Diurnal variations in blood flow at optic nerve head and choroid in healthy eyes: diurnal variations in blood flow

The Effect of β-Blocker Eye Drops on Pulse Rate, Ocular Blood Flow, and Glaucoma Progression: A Retrospective Longitudinal Study

INTRODUCTION

Our study was conducted to determine factors associated with the effectiveness of a β-blocker eye drop add-on in altering pulse rate (PR) in glaucoma patients.

METHODS

This retrospective study examined 236 eyes of 138 patients who received a β-blocker eye drop add-on during follow-up. Patients were included if at least one PR measurement was available both before and after the add-on was started. We collected data on ophthalmic parameters: longitudinal PR; longitudinal choroidal blood flow, represented by laser speckle flowgraphy-measured mean blur rate (MBR); and diacron-reactive oxygen metabolites (d-ROMs). We used a multivariable linear mixed-effects model to investigate the effectiveness of the β-blocker eye drop add-on in altering PR and examined factors contributing to a larger PR alteration after the add-on was started by analyzing the effect on PR of the interaction term between the add-on and clinical factors. We used the k-means method to classify the patients.

RESULTS

The β-blocker eye drop add-on reduced PR (- 7.61 bpm, P < 0.001). Female gender, higher PR when the add-on was started, lower central corneal thickness, and a higher d-ROM level were associated with greater reduction in PR (P < 0.05). In a cluster of patients with these clinical features, choroidal MBR increased by + 3.42% when we adjusted for change over time; MD slope, which represents the speed of glaucoma progression, improved by + 0.64 dB/year (P < 0.05).

CONCLUSIONS

We identified a glaucoma subgroup in which PR decreased, choroidal blood flow increased, and glaucoma progression slowed after a β-blocker eye drop add-on was started.

Retinal thickness and fundus blood flow density changes in chest pain subjects with dyslipidemia

AIM

To assess the retinal thickness and fundus blood flow density changes in chest pain patients with dyslipidemia using optical coherence tomography angiography (OCTA).

METHODS

All subjects with chest pain as the main symptom accepted a comprehensive ophthalmological examination. According to the serum lipid levels, the participants were divided into the control group and the dyslipidemia group. The retina thickness and fundus blood flow density were determined using OCTA.

RESULTS

The study enrolled 87 left eyes from 87 adults with dyslipidemia and 87 left eyes from age- and sex-matched participants without dyslipidemia. The retina of dyslipidemia subjects was significantly thinner than that of the controls in the inferior (P=0.004 and P=0.014, respectively) and temporal (P=0.015 and P=0.019, respectively) regions, both inner and outer layers. In terms of blood flow density in the macula or optic disk, there was a decreasing trend in the dyslipidemia group compared with the control group, especially in the inferior and temporal regions.

CONCLUSION

Dyslipidemia may contribute to the decrease in retinal thickness and fundus blood flow density. Further validation of the association between abnormal lipid metabolism and fundus microcirculation alterations needs to be carried out in chest pain patients.

Age-Related Alterations of the Macular Choroid in Healthy Eyes Assessed by Swept-Source Optical Coherence Tomography Angiography

OBJECTIVE

To analyze age-related changes in the choroid in healthy eyes using swept-source optical coherence tomography angiography (SS-OCTA).

PATIENTS AND METHODS

This was a cross-sectional, prospective, observational study enrolling 222 eyes of 116 healthy participants. SS-OCTA images were captured using the PLEX Elite 9000 (Carl Zeiss Meditec) with a 6 x 6 mm pattern centered on the fovea. Subfoveal choroidal thickness (CT) and choroidal volume (CV) were generated automatically through manufacturer tools available in the Advanced Retinal Imaging (ARI) hub network. Choroidal vascularity index (CVI) and choriocapillaris flow deficits (CCFD) were computed using ImageJ.

