This case reports the successful 12-day space mission in 2008 of an astronaut who had undergone bilateral PRK for myopia in 1994.
In the space program's early days, potential astronauts were subjected to extremely rigorous physical criteria for selection - a process that largely eliminated the need for optical correction. Over time, these selection criteria have become less rigid as scientists, payload specialists, and other spaceflight participants make up a larger proportion of those flying in microgravity.
The more relaxed eye standards has by necessity led to the need for glasses and contact lenses in space travelers. Since these devices have proven suboptimal for use in a microgravity environment, refractive surgery would appear to be a logical alternative.
The astronaut, a 47-year-old white male, served as a spaceflight participant during a Soyuz mission to the International Space Station and performed several research projects and medical experiments that demanded good near and far visual acuity.
His pre-mission eye examination documented a UDVA of 20/25 in the right eye and 20/20 in the left eye, which corrected to 20/15 in each eye with cycloplegic refractions of -1.00 + 1.25 x 28 (right eye) and -0.75 + 0.50 x 155 (left eye). Corneal topography was consistent with a post-PRK shape in both eyes, and keratometry was 41.50/41.87 x 180 (right eye) and 42.00/42.12 x 180 (left eye). Wavefront analysis was also consistent with a refractive surgery optical profile.
Although his eyes were subjected to a wide spectrum of physiologic changes, he experienced no measurable changes in distance or near visual acuity, refraction or amplitude of accommodation during launch, 12 days of microgravity and re-entry. He also reported no dry eyes, light sensitivity, visual discomfort, or headaches related to vision.
To the authors' knowledge, this is the first case documenting the stability of corneal refractive surgery in an astronaut during spaceflight.
The authors conclude that this case report suggests that PRK is a safe, effective and well-tolerated procedure for use by astronauts during spaceflight.