Retinal Vessel Oxygen Saturation during 100% Oxygen Breathing in Healthy Individuals.

To access publisher's full text version of this article, please click on the hyperlink in Additional Links field or click on the hyperlink at the top of the page marked Files. This article is open access.To detect how systemic hyperoxia affects oxygen saturation in retinal arterioles and venules in healthy individuals.Retinal vessel oxygen saturation was measured in 30 healthy individuals with a spectrophotometric retinal oximeter (Oxymap T1). Oximetry was performed during breathing of room air, 100% oxygen (10 minutes, 6L/min) and then again room air (10 minutes recovery).Mean oxygen saturation rises modestly in retinal arterioles during 100% oxygen breathing (94.5%±3.8 vs. 92.0%±3.7% at baseline, p<0.0001) and dramatically in retinal venules (76.2%±8.0% vs. 51.3%±5.6%, p<0.0001). The arteriovenous difference decreased during 100% oxygen breathing (18.3%±9.0% vs. 40.7%±5.7%, p<0.0001). The mean diameter of arterioles decreased during 100% oxygen breathing compared to baseline (9.7±1.4 pixels vs. 10.3±1.3 pixels, p<0.0001) and the same applies to the mean venular diameter (11.4±1.2 pixels vs. 13.3±1.5 pixels, p<0.0001).Breathing 100% oxygen increases oxygen saturation in retinal arterioles and more so in venules and constricts them compared to baseline levels. The dramatic increase in oxygen saturation in venules reflects oxygen flow from the choroid and the unusual vascular anatomy and oxygen physiology of the eye.Icelandic Centre for Research 100429021 Landspitali-University Hospital Research Fund A-2013-023 Icelandic Fund for Prevention of Blindnes

Physical and cognitive impact following SARS-CoV-2 infection in a large population-based case-control study

© 2023. The Author(s).BACKGROUND: Persistent symptoms are common after SARS-CoV-2 infection but correlation with objective measures is unclear. METHODS: We invited all 3098 adults who tested SARS-CoV-2 positive in Iceland before October 2020 to the deCODE Health Study. We compared multiple symptoms and physical measures between 1706 Icelanders with confirmed prior infection (cases) who participated, and 619 contemporary and 13,779 historical controls. Cases participated in the study 5-18 months after infection. RESULTS: Here we report that 41 of 88 symptoms are associated with prior infection, most significantly disturbed smell and taste, memory disturbance, and dyspnea. Measured objectively, cases had poorer smell and taste results, less grip strength, and poorer memory recall. Differences in grip strength and memory recall were small. No other objective measure associated with prior infection including heart rate, blood pressure, postural orthostatic tachycardia, oxygen saturation, exercise tolerance, hearing, and traditional inflammatory, cardiac, liver, and kidney blood biomarkers. There was no evidence of more anxiety or depression among cases. We estimate the prevalence of long Covid to be 7% at a median of 8 months after infection. CONCLUSIONS: We confirm that diverse symptoms are common months after SARS-CoV-2 infection but find few differences between cases and controls in objective parameters measured. These discrepancies between symptoms and physical measures suggest a more complicated contribution to symptoms related to prior infection than is captured with conventional tests. Traditional clinical assessment is not expected to be particularly informative in relating symptoms to a past SARS-CoV-2 infection.Peer reviewe

Retinal vessel oxygen saturation in healthy individuals.

We measured oxygen saturation in retinal vessels of healthy eyes to determine the effects of age, sex, and cardiovascular parameters, as well as the reliability of the measurements and topographic differences. The Oxymap T1 retinal oximeter is based on a fundus camera. It simultaneously captures retinal images at two different wavelengths and estimates retinal vessel oxygen saturation. Mean saturation of main retinal arterioles and venules was measured in 120 healthy individuals aged 18-80 years (median 47 years). Of the 120 participants 44 (37%) were male (49 years) and 76 (63%) female (44 years). Oxygen saturation was 92.2 ± 3.7% (mean ± SD) in retinal arterioles and 55.6 ± 6.3% in venules. No significant difference in oxygen saturation was found between left and right eyes. The inferotemporal quadrant had lower oxygen saturation in arterioles and venules (P < 0.0001). Arteriolar oxygen saturation was stable with age. Venular oxygen saturation in males decreased by 1.9 ± 0.6% (mean ± SEM) per 10 years of age (P = 0.003) and by 0.7 ± 0.4% in females (P = 0.068). Arteriovenous (AV) difference increased by 1.5 ± 0.5% per 10 years in males (P = 0.004) and 1.0 ± 0.4% (P = 0.007) in females. For every 10 mm Hg increase in ocular perfusion pressure, oxygen saturation in arterioles increased by 0.9 ± 0.4% (P = 0.024) and in venules by 1.2 ± 0.7% (P = 0.075). Retinal arteriolar oxygen saturation is stable in healthy individuals, while there is a significant decrease in venular oxygen saturation with age in males and a similar trend in females. AV difference increases significantly with age for both sexes. Our study provided normative data for spectrophotometric retinal oximetry in the Caucasian population.Prevention of Blindness Fund Landspitali-University Hospital Research Fund University of Iceland Research Fund Icelandic Center for Research (Rannis) Fun

Retinal oximetry images must be standardized: a methodological analysis.

