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3 EW NEWS & OPINION in real time, hoping to elucidate the mechanisms behind them and help determine if a human future in space could become a reality. A shift in fluids and sight Although many of the physiologi- cal effects of long-term exposure to microgravity have been documented since spaceflight began, a precise description of the ocular changes was not reported until 2011. At that time, NASA physicians clear- ly documented optic disc edema, optic nerve sheath distention, globe flattening, choroidal folds, cotton wool spots, and hyperopic shifts in refraction in astronauts following long-duration space flight. While these findings have not been severe enough to cause visual impairment thus far, they can persist after the astronaut has returned to Earth, and the symptom severity of longer-term spaceflight remains a mystery. The exact mechanism behind these vision changes remains un- known, but investigators hypothe- size that the microgravity induced cephalad fluid shift—a net shift of body fluids toward the head—plays a major role. Some of these findings have been described in earthbound patients with increased intracranial pressures, suggesting that a similar mechanism is responsible for vision changes in space. "Hopefully the ongoing NASA ocular health study will help provide us with answers to the many ques- tions we have about the effects of long-duration microgravity exposure on the human visual system," said C. Robert Gibson, OD, an optom- etrist with the NASA program, in an interview with EyeWorld. "The purpose of this study is to obtain preflight, inflight, and postflight data to document the nature and possible risks of these anatomic and physiologic changes." Examining the eye in space Begun in 2013 and continuing for another 2–3 years, the Prospective Observational Study of Ocular Health should fill in many of the blanks regarding the progression of ocular damage in space. Par- ticipating crewmembers undergo pre- and postflight examinations of their visual systems that include fundoscopy, slit lamp exams, optical coherence tomography (OCT), visual acuity tests, brain MRI, optical biometry, ocular and optic nerve ultrasound, and tonometry, as well as vascular compliance and blood pressure tests. To document the time course of the visual system changes, these tests—excluding biometry, MRIs, and slit lamp exams—are performed at various inflight time points aboard the ISS. With no flight surgeon aboard the station, crew- members act as both doctor and pa- tient, performing self-examinations and helping fellow astronauts when necessary, while investigators on the ground interpret the results. The latest addition to the suite of inflight exams is OCT, which will be used to look for subtle changes in the optic nerve head and retinal nerve fiber layer (RNFL) that may explain the changes in vision. NASA delivered the Spectralis OCT (Heidelberg Engineering, Heidelberg, Germany) to the ISS in June 2013, and participating crewmembers cap- tured their first OCT scans several months later. Ophthalmology at zero gravity by Lauren Lipuma EyeWorld Staff Writer CAUTION: Federal (USA) law restricts this device to the sale by or on the order of a phy- sician. INDICATIONS: The AcrySof ® IQ Toric posterior chamber intraocular lenses are intended for primary implantation in the capsular bag of the eye for visual correction of aphakia and pre-existing corneal astigmatism second- ary to removal of a cataractous lens in adult patients with or without presbyopia, who de- sire improved uncorrected distance vision, reduction of residual refractive cylinder and increased spectacle independence for dis- tance vision. WARNING/PRECAUTION: Careful preopera- tive evaluation and sound clinical judgment should be used by the surgeon to decide the risk/benefit ratio before implanting a lens in a patient with any of the conditions described in the Directions for Use labeling. Toric IOLs should not be implanted if the posterior capsule is ruptured, if the zonules are dam- aged, or if a primary posterior capsulotomy is planned. Rotation can reduce astigmatic cor- rection; if necessary lens repositioning should occur as early as possible prior to lens encap- sulation. All viscoelastics should be removed from both the anterior and posterior sides of the lens; residual viscoelastics may allow the lens to rotate. Optical theory suggests that high astigmatic patients (i.e. > 2.5 D) may experience spatial distortions. Possible toric IOL related factors may include residual cylindrical error or axis misalignments. Prior to surgery, physicians should provide prospective patients with a copy of the Patient Information Brochure available from Alcon for this product inform- ing them of possible risks and benefits as- sociated with the AcrySof ® IQ Toric Cylinder Power IOLs. Studies have shown that color vision discrim- ination is not adversely affected in individu- als with the AcrySof ® Natural IOL and normal color vision. The effect on vision of the Ac- rySof ® Natural IOL in subjects with hereditary color vision defects and acquired color vision defects secondary to ocular disease (e.g., glaucoma, diabetic retinopathy, chronic uve- itis, and other retinal or optic nerve diseases) has not been studied. Do not resterilize; do not store over 45° C; use only sterile irrigating solutions such as BSS ® or BSS PLUS ® Sterile Intraocular Irrigating Solutions. ATTENTION: Reference the Directions for Use labeling for a complete listing of indications, warnings and precautions. © 2013 Novartis 2/13 TOR13020JAD www.AcrySofIQTORIC.com April 2015 NASA investigates vision changes that astronauts experience in microgravity T wo hundred and five miles above the Earth, aboard the International Space Station (ISS), astronauts are discov- ering what happens to the human eye in space. In addition to the muscle atro- phy and bone loss that plague astro- nauts in spaceflight, vision problems are a less recognized, yet no less important, side effect of life at zero gravity. Mitigating these deleterious effects is paramount if humans hope to visit other planets or solar systems in the future, so NASA has begun to use the ISS as a platform for research to better understand the effects of long-term exposure to microgravity on the human body. The Prospective Observational Study of Ocular Health, begun in the spring of 2013, is a collaborative effort between scientists, ophthal- mologists, and optometrists to evaluate the vascular system, central nervous system, and vision chang- es that occur during long-duration spaceflight. Study investigators are measuring how these physiological changes unfold in ISS crewmembers Astronaut Koichi Wakata performs the Spectralis OCT examination onboard the International Space Station. Source: NASA continued on page 10

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