Obtaining corneal tissue for keratoplasty

Ocular emergencies visits after corneal transplantation at a tertiary eye care hospital in Saudi Arabia

PURPOSE

To evaluate the characteristics of patients with post-keratoplasty complications and their presentation at an emergency center.

DESIGN

Retrospective one-armed cohort study.

METHODS

Data were evaluated on patients who underwent corneal grafts in 2019 and presented to an emergency unit. Data were collected on patient demographics, presenting symptoms, clinical details, diagnosis at emergency visit, final diagnosis, best-corrected visual acuity (BCVA) at presentation and at the last follow-up after management. Severe visual impairment (SVI) and graft rejection were tested for correlations to other factors.

RESULTS

The study sample was comprised of 149 eyes of 124 patients with a mean age of 27.5 years. Keratoconus was the indication for keratoplasty in 94 (75.8%) patients. The main presenting symptoms were pain 57 (38.3%) and red eye in 52 (34.9%) patients. The median interval between emergency visit and keratoplasty was 1.6 years. There were 63 (42.3%) patients who had emergency visits due to suture-related problems. The rates of SVI and graft rejection at the time of discharge after managing emergencies in eyes with previous keratoplasty were 14.1% (95% CI 8.5; 19.7) and 13.4 (95% CI 7.9; 18.9), respectively. Keratoconus (OR = 22.8) and young age (P < 0.001) were negatively associated with SVI after management.

CONCLUSION

Patients with keratoplasty are at high risk for severe vision loss and should be counseled to seek urgent eye care for early detection and management of sight-threatening complications to improve graft survival and vision.

Association of Federal Regulations in the United States and Canada With Potential Corneal Donation by Men Who Have Sex With Men

Question

Regarding federal policy in the United States that prohibits corneal donation by men who have had sex with another man (MSM) in the preceding 5 years (or 12 months in Canada), what is the association of these policies with the supply of donated corneas?

Findings

These policies were associated with the disqualification of an estimated 1558 to 3217 corneal donations by otherwise eligible MSM donors in the United States and Canada in 2018.

Meaning

With reliable modern HIV testing and with many countries experiencing severe corneal shortages, these federal policies may be decreasing the availability of vision-restoring surgery, suggesting these policies should be reevaluated in light of current scientific evidence.

Importance

Federal policy in the United States prohibits corneal donation by men who have had sex with another man (MSM) in the preceding 5 years, whereas Canada enforces a 12-month ban. The potential consequences of these policies on corneal donations should be evaluated.

Objective

To estimate the number of potential corneal donations associated with MSM deferral policies in the United States and Canada.

Design, Setting, and Participants

A nonvalidated telephone survey study was conducted of all 65 eye banks in the United States and Canada to investigate how many potential corneal donors were disqualified in 2018 because of federal MSM restrictions. Published demographic data were also used to arrive at a separate estimate. Survey data were gathered from May 2019 to February 2020.

Main Outcomes and Measures

Eye banks were asked if they keep records of referrals disqualified specifically because of the federal MSM restrictions and, if so, how many referrals they disqualified in 2018 owing to MSM status.

Results

Fifty-four of 65 eye banks (83%) responded to the survey, with 30 eye banks reporting they do not keep specific records of MSM deferrals. The remaining 24 eye banks reported disqualifying 360 referrals in 2018 because of MSM status, equating to 720 corneas. The 24 eye banks accounted for 46.2% of corneal donations in the United States and Canada in 2018, yielding an estimate of approximately 1558 corneas rejected that year because of MSM status. A separate estimate using published MSM demographic data indicates that up to 3217 potential corneal donations may have been disqualified in 2018 because of these federal policies.

Conclusions and Relevance

Findings suggest that between 1558 and 3217 corneal donations were disqualified in 2018 because of federal regulations prohibiting corneal donation by men who have had sex with another man in the preceding 5 years in the United States or 1 year in Canada. With modern virologic testing that is reliable within days of HIV exposure and given the global shortage of corneal tissue, these policies should be reevaluated using current scientific evidence to increase the availability of vision-restoring surgery worldwide.

Cornea donation process and tissue quality for transplantation

Introduction

The quality of the corneal tissue can be influenced by several factors inherent to the recipient, donor, and to the donation and transplantation process. The donated corneal tissue can be classified by its quality as excellent, good, regular, bad, or unacceptable for transplantation, evaluating it in a slit lamp.

