
==== Front
Ann Med
Ann Med
Annals of Medicine
0785-3890
1365-2060
Taylor & Francis

39247943
10.1080/07853890.2024.2398723
2398723
Version of Record
Research Article
Ophthalmology
Clinical characteristics and viral colonization of corneal donors with coronavirus disease 2019: a comprehensive analysis before and after corneal transplantation
S. Yang et al.
https://orcid.org/0000-0003-0859-2795
Yang Shuo *
Wang Ning *
Yuan Kelan
Wu Yaying
Chen Jianyao
Jin Xiuming
Eye Center, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Zhejiang Provincial Key Laboratory of Ophthalmology, Zhejiang Provincial Clinical Research Center for Eye Diseases, Zhejiang Provincial Engineering Institute on Eye Diseases, Hangzhou, China
* These authors are Contributed equally to this work

CONTACT Xiuming Jin lzyjxm@zju.edu.cn
Shuo Yang youngshuo@zju.edu.cn Eye Center, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Zhejiang Provincial Key Laboratory of Ophthalmology, Zhejiang Provincial Clinical Research Center for Eye Diseases, Zhejiang Provincial Engineering Institute on Eye Diseases, Hangzhou 310009, China.
9 9 2024
2024
9 9 2024
56 1 239872319 11 2023
18 1 2024
26 3 2024
KnowledgeWorks Global Ltd.7 9 2024
published online in a building issue7 9 2024
© 2024 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group
2024
The Author(s)
https://creativecommons.org/licenses/by-nc/4.0/ This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial License (http://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. The terms on which this article has been published allow the posting of the Accepted Manuscript in a repository by the author(s) or with their consent.

Abstract

Purpose

To evaluate the clinical characteristics and viral Colonization of corneas donated by volunteers with coronavirus disease 2019 (COVID-19) before and after corneal transplantation.

Methods

We retrospectively compared the characteristics and clinical outcomes of patients who received corneas from donors with and without a history of COVID-19 after corneal transplantation. Reverse transcription-polymerase chain reaction (RT-PCR) was performed to evaluate the expression of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA on ocular surfaces in corneal preservation solutions as well as the recipients’ tears. Immunofluorescence was also performed to evaluate the expression of viral spike proteins in the corneas. Intraocular pressure (IOP) measurement, optical coherence tomography (OCT), and slit-lamp inspection at each follow-up examination were performed to assess the surgical efficacy.

Results

The RT-PCR results of eye surface swabs before corneal extraction, the corneal preservation solutions before transplantation as well as the recipients’ tears were negative, thereby indicating the suitability for transplantation. No significant differences in IOP measurements, OCT findings, or in the incidence of post transplantation complications were observed between donors with and without COVID-19.

Conclusions

Corneal transplantation using corneas from COVID-19 infected donors does not alter clinical outcomes when compared to controls receiving corneas from non-infected donors.

Keywords

COVID-19
cornea
corneal donors
corneal transplantation
National Natural Science Foundation of China 10.13039/501100001809 81900816 National Natural Science Foundation of China 10.13039/501100001809 82171013 Natural Science Foundation of Zhejiang Province 10.13039/501100004731 LQ19H120010 This research was supported by the National Natural Science Foundation of China (Grant No:81900816), the National Natural Science Foundation of China (Grant No:82171013), and the Natural Science Foundation of Zhejiang Province (No: LQ19H120010).
==== Body
pmc1. Introduction

Corneal transplantation is the most prevalent transplant surgery globally, although a shortage of corneal grafts in developing countries is an urgent problem [1–5]. Since the advent of the coronavirus disease 2019 (COVID-19) pandemic, this issue has exacerbated. During the initial COVID-19 outbreak, certain institutions suggested that donors infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) should be excluded, ultimately resulting in a significant loss of corneal donors. Given the high transmission rate of COVID-19, this advice has remained impractical.

Prominent eye banks such as the American Eye Bank Association (EBAA) and the Global Association of Eye Bank Associations (GAEBA) have cautiously relaxed their exclusion criteria [6–10]. This conservative exclusion criterion is based on the transmission, prevalence, and impact of the virus [7]. However, there is no clear evidence to explain whether COVID-19 affects clinical outcomes.

SARS-CoV-2 primarily invades host cells through angiotensin-converting enzyme 2 (ACE-2) and transmembrane serine protease 2 (TMPRSS2) or Furin protease. Although ocular surface cells of corneal and conjunctival epithelial cells also express ACE-2 and TMPRSS2, the primary source of ACE-2 expression is superficial epithelial cells surrounding the cornea, limbus, and bulbar conjunctiva. Meanwhile, TMPRSS2 is predominantly expressed in all layers of the bulbar conjunctiva, with almost no expression in the corneal epithelium [11,12]. Hence, the central part of the cornea, which comprises the transplanted portion in >99% of cases, may be considered safe [13]. Bayyoud et al. reported that no viral RNA was identified in fresh (unstored) corneas donated by five participants diagnosed with COVID-19 [14]. Sawant et al. also confirmed that the prevalence of SARS-CoV-2 in the eye tissues of COVID-19 donors was exceedingly low [15].

Based on the current research, it can be deduced that COVID-19 is unlikely to be transmitted through corneal transplantation. It is unclear, however, whether the use of donor cornea from those with a history of COVID-19 alters clinical outcomes of the recipients. Therefore, in this study, we sought to conduct a retrospective analysis on the pathological and clinical data of donor corneas obtained from the central eye bank, both before and after corneal transplantation. Corneas were analyzed using immunofluorescence staining. Additionally, recipient patients were followed-up to evaluate the influence of potential COVID-19 infection on the pathological characteristics of corneas before corneal transplantation and postoperative clinical outcomes.

2. Material and methods

This study complied with the Helsinki Declaration and the regulations of the Eye Bank of Zhejiang University Eye Hospital and was approved by the Ethics Committee of the Second Affiliated Hospital, Zhejiang University School of Medicine (Ethics Approval Number: 2023-0799). All donors signed the informed consent form and agreed to the use of the donated cornea for clinical and scientific research. The eye bank sampled the conjunctival exfoliated cells and secretions of the donor’s ocular surface before extracting the cornea and conducted RT-PCR test subsequently. RT-PCR testing of the corneal preservation solution was conducted before the transplantation procedure. Transplantation can only be performed if the results of these tests are negative. To ensure safety, the recipients’ tears were collected 1 day and 1 week after surgery for RT-PCR testing. The COVID-19 history of the donors was investigated, and the recipients who received corneal transplants were categorized into two groups based on the SARS-CoV-2 infection history of the donor. Each group included ten participants: group A received a cornea from a donor with a previous SARS-CoV-2 infection history, and group B received a cornea from a donor without SARS-CoV-2 infection history. 1-week, 1-month, and 6-month follow-up data was collected from the recipients for postoperative outcome analysis. Regarding the donor graft, immunofluorescence staining was conducted on the remaining corneal donor rim following corneal transplantation surgery to observe its features. The study flowchart is shown in Figure 1A.

Figure 1. (A) The schematic diagram of coronavirus detection in donor corneas. (B) The SARS-CoV-2 spike protein is not detected in the corneas of COVID-19 donors (n = 10). COVID-19, coronavirus disease 2019; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.

2.1. Extraction and processing of the corneal grafts

Extraction site: Eyeball extraction was performed exclusively in the hospital mortuary.

Protective measures: During the eyeball extraction procedure, surgical personnel wore appropriate personal protective equipment, including gloves, protective eyewear or face masks, protective gowns, and masks, to protect themselves from potential sources of infection. Prior to, during, and after the surgery, the surgical staff washed their hands and used decontaminants or disinfectants to reduce the risk of pathogen transmission.

