	61	31%
Present	572	64%	138	69%
Descemet’s Membrane Folds
None	304	34%	72	36%
Mild/moderate	587	66%	127	64%
Snail Tracks-Central
None	822	92%	189	95%
Mild/moderate	69	8%	10	5%
Snail Tracks-Diffuse
None	737	83%	166	83%
Mild/moderate	154	17%	33	17%
Snail Tracks-Peripheral
None	713	80%	167	84%
Mild/moderate/severe	178	20%	32	16%
Donor Graft Size
<8.0 mm	198	22%	46	23%
=8.0 mm	210	24%	55	28%
>8.0 mm	483	54%	98	49%

Recipient characteristics also were well-balanced between cases with a donor with diabetes and cases with a donor without diabetes, including age, gender, race, diabetes, diagnosis, lens status and glaucoma history. Of the 1090 recipients, 141 (13%) had known diabetes, 899 (82%) did not have known diabetes, and 50 (5%) had unknown diabetes status. Twenty-eight of the 141 diabetic recipients (20%) received a cornea from a diabetic donor.

Graft Failure

The 10-year graft failure rate was 23% in the 199 cases receiving a cornea from a donor with diabetes versus 26% in the 891 cases receiving a cornea from a donor without diabetes (95% confidence interval for the difference: −10% to +6%; p-value for the difference at 10 years =0.60; Figure 1). There was also no detectable effect of donor diabetes history in the multivariate analysis adjusting for donor race and stratifying by donor age (p=0.14). Comparisons of graft failure rates in cases receiving corneas from donors with and without a history of diabetes were similar in subgroups by recipient diabetes history (recipient had diabetes: 25% versus 23%; recipient did not have diabetes: 22% versus 25% respectively) and recipient diagnosis (Fuchs’: 17% versus 20%; PACE: 36% versus 37%, respectively). Additional subgroup analyses by recipient age, donor age, donor race and baseline donor ECD similarly found no effect modification of donor diabetes history (Figure 2).

Figure 1. Graft Failure over Time According to Donor Diabetes History.

The table beneath the figure presents the number of subjects at risk in the beginning of each year along with the number of graft failures, deaths, losses to follow-up, and censored subjects during the year.

Figure 2.

Association of Donor Diabetes History and Graft Failure within Subgroups

Endothelial Cell Density

Median baseline ECD was 2618 cells/mm² (interquartile range [IQR] 2445 to 2864 cells/mm²) in cases receiving a cornea from a diabetic donor versus 2671 cells/mm² (IQR 2462 to 2874 cells/mm²) in cases receiving a cornea from a non-diabetic donor (unadjusted p=0.15, p-value adjusted for donor age =0.71). No associations were apparent in subgroups based on recipient diabetes history, recipient diagnosis, recipient age and donor age (Table 3). There was a trend toward lower ECD among non-White donors (p=0.05 uncorrected for multiple comparisons), but the number of non-White donors with diabetes was small (N=15).

Table 3.

ECD According to Donor Diabetes History

Baseline Model (N=1090)
	Donor Diabetes History				P-value*
		No		Yes
	N	Baseline ECD median (quartiles)	N	Baseline ECD median (quartiles)
Overall	891	2671 (2462, 2874)	199	2618 (2445, 2864)
Recipient Diabetes History‡					0.69
No	736	2670 (2448, 2874)	163	2618 (2444, 2834)
Yes	113	2652 (2500, 2862)	28	2670 (2508, 2873)
Recipient Diagnosis‡					0.10
Fuchs’	552	2668 (2442, 2873)	124	2655 (2490, 2846)
PACE	298	2668 (2496, 2857)	71	2594 (2426, 2816)
Recipient Age					0.86
<60 years	135	2670 (2487, 2894)	27	2695 (2397, 2959)
60–<70 years	235	2646 (2428, 2842)	49	2577 (2445, 2794)
≥70 years	521	2686 (2475, 2879)	123	2637 (2487, 2881)
Donor Age					0.18
<50 years	218	2767 (2543, 2971)	18	2721 (2483, 2902)
50 – <66 years	376	2658 (2443, 2870)	95	2603 (2439, 2829)
≥66 years	297	2625 (2448, 2824)	86	2621 (2445, 2866)
Donor Race					0.05
White	840	2668 (2459, 2874)	184	2627 (2472, 2861)
Non-White	51	2679 (2551, 2878)	15	2550 (2166, 2959)