RESULTS

CV was found to be significantly higher in women than men. Overall, there was a significant positive correlation between CVI and CCFD, and a significant negative correlation between CT and CV with age. The relationship, however, was more complex, as a decade-wise analysis showed that CT and CV increased until the second decade, followed by a decrease until the sixth decade, and then an increase again in the seventh and eighth decades. CVI was highest in the seventh decade. In contrast, CCFD increased consistently with age and in all the Early Treatment of Diabetic Retinopathy Study (ETDRS) rings.

CONCLUSION

The choroidal blood flow and its thickness reduces as the age advances. While the choroidal flow deficits show a consistent increase with age and the distance from the foveal center, the relationship of other parameters with age is more complex. Having a normative database from healthy subjects is imperative for understanding the changes taking place in diseased states. Choroidal parameters can show significant variations with age. These differences are not uniform or consistent with age, highlighting the importance of a normative reference database to assess the significance of choroidal alterations associated with disease. [Ophthalmic Surg Lasers Imaging Retina 2023;54:526-534.].

IMI-The Dynamic Choroid: New Insights, Challenges, and Potential Significance for Human Myopia

The choroid is the richly vascular layer of the eye located between the sclera and Bruch's membrane. Early studies in animals, as well as more recent studies in humans, have demonstrated that the choroid is a dynamic, multifunctional structure, with its thickness directly and indirectly subject to modulation by a variety of physiologic and visual stimuli. In this review, the anatomy and function of the choroid are summarized and links between the choroid, eye growth regulation, and myopia, as demonstrated in animal models, discussed. Methods for quantifying choroidal thickness in the human eye and associated challenges are described, the literature examining choroidal changes in response to various visual stimuli and refractive error-related differences are summarized, and the potential implications of the latter for myopia are considered. This review also allowed for the reexamination of the hypothesis that short-term changes in choroidal thickness induced by pharmacologic, optical, or environmental stimuli are predictive of future long-term changes in axial elongation, and the speculation that short-term choroidal thickening can be used as a biomarker of treatment efficacy for myopia control therapies, with the general conclusion that current evidence is not sufficient.

Diurnal changes in choroidal optical coherence tomography angiography indices over 24 hours in healthy young adults

This prospective study investigated the magnitude and pattern of variation in choroidal optical coherence tomography angiography (OCT-A) indices every 4 h over 24 h in healthy young myopic (n = 24) and non-myopic (n = 20) adults. Choriocapillaris and deep choroid en-face images from macular OCT-A scans were analysed from each session to extract magnification-corrected vascular indices including choriocapillaris flow deficit number, size and density and deep choroid perfusion density in the sub-foveal, sub-parafoveal, and sub-perifoveal regions. Choroidal thickness was also obtained from structural OCT scans. Significant variations over 24 h (P < 0.05) were observed in most of the choroidal OCT-A indices excluding sub-perifoveal flow deficit number, with peaks observed between 2 to 6 AM. For myopes, peaks occurred significantly earlier (3-5 h), and the diurnal amplitude was significantly greater for sub-foveal flow deficit density (P = 0.02) and deep choroidal perfusion density (P = 0.03) compared with non-myopes. Choroidal thickness also showed significant diurnal changes (P < 0.05) with peaks between 2 to 4 AM. Significant correlations were found between diurnal amplitudes or acrophases of choroidal OCT-A indices and choroidal thickness, intraocular pressure, and systemic blood pressure. This provides the first comprehensive diurnal assessment of choroidal OCT-A indices over 24 h.