Eyeball extraction: The outer skin of the eyelids was disinfected thrice using a 5% povidone-iodine solution. The conjunctival sac was rinsed once with normal saline and then with the new Kjer disinfectant solution. An eyelid speculum was used to open the eyelids. The conjunctiva was incised along the corneal edge and separated posteriorly. The medial rectus (or lateral rectus) muscle was hooked, its distal end clamped with vascular forceps, and then cut. The optic nerve was severed with scissors, the eyeball was removed, and the muscles were severed. The eyeball was placed in an eyebath with the cornea facing upwards. The eyebath contained a saline gauze soaked in gentamicin. The eye was marked with an identifying pen and placed in a cooler.

Corneal separation: The eyeball was removed from the laminar flow table, and a surgical blade was used to make an incision on the sclera approximately 2–3 mm behind the corneal edge. A corneal scissor was inserted into the incision, and a 360°-cut was made around the cornea. The edge of the sclera was lifted with corneal forceps, and the choroidal tissue was gently separated. The corneal button (including a 2–3 mm wide strip of sclera) was placed in Optisol solution for preservation.

2.2. Preoperative information collection

2.2.1. Donor information and recipient information

In this retrospective study, we examined data from 20 recipients who had undergone corneal transplants between January and April of 2023 at Zhejiang University Eye Hospital. Information about five donors with confirmed COVID-19 and 10 grafts derived from these donors is showed in Table 1. The recipient demographic and clinical characteristics are shown in Table 2.

Table 1. Demographic data and virus test results of the ocular surface and corneal preservation fluid in five donors confirmed with COVID-19 diagnosis.

Case	Sex	COVID-19 diagnosis date	Date of death	Interval Date	Virus Test result: ocular surface	Virus Test result: corneal preservation solution	Corneal endothelial measurement results (cells/cm2)	
OD	OS	
1	Female	2022.12.25	2023.01.13	19	Negative	Negative	1346	1786	
2	Male	2023.01.14	2023.01.20	6	Negative	Negative	1362	1109	
3	Male	2022.12.27	2023.02.13	48	Negative	Negative	1709	2703	
4	Male	2022.12.22	2023.02.27	67	Negative	Negative	1852	1116	
5	Female	2023.01.08	2023.03.10	61	Negative	Negative	4000	3106	
COVID-19: coronavirus disease.

Table 2. Demographic and clinical characteristics of two groups of recipients.

 	Group A	Group B	
Age, y	 	 	
 Mean ± SD	58.4	48.7	
Sex	 	 	
 Female	5	1	
 Male	5	9	
Main diagnosis	 	 	
 Herpetic keratitis and keratoleukoma	1	3	
 Corneal dystrophy	1	1	
 Endothelial dysfunction	1	0	
 Corneal ulcer	6	4	
 Keratoconus	1	2	
Comorbidities	 	 	
 Iritis/uveitis	0	0	
 Glaucoma	1	0	
 Diabetes	3	1	
 Hypertension	0	2	
 Arthritis deformans	0	0	
Surgical methods	 	 	
 Lamellar keratoplasty	5	9	
 Penetrating keratoplasty	5	1	
Group A: n = 10, group B: n = 10.

2.3. Sample collection

2.3.1. Conjunctival swabs

Conjunctival samples were collected with dedicated swabs for subsequent viral testing. The sampling procedure involved gently swabbing the conjunctival surfaces to collect conjunctival exfoliated cells and secretions. The conjunctival swab was then inserted into transport fluid. The vials were delivered to the laboratory and stored at −80°C.

2.3.2. Tear collection

To collect tears from a recipient, a disposable capillary tear collector (Guangdong Shengze Kanghua Biopharmaceutical Co., Ltd) was used. The recipient was instructed to sit in a steady position, tilt their head towards the side of the eye being assessed, and gaze upwards to allow the tears to gather at the outer corner of the lacrimal river. Using their thumb and index finger, they gently held the back tube of the collecting device and positioned the capillary end of the collecting head at the lower edge of the lacrimal river. Tears were then automatically collected into the capillary via capillary action. The tear fluid samples were collected multiple times, with a total volume of approximately 10 μL. The collected tears were then placed into the RNA laterTM Viral RNA Stable Preservation Solution (Beyotime, China).

2.4. Diagnostic testing

2.4.1. RT-PCR detection for SARS-CoV-2

For the eye surface swab, corneal preservation solution, and tear samples, we followed the manufacturer’s instructions and used the RNAeasyTM Viral RNA Isolation Kit with Spin Column (Beyotime, China) to extract the viral RNA. For RT-PCR testing, we used the SARS-CoV-2 Dual Probes qRT-PCR Kit (Beyotime, China) as per the manufacturer’s instructions, and the quantification of gene expression was determined using standard quantification methods and expressed by the cycle threshold (Ct) value. A sample was considered positive if the Ct value of both the VIC channel and the FAM channel was ≤35. Conversely, a sample was considered negative if the Ct value detected by the two channels had no value or the Ct value was >38, and the positive control test result was positive. To ensure accuracy, each test was set with a negative control and a positive control, where the positive control showed a typical S-shaped amplification curve with a Ct value ≤33, and the negative control either did not show a typical S-shaped amplification curve or had a Ct value >33.

2.4.2. Immunofluorescence

After the fixed cornea was treated in a series of sucrose gradients at 10, 20, and 30%, it was embedded in the optimal cutting temperature solution and dissected into 10 μm thin sections using a cryomicrotome. The sections were then placed onto lysine-coated glass slides. To prepare the sections for antibody staining, they were sealed with 10% normal goat serum and 0.5% Triton X-100 for 2 h at room temperature and then incubated overnight with primary mouse anti-SARS-CoV-2 Spike monoclonal antibodies (Proteintech, China) (1:5000) at 4°C. On the following day, the sections were rinsed four times with 1X PBST (containing 0.1% Tween) for 5 min each time to remove excess water. Thereafter, an appropriate amount of fluorescent secondary antibody, diluted with antibody dilution buffer, was added to the sections, and they were incubated at room temperature in a damp and dark environment for 1 h. The slices were then extensively rinsed with PBST (four times, each time for 5 min). Finally, after the sections were dried, the samples were sealed onto a glass slide using an anti-fluorescence quenching sealing agent containing DAPI and observed under a fluorescence microscope.

2.4.3. Evaluation of corneal transplantation

Through the utilization of a descriptive research methodology, we have devised a table to document the observed indicators under slit-lamp (Topcon, SL-D701) and postoperative IOP and OCT (Tomey, SS-1000) examination findings. The observed indicators under the slit lamp included: (1) Corneal epithelial nonhealing: evident irregularities and patchy defects in the smoothness of the corneal epithelium; (2) Corneal opacification: characterized by a milky or porcelain-white opaque appearance, rendering the iris texture non-visible; (3) Infection: eye redness, eye pain, and increased levels of secretion; (4) Corneal graft detachment or displacement; (5) Persistent corneal graft edema: identification of increased corneal thickness with a hazy appearance; (6) Neovascularization: the presence of newly formed blood vessels observable on the surface of the graft, extending from the periphery towards the center. IOP measurements help assess the pressure inside the eye. Finally, OCT was utilized to obtain detailed cross-sectional images of the cornea. This imaging technique allows for the evaluation of corneal thickness, graft–host interface, and other relevant structural characteristics.

2.5. Surgical methods and classification

Deep anterior lamellar keratoplasty (DALK): Routine surgical anesthesia, disinfection, application of a hole towel, opening the eyelids with a lid speculum, and rinsing of the conjunctival sac with physiological saline was performed done. Using a surgical microscope, the position and dimensions of the graft bed were determined based on the characteristics of the corneal lesions, allowing for appropriate sizing of the graft. A corneal trephine was utilized to create the graft bed. The affected corneal layers were meticulously dissected, layer by layer, based on the depth of the lesion, aiming for complete removal. The graft bed was thoroughly irrigated to ensure the absence of any residual lesions. The donor corneal allograft, with the stroma and corneal endothelium removed, was meticulously placed onto the graft bed, ensuring proper alignment through intermittent suturing using a fine 10-0 suture.

