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Eye (Lond)
Eye (Lond)
Eye
0950-222X
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Nature Publishing Group UK London

38643267
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10.1038/s41433-024-03072-7
Comment
Corneal thermal burn injuries during long-duration spaceflight: mechanisms, evaluation, and management
http://orcid.org/0009-0005-7241-0994
Suh Alex asuh@tulane.edu

1
http://orcid.org/0000-0003-4860-827X
Ong Joshua 2
http://orcid.org/0000-0001-8999-0212
Waisberg Ethan 3
Lee Andrew G. 4567891011
1 https://ror.org/04vmvtb21 grid.265219.b 0000 0001 2217 8588 Tulane University School of Medicine, New Orleans, LA USA
2 https://ror.org/00jmfr291 grid.214458.e 0000 0004 1936 7347 Department of Ophthalmology and Visual Sciences, University of Michigan Kellogg Eye Center, Ann Arbor, MI USA
3 Department of Ophthalmology, University of Cambridge, Cambridge, USA
4 https://ror.org/02pttbw34 grid.39382.33 0000 0001 2160 926X Center for Space Medicine, Baylor College of Medicine, Houston, TX USA
5 https://ror.org/027zt9171 grid.63368.38 0000 0004 0445 0041 Department of Ophthalmology, Blanton Eye Institute, Houston Methodist Hospital, Houston, TX USA
6 https://ror.org/027zt9171 grid.63368.38 0000 0004 0445 0041 The Houston Methodist Research Institute, Houston Methodist Hospital, Houston, TX USA
7 https://ror.org/02r109517 grid.471410.7 0000 0001 2179 7643 Departments of Ophthalmology, Neurology, and Neurosurgery, Weill Cornell Medicine, New York, NY USA
8 https://ror.org/016tfm930 grid.176731.5 0000 0001 1547 9964 Department of Ophthalmology, University of Texas Medical Branch, Galveston, TX USA
9 https://ror.org/04twxam07 grid.240145.6 0000 0001 2291 4776 University of Texas MD Anderson Cancer Center, Houston, TX USA
10 grid.264756.4 0000 0004 4687 2082 Texas A&M College of Medicine, Bryan, TX USA
11 grid.412584.e 0000 0004 0434 9816 Department of Ophthalmology, The University of Iowa Hospitals and Clinics, Iowa City, IA USA
20 4 2024
20 4 2024
9 2024
38 13 24882490
1 3 2024
12 3 2024
5 4 2024
© The Author(s) 2024
2024
https://creativecommons.org/licenses/by/4.0/ 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://creativecommons.org/licenses/by/4.0/.
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Education
Risk factors
issue-copyright-statement© The Royal College of Ophthalmologists 2024
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pmcEmbarking on long-duration spaceflights with limited resources and absence of immediate medical facilities necessitates careful consideration of potential health hazards in the unforgiving confines of space. Among the extensive possible risks inherent in space exploration, ocular injuries [1–3], particularly corneal thermal burns, stand out as significant focal points of concern. The Lifetime Surveillance of Astronaut Health database highlights numerous ocular injuries in the history of the U.S. space program, prompting concerns about potential vision-threatening injuries on the International Space Station (ISS) [4]. Reports of ocular, orbital, and cranial trauma during various ISS missions exist, but as of now, none have yet been secondary to a corneal thermal burn [5]. Recognizing the critical importance of understanding and efficiently addressing these injuries in space, this paper explores the unique circumstances that make corneal thermal burns a critical health concern for the Artemis Program and Martian missions. As the scope and duration of space exploration expands, especially in the context of commercialization, proactive approaches towards developing comprehensive protocols must addressed. This paper aims to discuss onboard diagnostic tools and potential modalities for treating thermal burns of the cornea during spaceflight with the current medications available on the ISS.

Risk Factors for Corneal Thermal Burns During Spaceflight

Examining the equipment used on the ISS reveals potential hazards and exposures to corneal thermal burns. Tools like the space oven for meal preparation highlight sources of heat the crewmembers interact with daily during their missions. The Zero G Kitchen Space Oven utilizes electrical heating elements to heat food to a nominal temperature of 177 degrees Celsius (350 degrees Fahrenheit) [6]. Although there is a cooling rack, and the space oven is thoroughly tested before integration into the ISS, technical malfunctions or exposure to hot food particles may induce a corneal burn. Moreover, the limited and confined nature of the spacecraft amplifies the risk of thermal burns, as the proximity of equipment and limited spatial freedom heightens the likelihood of accidental exposure to sources of heat. Crewmembers are also notably susceptible to radiant energy burns (aka flash burns) from direct or reflective UV light from the sun [7].

During a Apollo-Soyuz test project in 1975, propellant and combustion products (e.g., hydrazine, nitrogen oxide, nitrogen tetroxide) were inadvertently admitted into the cabin during re-entry [8]. In a hypothetical scenario with similar conditions aboard the ISS, the propellants could combine with other reagents to create an exothermic reaction and a potential burn risk to crewmembers [4]. Scientific experiments with flames or exothermic chemical reactions may put crewmembers at increased risk of obtaining corneal thermal burns as well. Terrestrially, gravity draws colder, denser air to the base of flames, thereby displacing hotter, lighter air upward. In a microgravity environment, flames do not exhibit upward flow and thus produce more unpredictable behaviours for combustion [9]. Flames in microgravity also may survive in less oxygen environments and burn for longer periods of time, thus increasing risk of thermal burns if an uncontrolled fire were to ignite [10].

Diagnostic and Medical Management

For crewed missions without a medical doctor, a designated medical officer is appointed who undergoes 40 h of paramedic-level training. This comprehensive training includes skills such as administering injections, suturing wounds, and implementing eye-washing protocols [11]. In the event of a corneal thermal burn injury, management should be initiated immediately with copious irrigation. A Space Eye-Wash apparatus is available aboard the ISS, complete with a saline solution for continuous irrigation. The device aids in removing potential foreign bodies and chemical exposures [12]. Topical anaesthetic (tetracaine (0.5%, 15 mL) is also available [13]. Following the eye-wash, the medical officer can complete the ocular examination including topical fluorescein staining of the cornea [14]. The crew also has access to remote health guidance from the terrestrial based flight surgeon and other subject matter experts on the ground at NASA’s Johnson Space Center. Remote imaging including ocular photography, an onboard portable ocular ultrasound, and an optical coherence tomography (Heidelberg Spectralis OCT2) are available on ISS [15].

The blink reflex typically prompts the eye to close when exposed to a stimulus taking longer than 0.1 s to travel to the eye [16]. Consequently, terrestrial thermal burns often impact the eyelid more than the conjunctiva or cornea. Mild eyelid burns can be irrigated with sterile isotonic saline solution, followed by the application of an ophthalmic antimicrobial ointment [17]. Fortunately, the risks for thermal burn in space impacting the conjunctiva or cornea is low and most mild cases resolve without significant complications [18]. Treatments available on the ISS include oral anti-inflammatory and analgesic treatments (Acetaminophen (Tylenol) 325 mg, Aspirin 325 mg, Ibuprofen (Motrin) 400 mg, Ketorolac (Toradol) 30 mg/mL (2 mL)); topical cycloplegic mydriatics (e.g., cyclopentolate (Cyclogyl, 2%, 15 mL) and tropicamide (Mydriacyl, 1%, 15 mL)); and topical ophthalmic antibiotics (Erythromycin ointment (0.5%); Moxifloxacin (Vigamox, 0.5%); Tobramycin and Dexamethasone (Tobradex), 0.3%; 0.1%) [13]. Cool saline compresses and adequate lubrication with artificial tears (Refresh Plus, 0.5%); Hypromellose (Nature’s Tears, 0.4%); Mineral Oil and White Petrolatum (Refresh PM, 42.5%; 57.3%, 3.5 gm) can also be given as comfort measures.

In contrast to ISS missions, where evacuation to Earth is possible with a Crew Return Vehicle, lunar sorties, lunar outposts, Near-Earth missions, and a Mars mission do not provide evacuation options for an urgent return trip to Earth [19]. Additionally, the communication latencies, with up to 20 min for the signal to travel to and from Mars, will add complexity to medical decision-making processes [20]. Given the rapid advancements in machine learning, the integration of artificial intelligence (AI) into telemedicine may prove beneficial for determining optimal management steps, particularly in cases of corneal thermal burns where communication delays impede immediate intervention during medical emergencies [21]. Large language models specifically trained for space medical emergencies can potentially provide a suitable response in the absence of a doctor [22–24].

Conclusion

Although the risk for corneal thermal burn during spaceflight is low, awareness of the risks and prevention (e.g., safety goggles) may mitigate the need for potentially mission threatening interventions. Onboard ocular imaging technology supported by remote guidance on the Earth can manage most minor (e.g., corneal abrasion) or mild (eyelid thermal exposure) injuries. More severe injuries pose a greater risk in austere and distant environments (e.g., the moon or Mars) and AI enabled autonomous or semi-autonomous telemedicine may be useful countermeasures especially given the potential communication signal delay created by long distance space exploration. Testing these risk protocols in advance including virtual reality and computerized simulation may be warranted to reduce the risk for future long duration space travel.

Author contributions

AS was responsible for the initial write up of the manuscript as well as the preliminary literature review for ocular injuries during spaceflight and terrestrial management of such injuries. AS reviewed the medications available on the International Space Station (ISS) and accordingly determined appropriate protocols for spaceflight treatment. JO was responsible for development of the research idea and approval of the outline before the manuscript outline was created. JO reviewed the first rough draft for quality control before extending to the other authors. EW provided additional expert advice on current ophthalmology practices as well as preliminary edits before extending to other authors. AGL oversaw the project and provided extensive initial edits, which highlighted artificial intelligence and emergent evacuation. All authors contributed beneficial insights and edits to ensure the success of the manuscript.

Competing interests

The authors declare no competing interests.

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
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References

1. Waisberg E, Ong J, Masalkhi M, Lee AG, Berdahl J. Anatomical considerations for reducing ocular emergencies during spaceflight. Ir J Med Sci 1971 -. Published online May 27, 2023. 10.1007/s11845-023-03407-5.
2. Ong J Waisberg E Masalkhi M Kamran SA Lowry K Sarker P Artificial Intelligence Frameworks to Detect and Investigate the Pathophysiology of Spaceflight Associated Neuro-Ocular Syndrome (SANS) Brain Sci 2023 13 1148 10.3390/brainsci13081148 37626504
Ong J, Waisberg E, Masalkhi M, Kamran SA, Lowry K, Sarker P, et al. Artificial Intelligence Frameworks to Detect and Investigate the Pathophysiology of Spaceflight Associated Neuro-Ocular Syndrome (SANS). Brain Sci. 2023;13:1148 10.3390/brainsci1308114837626504 10.3390/brainsci13081148
3. Waisberg E, Ong J, Masalkhi M, Zaman N, Kamran SA, Sarker P, et al. The Case for Expanding Visual Assessments During Spaceflight. Prehospital Disaster Med. Published online June 27, 2023:1-4. 10.1017/S1049023X23005964.
4. Meer E Grob S Antonsen EL Sawyer A Ocular conditions and injuries, detection and management in spaceflight NPJ Microgravity 2023 9 37 10.1038/s41526-023-00279-y 37193709
Meer E, Grob S, Antonsen EL, Sawyer A. Ocular conditions and injuries, detection and management in spaceflight. NPJ Microgravity. 2023;9:37 10.1038/s41526-023-00279-y37193709 10.1038/s41526-023-00279-y
5. Meer E Grob SR Lehnhardt K Sawyer A Ocular complaints and diagnoses in spaceflight Npj Microgravity 2024 10 1 7 10.1038/s41526-023-00335-7 38167407
Meer E, Grob SR, Lehnhardt K, Sawyer A. Ocular complaints and diagnoses in spaceflight. Npj Microgravity. 2024;10:1–7. 10.1038/s41526-023-00335-738167407 10.1038/s41526-023-00335-7
6. Space Oven. Zero G Kitchen. Accessed February 5, 2024. https://www.zerogk.space/space-oven
7. Waisberg E, Ong J, Paladugu P, Kamran SA, Zaman N, Tavakkoli A, et al. Radiation-induced ophthalmic risks of long duration spaceflight: Current investigations and interventions. Eur J Ophthalmol. Published online December 27, 2023:11206721231221584. 10.1177/11206721231221584
8. Johnson GW Gary Johnson: Lessons Learned from 50+ Years in Human Spaceflight and Safety. Published online April 30, 2018. Accessed January 5, 2024. https://ntrs.nasa.gov/citations/20190028301
9. Fire in Microgravity. American Scientist. Published February 6, 2017. Accessed February 5, 2024. https://www.americanscientist.org/article/fire-in-microgravity
10. Magazine S In Space, Flames Behave in Ways Nobody Thought Possible. Smithsonian Magazine. Accessed February 5, 2024. https://www.smithsonianmag.com/science-nature/in-space-flames-behave-in-ways-nobody-thought-possible-132637810/
11. Medical Operations Team Activities. JAXA Human Spaceflight Technology Directorate. Accessed January 18, 2024. https://humans-in-space.jaxa.jp/en/biz-lab/med-in-space/healthcare/medops/system/
