Progression of functional and structural glaucomatous damage in relation to diurnal and nocturnal dips in mean arterial pressure

Background: Systemic hypoperfusion plays a pivotal role in the pathogenesis of primary open-angle glaucoma (POAG). Extreme dips in mean arterial pressure (MAP) due to high 24-h variability are associated with POAG, however, whether this is driven by diurnal or nocturnal dips remains undocumented. We aimed this study to investigate the association of POAG damage with variability and dips in the diurnal and nocturnal MAP. Methods: We conducted a retrospective longitudinal study that included 110 POAG patients who underwent 24-h ambulatory blood pressure monitoring. Our outcomes included (i) functional [visual field defects expressed as mean deviation (MD)] and (ii) structural (optic disc cupping obtained from cup-to-disc ratio) glaucoma damage. MAP variability independent of the mean (VIMmap) was computed for diurnal and nocturnal MAP. Dips were the five diurnal and three nocturnal lowest drops in MAP. We also calculated the night-to-day ratio. We applied mixed models to evaluate the progression of visual field defects and optic disc cupping in relation to diurnal and nocturnal MAP measures. Results: The mean age was 64.0 y (53% women). The median follow-up was 9 years. In adjusted mixed models, functional progression of glaucoma damage was associated with VIMmap (−2.57 dB change in MD per every 3 mmHg increase in VIMmap; P \u3c 0.001) and diurnal MAP dips (changes in the MD ranged from −2.56 to −3.19 dB; P \u3c 0.001). Every 5 mmHg decrease in the nocturnal MAP level was associated with −1.14 dB changes in MD [95% confidence interval (CI), −1.90 to −0.40] and 0.01 larger optic disc cupping (95% CI, 0.01–0.02). Lower night-to-day ratio was also related to both outcomes (P ≤ 0.012). Functional glaucoma damage worsened if nocturnal hypotension was combined with high variability or extreme dips in the diurnal MAP (P ≤ 0.022). Conclusion: Progression of glaucoma damage in POAG associates with high variability and extreme dips in the diurnal MAP. Structural glaucoma damage seems more vulnerable to nocturnal hypotension. Ambulatory blood pressure monitoring allows the assessment of sporadic diurnal and persistent nocturnal hypotension episodes. These phenotypes might offer an opportunity to improve the risk-stratification of open-angle glaucoma (OAG)

Elevated Intraocular Pressure After Intravitreal Steroid Injection in Diabetic Macular Edema: Monitoring and Management

<p><b>Article full text</b></p> <p><br></p> <p>The full text of this article can be found here<b>.</b> <a href="https://link.springer.com/article/10.1007/s40123-016-0052-8?view=classic">https://link.springer.com/article/10.1007/s40123-016-0052-8?view=classic</a></p><p></p> <p><br></p> <p><b>Provide enhanced content for this article</b></p> <p><br></p> <p>If you are an author of this publication and would like to provide additional enhanced content for your article then please contact <a href="http://www.medengine.com/Redeem/”mailto:[email protected]”"><b>[email protected]</b></a>.</p> <p><br></p> <p>The journal offers a range of additional features designed to increase visibility and readership. All features will be thoroughly peer reviewed to ensure the content is of the highest scientific standard and all features are marked as ‘peer reviewed’ to ensure readers are aware that the content has been reviewed to the same level as the articles they are being presented alongside. Moreover, all sponsorship and disclosure information is included to provide complete transparency and adherence to good publication practices. This ensures that however the content is reached the reader has a full understanding of its origin. No fees are charged for hosting additional open access content.</p> <p><br></p> <p>Other enhanced features include, but are not limited to:</p> <p><br></p> <p>• Slide decks</p> <p>• Videos and animations</p> <p>• Audio abstracts</p> <p>• Audio slides</p

Non-invasive assessment of cerebral oxygenation: A comparison of retinal and transcranial oximetry

<div><p>Background</p><p>To investigate the correlation between cerebral (SO_{2-transcranial}), retinal arterial (SaO_2-retinal) and venous (SvO_2-retinal) oxygen saturation as measured by near-infrared spectroscopy (NIRS) and retinal oximetry respectively.</p><p>Methods</p><p>Paired retinal and cerebral oxygen saturation measurements were performed in healthy volunteers. Arterial and venous retinal oxygen saturation and diameter were measured using a non-invasive spectrophotometric retinal oximeter. Cerebral oxygen saturation was measured using near-infrared spectroscopy. Correlations between SO_{2-transcranial} and retinal oxygen saturation and diameter measurements were assessed using Pearson correlation coefficients. Lin’s concordance correlation coefficient (CCC) and Bland-Altman analysis were performed to evaluate the agreement between SO_{2-transcranial} as measured by NIRS and as estimated using a fixed arterial:venous ratio as 0.3 x SaO_2-retinal + 0.7 x SvO_2-retinal. The individual relative weight of SaO_2-retinal and SvO_2-retinal to obtain the measured SO_{2-transcranial} was calculated for all subjects.</p><p>Results</p><p>Twenty-one healthy individuals aged 26.4 ± 2.2 years were analyzed. SO_{2-transcranial} was positively correlated with both SaO_2-retinal and SvO_2-retinal (r = 0.44, p = 0.045 and r = 0.43, p = 0.049 respectively) and negatively correlated with retinal venous diameter (r = -0.51, p = 0.017). Estimated SO_{2-transcranial} based on retinal oximetry showed a tolerance interval of (-13.70 to 14.72) and CCC of 0.46 (95% confidence interval: 0.05 to 0.73) with measured SO_{2-transcranial}. The average relative weights of SaO_2-retinal and SvO_2-retinal to obtain SO_{2-transcranial} were 0.31 ± 0.11 and 0.69 ± 0.11, respectively.</p><p>Conclusion</p><p>This is the first study to show the correlation between retinal and cerebral oxygen saturation, measured by NIRS and retinal oximetry. The average relative weight of arterial and venous retinal oxygen saturation to obtain the measured transcranial oxygen saturation as measured by NIRS, approximates the established arterial:venous ratio of 30:70 closely, but shows substantial inter-individual variation. These findings provide a proof of concept for the role of retinal oximetry in evaluating cerebral oxygenation.</p></div

Bland-Altman plot comparing estimated and measured SO_{2-transcranial}.

<p>Plot shows mean bias (solid line) and 95% limit of agreement (dashed lines).</p

Correlation coefficients per vessel type.

<p>Correlation coefficients per vessel type.</p

Retinal oximetry.

<p>Sample monochromatic retinal image at 570nm (A) and 600nm (B) and resulting pseudo-color oxygen saturation overlay map (C), showing oxygen saturation in arteries (red) and veins (green) separately. Note the darker appearance of veins compared to arteries at 600nm (B) but not at 570nm (A).</p

Characteristics of the study population^*.

<p>Characteristics of the study population^{<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0190612#t001fn001" target="_blank">*</a>}.</p

Correlation with transcranial saturation.

<p>Correlation with transcranial saturation.</p

Relative weight of SaO_2-retinal to obtain measured SO_{2-transcranial}.

<p>Plot showing individual arterial weights for each study participant (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0190612#pone.0190612.e003" target="_blank">Eq 2</a>). Average arterial weight is 0.31 (solid horizontal line) but inter-individual differences are large, ranging from 0.10 to 0.49.</p

Experimental setup.

<p>Experimental setup showing seated subject, retinal oximeter, NIRS device, sphygmomanometer and pulse oximeter. Magnified detail of the dual-wavelength retinal oximeter consisting of a funduscamera, beam splitter, two band-pass filters and two digital cameras.</p