10-Year Model (N=176)
	Donor Diabetes History				P-value†
		No		Yes
	N	10-Year ECD median (quartiles)	N	10-Year ECD median (quartiles)
Overall	149	622 (502, 764)	27	570 (493, 774)
Recipient Diabetes History					NA
No	134	616 (506, 762)	24	562 (493, 703)
Yes	15	646 (454, 869)	3	NA
Recipient Diagnosis§					NA
Fuchs’	125	613 (500, 758)	20	534 (483, 609)
PACE	21	675 (589, 1094)	6	NA
Recipient Age					NA
<60 years	46	675 (530, 846)	5	NA
60–<70 years	48	623 (486, 912)	7	NA
≥70 years	55	613 (493, 730)	15	570 (493, 860)
Donor Age					NA
<50 years	51	688 (565, 942)	4	NA
50 – <66 years	59	606 (461, 760)	11	600 (472, 850)
≥66 years	39	590 (480, 698)	12	513 (488, 562)
Donor Race					NA
White	144	623 (504, 771)	25	570 (502, 774)
Non-White	5	NA	2	NA
Longitudinal Model (N=2344 images from 591 subjects)					P-value*
Recipient Diabetes History‡	NA				0.69
Recipient Diagnosis‡					0.43
Recipient Age					0.90
Donor Age					0.09
Donor Race					0.91

^*Test for effect modification with donor diabetes and the indicated factor. Continuous factors were used for donor age and recipient age.

^†Too few cases at 10 years for subgroup analyses.

^‡There were 50 patients with unknown diabetes history and 45 patients with “other” diagnoses at baseline.

^§There were 4 patients with “other” diagnoses at 10 years.

Likewise, for the 176 participants with a surviving graft and a gradable image at 10 years, there was no significant difference in 10-year ECD by donor diabetes history (median 570 cells/mm², IQR 493 to 774 cells/mm² for corneas from donors with diabetes versus median 622 cells/mm², IQR 502 to 764 cells/mm² for corneas from non-diabetic donors; Table 3; unadjusted p=0.40, p-value adjusted for donor age and baseline ECD >0.99).

In the longitudinal analysis incorporating follow-up measurements through 10 years, there was no overall effect of donor diabetes history after adjusting for donor age and baseline ECD (Figure 3; p=0.86) and no associations in subgroups based on recipient diabetes history, recipient diagnosis, recipient age, donor age and donor race (Table 3).

Figure 3. ECD over Time According to Donor Diabetes History.

In the box plot, black dots indicate mean values; horizontal lines in the boxes, medians; and the bottom and top of the boxes, the 25th and 75th percentiles.

Discussion

In an analysis of the CDS, we found that a history of diabetes in the donor did not adversely affect graft survival or ECD following PKP performed primarily for Fuchs’ dystrophy or pseudophakic/aphakic corneal edema. These findings are reassuring given the dramatically increased prevalence of diabetes in the donor pool between 2000 – 2002 (18% in this study) and 2013 (29%, Midwire database, personal communication, Michael O’Keefe). We believe that this 61% increase in diabetes over the past decade between these historically determined donor populations is influenced by: a dramatic increase in diabetes, diagnosed and undiagnosed in the population as a whole; the strong association between cardiovascular disease and stroke associated with diabetes leading to a higher mortality rate; and the increasing use of older donor tissue.

