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Purpose. Using retinal optical coherence tomography angiography (OCTA), we aimed to investigate the changes in important indicators of cerebral microcirculatory disorders, such as the properties of the radial peripapillary capillaries, vascular complexes, and the retinal nerve fiber layer, caused by carotid stenosis and postoperative reperfusion. Methods. In this prospective longitudinal cohort study, we recruited 40 carotid stenosis patients and 89 healthy volunteers in the First Affiliated Hospital of Harbin Medical University (Harbin, China). Eyes with ipsilateral carotid stenosis constituted the experimental group, while the fellow eyes constituted the contralateral eye group. Digital subtraction angiography, CT perfusion imaging (CTP), and OCTA examinations were performed in all subjects. The vessel density of the radial peripapillary capillaries (RPC), superficial retinal vascular complexes (SVC), deep vascular complexes (DVC), choriocapillaris (CC), and the thickness of the retinal nerve fiber layer (RNFL) were assessed. Propensity-matched analysis was undertaken to adjust for covariate imbalances. Intergroup comparative analysis was conducted, and the paired sample t -test was used to evaluate the preoperative and postoperative changes in OCTA variables. Results. The ocular vessel density in the experimental group was significantly lower than that in the control group (RPC: 55.95 vs. 57.24, P = 0.0161 ; SVC: 48.65 vs. 52.22, P = 0.0006 ; DVC: 49.65 vs. 57.50, P < 0.0001 ). Participants with severe carotid stenosis have reduced contralateral ocular vessel density (RPC 54.30; SVC 48.50; DVC 50.80). Unilateral stenosis removal resulted in an increase in vessel density on both sides, which was detected by OCTA on the 4th day (RPC, P < 0.0001 ; SVC, P = 0.0104 ; DVC, P = 0.0104 ). Moreover, the ocular perfusion was consistent with that established by CTP. Conclusion. OCTA can be used for sensitive detection and accurate evaluation of decreased ocular perfusion caused by carotid stenosis and may thus have the potential for application in noninvasive detection of cerebral microcirculation disorders. This trial is registered with NCT04326842.

Aim and objective To establish the association between 12-month inter-visits ocular perfusion pressure (OPP) and severity of glaucoma. Materials and methods A total of 164 eyes (60 primary open-angle glaucoma, 52 normal-tension glaucoma, and 52 primary angle-closure glaucoma) of 164 patients were analyzed in this prospective cohort study. Patients who demonstrated good compliance to treatment were recruited. The severity of glaucoma was stratified according to the Advanced Glaucoma Intervention Study (AGIS) score based on reliable and reproducible visual field analysis at baseline. OPP was obtained at baseline and a 3-monthly follow-up visit over a 12-month duration. The pattern and fluctuation of mean OPP were studied. Repetitive measure ANOVA and one-way ANOVA were used for statistical analysis. Results The inter-visits mean OPP (p = 0.010), systolic OPP (p = 0.020), diastolic OPP (p = 0.010), systolic blood pressure (p = 0.040), and diastolic blood pressure (p = 0.006) showed significant difference with severity of glaucoma. There was no significant difference between mean inter-visits intraocular pressure (IOP) and severity of glaucoma (p = 0.410). The end-stage glaucoma group had the lowest mean OPP and widest inter-visit mean OPP fluctuation. Early and mild glaucoma patients demonstrated higher mean OPP compared with moderate, severe, and end-stage glaucoma. Conclusion There is a significant association between OPP and the severity of glaucoma. Balancing blood pressure and IOP is important in optimizing adequate perfusion and prevent further damage to the optic nerve head. How to cite this article Ch'ng TW, Chua CY, Ummi Kalsom MA, et al. Ocular Perfusion Pressure and Severity of Glaucoma: Is There a Link? J Curr Glaucoma Pract 2021;15(2):78–85.

PURPOSE The aim was to investigate the effects of hemodialysis (HD) on peripapillary choroidal thickness (PCT) by swept-source optical coherence tomography and on other ophthalmologic parameters in patients with end-stage kidney disease. MATERIALS AND METHODS This was a prospective observational study. The authors evaluated 29 patients who underwent HD for end-stage kidney disease. Detailed ophthalmologic examinations and swept-source optical coherence tomography were performed immediately before and after HD. PCT was measured using the modification tool in the built-in OCT image viewer program. Changes in PCT before and after HD were statistically analyzed. RESULTS The average PCT significantly decreased from 127.3±49.2 μm before HD to 117.1±50.9 μm after HD (P

Purpose. To measure the macular retinal vessel density (VD) and peripapillary retinal nerve fiber layer (RNFL) in primary angle-closure suspects (PACS) by Angio-OCT to be compared with normal subjects. Methods. Primary angle-closure suspect patients and normal subjects were enrolled in this study. The demographic and clinical characteristics of all subjects, such as RNFL thickness, retinal vessel density, and ocular perfusion pressure, were compared. Results. No significant difference was found in both groups on age, sex distribution, intraocular pressure (IOP), and retinal vessel density. The PACS group exhibited significantly thicker RNFL thickness compared with the control group. The deep vessel density was negatively associated with age ( P = − 0.034 ), while IOP had negative association with ACD ( P = − 0.019 ). OPP was independently associated with RNFL ( B = 0.334 , P = 0.038 ) in the PACS group. Conclusions. OCTA showed significant thicker change on RNFL in the PACS group. Only OPP was independently associated with RNFL in the PACS group.