Penetrating corneal transplantation: Routine surgical anesthesia, disinfection, application of a hole towel, opening the eyelids with a lid speculum, and rinsing of the conjunctival sac with physiological saline was performed. Under microscopic guidance, the implant bed was precisely determined based on the characteristics of the corneal lesions. A corneal trephine was used to create an accurate circular incision, and a 15-degree knife employed to create an anterior chamber puncture at 11:30 above, followed by the injection of a viscoelastic agent to maintain anterior chamber stability. The affected cornea was carefully excised along the circular incision, providing access for the corneal grafts. All preserved corneal allografts were meticulously prepared and placed onto the implant bed. The grafts were precisely aligned with the bed using 10-0 sutures, ensuring secure and stable positioning. Throughout the suturing process, continuous monitoring and adjustment of the anterior chamber depth was maintained. The viscoelastic agent was carefully rinsed from the anterior chamber, creating a well-formed anterior chamber.

Postoperatively, the surgical bed was carefully treated with tobramycin and dexamethasone ophthalmic ointment, followed by a pressure bandage for optimal protection and healing. After surgery, anti-inflammatory treatment was administered with Dianbishu and Tacrolimus eye drops.

2.6. Statistical methods

Data analysis was conducted using SPSS 23.0 (SPSS, Chicago, IL, USA) and expressed as median ± median absolute deviation (MAD). Comparison was conducted using Mann–Whitney U and Fisher’s exact tests. A value of p < 0.05 indicated a statistically significant difference.

3. Results

3.1. SARS-CoV-2 was not detected in the donor cornea

Table 1 summarizes the demographic data of donors with confirmed diagnosis of COVID-19 and their ocular surface and corneal preservation solution test results. The average time from diagnosis of COVID-19 to death was 41.2 days, with the shortest time being only 7 days for the fourth case. The immunofluorescence analysis results were consistent with the negative eye surface virus test results. No SARS-CoV-2 spike protein was detected in the corneas of the COVID-19 donors (Figure 1B).

3.2. Negative tear nucleic acid test results after transplantation

We conducted nucleic acid testing on the donor’s ocular surfaces, corneal preservation solutions, and recipients tear samples obtained on the first day and week after the procedure. Despite our rigorous efforts, we were unable to detect any significant cycle threshold values in either the donor or recipient tear samples, indicating no active SARS-CoV-2 in either the donor grafts or the recipient. Furthermore, the recipient did not manifest any COVID-19 symptoms during the observation period.

3.3. Transplanting corneal grafts from donors infected with SARS-CoV-2 was unlikely to affect the efficacy of corneal surgery

The median IOP was 13.2 ± 0.5 mmHg and 12.15 ± 0.05 mmHg in groups A and B, respectively. This difference was not statistically significant (p = 0.880). At 1 week post implantation, the slit lamp examination results demonstrated that the corneal grafts in each group were transparent, the epithelium well healed, no obvious folds were identified on the endothelium, and there was no loosening of the sutures. Slit lamp examination findings at 1 month post implantation demonstrated that there was one case of persistent corneal graft edema in group A, and at 6 months, a recipient experienced significant rejection. Slit lamp examination results in group B showed that the majority of recipients recovered well at 1 and 6 months of follow-up. However, a recipient experienced suture rejection and significant corneal opacity at the suture site at 6 months. A follow-up image from each group is displayed in Figure 2. However, there was no statistically significant difference in the total incidence of complications between the two groups (1 month: p = 1.000; 6 months: p = 1.000; Table 3). OCT examination results showed that the grafts were well arranged, characterized by a uniform and smooth corneal surface in all recipients, without iris adhesion (Figure 2).

Figure 2. Representative results of slit lamp and optical coherence tomography examinations conducted at 1 week, 1 month, and 6 months after surgery in group A (n = 10) and group B (n = 10).

Table 3. Comparison of complications between donor corneas with a confirmed history of COVID-19 (group A: n = 10) and donor corneas without COVID-19 history (group B: n = 10) at the 1-month and 6-month follow-up. No cases of loss to follow-up were observed.