Interpretation of our results is tempered by a limited determination for presence of donor diabetes by the CDS eye banks. If there is a subset of donors with diabetes who were poorly controlled or had associated significant ocular and/or systemic complications (e.g, retinopathy, neuropathy, nephropathy, peripheral vascular disease), that could be reflective of a generalized deleterious effect on cells in diabetes, this subset may have a compromised corneal endothelium subject to a higher percentage of graft failures and/or endothelial cell loss. Unfortunately our data set was insufficiently informed to detect this effect. Nevertheless, we found no significant association between donor diabetes and graft failure or endothelial cell loss. The apparent lack of an adverse effect of donor diabetes is reassuring given the sizable literature suggesting that the corneal endothelium in diabetes is affected biochemically^1–5, morphologically^6–13, functionally^{8, 13–21} and clinically at least with cataract surgery^35–38 and may possibly cause a recipient effect in PKP³⁹. The biochemical and pathophysiologic effects of chronic hyperglycemia on the endothelium are compelling evidence of potential for cell damage in diabetes. One author has suggested that high glucose levels in the tear film and aqueous humor result in the accumulation of intracellular sorbitol and disruption of Na+ handling³, affecting the endothelial pump. Another author has examined the corneal redox state and found significant changes in the diabetic corneal endothelium⁵. Finally, the accumulation of advanced glycation end products, oxidative stress and nuclear factor kappa-B in diabetes have been found to advance endothelial apoptosis.¹

Studies examining endothelial barrier and pump functions have had mixed results with some showing increased endothelial permeability in diabetes^{13, 16}, while others have found no effect on endothelial permeability in this population^{7, 8, 20}. Corneal stress studies with induced hypoxia have shown delayed recovery in diabetes.^{15, 17, 18, 21} Morphologic studies comparing the endothelium in diabetes to age matched controls have consistently found morphometric differences in coefficient of variation and % of hexagonal cells.^{6–8, 13, 40, 41} Some studies noted a lower ECD ^{9, 10, 42}, and in some studies have related these changes to duration of diabetes⁹ HbA1c levels and degree of retinopathy¹⁰.

Numerous studies of cataract surgery^35–38 comparing diabetic patients with normal controls have shown differences in morphologic and corneal thickness recovery in the diabetic group, emphasizing that this population of endothelial cells is under stress. One PKP study showed a significantly higher graft failure rate at 5 years in recipients with diabetes compared to recipients without diabetes (5.7% vs. 2.4%); the effect of donor diabetes was not examined.³⁹ Interestingly, in our study the presence of diabetes in both the donor and recipient did not adversely affect graft outcome, although this group was small (n = 28). We also did not note a greater effect of graft failures and cell loss associated with donor age, even in the group where age had the greatest effect (>71 to 75 years of age) on graft failures and cell loss.

The adhesive quality of Descemet’s membrane to the overlying stroma may also be altered in donor corneas from individuals from diabetes. Greiner et al reviewed 359 donor corneas prepared for Descemet’s membrane endothelial keratoplasty (DMEK) surgery and found that the 114 diabetic donors had a 9-fold increased risk of destruction by tearing during the pre-stripping process.⁴³ They attributed this increased risk of Descemet’s membrane tearing in diabetic donors to an increase in the adhesive glycoproteins present in the interfacial matrix between Descemet’s membrane and the posterior stroma.⁴⁴ An increasing number of surgeons are switching from Descemet’s stripping endothelial keratoplasty (DSEK) to performing DMEK surgery for the treatment endothelial dysfunction because of DMEK’s possibly improved visual results and lower graft rejection rates, so the role of diabetic donors in keratoplasty is likely to increase in clinical relevance.

In conclusion, with 1) the increasing donor population with diabetes; 2) conflicting results between our reassuring findings in PKP in regards to graft success and endothelial cell loss in donors with or without diabetes defined historically compared with laboratory, in vivo endothelial imaging, functional studies, and the cataract surgery studies, showing a possible deleterious effect; 3) a reluctance on some surgeons and medical directors to use donors from diabetes, particularly associated with ocular and/or systemic complications, and 4) the growth of endothelial keratoplasty (DSEK, DMEK) with its demands on the donor cornea physically and functionally, a clinical trial examining the effect of diabetes in the donor in a more precisely defined manner on graft success and endothelial changes following endothelial keratoplasty may be warranted to assure a healthy donor pool with advances in keratoplasty.