Orbital and ocular perfusion in thyroid eye disease

Thyroid eye disease (TED) is characterized by enlargement of extraocular muscles, an increase in retrobulbar fat, orbital fibrosis, and fluctuations in plasma thyroid hormone levels in most patients, often associated with raised autoantibody titers. The occurrence of orbital space conflict compromises the orbital perfusion, unchecked progression of which results in irreversible loss of visual acuity and visual fields. The quantitative assessment of orbital perfusion can be done by measurement of blood flow velocities in the superior ophthalmic vein (SOV), ophthalmic artery (OA), central retinal artery (CRA), and posterior ciliary artery by color Doppler imaging. The retinal and choroidal microvasculature is studied by optical coherence tomography and optical coherence tomography angiography. The orbital and ocular perfusion fluctuates during the course of TED. Orbital congestion is reflected by the reduction or reversal of SOV flow and an increase in subfoveal choroidal thickness. The active phase is characterized by high blood flow velocities of the OA and CRA. The onset of dysthyroid optic neuropathy is associated with reduced arterial perfusion and reduction in parafoveal and peripapillary vascular density. Orbital decompression improves the SOV flow and decreases the resistivity index of CRA. Sequential evaluation of orbital hemodynamic changes can thus supplement the clinical scoring systems for monitoring and planning intervention in TED.

Acute Increase in Ocular Microcirculation Blood Flow Upon Cholesterol Removal. The Eyes Are the Window of the Heart

BACKGROUND

Lipoprotein apheresis acutely increases coronary microvascular blood flow. However, measurement techniques are time-consuming, costly, and invasive. The ocular vasculature may be an appropriate surrogate and an easily accessible window to investigate the microcirculation. Recent advances in ocular imaging techniques enable quick, noninvasive quantification of ocular microcirculation blood flow. The insights from these techniques represent a significant opportunity to study the short-term changes in optic disk blood flow after lipoprotein apheresis for inherited hypercholesterolemia.

METHODS

This study was performed at the Italian Reference Center for Inherited Dyslipidemias in Tuscany. The study sample was comprised of 22 patients with inherited hypercholesterolemia who were previously studied for coronary microcirculation. Laser speckle flowgraphy (LSFG) was used to measure optic disk blood flow before and after lipoprotein apheresis. The main outcomes measures were average tissue blood flow (referred to as mean tissue) and arteriolar/venular average blood flow (referred to as mean vessel). Eyes were divided into 2 groups based on pre-lipoprotein apheresis optic disk blood flow values. P < .05 was considered statistically significant.

RESULTS

After each lipoprotein apheresis treatment resulting in the reduction of plasma lipids, there was a concurrent increase in all optic disk microcirculatory parameters. The increase was statistically significant in eyes with lower pre-apheresis optic disk blood flow values (mean tissue +7.0%, P < .005; mean vessel +7.2%, P < .05).

CONCLUSIONS

A single lipoprotein apheresis session resulted in a statistically significant short-term increase in optic disk blood flow. These findings together with previous coronary microcirculation data suggest a similar ocular and coronary blood flow response to lipoprotein apheresis. Ocular microcirculation may represent a versatile biomarker for evaluating systemic microcirculatory health, including coronary microcirculation. Hence, it is plausible that plasma lipoprotein levels may influence optic disk blood flow.

APSified OCT-angiography analysis: Macula vessel density in healthy eyes during office hours

PURPOSE

Optical coherence tomography angiography (OCT-A) can visualize retinal capillary microcirculation non-invasively. In order to investigate potential factors influencing OCT-A diagnostics, the aim of the present study was to determine circadian changes in macular vessel density (VD) in healthy adults during office hours, considering axial length (AL) and subfoveal choroidal thickness (CT).

METHODS

In the prospective study 30 eyes of 30 healthy subjects (mean age 28.7 ± 11.8, range 19-60 years) were recruited who underwent repeated measurements of AL, subfoveal CT and three-layer macula VD (superficial vascular plexus (SVP), intermediate capillary plexus (ICP) and deep capillary plexus (DCP)) on a single day at three predetermined timepoints (9 AM, 3 PM, and 9 PM). For better intra- and interindividual scan comparability, the new Anatomic Positioning System function (APS, part of Glaucoma Module Premium Edition [GMPE], Heidelberg Engineering, Germany) allowing analysis of identical retinal areas, was used for quantitative OCT-A analysis.