 	Group	Corneal opacification	Persistent corneal edema	Infection	Corneal detachment or displacement	Corneal epithelial nonhealing	Neovascularization	
1 month	GroupA	0	1	0	0	0	0	
GroupB	0	0	0	0	0	0	
6 months	GroupA	0	0	1	0	0	0	
GroupB	1	0	0	0	0	0	
COVID-19: coronavirus disease.

4. Discussion

Since 2019, COVID-19 has been prevalent worldwide to varying degrees. To date, repeated and new infections are reported in some regions. COVID-19 has overwhelmingly affected the elderly and immunosuppressed. Some studies have suggested that SARS-CoV-2 may exist in the human tissues for protracted time periods or have a lasting impact on the human body [16].

In developing countries, corneal blinding diseases such as infectious keratitis, keratoconus related corneal leukoplakia, and corneal dystrophy are very common. However, the supply of corneal donors is a major issue. In China, there is a severe shortage of corneal donors, with approximately 2 million corneal disease patients waiting for corneal transplantation. The disease is increasing at a rate of 100,000 patients per year, but only 8,000–10,000 corneal transplant surgeries are completed per year [5].

The eye bank adheres to meticulously crafted protocols aimed at mitigating the transmission risk of corneal transplantation through the detection of microbial pathogens during extraction as well as preoperatively. This approach allows for more SARS-CoV-2 -infected donors to be viable corneal transplant donors. To date, there have been no reported cases of transmission of SARS-CoV-2 through corneal transplantation, which is a reassuring finding. However, the impact of corneal transplantation from a donor infected with SARS-CoV-2 on the surgical outcomes remains unclear. In our study, we analyzed recipients who underwent corneal transplantation at our hospital between January and April, 2023. To the best of our knowledge, this is the first report to compare and summarize the clinical characteristics of surgical efficacy of corneal grafts from donors with different SARS-CoV-2 infection history.

Herein, we conducted ocular surface sampling and virus testing prior to enucleation as well as virus testing of the corneal preservation solution before transplantation. Both the tests had negative results, confirming our hypothesis about the probability of SARS-CoV-2 infection in corneal grafts being relatively low. Moreover, we performed a comprehensive clinical assessment to evaluate the impact of SARS-CoV-2 infection in corneal donors on transplantation outcomes. We compared postoperative intraocular pressure, OCT examination results, and the incidence of complications between two groups: donors with a history of SARS-CoV-2 infection and those without such history. Our results revealed no significant differences in these indicators between the two groups, suggesting the absence of substantial variations in corneal tissue characteristics prior to transplantation and clinical outcomes after transplantation. However, while SARS-CoV-2 does not contaminate the corneal epithelium postmortem, it may persist in other ocular surface structures, such as the conjunctiva [17]. Although the viral genome and subgenomic RNA of SARS-CoV-2 have been detected in the corneas of patients with COVID-19 viremia, the presence of infectious virus or viral structural proteins remains unconfirmed [18]. SARS-CoV-2 RNA has been detected in the conjunctiva, cornea, and vitreous humor, as well as in spike and envelope proteins found in non-disinfected corneal epithelium. However, these occurrences are rare [15]. Additionally, a study with 21 patients found that at least one eye tissue sample from 6 patients who tested positive for SARS-CoV-2 by nasopharyngeal swab RT-PCR was positive for the virus [19]. Although viral presence can be detected in ocular tissues, comprehensive analysis indicates a relatively low probability. This likelihood can be influenced by various factors, including the time, location, and techniques used during autopsy [20–22]. Therefore, the occurrence of transmission of SARS-CoV-2 from infected donors to healthy recipients through corneal transplantation is exceedingly rare. However, during the COVID-19 pandemic, concerns about potential cross-infection have significantly reduced the number of corneal donors, resulting in a severe impact on corneal transplantation procedures and the donor pool [23]. Nevertheless, maintaining vigilance is crucial to ensure transplantation safety. To prevent the recurrence of similar incidents during future viral outbreaks or pandemics, we propose implementing stringent donor screening protocols, including testing before enucleation and transplantation. These comprehensive screening measures contribute to mitigating the extremely low probability of cross-infection. Furthermore, we emphasize the importance of disinfection during the enucleation process to minimize potential risks of cross-infection and ensure the safety of corneal transplantation.