CORNEA DONOR STUDY INVESTIGATOR GROUP

Listed in order of number of participants enrolled in the Cornea Donor Study are the clinical sites with city, state, site name, number of participants in parentheses, and names of the investigators ordered alphabetically that participated in the study as part of the CDS Investigator Group by enrolling or following participants. The names of the coordinators ordered alphabetically that participated in the extended follow-up phase of the study are also included.

CLINICAL SITES

Southfield, MI; Michigan Cornea Consultants, PC (77): Christopher Y. Chow, MD, Steven P. Dunn, MD, David G. Heidemann, MD, Tina MacLeod, Theresa Price Albany, NY; Cornea Consultants of Albany (58): Michael W. Belin, MD, Robert L. Schultze, MD, Cassandra Semeiks, Charity Sutherland Seattle, WA (47): Matthew S. Oliva, MD, Walter M. Rotkis, MD, Cindy Huddleston, Richard McDonald, Joy Taylor Grand Rapids, MI; Verdier Eye Center, P.C. (41): David D. Verdier, MD, Paula Johnson Cleveland, OH; Case Western Reserve University and University Hospitals Eye Institute (33): Jonathan H. Lass, MD, William J. Reinhart, MD, Annapurna Singh, MD, Joseph M. Thomas, MD, Stefan D. Trocme, MD, Lauren Brown, Kristee Mines, Megin Murray, Marie Norell, Stephanie Shaffer, Kalisha Washington Atlanta, GA; Eye Consultants of Atlanta, P.C. (30): Stephen M. Hamilton, MD, Gina C. Jayawant, MD, W. Barry Lee, MD, Jacqueline Larson, Melanie Simner Phoenix, AZ; Cornea Consultants of Arizona (28): Robert H. Gross, MD, Edward L. Shaw, MD, Pamela Blackburn Tampa, FL; Cornea and Eye Surface Center (28): Steven L. Maskin, MD, Eloise Eggers, Harriet Lutzk, Sherry Wagner Narberth, PA; Ophthalmic Subspecialty Consultants (26): Brandon D. Ayres, MD, Parveen K. Nagra, MD, Irving M. Raber, MD, Joy DiCicco, Irene Spanelis-Diaz Chicago, IL; University of Illinois at Chicago (25): Joel Sugar, MD, Elmer Tu, MD, Dolores Byrne Fort Myers, FL; Eye Associates of Fort Myers (24): Mark S. Gorovoy, MD, Deborah Glinos, Robert Lehet, Bernadette Nolan Lancaster, PA; Eye Physicians of Lancaster (24): Francis J. Manning, MD, Brenda Shelly Scranton, PA; Northeastern Eye Institute (23): Thomas S. Boland, MD, Stephen E. Pascucci, MD, Donna Kunz Ann Arbor, MI; W.K. Kellogg Eye Center, The University of Michigan (21): Qais A. Farjo, MD, Roger F. Meyer, MD, Shahzad I. Mian, MD, H. Kaz Soong, MD, Alan Sugar, MD, Munira Hussain, Jessica Knowlton, Cindy Pope, Paulina Radenbaugh Charlotte, NC; Horizon Eye Care (21): Paul G. Galentine, MD, Gerald B. Rosen, MD, David N. Ugland, MD, Mara Schafer Langhorne, PA (21): Sadeer B. Hannush, MD San Diego, CA; Eye Care of San Diego (21): John E. Bokosky, MD, Donna Riner Charleston, WV; Charleston Eye Care, PLLC (20): James W. Caudill, MD, Lea Coleman Chicago, IL; Northwestern University (20): Robert S. Feder, MD, Lori Kaminski Colton, CA; Inland Eye Institute (20): John C. Affeldt, MD, Christopher L. Blanton, MD, Monica Cancino Cincinnati, OH; Cincinnati Eye Institute (20): Edward J. Holland, MD, Amy Jost, Aimee Meyer Dallas, TX; The