Elsevier

Ophthalmology

Volume 118, Issue 10, October 2011, Pages 2058-2069
Ophthalmology

Original article
Optic Disc Edema, Globe Flattening, Choroidal Folds, and Hyperopic Shifts Observed in Astronauts after Long-duration Space Flight

https://doi.org/10.1016/j.ophtha.2011.06.021 Get rights and content

Purpose

To describe the history, clinical findings, and possible etiologies of ophthalmic findings discovered in 7 astronauts after long-duration space flight, and document vision changes in approximately 300 additional astronauts.

Design

Retrospective, observational examination of ophthalmic findings in 7 astronauts and analysis of postflight questionnaires regarding in-flight vision changes in approximately 300 additional astronauts.

Participants

Seven astronauts with ophthalmic anomalies upon return from long-duration space missions to the International Space Station and 300 additional astronauts who completed postflight questionnaires regarding in-flight vision changes.

Methods

Before and after long-duration space flight, all 7 subjects underwent complete eye examinations, including cycloplegic and/or manifest refraction and fundus photography. Six underwent postmission optical coherence tomography (OCT) and magnetic resonance imaging (MRI); 4 had lumbar punctures (LP). Approximately 300 astronauts were queried regarding visual changes during space missions.

Main Outcome Measures

Refractive change, fundus photograph examination, retina OCT, orbital MRI, LP opening pressures, and examination of visual acuity data.

Results

After 6 months of space flight, 7 astronauts had ophthalmic findings, consisting of disc edema in 5, globe flattening in 5, choroidal folds in 5, cotton wool spots (CWS) in 3, nerve fiber layer thickening by OCT in 6, and decreased near vision in 6 astronauts. Five of 7 with near vision complaints had a hyperopic shift ≥+0.50 diopters (D) between pre/postmission spherical equivalent refraction in 1 or both eyes (range, +0.50 to +1.75 D). These 5 showed globe flattening on MRI. Lumbar punctures performed in the 4 with disc edema documented opening pressures of 22, 21, 28, and 28.5 cm H2O performed 60, 19, 12, and 57 days postmission, respectively. The 300 postflight questionnaires documented that approximately 29% and 60% of astronauts on short and long-duration missions, respectively, experienced a degradation in distant and near visual acuity. Some of these vision changes remain unresolved years after flight.

Conclusions

We hypothesize that the optic nerve and ocular changes we describe may result from cephalad fluid shifts brought about by prolonged microgravity exposure. The findings we report may represent parts of a spectrum of ocular and cerebral responses to extended microgravity exposure.

Financial Disclosure(s)

The authors have no proprietary or commercial interest in any of the materials discussed in this article.

Section snippets

Subjects and Methods

A postflight survey of approximately 300 astronauts, some of whom were repeat flyers, revealed that vision changes were commonly observed during and after long-duration space missions. Since 1989, as part of the postflight eye examination, astronauts were queried as to whether they perceived a subjective improvement or degradation in distant or near vision (none, mild, moderate, or severe) during their short- and long-duration missions. Prompted by persistent reports of vision changes, NASA

Results

After approximately 6 months of continuous orbital flight, 7 astronauts (all male; age 50.2±4.2 years) were documented to have findings as summarized in Table 1. Table 2 is a summary of data from postflight questionnaires completed by approximately 300 astronauts after their short- and long-duration space missions. Approximately 23% of the short-duration and 48% of the long-duration mission astronauts complained of near vision difficulties.

Case 1

This astronaut's preflight manifest refraction at 90 days before launch was: right eye, −1.50 sphere and left eye, −2.25 −0.25×135, with a +1.50 add. He was correctable to 20/20 in each eye and his dilated eye examination and fundus photos were normal. The only medication he used was promethazine for space adaptation syndrome. He noticed a marked decrease in near visual acuity starting about 6 weeks into the mission that persisted without progression for the remainder of the flight. At no time

Discussion

In this report, we have described the development of ophthalmic findings in astronauts after long-duration space flight. Although the etiology of these findings remains unknown we propose that one of several mechanisms, or a combination thereof, may best explain our observations. The first possible explanation is that the findings we describe resulted from increased ICP brought about by prolonged microgravity exposure. Numerous authors have described optic disc edema, globe flattening,

Acknowledgments

The authors thank the Lifetime Surveillance of Astronaut Health Program, NASA Johnson Space Center, for their help with statistical and data management.

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    Manuscript no. 2011-155.

    Financial Disclosure(s): The authors have no proprietary or commercial interest in any of the materials discussed in this article.

    Some activities related to this report were accomplished while under contract paid by the National Aeronautics and Space Administration.

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