Structural and Functional Changes of the Human Macula during Acute Exposure to High AltitudeReport as inadecuate




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Background

This study aimed to quantify structural and functional changes at the macula during acute exposure to high altitude and to assess their structure-function relationship. This work is related to the Tuebingen High Altitude Ophthalmology THAO study.

Methodology-Principal Findings

Spectral domain optical coherence tomography and microperimetry were used to quantify changes of central retinal structure and function in 14 healthy subjects during acute exposure to high altitude 4559 m. High-resolution volume scans and fundus-controlled microperimetry of the posterior pole were performed in addition to best-corrected visual acuity BCVA measurements and assessment of acute mountain sickness. Analysis of measurements at altitude vs. baseline revealed increased total retinal thickness TRT in all four outer ETDRS grid subfields during acute altitude exposure TRTouter = 2.80±1.00 μm; mean change±95%CI. This change was inverted towards the inner four subfields TRTinner = −1.89±0.97 μm with significant reduction of TRT in the fovea TRTfoveal = −6.62±0.90 μm at altitude. BCVA revealed no significant difference compared to baseline 0.06±0.08 logMAR. Microperimetry showed stable mean sensitivity in all but the foveal subfield MSfoveal = −1.12±0.68 dB. At baseline recordings before and >2 weeks after high altitude exposure, all subjects showed equal levels with no sign of persisting structural or functional sequels.

Conclusions-Significance

During acute exposure to high altitude central retinal thickness is subject to minor, yet statistically significant changes. These alterations describe a function of eccentricity with an increase in regions with relatively higher retinal nerve fiber content and vascular arcades. However, these changes did not correlate with measures of central retinal function or acute mountain sickness. For the first time a quantitative approach has been used to assess these changes during acute, non-acclimatized high altitude exposure.



Author: M. Dominik Fischer, Gabriel Willmann , Andreas Schatz, Kai Schommer, Ahmad Zhour, Eberhart Zrenner, Karl U. Bartz-Schmidt, Floria

Source: http://plos.srce.hr/



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