University of Texas Southwestern Medical Center at Dallas (20): R. Wayne Bowman, MD, H. Dwight Cavanagh, MD, PhD, Mohamed-Sameh H. El-Agha, MD (now in Cairo, Egypt), James P. McCulley, MD, Mike Molai Seattle, WA; Eye Associates N.W., Inc., P.S. (20): Thomas E. Gillette, MD, Isabel Buchan, Michelle Corrigan Allentown, PA; Lehigh Valley Eye Center, P.C. (19): Alan B. Leahey, MD, Ann Malinowski Madison, WI; Davis Duehr Dean Clinic (19): Christopher R. Croasdale, MD, Stephanie Blaser, Jane DeBaufer, LuAnne Moudry Louisville, KY; University of Louisville (16): Richard A. Eiferman, MD, Pamela Durham, Shannon Shields Burlington, MA; Lahey Clinic (15): Sarkis H. Soukiasian, MD, Ken Brown, Patti-Ann Morse, Patricia Sexton Atlanta, GA; Emory University (14): Bhairavi K. Dholakia, MD, James B. Randleman, MD, R. Doyle Stulting, MD, PhD, Jayne Brown, Paul Larson, Donna Loupe Baltimore, MD; The Johns Hopkins University School of Medicine (14): Walter J. Stark, MD, Kimberly Pratzer N. Dartmouth, MA; Eye Health Vision Center (14): Kenneth R. Kenyon, MD, Richard C. Rodman, MD, Kari Crompton Dallas, TX; Cornea Associates of Texas (13): Walter E. Beebe, MD, Henry Gelender, MD, Sidney Heinle Rochester, NY; University of Rochester (13): Steven S. Ching, MD, Ronald D. Plotnik, MD, Jennifer Anstey, Nancy Fedick, Peter MacDowell, Karen Skrine, Ann Stoutenburg Tulsa, OK; The Eye Institute (13): Marc A. Goldberg, MD, Kathy Owen Atlanta, GA (12): Karen Sumers, MD, Lisa Spentz, Amanda Wykle Boston, MA; Center for Eye Research and Education (12): Kenneth C. Chern, MD, Nicoletta A. Fynn-Thompson, MD, Ann Z. McColgin, MD, Michael B. Raizman, MD, Patricia Healy, Jacqueline Pereira Delray Beach, FL; Delray Eye Associates, P.A. (12): Steven I. Rosenfeld, MD, Ellen Salvati Minneapolis, MN; Minnesota Eye Consultants, P.A. (12): Elizabeth A. Davis, MD, David R. Hardten, MD, Richard L. Lindstrom, MD, Janet DeMarchi, Alexander Jordan, Richard Lindstrom, Sara Mork, Allison Rockvam Sacramento, CA; University of California, Davis (12): Mark J. Mannis, MD, Katrina Imson, Michael Saya, Marilyn Sponzo, Cindy Wallace Tallahassee, FL; Eye Associates of Tallahassee (12): Jerry G. Ford, MD Cleveland, OH; The Cleveland Clinic Foundation (11): David M. Meisler, MD, Laura Holody Indianapolis, IN; Price Vision Group (11): Kendall Dobbins, MD, Francis W. Price, Jr., MD, William G. Zeh, MD, Clorissa Quillin Pittsburgh, PA (11): Peter J. Berkowitz, MD, Lori Zubik Seattle, WA; Group Health Cooperative (11): Thomas D. Lindquist, MD, PhD, Linda Sims San Francisco, CA (10): Daniel F. Goodman, MD, Minah Yang, MD Denver, CO; Colorado Eye Physicians and Surgeons (9): Abdulfatah M. Ali, MD, Richard F. Beatty, MD, Michaela Kavanagh, Elizabeth Salinas, Jackie Varela Iowa City, IA; University of Iowa (9): John E. Sutphin, MD, Ayad A. Farjo, MD, Kenneth M. Goins, MD, Connie Mullinnix Portland, OR; Northwest Corneal Services (9): Terry E. Burris, MD, Desiree Crowell, Susan Johnson, Dawn Kerns, Jenni Powell, Portia Swenson Pinellas Park, FL; Southeast Eye Institute, P.A. (9): Peter