Objective

To analyze the relationship between the clinical and sociodemographic variables of the donors and the donation process and the classification of the quality of the corneal tissue collected for transplantation.

Methods

This is an epidemiologic study, retrospective cohort type, which addressed the process of cornea donation by the Human Eye Tissue Bank in a reference service in Northeast Brazil. The sample consisted of corneas processed by the Human Eye Tissue Bank of Rio Grande do Norte (n = 419). For descriptive and inferential analysis, the study used the Statistical Package for the Social Sciences (SPSS) software, version 25.0, and considered a significance level of 0.05. Logistic regression analysis was used for the adjustment of the final model.

Results

It was verified that the epidemiological profile showed a prevalence of individuals with a mean age of 42.54 years old, male (73.99%), and living in the metropolitan region of the state capital (75.66%). When analyzing the relationship between the clinical and sociodemographic variables of the donors, it was identified that those aged 45 years old or less had better quality corneas (excellent and good), while the chronological variables were predictive factors for corneas of regular and bad qualities.

Conclusion

The identification of the factors inherent to the donation process and predictors of corneal tissue quality contribute to minimizing the risk of transplantation and to a better ocular prognosis.

A new approach to extend the storage of donor corneas after 28 days of corneal culture in an Italian eye bank

This study aimed to evaluate the possibility to extend the storage of unused organ-cultured donor corneas. After 28 days of corneal culture in TISSUE-C (AL.CHI.MI.A. S.R.L., Italy) and 5-day storage in transport/deswelling medium CARRY-C (AL.CHI.MI.A. S.R.L., Italy), 25 corneas that were deemed suitable for transplantation were transferred in fresh TISSUE-C at 31 °C for additional 7 days and then in fresh CARRY-C at room temperature for 24 h. Tissues were assessed for endothelial cell density (ECD), endothelial mortality and morphology after the standard and the extended corneal storage. In addition, the effect of donor age < 85 years and ≥ 85 years on corneal characteristics was assessed. After the extended storage, 6 out of 25 tested corneas (24%) showed ECD values below the acceptance limit (< 2000 cells/mm²). 19 corneas (76%) were still suitable for transplantation and showed a 5.9% loss in ECD, which was not statistically significant (P = 0.0949) compared to standard storage period. The two donor age groups did not show statistically significant differences in any tested parameter, although a trend for lower ECD and higher mortality in Descemet's folds after standard storage was observed in the ≥ 85 age donor group. Thus, the attempt of the current study to provide new sight-restorative options for unused tissues and increasing the availability of corneas in case of shortage gave encouraging results. Although a higher vulnerability of corneas from very old donors could not be statistically demonstrated in the present study, higher sample size could be required for prolonging the shelf life of these tissues.

A two-centre validation study of sterility test of corneal storage media with elimination of interfering antimicrobials in compliance with the European Pharmacopoeia

The purpose of this study was to validate the sterility test of corneal culture and deswelling/transport media using a device for removal of antimicrobials before incubation in BACTEC™ automated system in two Italian Eye Banks. Corneal culture medium, TISSUE-C, and deswelling/transport medium, CARRY-C, were inoculated with 10-100 cfu of six European Pharmacopoeia (EP) reference strains and either treated with medical device RESEP for removal of antimicrobials (RESEP+ group) or left untreated (RESEP- group) before injection into the BACTEC Plus bottles. The same steps were repeated in the absence of inocula with tryptone soy broth samples as negative controls, and the inocula were also directly injected in the BACTEC™ bottles as growth controls. All the samples were incubated in BACTEC™ automated system for 7 days, and the time to detection of microbial growth was recorded automatically. At both the Eye Banks, in the RESEP+ groups, microbial growth was detected in 100% of samples. In the RESEP- group, the method sensitivity ranged from 66.7 ± 21.1 to 88.9 ± 6.4% for TISSUE-C samples while for CARRY-C samples the method sensitivity ranged from 94.5 ± 5.1 to 100%. The method specificity corresponded to 100% for all the groups at both Eye Banks. This two-centre validation study showed that the use of RESEP increased the sensitivity of sterility test using BACTEC™ automated system up to 100% and, consequently, allowed validation of the method for sterility testing of corneal storage and deswelling/transport media according to the EP requirements. The test could not be validated without the use of RESEP.