Nevertheless, there are also some limitations of our current research. First, the sample size was small. Second, observation of long-term efficacy after corneal transplantation lacked in this study. Finally, we had no information regarding the viral load of the donors infected with SARS-CoV-2 at the time of their death because autopsy was not performed.

In conclusion, we conducted a comprehensive evaluation of the clinical characteristics of donor corneas infected with SARS-CoV-2 before and after corneal transplantation for the first time. Donor corneas from patients with a history of SARS-CoV-2 infection did not produce negative clinical effects. Therefore, the use of donor cornea from patients with a history of COVID-19 seems a safe addition to the donor corneal transplant pool.

Acknowledgements

The article was partially written during the 7th National Organ Donation Day in China. We want to take this opportunity to express our deepest gratitude and pay our respects to all the individuals and their families who have donated corneas to us.

Ethics approval

The human ethics committees at the Second Affiliated Hospital, School of Medicine, Zhejiang University approved the study protocol (2023-0494/I2023588). All protocols adhered to the tenets of the Declaration of Helsinki. All participants provided their written informed consent.

Author Contributions

YS and MXJ designed the study. NW, YCW, LKY, YYW, and YJC conducted the study. NW collected, analyzed, and interpreted the data. NW and YS wrote the initial draft. SY and MXJ revised the manuscript. All authors provided a final review and approved the manuscript before submission.

Disclosure statement

No potential conflict of interest was reported by the authors.

Patient consent for publication

Not required.

Data availability statement

All data generated or analyzed during this study are included in this published article and the supplementary information files. The datasets used and/or analyzed during the current study can be obtained from the corresponding author upon reasonable request.
==== Refs
References