A. Shriver, DO, Dennis Williams MD, Kelly Perry, Monica Wells Bangor, ME; Eastern Maine Eye Associates, P.A. (8): Cynthia A. Self, MD, Garth A. Wilbanks, MD, Courtney Chute, Cheryl Hart Irvine, CA; University of California, Irvine (8): Roy S. Chuck, MD, PhD, Ronald N. Gaster, MD, Michael Bradley, MD, Winston Chamberlain, MD, Andre Cohen, MD, Kouroush Eghbali, Marjan Farid, MD, Sumit Garg, MD, Jeff Grijalva, Whitney Lomazow, MD N. Dartmouth, MA; Southcoast Eye Care, Inc. (7): David W. Kielty, MD Galveston, TX; University of Texas Medical Branch at Galveston (6): Garvin H. Davis, MD, J. Mike Bourg, Rhonda Nolen, MD, Teresa Solis Lexington, KY (6): Woodford S. Van Meter, MD, Jane Webb Raleigh, NC (6): Patricia W. Smith, MD, Robbin Bradshaw, Tineta Mewborn, Jorge Sanchez, OD Memphis, TN; Associated Ophthalmic Specialists (6): Alan R. Schaeffer, MD, Chasity Owens, Charlisha Price Philadelphia, PA; Corneal Associates, P.C. (6): Elisabeth J. Cohen, MD, Peter R. Laibson, MD, Christopher J. Rapuano, MD, Andrea Gardiner Rochester, MN; Mayo Clinic College of Medicine (6): Keith H. Baratz, MD Lancaster, PA; Eye Doctors of Lancaster (5): Barton L. Halpern, MD, Mark A. Pavilack, MD (now at Tidewater Eye Center, Virginia Beach, VA), Shawn Gallagher, PhD Lansdale, PA (5): Gerald B. Rosen, MD (now at Horizon Eye Care, Charlotte, NC) Minneapolis, MN; University of Minnesota (5): Donald J. Doughman, MD, Stephen C. Kaufman, MD, PhD, Sally Cook, Ann Holleschau Fairfield,, NJ; Corneal Associates of New Jersey (5): Theodore Perl, MD, Soo Mee Pak, MD, Angelina Fornelos Columbia, MO; University of Missouri (4): John W. Cowden, MD, Sue Mussatt Providence, RI; Rhode Island Eye Institute (4): Elliot M. Perlman, MD, Joanie Cozzo, Margaret Gallagher-Sylvia Spokane, WA; Spokane Eye Clinic (4): Lance E. Olson, MD, Erik D. Skoog, MD, Elaine Dobbs Tacoma, WA; Pacific Cataract and Laser Institute (4): William D. Gruzensky, MD Nashville, TN; Cornea Consultants of Nashville, P.L.L.C. (3): Erich B. Groos, Jr., MD, Denise Alexander Salt Lake City, UT; University of Utah (3): Mark D. Mifflin, MD, Maureen K. Lundergan, MD, Deborah Harrison Springfield, MA (3): Steven T. Berger, MD, Sandy Hyszczak Charleston, SC; Medical University of South Carolina (2): Kerry D. Solomon, MD, Carol Bradham Chicago, IL; Rush University Medical Center (2): Richard F. Dennis, MD, Jonathan B. Rubenstein, MD, Sarah Levine, Heena Khan, Nisha Sheth, Denise Voskull-Marre Palm Coast, FL; Atlantic Eye Center (2): Alexandra M. P. Kostick, MD Raleigh, NC (2): Samuel H. Santander, MD, MPH Beachwood, OH; The Cleveland Clinic Foundation (1): Allen S. Roth, MD Decatur, GA; Eye Physicians and Surgeons, P.C. (1): Laura A. Bealer, MD Los Angeles, CA (1): Jonathan I. Macy, MD Mount Pleasant, SC; Charleston Cornea & Refractive Surgery, P.A. (1): David G. O’Day, MD, Linda Maynard Portland, OR; Devers Eye Institute (1): Mark A. Terry, MD West Palm Beach, FL; Palm Beach Eye Clinic (1): Nunzio P. Sossi, MD, PhD Winston-Salem, NC; Wake Forest University School of Medicine (1): Keith A. Walter, MD, Joan Fish

