Motion perception deficits in glaucomatous optic neuropathy

AbstractThe mechanisms mediating impaired motion perception in glaucoma were investigated. Direction discrimination thresholds for low (4.2 deg/sec) and high (12.5 deg/sec) velocity random-dot kinematograms were measured in controls and patients with glaucoma or ocular hypertension. Thresholds were elevated significantly in glaucoma patients and individual ocular hypertensives. Threshold elevations were not due to blur or pupil size. After compensating for motion reversals, high but not low velocity thresholds remained elevated. Only high velocity thresholds correlated with differential luminance sensitivity. A hypothesis that different mechanisms mediate glaucoma-induced deficits at high and low velocities is presented

Green Edge ice camp campaigns : understanding the processes controlling the under-ice Arctic phytoplankton spring bloom

The Green Edge initiative was developed to investigate the processes controlling the primary productivity and fate of organic matter produced during the Arctic phytoplankton spring bloom (PSB) and to determine its role in the ecosystem. Two field campaigns were conducted in 2015 and 2016 at an ice camp located on landfast sea ice southeast of Qikiqtarjuaq Island in Baffin Bay (67.4797∘ N, 63.7895∘ W). During both expeditions, a large suite of physical, chemical and biological variables was measured beneath a consolidated sea-ice cover from the surface to the bottom (at 360 m depth) to better understand the factors driving the PSB. Key variables, such as conservative temperature, absolute salinity, radiance, irradiance, nutrient concentrations, chlorophyll a concentration, bacteria, phytoplankton and zooplankton abundance and taxonomy, and carbon stocks and fluxes were routinely measured at the ice camp. Meteorological and snow-relevant variables were also monitored. Here, we present the results of a joint effort to tidy and standardize the collected datasets, which will facilitate their reuse in other Arctic studies

Errors in the Diagnosis of Visual Field Progression in Normal-tension Glaucoma

Background: Despite strictly defined criteria for visual field progression in the ongoing Normal-tension Glaucoma Study, the authors noted a surprisingly large number of patients reaching the endpoint. Traditional methods could not be used to check the diagnostic accuracy of their criteria, because no "gold standard" was established for distinguishing true change from physiologic long-term fluctuation. Methods: The authors developed a statistical method based on the results of duplicate tests for progression in their subjects. This method allowed the authors to assess the sensitivity, specificity, and predictive values of their diagnostic criterion. It also estimated the true incidence of progression and provided standard errors for the estimates. Results: The authors found that their original strict criteria for progression, based on duplicate testing, produced false calls of progression 57% of the time. By raising the requirement for deterioration and by repeating the entire sequence of duplicate testing once more, the authors have successfully reduced the rate of false calls to 2%. Conclusion: Accuracy in recognizing progression is improved by not accepting small changes as evidence of progression and by confirming the findings on repeat testing

The Green Edge cruise: investigating the marginal ice zone processes during late spring and early summer to understand the fate of the Arctic phytoplankton bloom

The Green Edge project was designed to investigate the onset, life, and fate of a phytoplankton spring bloom (PSB) in the Arctic Ocean. The lengthening of the ice-free period and the warming of seawater, amongst other factors, have induced major changes in Arctic Ocean biology over the last decades. Because the PSB is at the base of the Arctic Ocean food chain, it is crucial to understand how changes in the Arctic environment will affect it. Green Edge was a large multidisciplinary, collaborative project bringing researchers and technicians from 28 different institutions in seven countries together, aiming at understanding these changes and their impacts on the future. The fieldwork for the Green Edge project took place over two years (2015 and 2016) and was carried out from both an ice camp and a research vessel in Baffin Bay, in the Canadian Arctic. This paper describes the sampling strategy and the dataset obtained from the research cruise, which took place aboard the Canadian Coast Guard ship (CCGS) Amundsen in late spring and early summer 2016. The sampling strategy was designed around the repetitive, perpendicular crossing of the marginal ice zone (MIZ), using not only ship-based station discrete sampling but also high-resolution measurements from autonomous platforms (Gliders, BGC-Argo floats …) and under-way monitoring systems. The dataset is available at https://doi.org/10.17882/86417 (Bruyant et al., 2022)

Green Edge ice camp campaigns: understanding the processes controlling the under-ice Arctic phytoplankton spring bloom

International audienceThe Green Edge initiative was developed to investigate the processes controlling the primary productivity and the fate of organic matter produced during the Arctic phytoplankton spring bloom (PSB) and to determine its role in the ecosystem. Two field campaigns were conducted in 2015 and 2016 at an ice camp located on landfast sea ice southeast of Qikiqtarjuaq Island in Baffin Bay (67.4797N, 63.7895W). During both expeditions, a large suite of physical, chemical and biological variables was measured beneath a consolidated sea ice cover from the surface to the bottom at 360 m depth to better understand the factors driving the PSB. Key variables such as temperature, salinity, radiance, irradiance, nutrient concentrations, chlorophyll-a concentration, bacteria, phytoplankton and zooplankton abundance and taxonomy, carbon stocks and fluxes were routinely measured at the ice camp. Here, we present the results of a joint effort to tidy and standardize the collected data sets that will facilitate their reuse in other Arctic studies. The dataset is available at http://www.seanoe.org/data/00487/59892/ (Massicotte et al., 2019a)

The Green Edge cruise: Understanding the onset, life and fate of the Arctic phytoplankton spring bloom

Abstract. The Green Edge project was designed to investigate the onset, life and fate of a phytoplankton spring bloom (PSB) in the Arctic Ocean. The lengthening of the ice-free period and the warming of seawater, amongst other factors, have induced major changes in arctic ocean biology over the last decades. Because the PSB is at the base of the Arctic Ocean food chain, it is crucial to understand how changes in the arctic environment will affect it. Green Edge was a large multidisciplinary collaborative project bringing researchers and technicians from 28 different institutions in seven countries, together aiming at understanding these changes and their impacts into the future. The fieldwork for the Green Edge project took place over two years (2015 and 2016) and was carried out from both an ice-camp and a research vessel in the Baffin Bay, canadian arctic. This paper describes the sampling strategy and the data set obtained from the research cruise, which took place aboard the Canadian Coast Guard Ship (CCGS) Amundsen in spring 2016. The dataset is available at https://doi.org/10.17882/59892 (Massicotte et al., 2019a)