1 Liu S, Wong YL, Walkden A. Current perspectives on corneal transplantation. Clin Ophthalmol. 2022;16 :631–646. doi:10.2147/OPTH.S289359.35282172
2 Garg P, Krishna PV, Stratis AK, et al. The value of corneal transplantation in reducing blindness. Eye (Lond). 2005;19 (10 ):1106–1114. doi:10.1038/sj.eye.6701968.16304591
3 Pandey AK, Mudgil N, Wadgave Y, et al. Corneal transplantation during COVID-19 pandemic: need for special considerations—A live review . AIMS Public Health. 2021;8 (2 ):186–195. doi:10.3934/publichealth.2021014.34017884
4 Alio JL, Montesel A, El Sayyad F, et al. Corneal graft failure: an update. Br J Ophthalmol. 2021;105 (8 ):1049–1058. doi:10.1136/bjophthalmol-2020-316705.32788325
5 Pineda R. Corneal transplantation in the develo** world: lessons learned and meeting the challenge. Cornea. 2015;34 (Suppl 10 ):S35–S40. doi:10.1097/ICO.0000000000000567.26266438
6 AlMutlak M, Li JY, Helayel HB, et al. Future of corneal donation and transplantation: insights from COVID-19 pandemic. Cornea. 2021;40 (3 ):274–276. doi:10.1097/ICO.0000000000002538.32826649
7 Desautels JD, Moshirfar M, Martheswaran T, et al. Risks posed to corneal transplant recipients by COVID-19-affected donors. Ophthalmol Ther. 2020;9 (3 ):371–379. doi:10.1007/s40123-020-00254-w.32378180
8 Ang M, Moriyama A, Colby K, et al. Corneal transplantation in the aftermath of the COVID-19 pandemic: an international perspective. Br J Ophthalmol. 2020;104 (11 ):1477–1481. doi:10.1136/bjophthalmol-2020-317013.32732343
9 Aldave AJ, DeMatteo J, Chamberlain WD, et al. COVID and the cornea: from controversies to consensus: report of the Eye Bank Association of America Medical Advisory Board Policy and Position Review Subcommittee. Cornea. 2021;40 (7 ):809–816. doi:10.1097/ICO.0000000000002741.33782270
10 GAEBA. Coronavirus (COVID-2019) and Ocular Tissue Donation[EB/OL]. 2020/2023. https://www.gaeba.org/alert-coronavirus-2019-ncov-and-ocular-tissue-donation/
11 Collin J, Queen R, Zerti D, et al. Co-expression of SARS-CoV-2 entry genes in the superficial adult human conjunctival, limbal and corneal epithelium suggests an additional route of entry via the ocular surface. Ocul Surf. 2021;19 :190–200. doi:10.1016/j.jtos.2020.05.013.32502616
12 Zhou L, Xu Z, Castiglione GM, et al. ACE2 and TMPRSS2 are expressed on the human ocular surface, suggesting susceptibility to SARS-CoV-2 infection. Ocul Surf. 2020;18 (4 ):537–544. doi:10.1016/j.jtos.2020.06.007.32544566
13 Maurin C, He Z, Mentek M, et al. Exploration of the ocular surface infection by SARS-CoV-2 and implications for corneal donation: an ex vivo study. PLoS Med. 2022;19 (3 ):e1003922. doi:10.1371/journal.pmed.1003922.35231027
14 Bayyoud T, Iftner A, Iftner T, et al. Absence of severe acute respiratory syndrome-coronavirus-2 RNA in human corneal tissues. Cornea, 2021. Cornea. 2021;40 (3 ):342–347. doi:10.1097/ICO.0000000000002479.32604196
15 Sawant OB, Singh S, Wright IRE, et al. Prevalence of SARS-CoV-2 in human post-mortem ocular tissues. Ocul Surf. 2021;19 :322–329. doi:10.1016/j.jtos.2020.11.002.33176215
16 Nie X, Qian L, Sun R, et al. Multi-organ proteomic landscape of COVID-19 autopsies. Cell. 2021;184 (3 ):775–791. e14. doi:10.1016/j.cell.2021.01.004.33503446
17 Aiello F, Ciotti M, Gallo Afflitto G, et al. Post-mortem RT-PCR assay for SARS-CoV-2 RNA in COVID-19 patients’ corneal epithelium, conjunctival and nasopharyngeal swabs. J Clin Med. 2021;10 (18 ):4256. doi:10.3390/jcm10184256.34575369
18 Casagrande M, Fitzek A, Spitzer MS, et al. Presence of SARS-CoV-2 RNA in the cornea of viremic patients with COVID-19. JAMA Ophthalmol. 2021;139 (4 ):383–388. doi:10.1001/jamaophthalmol.2020.6339.33475692
19 Korkmaz HA, Ceylan I, Ulutas HG. Investigation of SARS-CoV-2 in postmortem ocular tissues and evaluation of its effects on corneal donation. Cornea. 2022;41 (10 ):1265–1270. doi:10.1097/ICO.0000000000003093.36107844
20 Ho D, Low R, Tong L, et al. COVID-19 and the ocular surface: a review of transmission and manifestations. Ocul Immunol Inflamm. 2020;28 (5 ):726–734. doi:10.1080/09273948.2020.1772313.32543262
21 Bal S, Chodosh J, Venkateswaran N. Impact of SARS-CoV-2 on Ocular Surface Pathology and treatment practices: a review. Curr Ophthalmol Rep. 2021;9 (3 ):77–82. doi:10.1007/s40135-021-00271-3.34377601
22 Salz AK, Acharya M, Hofmann N, et al. Risk of SARS-CoV-2 virus transmission from donor corneal tissue: a review. Indian J Ophthalmol. 2021;69 (6 ):1592–1597. doi:10.4103/ijo.IJO_3249_20.34011748
23 Aiello F, Afflitto GG, Pocobelli G, et al. Effect of COVID-19 on eye banks and corneal transplantations: current perspectives. Clin Ophthalmol. 2022;16 :4345–4354. doi:10.2147/OPTH.S379849.36606249