Aim: To evaluate the correlation between the translaminar pressure difference (TLPD) and the ocular perfusion pressure (OPP) in glaucoma patients. Methods: This was a cross-sectional study. Primary open-angle glaucoma (POAG) patients and normal individuals underwent an ophthalmic evaluation as well as blood pressure, height, and weight measurements. Intracranial pressure (ICP) and OPP were calculated using proxy mathematical formulas to attain indirect surrogate parameter values. The TLPD was calculated as intraocular pressure minus ICP. The association between the variables was evaluated using linear and non-linear regression analysis and the correlation estimated with Pearson’s correlation coefficient. Results: The sample included 50 POAG patients and 25 normal subjects. The mean OPP for all 75 subjects (75 eyes) was 53.1 ± 9.3 mmHg and the calculated TLPG was 3.1 ± 4.2 mmHg. TLPG showed a negative correlation with OPP ( r = −0.580; 95% CI, −0.690 to −0.366; p Conclusion: The negative correlation between OPP and TLPD observed in the study substantiates the concept of glaucoma as a three-pressure disease.

Aim: To describe the distribution of ocular perfusion pressure hypertensive patients. Design: Cross-sectional observation study. Materials and Methods: Hospital-based, case control cross-sectional study conducted on 100 patients. Systolic and diastolic blood pressure (SBP and DBP) was measured with a Mercury Sphygmomanometer. Mean ocular perfusion pressure (MOPP) = ⅔ (mean arterial pressure − IOP), where mean arterial pressure (MAP) = DBP + ⅓ (SBP − DBP), systolic perfusion pressure (SPP) = SBP – IOP and diastolic perfusion pressure (DPP) = DBP − IOP was calculated. Results: High values of diastolic BP (>90 mmHg) and low values of OPP (

BackgroundTo investigate the relationship between estimated mean ocular perfusion pressure (MOPP) and peripapillary perfusion density (PD) or vessel density (VD) as measured by spectral-domain optical coherence tomography angiography (OCTA) in young healthy eyes.Methods132 healthy participants (264 eyes) under 45 years of age underwent optic disc OCTA scan sized 3×3 mm to acquire PD and VD in the superficial vascular complex (SVC). Optic nerve head (ONH) parameters including retinal nerve fibre layer (RNFL) thickness, rim area and disc area were measured. MOPP was estimated from systemic blood pressure and intraocular pressure (IOP). A linear mixed model was used to find the systemic and ocular factors associated with PD and VD.ResultsThe average age of the subjects was 25.8±6.5 years. PD and VD showed a significant correlation with RNFL thickness (r=0.224, p0.05).ConclusionPD and VD in the SVC were significantly associated with ONH parameters while showing no association with estimated MOPP. OCTA-derived VD may not represent perfusion pressure, but is rather more dependent on peripapillary structure.

Aim: To describe a case of glaucoma which showed increase in optical coherence tomography (OCT) angiographic vessel densities after intraocular pressure reduction suggesting reperfusion of optic nerve. Presentation of Case: A 55 year old female with primary open angle glaucoma was taken up for trabeculectomy in view of inadequate control of intraocular pressure (IOP) despite maximal medical therapy. In addition to routine glaucoma assessment by visual fields and nerve fiber layer assessment by OCT, OCT angiographic evaluation of peripapillary vessel density was done preoperatively. Three months after trabeculectomy, her intraocular pressure decreased from 35mmHg to 14mmHg. Compared with the preoperative baseline value, the vessel density increased significantly in all quadrants after three months from surgery as demonstrated by OCT angiography. Discussion: This case report suggests that decreased optic nerve head perfusion due to high IOP can be reversed by reduction of IOP. Conclusion: Vascular parameters like angiographic vessel density can show reversible changes as decreased blood flow reinstates and thus can be better prognostic indicators than structural parameters like OCT retinal nerve fiber layer (RNFL) in glaucoma patients.

Intravitreal (ITV) drug delivery is a new cornerstone for retinal therapeutics. Yet, predicting the disposition of formulations in the human eye remains a major translational hurdle. A prominent, but poorly understood, issue in pre-clinical ITV toxicity studies is unintended particle movements to the anterior chamber (AC). These particles can accumulate in the AC to dangerously raise intraocular pressure. Yet, anatomical differences, and the inability to obtain equivalent human data, make investigating this issue extremely challenging. We have developed an organotypic perfusion strategy to re-establish intraocular fluid flow, while maintaining homeostatic pressure and pH. Here, we used this approach with suitably sized microbeads to profile anterior and posterior ITV particle movements in live versus perfused porcine eyes, and in human donor eyes. Small-molecule suspensions were then tested with the system after exhibiting differing behaviours in vivo . Aggregate particle size is supported as an important determinant of particle movements in the human eye, and we note these data are consistent with a poroelastic model of bidirectional vitreous transport. Together, this approach uses ocular fluid dynamics to permit, to our knowledge, the first direct comparisons between particle behaviours from human ITV injections and animal models, with potential to speed pre-clinical development of retinal therapeutics.

