key: cord-1045060-jon7mkd7 authors: Rokohl, Alexander C.; Fätkenheuer, Gerd; Cursiefen, Claus; Heindl, Ludwig M. title: No secret hiding place on the ocular surface: what about after systemic SARS-CoV-2 infection? date: 2021-05-18 journal: Graefes Arch Clin Exp Ophthalmol DOI: 10.1007/s00417-021-05230-z sha: 75702db11f810cea7a5b04fd038cf47f3045e7d1 doc_id: 1045060 cord_uid: jon7mkd7 nan In our prospective study, we looked deeply into the possibility that SARS-CoV-2 may hide on the ocular surface of pre-screened asymptomatic patients in a tertiary eye care center [1] . The risk for an isolated conjunctival viral activity in patients with a negative nasopharyngeal swab-based RT-PCR seems to be absent or extremely low, suggesting no need to perform additional conjunctival swabs in patients with negative nasopharyngeal swabs [1] . However, previous studies reported the presence of the entrance receptor of SARS-CoV-2, the angiotensin-converting enzyme 2 (ACE 2), on the ocular surface [2] [3] [4] . In addition, SARS-CoV-2 was detected in ocular tissues, tears, and conjunctival secretions of patients with systemic SARS-CoV-2 infection [2] [3] [4] . Therefore, a potential hiding place on the ocular surface after systemic SARS-CoV-2 infection seems to be possible, especially in patients showing unspecific conjunctivitis during COVID-19 or in patients with ongoing systemic symptoms [4] [5] [6] [7] [8] [9] . Furthermore, there is not much known about SARS-CoV-2 on the ocular surface in asymptomatic carriers. These potential hiding places might be a significant risk factor of SARS-CoV-2 transmission to both medical staff as well as other patients [10, 11] . In addition, the authors raise the very interesting, yet unanswered and clinically highly relevant question of whether SARS-CoV-2 may-as it is known for Ebola virus [12] persist inside the immune-privileged eye even if the patient is otherwise healthy and PCR "negative." This would be compatible with ocular immune privilege [13] and put ophthalmic surgeons and theater personal at risk if ocular surgery is performed even in extraocular "negative" COVID survivors. Therefore, we fully agree with our highly appreciated colleagues that research regarding other hiding places of SARS-CoV-2 within the eye and on the ocular surface should be expanded. The key question of whether long(er) term SARS-CoV-2 persistence on the ocular surface and intraocularly of COVID-19 survivors or asymptomatic carriers may hold long-term risks is empirically open. Exploring these concerns using targeted research is now a high priority. The authors declare no competing interests. All authors have full control of all primary data and they agree to allow to review their data upon request. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http:// creat iveco mmons. org/ licen ses/ by/4. 0/. No secret hiding place? Absence of SARS-CoV-2 on the ocular surface of 1145 hospitalized patients in a pandemic area Malignancy going viral: ACE2 and TMPRSS2 expression in conjunctival neoplastic diseases A missing link between SARS-CoV-2 and the eye?: ACE2 expression on the ocular surface The role of ophthalmology in the COVID-19 pandemic More than loss of taste and smell: burning watering eyes in coronavirus disease 2019 Heindl LM (2020) Olfactory and gustatory dysfunction in coronavirus disease 2019 Reply to Gourtsoyannis Conjunctivitis in COVID-19 patients: frequency and clinical presentation Timing of surgery following SARS-CoV-2 infection: an international prospective cohort study Risk of SARS-CoV-2 transmission to medical staff and patients from an exposure to a COVID-19-positive ophthalmologist SARS-CoV-2 vaccination modelling for safe surgery to save lives: data from an international prospective cohort study Persistence of Ebola Virus in Ocular Fluid during Convalescence Ocular immune privilege: therapeutic opportunities from an experiment of nature Acknowledgements We thank our highly appreciated colleagues Rafael S. Grajewski, Philomena A. Wawer Matos, Hannah-Leah Koch, Felix Dewald, Florian Klein, and Clara Lehmann for their extraordinary help in this important project.