Listed in order of number of patients enrolled in the Cornea Donor Study are the eye banks with eye bank name, city, state, number of patients in parentheses and names of the eye bank directors and coordinators who participated in the study during the enrollment phase (D=Director, C=Coordinator).

EYE BANKS

Midwest Eye-Banks (192) [Ann Arbor, MI; Michigan Eye Bank, (145); Chicago, IL; Illinois Eye Bank, (47)]: Florence M. Johnston (D), Kyle L. Mavin (C), Kristen E. McCoy (C), Michael B. O’Keefe (C) Tissue Banks International (119) [Boston, MA; New England Eye & Tissue Transplant Bank (47); Indianapolis, IN; Indiana Lions Eye & Tissue Transplant Bank (22); Bismarck, ND; Lions Eye Bank of North Dakota, Inc. (19); Dayton, OH; Lions Eye Bank of West Central Ohio (11); Baltimore, MD; Medical Eye Bank of Maryland & Washington Eye Bank (4); Santa Ana, CA; Orange County Eye & Tissue Bank (4); Albuquerque, NM; New Mexico Lions Eye Bank (3); Los Angeles, CA; Doheny Eye and Tissue Transplant Bank (3); Orlando, FL; Medical Eye Bank of Florida (2); Oakland, CA; Northern California Transplant Bank (2); Springfield, NJ; Lions Eye Bank of New Jersey (2)]: Gerald J. Cole, MBA (D), Diane F. Johnston (C), Mark A. Jones (C), Sameera M. Farazdaghi, MPH (C), Elizabeth N. Walunas (C) Seattle, WA; SightLife (86): Monty M. Montoya, MBA (D), Bernie Iliakis (C), Rick D. McDonald (C), Misty L. Ostermiller (C), Cathy E. Saltwick (C) Tampa, FL; Central Florida Lions Eye & Tissue Bank, Inc. (73): Jason K. Woody (D, C) Allentown, PA; Northeast Pennsylvania Lions Eye Bank, Inc. (70): Mark H. Weaver (D), Michael J. Christ (C), Mark B. Gross (C) Minneapolis, MN; Minnesota Lions Eye Bank (61): Carol R. Engel (D), Raylene A. Dale(C), Stephanie K. Hackl(C), Elena J. Henriksen(C), Kathryn J. Kalmoe(C), Jennifer M. Larson(C), Jackie V. Malling(C), Brian J. Philippy (C) Albany, NY; Sight Society of Northeastern New York (58): Maryann Sharpe-Cassese, RN, MSN (D), Sue M. Hayes (C) Philadelphia, PA; Lions Eye Bank of Delaware Valley (58): Robert E. Lytle (D), David A. Rechtshaffen (C) Atlanta, GA; Georgia Eye Bank, Inc. (57): Bruce Varnum (D), Erin B. Angel (C), Matt D. Durell (C), Teresa R. Williams (C) Cleveland, OH; Cleveland Eye Bank (45): Susan V. Janssen (D), Brian E. Kraus (C), Marcy B. McLain (C), Jackie A. Rossi (C) Dallas, TX; Transplant Services Center UT Southwestern (33): Ellen L. Heck, MS, MA (D), Marilyn S. Hayes (C) Phoenix, AZ; Donor Network of Arizona (28): Gregory C. Davis (D), Tara L. Chavez (C), Lori D. Oswald (C), Noreen B. Ruiz (C) San Diego, CA; San Diego Eye Bank (26): Jeffrey G. Penta, MBA (D), Wayne E. Dietz (C), Jennifer L. Nary (C) Charleston, WV; Medical Eye Bank of West Virginia (21): Kenneth R. Sheriff (D), Nancy C. Driver (C) Charlotte, NC; Lifeshare of the Carolinas (21): William J. Faircloth (D), Paul E. Williams (C) Winston-Salem, NC; The North Carolina Eye Bank, Inc. (21): Kurt Weber, MA, MBA (D), Jerry W. Barker (C), Donna M. Bridges (C), Lee Chenier (C), Mark Soper (C) Redlands, CA; Inland Eye & Tissue Bank (20): Betsy Allen (D), Samantha J. Wright (C) Louisville, KY; University of Louisville Lions Eye Bank (16): James R. Martin (D), Anne J. Watson (C) Sacramento, CA; Sierra Eye & Tissue Donor Services-DCI (15): Greg McDonough, MS (D), Kristel D. Beilby (C) Rochester, NY; Rochester Eye & Human Parts Bank, Inc. (13): Linda K. Fraser (D), Tammi S. Sharpe (C) Pittsburgh, PA; Center for Organ Recovery and Education (11): Robert C. Arffa, MD, Michael A. Tramber (C) Portland, OR; Lions Eye Bank of Oregon (10): Barbara L. Crow (D), Matthew M. Fisher (C), Chris G. Stoeger (C) Aurora, CO; Rocky Mountain Lions Eye Bank (9): Edmund Jacobs (D), Michael P. Filbin (C), James I. Mather (C), Christopher M. McGriff (C), Eric E. Meinecke (C) Iowa City, IA; Iowa Lions Eye Bank (9): Patricia J. Mason (D), Garret D. Locke (C), Janice F. Reiter (C) Norfolk, VA; Lions Medical Eye Bank of Eastern Virginia, Inc. (7): David E. Korroch (D), Penelope M. Thomas (C) Galveston, TX; Southeast Texas Lions Eye Bank, Inc. (6): Wayne A. Lange (D, C), Rosemary F. Moore (C) Memphis, TN; Mid-South Eye Bank for Sight Restoration (6): Lee J. Williams (D), Yvette D. Friedhoff (C) Columbia, MO; Heartland Lions Eye Bank (4): Ronald J. Walkenbach, PhD (D), Jennifer E. Glover (C), Brenda A. Kafton (C), Kraig J. Lage (C) Charleston, SC; South Carolina Lions Eye Bank, Inc. (3): Brenda S. Horn (D), H. Tommy Bottoms (C), Ellen R. Kerns (C) Salt Lake City, UT; Utah Lions Eye Bank (3): Raymond Jessen, MPH (D, C), William H. Dennis (C)

COORDINATING CENTER

Jaeb Center for Health Research, Tampa, FL: Roy W. Beck, MD, PhD (Principal Investigator), Robin L. Gal, MSPH (Coordinating Center Director), Mariya Dontchev, MPH, Craig Kollman, PhD, Dan Raghinaru, MS, Alandra Powe, Katrina J. Ruedy, MSPH, Lee Anne Lester, Tonya D. Riddlesworth, PhD, Heidi J. Strayer, PhD, Shelly T. Mares, Amber Evans, Yazandra A. Parrimon, Michael Gray

CORNEA IMAGE ANALYSES CENTER

Case Western Reserve University and University Hospitals Eye Institute, Cleveland, OH: Jonathan H. Lass, MD (Medical Director), Beth Ann Benetz, MA (Technical Director), Stephanie Burke, Shannon Edwards, Carmella Gentile, Lori Karpinecz, Mark Madere

NATIONAL INSTITUTES OF HEALTH

National Eye Institute, Bethesda, MD: Maryann Redford, DDS, MPH, Mary Frances Cotch, PhD

DATA AND SAFETY MONITORING COMMITTEE

Marian Fisher, PhD (DSMC Chair), William Bourne, MD, Maryann Redford, DDS, MPH., Rabbi Samuel Fishman, Gary Foulks, MD, David C. Musch, PhD, MPH

STEERING COMMITTEE

Edward J. Holland, MD (Study Co-Chair, 1999-current), Mark J. Mannis, MD (Study Co-Chair, 1999-current), Mary Frances Cotch, PhD (1999–2001), Steven Dunn, MD (2001–2002), Ellen Heck, MS, MA (1999–2000), Florence Johnston (2000–2001, 2002–2004), Jonathan H. Lass, MD (1999-current), Thomas Lindquist, MD, PhD (2000–2001), Monty M. Montoya, MBA (2004-current), Maryann Redford, DDS, MPH (2001-current), Alan Sugar, MD (2004-current), Joel Sugar, MD (1999–2000), Jason Woody (2001–2002)