Hintergrund: Mit dem Ocular Pressure Blood Flow Analyzer (OPFA) kann erstmals der okuläre Perfusionsdruck (OPP), der okuläre Blutdruck (OBP), der okuläre pulsatile Blutfluss in Relation zum OPP und die autoregulatorische Kapazität (AC) der okulären Perfusion nichtinvasiv und ohne Pupillenerweiterung simultan an beiden Augen gemessen werden. Aufgabenstellung: Aufgabe der vorliegenden Arbeit war es, zu überprüfen, ob die Untersuchungen der okulären Hämodynamik mit dem OPFA-Gerät in einem gesunden Probandenkollektiv unterschiedlichen Alters zu einem festgelegten Zeitpunkt reproduzierbar sind. Methoden und Material: Die vorliegende Studie war als kontrollierte monozentrische, prospektive, einarmige Studie geplant. Das Ziel der Studie bestand im Nachweis der Reproduzierbarkeit der Messungen mit dem OPFA-Gerät der Firma taberna pro medicum (tpm), Lüneburg, Deutschland. Es wurden insgesamt 145 OPFA-Untersuchungen (290 Augen) bei 47 augengesunden Probanden durchgeführt. Die Probanden wurden zunächst von zwei (unterschiedlichen) Untersuchern untersucht. Im zweiten Schritt wurden 13 augengesunde Probanden von den beiden Untersuchern mehrfach untersucht, wobei jeder Proband zweimal von zwei Untersuchern untersucht wurde, um in einem komplexen statistischen Modell gleichzeitig die Wiederholbarkeit und die Reproduzierbarkeit der Messungen zu prüfen. Geprüft wurden die OPFA-Messwerte retinaler und ziliarer Perfusionsdruck (OPPret, OPPcil), retinaler und ziliarer Blutdruck (OBPret, OBPcil), maximales okuläres Pulsblutvolumen und Pulsblutminutenvolumen (PVmax, PMVmax) sowie die autoregulatorische Kapazität (AC). Zur Prüfung wurde eine zweifaktorielle Varianzanalyse eingesetzt (1. Faktor: Proband, 2. Faktor: Untersucher [Operator] und Wechselwirkungen zwischen Probanden und Untersucher). Statistische Methoden: Die resultierenden Daten wurden der SOSTANA GmbH in Form von EXCEL-Dateien zur Verfügung gestellt. Nach entsprechender Datenaufbereitung und -kontrolle erfolgte in der CRO (Clinical Research Organization) SOSTANA die Übertragung der medizinischen Daten in das SPSS-Format zur weiteren Verarbeitung mit dem Statistik-Programmsystem IBM© SPSS© Statistics. Mit Hilfe der zweifaktoriellen Varianzanalyse (ANOVA) wurden die Wiederholbarkeit und die Reproduzierbarkeit getestet. Ergebnisse: Die statistische Auswertung beginnt mit einer beschreibenden Statistik für die untersuchten Probanden und alle Messungen, wobei die Resultate stets getrennt für beide Augen und nach den beiden Untersuchern angegeben wurden. Die Messungen mit dem OPFA-Gerät ergeben statistisch signifikante Ergebnisse, d.h. das Gerät ist in der Lage, die Unterschiede zwischen den Probanden zu erkennen, und die Messungen sind reproduzierbar, weisen also weder einen Untersucher-Effekt noch einen Wechselwirkungseffekt auf. Schlussfolgerung: Mit dem OPFA-Gerät lassen sich reproduzierbare und stabile Messergebnisse erzielen. OPPret, OPPcil, OBPret, OBPcil, PVmax, PMVmax und AC sind geeignete Parameter, um die Leistungsfähigkeit der okulären Hämodynamik zu beurteilen und um Störungen der Augendurchblutung frühzeitig zu erkennen., Background: The Ocular Pressure Blood Flow Analyzer (OPFA) measures for the first time noninvasively and simultaneously the ocular blood flow in relation to the ocular perfusion pressure (OPP) and the autoregulatory capacity (AC) of the ocular perfusion in both eyes without dilating the pupils. Purpose: The objective was whether OPFA examination of the ocular hemodynamics in healthy volunteers of different ages can be reproduced at a specific point in time. Methods and material: The present study was planned as a controlled monocentric, prospective, one-arm study. The study was aimed at demonstrating whether measurements with the OPFA device produced by taberna pro medicum (tpm), Lüneburg, Germany are reproducible. A total of 145 OPFA exami-nations (290 eyes) were carried out on 47 healthy subjects. The subjects were initially examined by two (different) examiners. In the second step, 13 healthy eyes subjects were examined several times by the two examiners, whereby each subject was exam-ined twice by two examiners in order to simultaneously determine the repeatability and the reproducibility of the measurements in a complex statistical model. The following OPFA measurements were checked: retinal and ciliary OPP, retinal and ciliary blood pressure, the ocular pulse blood volumes and the AC. A two-factorial analysis of variance was used for the test (1st factor: test subject, 2nd factor: investigator [operator] and interactions between test subject and investigator). Statistical methods: The resulting data was made available to SOSTANA GmbH in the form of EXCEL files. After appropriate data processing and data control, the medical data was transferred to SPSS format in CRO SOSTANA GmbH for further processing with the statistics pro-gram system IBM © SPSS © Statistics. With the help of the two-factorial analysis of variance (ANOVA), the repeatability and reproducibility) were tested. Results: The statistical evaluation started with a descriptive statistic for the examined subjects and all measurements, whereby the results were always indicated separately for both eyes and based on which examiner conducted the test. The OPFA measurements yielded statis-tically significant results, that is the device is able to differentiate between the test sub-jects and does not show an operator effect or an interaction effect. Conclusion: The OPFA device produces reproducible and stable measurement results to assess ocular hemodynamics and recognize early on any circulatory disturbances in the eye.

