Krishna Shah, M. Optom

Department of Contact lens, Sankara Nethralaya, Chennai, India



As humanity ventures further into space exploration, the importance of ensuring astronaut eye health becomes increasingly evident. Among the many challenges faced by astronauts, maintaining optimal vision health is paramount. In this blog post, we delve into the fascinating realm of space optometry, exploring the unique challenges astronauts face in microgravity, the development of specialised eyewear for space missions, and the crucial role of optometrists in safeguarding astronaut vision health.

Visual function of an Astronaut

1. Visual Acuity (VA)

Microgravity conditions in space can lead to fluid shifts in the body, including the eyes. These fluid shifts can cause changes in the shape of the eyeball, affecting the way light is focused on the retina. As a result, astronauts may experience blurred vision or difficulty focusing on objects.(1)

2. Contrast Sensitivity (CS)

Fluid shifts and changes in Intraocular pressure (IOP) can also affect contrast sensitivity. Astronauts may have difficulty distinguishing between different shades of light and dark, impacting their ability to perceive details in their environment.(2)

3. Visual Field and Perimetry

Chorio-retinal folds, caused by fluid shifts or changes in pressure, can result in visual distortions and metamorphopsia. Astronauts may perceive straight lines as wavy or distorted, making it challenging to accurately interpret visual information. Increased intracranial pressure in space can compress the optic nerve, leading to changes in visual field and potential blind spots. Astronauts may experience alterations in their peripheral vision, which could affect their spatial awareness and ability to detect objects in their surroundings.(3)

4. Challenges of Vision in Microgravity

In the weightless environment of space, astronauts experience a range of vision changes that can impact their ability to perform tasks safely and effectively. Space-induced ocular changes, such as optic disc oedema and choroidal folds, have been observed in long-duration space missions. Additionally, astronauts often experience an increase in Intraocular pressure, which can lead to discomfort and vision impairment.(4)

5. Development of Specialised Eyewear

Recognising the importance of mitigating vision issues in space, organisations like National Aeronautics and Space Administration (NASA) have invested in the development of specialised eyewear for astronauts. Protective eyewear is designed to shield astronauts’ eyes from harmful radiation and debris, while vision correction solutions ensure optimal visual acuity durng space missions. (Figure 1)  The FG-58 issued to the astronauts were 52 mm in size and featured gold frames, Calobar green glass lenses, bayonet temples, and a special “space case” that could be kept in a pocket in the arm of their jackets. These advancements in space optometry play a crucial role in preserving astronaut vision health.

Figure.1: Michael Collins Apollo 11 Sunglasses, Smithsonian Air & Space

Impact of Long-Duration Space Travel

Extended space missions pose significant challenges to astronauts’ visual health. Studies have shown that prolonged exposure to microgravity can result in changes to the structure and function of the eye, including alterations in Intraocular pressure and changes in the shape of the eyeball. Understanding these effects is essential for mitigating vision-related risks during long-duration space travel.(5)

Contribution of Optometrists to Space Missions:

Optometrists play a vital role in ensuring the health and safety of astronauts during space missions. They are involved in the selection and training of astronauts, assessing their visual health before, during, and after missions. Optometrists work closely with other medical professionals to monitor astronauts’ vision and provide necessary interventions to address any issues that may arise.


Space optometry represents a frontier in both optometry and space exploration, where science and innovation converge to ensure the health and well-being of astronauts as they journey beyond Earth’s bounds. By understanding the challenges of vision in space, developing specialised eyewear, and leveraging the expertise of optometrists, we can pave the way for safer and more successful space missions in the future. As we continue to push the boundaries of human exploration, space optometry will undoubtedly play a crucial role in shaping the future of space travel.



  1. Palidis, D. J., Wyder-Hodge, P. A., Fooken, J., & Spering, M. (2017). Distinct eye movement patterns enhance dynamic visual acuity. PloS one12(2), e0172061.
  2. Mohammadi A, Hashemi H, Mirzajani A, et al.: Comparison of two methods for measuring contrast sensitivity in anisometropic amblyopia. J Curr Ophthalmol 30:343-347, 2018
  3. Matsumoto, C., Yamao, S., Nomoto, H., Takada, S., Okuyama, S., Kimura, S & Shimomura, Y. (2016). Visual field testing with head-mounted perimeter ‘imo’. PLoS One11(8), e0161974.
  4. Mader, T. H., Gibson, C. R., Pass, A. F., Kramer, L. A., Lee, A. G., Fogarty, J., … & Polk, J. D. (2011). Optic disc edema, globe flattening, choroidal folds, and hyperopic shifts observed in astronauts after long-duration space flight. Ophthalmology118(10), 2058-2069.
  5. Ong, J., Lee, A. G., & Moss, H. E. (2021). Head-down tilt bed rest studies as a terrestrial analog for spaceflight associated neuro-ocular syndrome. Frontiers in Neurology12, 648958.