12. Ocular Burns and Chemical Injuries: Background, Pathophysiology, Etiology. Published online September 18, 2023. Accessed November 4, 2023. https://emedicine.medscape.com/article/798696-overview
13. NASA. Medical Kit - Contents and Reference. Published online April 9, 2015. chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/ https://www.nasa.gov/wp-content/uploads/2015/03/medical_kit_checklist_-_full_release.pdf
14. Bawany S Macintosh T Ganti L Ocular Thermal Burn Injury in the Emergency Department Cureus 2020 12 e7137 10.7759/cureus.7137 32257682
Bawany S, Macintosh T, Ganti L. Ocular Thermal Burn Injury in the Emergency Department. Cureus. 2020;12:e7137 10.7759/cureus.713732257682 10.7759/cureus.7137
15. Sargsyan AE Dulchavsky AG Adams J Melton S Hamilton DR Dulchavsky SA Ultrasound detection of simulated intra-ocular foreign bodies by minimally trained personnel Aviat Space Environ Med 2008 79 58 61 10.3357/asem.2191.2008 18225781
Sargsyan AE, Dulchavsky AG, Adams J, Melton S, Hamilton DR, Dulchavsky SA. Ultrasound detection of simulated intra-ocular foreign bodies by minimally trained personnel. Aviat Space Environ Med. 2008;79:58–61. 10.3357/asem.2191.200818225781 10.3357/asem.2191.2008
16. Waisberg E, Ong J, Masalkhi M, Memon H, Lee AG. Cheers not tears: champagne corks and eye injury. BMJ. Published online December 20, 2023:p2520. 10.1136/bmj.p2520
17. Ocular Burns - Injuries; Poisoning. Merck Manuals Professional Edition. Accessed February 5, 2024. https://www.merckmanuals.com/professional/injuries-poisoning/eye-trauma/ocular-burns
18. Fitzgerald O’Connor E Frew Q Din A Pleat J Ashraff S Ghazi-Nouri S Periorbital burns – a 6 year review of management and outcome Burns J Int Soc Burn Inj 2015 41 616 23 10.1016/j.burns.2014.08.022
Fitzgerald O’Connor E, Frew Q, Din A, Pleat J, Ashraff S, Ghazi-Nouri S, et al. Periorbital burns – a 6 year review of management and outcome. Burns J Int Soc Burn Inj. 2015;41:616–23. 10.1016/j.burns.2014.08.02210.1016/j.burns.2014.08.022
19. HumanResearchWiki. Eye Penetration (Foreign Body). https://humanresearchroadmap.nasa.gov/Evidence/medicalConditions/Eye_Penetration_(Foreign_Body).pdf
20. mars.nasa.gov. Communications - NASA. Accessed January 18, 2024. https://mars.nasa.gov/mars2020/spacecraft/rover/communications/
21. Ahn H Artificial intelligence method to classify ophthalmic emergency severity based on symptoms: a validation study BMJ Open 2020 10 e037161 10.1136/bmjopen-2020-037161 32624476
Ahn H. Artificial intelligence method to classify ophthalmic emergency severity based on symptoms: a validation study. BMJ Open. 2020;10:e037161 10.1136/bmjopen-2020-03716132624476 10.1136/bmjopen-2020-037161
22. Waisberg E Ong J Masalkhi M Zaman N Kamran SA Sarker P Generative pre-trained transformers (GPT) and space health: a potential frontier in astronaut health during exploration missions Prehosp Disaster Med 2023 38 1 5 10.1017/S1049023X23005848
Waisberg E, Ong J, Masalkhi M, Zaman N, Kamran SA, Sarker P, et al. Generative pre-trained transformers (GPT) and space health: a potential frontier in astronaut health during exploration missions. Prehosp Disaster Med. 2023;38:1–5. 10.1017/S1049023X23005848. Published online June 210.1017/S1049023X23005848
23. Alser M Waisberg E Concerns with the usage of ChatGPT in Academia and Medicine: a viewpoint Am J Med Open 2023 9 100036 10.1016/j.ajmo.2023.100036 39035060
Alser M, Waisberg E. Concerns with the usage of ChatGPT in Academia and Medicine: a viewpoint. Am J Med Open. 2023;9:100036 10.1016/j.ajmo.2023.100036.39035060 10.1016/j.ajmo.2023.100036
24. Paladugu PS, Ong J, Nelson N, Kamran SA, Waisberg E, Zaman N, et al. Generative Adversarial Networks in Medicine: Important Considerations for this Emerging Innovation in Artificial Intelligence. Ann Biomed Eng. Published online July 24, 2023. 10.1007/s10439-023-03304-z