Low ocular perfusion pressure (OPP) may increase the risk of optic neuropathy. This study investigated the effects of OPP on the ganglion cell complex (GCC) and optic nerve head-retinal nerve fibre layer (ONH-RNFL) thickness in presumed systemic hypotensives (PSH). Fifteen participants with PSH and 14 controls underwent automated sphygmomanometry and Icare tonometry to calculate OPP: mean OPP (MOPP), systolic OPP (SOPP), and diastolic OPP (DOPP). ONH-RNFL and macula GCC thickness were evaluated using the Optovue iVue optical coherence tomographer. Statistical analysis comprised independent t-tests, the Mann–Whitney U test and binary logistic regression analysis. There was no significant difference when comparing ONH-RNFL and macula GCC thickness between both groups. Increased MOPP (OR = 0.51, 95% CI: 0.27–0.97, p = 0.039) and SOPP (OR = 0.79, 95% CI: 0.64–0.98, p = 0.035) were significantly associated with a decreased risk of reductions in GCC total thickness. Increased SOPP (OR = 0.11, 95% CI: 0.01–0.89, p = 0.027) was significantly associated with a decreased risk of reductions in the average ONH-RNFL thickness. The study found no significant retinal thickness changes in PSH’s, in comparison to the controls. The study established that, by increasing MOPP and SOPP, there was a decreased risk of reductions in the total GCC thickness and average ONH-RNFL thickness. Higher SOPP may decrease the possibility of retinal thinning of the GCC and ONH-RNFL. However, higher MOPP may decrease the odds of thinning of the GCC before ONH-RNFL changes.

Potential differences in the nature of the influences of aging and gender on the optic nerve head (ONH) microcirculation, using laser speckle flowgraphy (LSFG) were evaluated. We studied 908 healthy subjects (men = 701, age: 50.0 ± 9.1 yrs, women = 208, 49.8 ± 9.5 yrs, p = 0.76). The average, maximum (Max), and minimum (Min) mean blur rate (MBR) in a heartbeat were evaluated. The parameters were analyzed separately for the tissue, vessels, and throughout the ONH (All). We investigated which MBR sections are correlated with gender and age by univariate and multivariate regression analyses. The Max MBR-All (r = −0.31) was most strongly correlated with gender (men = 1, women = 0). The Min MBR-All (r = −0.24) was most strongly correlated with age, followed by Min MBR-All (r = −0.20). The factors contributing independently to the Max MBR-All were gender (β = −0.15), pulse pressure, spherical refraction, ocular perfusion pressure, and red blood cell (RBC) count. The factors contributing independently to the Min MBR-Vessel were gender (β = −0.09), age (β = −0.25), body mass index, heart rate, and spherical refraction. The factors contributing independently to the Min-MBR-All were age (β = −0.22), heart rate, and RBC count. Our results revealed that gender differences influence the Max MBR, and aging influences the Min MBR. These correlations were stronger than that of average MBR.

Background: Recent investigations show that phacoemulsification causing an inflammatory insult to the eye has an effect not only on retina but on the choroid as well. The purpose of this study was to evaluate the subfoveal choroidal thickness (SFCT) after uneventful phacoemulsification using swept-source optical coherence tomography (SS-OCT). Methods: This prospective study included 30 eyes of 23 patients with senile cataract undergoing uncomplicated phacoemulsification and intraocular lens implantation. SFCT and foveal retinal thickness (FRT) measurements were made at the same time, 1-2 PM preoperatively (P), 1 month (M1) and 3 months (M3) postoperatively using 1050 nm DRI Triton SS-OCT (Topcon, Tokyo, Japan). Postoperative changes in the SFCT, FRT and correlation of SFCT change with axial length, age, baseline intraocular pressure (IOP), IOP change were assessed. Results: The mean SFCT increased statistically significantly 3 months after surgery in all sectors except the superior inner region. Of the factors affecting the SFCT, the change in the SFCT (M3/P), correlation with age and baseline IOP in almost all sectors was observed. The mean FRT increased significantly after the surgery in all sectors. Conclusions: Insignificant subclinical increase in SFCT was observed 1 month after the cataract surgery. Significant increment in SFCT was detected 3 months postoperatively, which was correlated with surgery-induced IOP and ocular perfusion pressure change in the short term.

AimsTo investigate changes in ocular perfusion following three consecutive intravitreal injections with aflibercept for treatment of neovascular age-related macular degeneration (nAMD).MethodsThe study included 20 eyes from 20 Caucasian patients with unilateral nAMD and 20 fellow eyes. All nAMD eyes were treated with standard intravitreal injection of aflibercept (IVA; 2 mg). Measurements of ocular perfusion at the optic nerve head (ONH) and the choroid were performed with laser speckle flowgraphy (LSFG). Measurements were conducted at baseline, 1 week after the first injection, at the time point of the second and third injection as well as 1 month after the third injection.ResultsIn treated eyes, mean blur rate (the main output parameter of LSFG) in the ONH microvasculature and in the choroid was significantly reduced 1 week after the first IVA treatment. The effect persisted throughout the entire follow-up period (pConclusionsIVA for treatment of nAMD leads to a reduction in perfusion of the ONH and the choroid in the treated eye with no apparent effect on the fellow eye.

