Navigation Links
NASA-sponsored study describes how space flight impacts astronauts' eyes and vision

SAN FRANCISCO November 3, 2011 A new study sponsored by NASA finds that space flights lasting six months or more can cause a spectrum of changes in astronauts' visual systems. Some problems, including blurry vision, appear to persist long after astronauts' return to Earth. The results are affecting plans for long-duration manned space voyages, such as a trip to Mars. The study team included ophthalmologists Thomas H. Mader, MD, of Alaska Native Medical Center and Andrew G. Lee, MD, of The Methodist Hospital, Houston, Texas. Their report is published in October's Ophthalmology, the journal of the American Academy of Ophthalmology

The researchers studied seven astronauts, all of whom were about age 50 and had spent at least six continuous months in space. All reported that their vision became blurry, to varying degrees, while on the space station. Vision changes usually began around six weeks into the mission and persisted in some astronauts for months after their return to Earth. Drs. Mader and Lee agree that the eye abnormalities appear to be unrelated to launch or re-entry, since they occurred only in astronauts who spent extended time in microgravity.

In-depth examination of the seven astronauts revealed several abnormalities. All of the subjects had one or more of the following changes in the tissues, fluids, nerves and other structures in the back of the eye:

  • Flattening of the back of the eyeball (five subjects);
  • Folds in the choroid, the vascular tissue behind the retina, which is the light sensitive area in the back of the eye (five subjects); and
  • Excess fluid around and presumed swelling of the optic nerve (five subjects).

Such abnormalities could potentially be caused by increased intracranial pressure−that is, pressure inside the head. However, none of these astronauts experienced symptoms usually associated with intracranial pressure, such as chronic headache, double vision, or ringing in the ears. Researchers believe other factors may be involved, such as abnormal flow of spinal fluid around the optic nerve, changes in blood flow in the choroid, or changes related to chronic low pressure within the eye, which is known as intraocular pressure. They hypothesize that these changes may result from the fluid shifts toward the head that occur when astronauts spend extended time in microgravity.

The visual system changes discovered by the researchers may represent a set of adaptations to microgravity. The degree and type of response appear to vary among astronauts. Researchers hope to discover whether some astronauts are less affected by microgravity and therefore better-suited for extended space flight, such as a three-year round trip to Mars.

In their report, Drs. Mader and Lee also noted a recent NASA survey of 300 astronauts that found that correctible problems with both near and distance vision were reported by about 23 percent of astronauts on brief missions and by 48 percent of those on extended missions. The survey confirmed that for some astronauts, these vision changes continue for months or years after return to Earth. The possibility of near vision problems has been recognized for decades, and special "space anticipation glasses" to improve visual sharpness have been provided on all spacecraft dating back to John Glenn, who had a pair in his space capsule.

"In astronauts over age 40, like non-astronauts of the same age, the eye's lens may have lost some of its ability to change focus," said Dr. Mader. "In the space program's early days most astronauts were younger, military test-pilots who had excellent vision. Today's astronauts tend to be in their 40s or older. This may be one reason we've seen an uptick in vision problems. Also, we suspect many of the younger astronauts were more likely to 'tough out' any problems they experienced, rather than reporting them."

As part of ongoing research all astronauts now receive comprehensive eye exams and vision testing. Diagnostic tests include pre- and post-flight magnetic resonance imaging, optical coherence tomography, which magnifies cross-section views of parts of the eye, and fundus photography, which records images of the retina and back of the eye. Intraocular pressure measurement and ultrasound imaging take place in flight, as well as pre- and post-mission.


Contact: Mary Wade
American Academy of Ophthalmology

Related medicine news :

1. Despite Treatment, Employees with Depression Generate Higher Absentee Costs, According to Thomson Reuters Study
2. American Council on Exercise (ACE) Study Reveals Kettlebells Provide Powerful Workout in Short Amount of Time
3. TV drama can be more persuasive than news program, study finds
4. Study carried out into biological risks of eating reptiles
5. Neuroimaging study may pave way for effective Alzheimers treatments
6. Study finds racial gaps continue in heart disease awareness
7. Luth Researchs IndicatorEDG(TM) Study Finds Americans Hopes of Achieving Their Dreams Are Fading
8. First blinded study of venous insufficiency prevalence in MS shows promising results
9. Soothing infants with food focus of childhood obesity study
10. People with anxiety disorder less able to regulate response to negative emotions, study shows
11. American Heart Association Rapid Access Journal Report: Study Finds Racial Gaps Continue in Heart Disease Awareness, Low Knowledge of Heart Attack Warning Signs Among Women
Post Your Comments:
(Date:11/27/2015)... LOS ANGELES, CA (PRWEB) , ... November 27, 2015 , ... MPWH, the No.1 Herpes-only ... age of 30 (see Table 1-1 ). More than 3.7 billion people under ... simplex virus type 1 (HSV-1), according to WHO's first global estimates of HSV-1 infection ...
(Date:11/27/2015)... , ... November 27, 2015 , ... ... Secura Consultants has prided itself for not only fulfilling the needs of advisers ... solutions at an affordable price and providing top-tier customer service. However, there's always ...
(Date:11/27/2015)... ... November 27, 2015 , ... Dr. Thomas Dunlap and ... Dr. Tucker Bierbaum with Emergency Medicine at St., Joseph Health System’s Santa Rosa ... Sepsis conditions present in similar ways and require time-critical intervention to avoid large area ...
(Date:11/26/2015)... ... 26, 2015 , ... Inevitably when people think Thanksgiving, they also think Holiday ... the Black Friday and Cyber Monday massage chair sales to receive the ... and low to find the best massage chair deals, they can see all of ...
(Date:11/26/2015)... ... ... Jobs in hospital medical laboratories and in the imaging field lead the many ... Medical Group . These fields, as well as travel nursing, ranked at ... through the company’s website, , The leading healthcare staffing agency released ...
Breaking Medicine News(10 mins):
(Date:11/25/2015)... Nov. 25, 2015  Amgen (NASDAQ: AMGN ) ... (BLA) with the United States ... a biosimilar candidate to Humira ® (adalimumab). Amgen ... submitted to the FDA and represents Amgen,s first BLA ... E. Harper , M.D., executive vice president of Research ...
(Date:11/25/2015)... N.Y. , Nov. 25, 2015  Linden Care, ... and optimizing treatment outcomes for patients suffering from chronic ... request for a Temporary Restraining Order (TRO) enjoining Express ... the two companies. --> ... pursuing all of its legal options. ...
(Date:11/25/2015)... On Tuesday, November 24, 2015, the ... Wright Medical Technology, Inc. for product liability and ... implant device, awarded $11 million in favor of ... and three days of deliberations, the jury found ... designed and unreasonably dangerous, and that Wright Medical ...
Breaking Medicine Technology: