Persistent Asymmetric Optic Disc Swelling After Long-Duration Space Flight: Implications for Pathogenesis.

BACKGROUND: Several ophthalmic findings including optic disc swelling, globe flattening and choroidal folds have been observed in astronauts following long-duration space flight. The authors now report asymmetric choroidal expansion, disc swelling and optic disc morphologic changes in a 45-year-old astronaut which occurred during long-duration space flight and persisted following his space mission. METHODS: Case study of ocular findings in an astronaut documented during and after a long-duration space flight of approximately 6 months. Before, during and after his spaceflight, he underwent complete eye examination, including fundus photography, ultrasound, and optical coherence tomography. RESULTS: We documented asymmetric choroidal expansion inflight that largely resolved by 30 days postflight, asymmetric disc swelling observed inflight that persisted for over 180 days postflight, asymmetric optic disc morphologic changes documented inflight by OCT that persisted for 630 days postflight and asymmetric globe flattening that began inflight and continued 660 days postflight. Lumbar puncture opening pressures obtained at 7 and 365 days post-mission were 22 and 16 cm H20 respectively. CONCLUSION: The persistent asymmetric findings noted above, coupled with the lumbar puncture opening pressures, suggest that prolonged microgravity exposure may have produced asymmetric pressure changes within the perioptic subarachnoid space.

Neuro-Ophthalmology of Space Flight.

BACKGROUND: To describe the history, clinical findings, and possible pathogenic etiologies of the constellation of neuro-ophthalmic findings discovered in astronauts after long-duration space flight and to discuss the terrestrial implications of such findings. EVIDENCE ACQUISITION: Retrospective review of published observational, longitudinal examination of neuro-ophthalmic findings in astronauts after long-duration space flight; analysis of postflight questionnaires regarding in-flight vision changes in approximately 300 additional astronauts; and hypothesis generating for developing possible future countermeasures and potential implications for neuro-ophthalmic disorders on Earth. Astronauts with neuro-ophthalmic findings, which were not present at the start of a space flight mission and only seen on return from long-duration space missions to the International Space Station, will be discussed. RESULTS: After 6 months of space flight, 7 astronauts had ophthalmic findings consisting of optic disc edema in 5, globe flattening in 5, choroidal folds in 5, cotton-wool spots in 3, nerve fiber layer thickening detected by optical coherence tomography in 6, and decreased near vision in 6. Five of 7 astronauts with near vision complaints had a hyperopic shift ≥+0.50 diopters (D) between pre-/post-mission spherical equivalent refraction in 1 or both eyes (range, +0.50 to +1.75 D). These 5 astronauts showed globe flattening on magnetic resonance imaging. A total of 6 lumbar punctures have been performed to date (4 in the originally described cohort) and documented opening pressures of 18, 22, 21, 21.5, 28, and 28.5 cm H2O. These were performed at 8, 66, 19, 7, 12, and 57 days after mission, respectively. The 300 postflight questionnaires documented that approximately 29% and 60% of astronauts on short-duration and long-duration missions, respectively, experienced a degradation in distant and near visual acuity. Some of these vision changes remain unresolved for years after flight. Several possible pathogenic mechanisms, as well as potential countermeasures and discussion of possible terrestrial implications, are described. CONCLUSIONS: We previously hypothesized that the optic nerve and ocular changes that we described in astronauts may be the result of orbital and cranial cephalad fluid shifts brought about by prolonged microgravity exposure. The findings we reported previously and continue to see in astronauts may represent parts of a spectrum of ocular and cerebral responses to extended microgravity exposure. Future investigations hopefully will lead to countermeasures that can be used to eliminate or lessen the magnitude of these potentially harmful findings before long-duration space flight including the possibility of a manned mission to Mars.

Real-time tele-echocardiography: diagnosis and management of a pericardial effusion secondary to pericarditis at an Antarctic research station.

The McMurdo Research Station medical facility functions at the level of a rural community hospital emergency department. Telehealth technology has played an increasingly important role in providing intercontinental tertiary healthcare consultations, particularly for assistance with diagnostically challenging cases or cases involving complicated medical management. The role of telehealth in Antarctica is vital given the harsh and remote environment. The following case discusses a real-time tele-ultrasound consultation between the station physician and a patient with pericarditis at the McMurdo Medical Clinic in Antarctica and a team of cardiology consultants at the University of Texas Medical Branch, Galveston, TX. The use of teleheath technologies prevented an unnecessary intercontinental medical evacuation and allowed the patient to receive treatment at the McMurdo Research Station. This case report demonstrates that real-time tele-ultrasound can serve as an important diagnostic resource in the delivery of healthcare to isolated populations in remote environments.