Primary open angle glaucoma is the most common form of glaucoma and it remains asymptomatic until the late stage of the disease. The purpose of this study is to compare the mean ocular perfusion pressure with the primary open angle glaucoma. A total of 60 study subjects were divided into two following groups: a) newly diagnosed patients with primary open angle glaucoma (case) and b) age and sex-matched healthy volunteers (control). The intraocular pressure and blood pressure were measured 3 hourly from 8:00 am to 11:00 pm. The mean ocular perfusion pressure of the right eyes in untreated primary open angle glaucoma was 39.9 ± 7.5 mm Hg whereas it was 47.7 ± 7.7 mm Hg in the control. The odds ratio was 6.6 (95% CI, 2.1-20.5; p=0.002). The right eyes of untreated primary open angle glaucoma had 6.6 times more risk compared to the control group. The mean ocular perfusion pressure of left eyes in untreated primary open angle glaucoma was 39.9 ± 7.5 mm Hg and 48.6 ± 4.0 mm Hg in the control group. The odds ratio was 5.7 (95% CI, 1.8-17.5; p=0.004). The left eyes of untreated primary open angle glaucoma had 5.7 times more risk compared to control group. The findings revealed the evidence of vascular mechanism in glaucoma pathogenesis: Reduction of mean ocular perfusion pressure ≤48 mm Hg, may lead to daily repetitive ischemic insult to the optic nerve.

The present study aims to investigate the effect of temporary cerebrospinal fluid pressure (CSFP) reduction on optic nerve head (ONH) and macular vessel density (VD) using optical coherence tomography angiography. Forty-four eyes of 44 adults with diagnostic lumbar puncture and CSFP reduction were recruited. Thirty-two eyes of 32 healthy volunteers were controls. ONH and macular VD images were evaluated differences between baseline and after CSFP reduction. The results showed that the mean CSFP decreased from (11.6±2.1) mmHg to (8.2±3.4) mmHg (P 0.05). In the study group, decreased VD in the macular parainferior region was associated with CSFP reduction (R2=0.192, P=0.003), the reduction of macular VD in parafoveal (R2=0.098, P=0.018), parainferior (R2=0.104, P=0.021), parasuperior (R2=0.059, P=0.058), paranasal (R2=0.057, P=0.042), paratemporal (R2=0.079, P=0.026) was associated with mean ocular perfusion pressure decrease following CSFP reduction. ONH vessel density did not differ after CSFP reduction (all P>0.05). In conclusion, macular vessel density decreased in association with CSFP reduction. Retinal vessel density in the macular region is more sensitive than that in peripapillary region after CSFP reduction.

Summary Background The main risks for glaucoma are increased intraocular pressure (IOP) and decreased ocular perfusion pressure (OPP). This review aims to examine the potential impact of lower limb isometric resistance exercise on intraocular pressure and ocular perfusion pressure. Method A meta-analysis was conducted to determine the potential impact of isometric exercise on IOP and OPP. The literature on the relationship between isometric resistance exercise and IOP was systematically searched according to the “Cochrane Handbook” in the databases of Pubmed, Web of Science, EBSCO, and Scopus through December 31, 2020. The search terms used were “exercise,” “train,” “isometric,” “intraocular pressure,” and “ocular perfusion pressure,” and the mean differences of the data were analyzed using the Stata 16.0 software, with a 95% confidence interval. Results A total of 13 studies, which included 268 adult participants consisting of 162 men and 106 women, were selected. All the exercise programs that were included were isometric resistance exercises of the lower limbs with intervention times of 1 min, 2 min, or 6 min. The increase in IOP after intervention was as follows: I2 = 87.1%, P = 0.001 using random-effects model combined statistics, SMD = 1.03 (0.48, 1.59), and the increase in OPP was as follows: I2 = 94.5%, P = 0.001 using random-effects model combined statistics, SMD = 2.94 (1.65, 4.22), with both results showing high heterogeneity. Conclusion As isometric exercise may cause an increase in IOP and OPP, therefore, people with glaucoma and related high risk should perform isometric exercise with caution.

To evaluate short-term retinal and choroidal vascularity changes in the healthcare professionals after four hours of use filtering facepiece respirators (FFR).This prospective study included 20 healthcare professionals. Oxygen saturation, pulse rate, systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), mean ocular perfusion pressure (MOPP), and spectral domain optical coherence tomography (OCT) imaging were evaluated at baseline and after four hours wearing of FFP3 FFRs without an exhalation valve. Superior temporal artery (STA), inferior temporal artery (ITA), superior temporal vein (STV), and inferior temporal vein (ITV) diameter were measured from OCT images. The total subfoveal choroidal area (TCA), luminal area (LA), stromal area (SA) choroidal vascularity index [(CVI), the ratio of LA to TCA] were determined after binarization of enhanced depth imaging OCT (EDI-OCT) images of the choroid.The mean age of the participants was 27.35 ± 2.80 years (range, 25-34). Eight of them were female and 12 were male. After wearing the FFR for four hours, a significant decrease was observed in the mean DBP (The current study shows that after four hours usage of FFR, in addition to systemic changes, retinal and choroidal vascularity might be affected significantly. With further studies, long-term effects and clinical significance of these short-term changes should be investigated on healthcare professionals.

Introduction: Various haemodynamic factors have been implicated as pathophysiological mechanisms in Primary Open Angle Glaucoma (POAG) other than raised Intraocular Pressure (IOP). However, the exact relationship still remains unclear. Aim: To examine the circadian pattern of Blood Pressure (BP), IOP and Ocular Perfusion Pressure (OPP) with the aim of understanding their relationships in a cohort of patients with POAG. Materials and Methods: A cross-sectional study was conducted in which 44 cases of newly diagnosed, non-hypertensive patients with POAG were enrolled and categorised based on the severity of glaucoma. Recording of BP and IOP were done every 4th hourly during a 24 hour hospital stay. The Mean OPP (MOPP) was calculated as 2/3×Mean Arterial Pressure (MAP)-IOP. Systolic OPP (SOPP) was calculated as Systolic BP-IOP and Diastolic OPP (DOPP) was calculated as Diastolic BP-IOP. The diurnal, nocturnal and 24 hour fluctuations were derived from the difference between the highest and lowest values within each period. Data was analysed using Statistical Package for the Social Sciences (SPSS) version 16.0. Univariate and multivariate regression analysis of the variables with age and severity of POAG were performed Results: Significant positive correlation of the nocturnal fluctuations in MAP (r=0.533), SOPP (r=0.835), DOPP (r =0.768), MOPP (r=0.685) and 24 hour fluctuation in MOPP (r=0.636) were noted with severity of glaucoma on multivariate analysis. No significant correlation of these parameters with age was noted on multivariate analyses. Conclusion: Nocturnal dip in OPP was an important observation among patients with POAG, potentially contributing to its pathophysiology.

SIGNIFICANCE This study increases foundational knowledge about the dynamic relationships between intraocular pressure (IOP), blood pressure (BP), and mean ocular perfusion pressure (MOPP) in the setting of steep Trendelenburg positioning and may inform medical decision making for patients in which this positioning is planned. PURPOSE The purpose of this study was to explore the demographic and clinical factors related to IOP, MOPP, and BP change during Trendelenburg positioning in a large sample of subjects. METHODS A single-cohort interventional study was conducted at the American Academy of Optometry 2017 annual meeting. Baseline demographic data were collected by a secure survey tool. IOP and BP were then measured while seated and again after 1 and 2 minutes in a steep Trendelenburg position. Raw and percentage differences for each variable were compared between time points, and regression analyses demonstrated factors related to change in IOP, BP, and MOPP during steep Trendelenburg positioning. RESULTS Median IOP increased from 16.3 mmHg (13.3 to 18.3 mmHg) at baseline to 25.0 mmHg (21.7 to 28.7 mmHg) at 1 minute after assuming the Trendelenburg position. More than 95% of individual eyes exhibited an IOP increase of at least 10%, and 45% had an IOP increase of 10 mmHg or greater. Correspondingly, MOPP fell from 50.3 mmHg (43.4 to 55.4 mmHg) at baseline to 36.3 mmHg (31.9 to 43.3 mmHg). Mean ocular perfusion pressure decreased by at least 10 in 90% of eyes. In multivariate regression analysis, factors independently related to percentage IOP increase were increasing weight, less myopic refractive error, lower baseline pulse, and lower baseline IOP (total r = 0.31, P < .001). Conversely, weight was the only variable independently related to percent MOPP change, and this relationship was weak (r = 0.05, P = .008). CONCLUSIONS Our results confirm that steep Trendelenburg positioning causes an increase in IOP and a decrease in MOPP in almost all eyes. Considering the identified causative factors will inform clinical education and provide foundational knowledge for future investigations.

Low ocular perfusion pressure (OPP) has been proposed as an important risk factor for glaucoma development and progression, but controversy still exists between studies. Therefore, we conducted a systematic review and meta-analysis to analyze the association between OPP and open-angle glaucoma (OAG). Studies were identified by searching PubMed and EMBASE databases. The pooled absolute and standardised mean difference in OPP between OAG patients and controls were evaluated using the random-effects model. Meta-regression analysis was conducted to investigate the factors associated with OPP difference between OAG patients and controls. A total of 43 studies were identified including 3,009 OAG patients, 369 patients with ocular hypertension, and 29,502 controls. The pooled absolute mean difference in OPP between OAG patients and controls was −2.52 mmHg (95% CI −4.06 to −0.98), meaning significantly lower OPP in OAG patients (P = 0.001). Subgroup analyses showed that OAG patients with baseline IOP > 21 mmHg (P = 0.019) and ocular hypertension patients also had significantly lower OPP than controls (P P = 0.996). In conclusion, although no causal relationship was proven in the present study, our findings suggest that in patients with high baseline IOP, who already have a higher risk of glaucoma, low OPP might be another risk factor.

Purpose To determine whether the blood flow in the superior retina is significantly different from that in the inferior retina, and to determine whether the posture affects the blood flow in the superior and inferior retina. Methods The blood flow in the vessels around the optic nerve head was measured by laser speckle flowgraphy in the sitting position in 68 healthy subjects. The blood flow in the superior peripapillary retina was compared with that in the inferior peripapillary retina. The measurements of the blood flow were performed in the sitting position, and the effect of switching to a supine position was determined at 2, 4, 6, 8, 10, and 30 minutes after the switch. Results The total relative flow volume (RFV)-all, RFV-artery, and RFV-vein were significantly greater in the superior retina than in the inferior retina (all P < 0.001). The mean diameter-all and mean diameter-artery in the superior retina were significantly larger than that in the inferior retina (all P < 0.05). The mean blur rate (MBR)-all, MBR-artery, and MBR-vein in the superior retina were also greater than that in the inferior retina (P < 0.001, P < 0.01, and P < 0.001, respectively). Although the ocular perfusion pressure was significantly changed with the postural alteration, the total RFV-all remained greater in the superior retina than in the inferior retina after the postural change. Conclusions Clinicians need to be aware of the differences in the blood flow between the superior and inferior retinal peripapillary area when considering the mechanisms of retinochoroidal diseases.

Significance The use of blood flow restriction allows obtaining beneficial physical adaptions when combined with low-intensity exercise or even when used alone. We found that using blood flow restriction may be a potential strategy to avoid IOP and ocular perfusion pressure fluctuations provoked by strength and endurance training. Purpose The purpose of this study was to assess the influence of bilateral blood flow restriction in the upper and lower body at two different intensities on IOP and ocular perfusion pressure, as well as the possible sex differences. Methods Twenty-eight physically active university students (14 men and 14 women) took part in the study, and blood flow restriction was bilaterally applied with two pressures in the legs and arms. There were five experimental conditions (control, legs-high, legs-low, arms-high, and arms-low). IOP was measured by rebound tonometry before, during (every 4 seconds), and immediately after blood flow restriction. Ocular perfusion pressure was measured before and after blood flow restriction. Results We found that only the arms-high condition promoted a statistically significant IOP rise when compared with the rest of the experimental conditions (all Bayes factors10, >100; effect sizes, 1.18, 1.06, 1.35, and 1.73 for the control, arms-low, legs-high, and legs-low conditions, respectively). For ocular perfusion pressure, there was strong evidence for the null hypothesis regarding the type of blood flow restriction (Bayes factor10, 0.012); however, men showed an ocular perfusion pressure reduction after blood flow restriction in the arms-high condition (Bayes factor10, 203.24; effect size, 1.41). Conclusions This study presents preliminary evidence regarding the safety of blood flow restriction in terms of ocular health. Blood flow restriction may be considered as an alternative training strategy to reduce abrupt fluctuations in IOP and ocular perfusion pressure because its use permits a considerable reduction of exercise intensity.

Background: The purpose of this pilot study was to investigate the differences in neurovascular coupling between Caucasian patients with normal tension glaucoma (NTG) and healthy subjects (HS) with...

Purpose To determine the incidence of parapapillary choroidal microvasculature dropout (MvD) in nonglaucomatous healthy eyes using optical coherence tomography angiography (OCTA) and to characterize the MvD observed in these eyes. Methods Seventy-six eyes (19 eyes with an MvD and 57 age-matched eyes without an MvD) from a cohort of 297 nonglaucomatous healthy eyes that underwent OCTA were included. The peripapillary choroidal microvasculature was evaluated in en-face images obtained using swept-source OCTA. An MvD was defined as a focal sectoral capillary dropout with no visible microvascular network identified in the en-face images of the choroidal layer. The incidence of MvD and clinical characteristics associated with the presence of an MvD was determined. Results MvD was found in 19 of the 297 nonglaucomatous healthy eyes (6.4%). Compared with age-matched eyes without an MvD, eyes with an MvD had lower systolic blood pressure (p = 0.021), diastolic blood pressure (p = 0.048), mean arterial pressure (p = 0.025) and mean ocular perfusion pressure (p = 0.032). Logistic regression analyses showed that cold extremities (p = 0.046), lower mean arterial pressure (p = 0.021) and lower mean ocular perfusion pressure (p = 0.023) were associated with the presence of an MvD. Conclusions Parapapillary choroidal MvD can be present in nonglaucomatous healthy eyes. The presence of an MvD is associated with systemic vascular dysregulation.

Optical coherence tomography angiography (OCTA) is a novel imaging modality that provides visualization and, in some machines, quantification of microcirculation in the superficial optic nerve, peripapillary retina, and the macula of glaucoma patients in a noninvasive fashion. Among commercially available OCTA devices, the AngioVue® (Optovue Inc., Fremont, CA), Swept-Source OCT Angio® (Topcon Corporation, Tokyo, Japan), and Spectralis angiography module (Heidelberg Engineering, Germany) are based on amplitude-derived algorithms [1]. The Angioplex® and PlexElite® (Zeiss Meditec Inc., Dublin, CA) employ a combination of amplitude and phase-variance techniques [2]. High intra-visit repeatability and inter-visit reproducibility have been demonstrated [3, 4].

Purpose Glaucoma studies have long taken into account the blood pressure (BP) status of patients. This study summarizes and evaluates the impact of the different criteria that have been used for BP-related variables in glaucoma research. Methods Studies included in two meta-analyses that reviewed the role of BP in glaucoma were analyzed. Additional studies published after the search periods of the meta-analyses were also included. Criteria for the definition of arterial hypertension and other BP-related variables, such as mean arterial pressure (MAP) and mean ocular perfusion pressure (MOPP), were retrieved. Results Sixty-four studies were evaluated. One-third used 140 mmHg as a systolic BP cut-off to define hypertension, 20% used 160 mmHg and the remaining half used various other criteria. Less than 20% of studies reported MAP and/or MOPP. While eight of the ten studies reporting MAP used a correct formula that only happened for five of the eleven studies reporting MOPP. Using as an example average blood pressure values, incorrectly used formulas could have led to an overestimation of more than 100% of the expected values. Conclusion Considerable heterogeneity exists in BP-related variables in glaucoma research and different definitions can lead to large disparities. Glaucoma research would benefit from a consensus regarding blood pressure parameters.

Purpose: The purpose of the study was to determine the 24-h effects of pilocarpine 2% ophthalmic solution on intraocular pressure (IOP) and ocular perfusion pressure (OPP) when used in addition to prostaglandin analog (PGA) therapy. Methods: Twenty-seven patients with ocular hypertension (OHTN) or open angle glaucoma who were receiving stable monotherapy with a PGA were admitted to an inpatient sleep laboratory for 24-h monitoring of IOP, blood pressure (BP), and heart rate over 2 separate visits. The first baseline visit was performed under PGA monotherapy only. During the second 24-h visit, pilocarpine 2% was administered four times daily in addition to their normal PGA dosing. For each study visit, measurements of all study metrics were performed every 2 h in the habitual position. OPP was calculated as 2/3[diastolic BP +1/3(systolic BP – diastolic BP)] – IOP. Results: During the diurnal period, pilocarpine significantly reduced IOP from a baseline of 18.2 ± 0.5 mmHg on PGA monotherapy to 17.1 ± 0.4 mmHg, P

We aimed to evaluate the influence of the level of effort during four basic resistance exercises leading to muscular failure on intraocular pressure (IOP) and ocular perfusion (OPP), as well as the role of exercise type and sex.Twenty-five young adults (12 women) performed 10 repetitions against their 10-RM (repetition maximum) load in the squat, military press, biceps curl and calf raise exercises. IOP was measured before, during and after exercise, whereas OPP was indirectly assessed before and after each exercise.There was a progressive IOP rise during exercise (p 0.001, η² = 0.531), which was dependent on exercise type (p = 0.020, η² = 0.125). The squat exercise induced higher IOP increments in comparison to the other exercises (corrected p-values 0.001), and higher IOP values were found for the military press and biceps curl than for the calf raise exercise (corrected p-values = 0.012 and 0.002). OPP exhibited a significant reduction when leading to muscular failure (p = 0.001, η² = 0.364), being statistically significant for the squat and military press exercises (corrected p-values = 0.037 and 0.047). No effect of sex was found for IOP and OPP (p 0.05).A single set of resistance training leading to muscular failure causes an instantaneous and progressive IOP rise in healthy young individuals. These IOP rises depend on exercise type (squat military press = biceps curl calf raise), but not on participant´s sex. OPP diminished as a consequence of performing resistance training exercise, being statistically significant for the squat and military press exercises. Future studies should include glaucoma patients aiming to corroborate the generalizability of our findings.

To provide the reader with information on the principal techniques of optical coherence tomography angiography (OCTA); the current literature on OCTA reproducibility; its applications to glaucoma detection and monitoring of progression; and the role of OCTA in the assessment of the vascular component in glaucoma pathogenesis.A literature review of the pertinent publications for the OCTA in relation to the development, techniques, and its use in glaucoma was carried out.Rapid improvements in optical coherence tomography (OCT) technology have allowed for enhancement of both image resolution and scanning speed, and the development of vascular assessment modality. OCTA is the non-invasive in vivo imaging of the vasculature located within the retina and optic nerve head area. The principle of OCTA is to use the variations in OCT signals caused by moving particles as the contrast mechanism for imaging of flow. Several algorithms which aim to maximize the contrast signal and minimize the noise have been developed including the phase-based techniques, intensity-based techniques (e.g., split-spectrum amplitude decorrelation angiography (SSADA)), and complex-based techniques (e.g., optical microangiography (OMAG)). With its reliable technique, high image resolution, and current availability, OCTA has been widely used in the assessment of posterior segment diseases including glaucoma in which ocular perfusion dysfunction has been proposed as a pathophysiological mechanism.OCTA may enhance our knowledge of glaucoma pathogenesis and offer an improvement in our ability to detect glaucomatous change.

Purpose. To investigate changes in eye coats, axial length, and ocular perfusion pressure (OPP) in hemodialysis (HD) patients with chronic renal failure (CRF). Methods. We included HD patients who were diagnosed with CRF in our hospital from January to December 2015. Fifty-two patients met the inclusion criteria; all right eyes were used for observation. Systolic and diastolic blood pressures were recorded to calculate OPP. Approximately 30 minutes before and after HD, we recorded multiple parameters, including lens thickness (LT), axial length of vitreous (VAL), axial length of eye (EAL), ciliary body thickness (CBT), choroidal thickness (CT), and retinal thickness (RT). Results. After HD, OPP significantly decreased (P<0.01, F=7.023) and CBT became significantly thinner (P<0.01, t=3.461). CT was significantly thinner and differed among measurement locations (P<0.01, t=6.240; P<0.01, t=6.169; P<0.01, t=3.405, respectively, fovea, nasal, and temporal side 1500 μm beside the fovea). Further, RT thickened and differed among measurement locations (P<0.05, t=−2.265; P<0.05, t=−2.624; P<0.05, t=−2.220, respectively, fovea, nasal, and temporal side 1500 μm beside fovea), whereas LT, VAL, and EAL significantly increased after HD (P<0.05, t=−2.076; P<0.01, t=−3.817; P<0.01, t=−4.010). Conclusions. HD impacts the thickness of the eye coats and VAL, particularly affecting CBT, CT, and RT. OPP transiently decreases during HD, which may contribute to an ischemic state.