To access publisher's full text version of this article. Please click on the hyperlink in Additional Links field.Retinal vessel oximetry is a new technology and needs detailed methodological scrutiny. We determine (1) the repeatability of retinal vessel oxygen saturation measurements, (2) whether measured saturation is different between retinal quadrants, and (3) whether the angle of gaze changes measurements of the same vessels. Fundus oximetry images were obtained from 26 healthy individuals, 18 to 30 years old, using the Oxymap retinal oximeter. Oxygen saturation in the same vessel segments was compared between two similar images of each individual to determine repeatability. Vessel oxygen saturation was also compared between different quadrants of the retina in the same oximetry image. Finally, oxygen saturation measurements were made on the same vessel segments at different angles of gaze. Mean and standard deviation of saturation measurements was 93.1% ± 2.3% in arterioles and 64.9% ± 3.3% in venules. Standard deviation of repeated saturation measurements on the same vessel segment was 1.0% in arterioles and 1.4% in venules. Significant differences were seen between retinal quadrants. When angle of gaze was altered, measured saturation was lower in the same vessels when they were located in the inferior portion compared with other parts of the image (-1.3% ± 1.7%, P = 0.0004 in arterioles and -1.9 ± 2.4%, P = 0.0007 in venules). Retinal vessel oxygen saturation measurements are repeatable with a small standard deviation. When oximetry results are compared between time points or eyes, the imaging must be standardized and similar parts of the images analyzed.Icelandic Center for Research (Rannis) University of Iceland Research Fund Landspitali University Hospita

Retinal oximetry with a scanning laser ophthalmoscope.

To access publisher's full text version of this article click on the hyperlink at the bottom of the pageThe purpose of the study was to assess if a scanning laser ophthalmoscope (SLO), Optomap 200Tx, could be used for measurements of hemoglobin oxygen saturation in retinal blood vessels.Optomap 200Tx uses two lasers for image acquisition, 532 and 633 nm. Retinal images of healthy individuals and patients with retinal vein occlusion were analyzed with modified Oxymap Analyzer software, which tracks retinal vessels and calculates relative hemoglobin oxygen saturation.Oxygen saturation in healthy individuals was measured as 92% ± 13% for arterioles and 57% ± 12% for venules (mean ± SD, n = 11, P = 0.0001). Standard deviation for repeated measurements of the same eye was 3.5% for arterioles and 4.4% for venules. In patients with confirmed venular hypoxia, central retinal vein occlusion (CRVO) or hemivein occlusion, the average venular oxygen saturation was measured as 23% ± 3% in the affected eyes and 59% ± 3% in the fellow eyes (n = 4, P = 0.0009).Technically, it is possible to derive information on retinal oxygen saturation from an SLO with a 2-wavelength oximetry algorithm. The system produced both sensitive and repeatable results. The remaining challenges include decreasing variability between vessels of the same eye and variability between individuals. Given the advantages that SLO imaging has over conventional fundus camera optics in retinal oximetry, further development of SLO oximetry may provide the optimal approach to retinal oximetry.Optos plc. Dunfermline (Scotland, United Kingdom) Icelandic Center for Research (Rannis, Iceland) Icelandic Prevention of Blindness Fund (Reykjavik, Iceland) Landspitali-University Hospital Research Fund (Reykjavik, Iceland) University of Iceland Research Fund (Reykjavik, Iceland) Helga Jonsdottir and Sigurlioi Kristjansson Memorial Fund (Reykjavik, Iceland

Moreton 20 chain map. Sheet 31A [cartographic material].

Cadastral map of the Moreton Bay area, Queensland.; Also available in an electronic version via the internet at: http://nla.gov.au/nla.map-rm2014-20

John Clarke (Fred Dagg), Windsor, Melbourne, 1982 [picture] /

Title from inscriptions on verso.; Part of collection: Rennie Ellis: Aussies all.; Inscriptions: titled, "1982/2006" and "Aussies All Exhibition"--In ink lower right on verso.; Item with accompanying exhibition note.; Condition: Good.; Also available in electronic version via the Internet at: http//nla.gov.au/nla.pic-vn4083978; Purchased from Rennie Ellis Photographic Archive through Josef Lebovic Gallery, 2007.; Exhibited: Rennie Ellis: Aussies all, National Portrait Gallery, Canberra, 2006. AuCNL

Physiological variables that were measured (mean± SD) during room air breathing (Baseline), 100% oxygen breathing and 10 minutes of room air breathing subsequent to 100% oxygen breathing (Recovery).

<p>EtCO₂, end tidal carbon dioxide; HR, heart rate; IOP, intraocular pressure; BP, blood pressure; MAP, mean arterial pressure; OPP, ocular perfusion pressure; SpO₂, finger oxygen saturation.</p><p>Physiological variables that were measured (mean± SD) during room air breathing (Baseline), 100% oxygen breathing and 10 minutes of room air breathing subsequent to 100% oxygen breathing (Recovery).</p

Retinal vessel oxygen saturation in arterioles and venules; before 100% oxygen breathing (baseline), during 100% oxygen breathing and 10 minutes after 100% oxygen breathing (recovery) in healthy individuals (n = 30).

<p>The lines show mean values for each group. Each point denotes value from one individual.</p