RESULTS

Overall mean macula VD was unchanged during office hours in SVP, ICP and DCP, respectively (p>0.05). In addition, AL and CT showed no statistically significant changes over time (p>0.05). Rather, a large interindividual variance of VD with different peak time was observed. Contrary to the overall data, sectorial VD changed in dependency of office hours in all layers with an increase of VD in SVP between 9 AM and 9 PM (p = 0.003), in ICP between 3 PM and 9 PM (p = 0.000), in DCP between 9 AM and 9 PM (p = 0.048), and 3 PM and 9 PM (p = 0.000), respectively.

CONCLUSION

Overall mean macula VD, subfoveal CT and AL tended not to show statistically significant changes over time in this cohort, whereas a regional analysis of VD did. Therefore, a circadian influence on capillary microcirculation should be kept in mind. Moreover, the results highlight the importance of a more detailed analysis of VD in different sectors and different vascular layers. In addition, the pattern of diurnal variation could vary inter-individually, thus a patient-specific fluctuation pattern would need to be considered when evaluating these parameters in clinical practice.

Waveform changes of laser speckle flowgraphy in the temporal optic nerve head and peripapillary atrophy after trabeculectomy in open-angle glaucoma

A prospective study was conducted on 33 eyes of 33 patients with open-angle glaucoma who underwent trabeculectomy to investigate hemodynamic changes in the temporal optic nerve head (ONH) and peripapillary atrophy (PPA) after trabeculectomy. Laser speckle flowgraphy of ONH and PPA was performed at baseline and at 1, 3, and 6 months postoperatively. The waveforms of the mean blur rate in the tissue area (MT) in the temporal ONH, βPPA (with Bruch’s membrane), and γPPA (without Bruch’s membrane) were evaluated. Mean intra-ocular pressure (IOP) decreased from 19.1 ± 0.8 to 8.5–9.6 ± 0.7 mmHg at postoperative visits. The average MT in the βPPA region increased significantly at all postoperative time points, whereas those in the ONH and γPPA regions remained unchanged. The blowout score (BOS) increased significantly, and the resistivity index decreased significantly at all time points in all regions, which was associated with decreased IOP. The current study showed two novel findings: MT increased after trabeculectomy only in βPPA, where the choroid was present. IOP decrease-associated BOS increase occurred postoperatively in all regions, which indicates that IOP reduction may decrease vascular transmural pressure and contribute to stable blood flow uniformly, despite structural differences between the regions.

Longitudinal Study of Optic Disk Perfusion and Retinal Structure in Leber's Hereditary Optic Neuropathy

Purpose

The purpose of this study was to evaluate optic disk perfusion and neural retinal structure in patients with subacute Leber's hereditary optic neuropathy (LHON) and LHON carriers, as compared with healthy controls.

Methods

This study included 8 patients with LHON in the subacute stage, 10 asymptomatic carriers of a LHON-associated mitochondrial DNA mutation, and 40 controls. All subjects underwent measurement of the retinal nerve fiber layer (RNFL) thickness, the ganglion cell-inner plexiform layer (GCIPL) thickness using optical coherence tomography and optic disk microvascular perfusion (Mean Tissue [MT]) using laser speckle flowgraphy (LSFG). Patients were re-examined after a median interval of 3 months from the baseline visit.

Results

LHON carriers had higher values of RNFL thickness, GCIPL thickness, and disk area than controls (P < 0.05), whereas MT was not different between the two groups (P = 0.936). Median MT and RNFL thickness were 32% and 15% higher in the early subacute stage of the disease than in controls (P < 0.001 and P = 0.001). MT declined below the values of controls during the late subacute stage (P = 0.024), whereas RNFL thickness declined later during the dynamic stage (P < 0.001). GCIPL thickness was lower in patients with LHON than in controls independently of the stage of the disease (P < 0.001).

Conclusions

The high blood flow at the optic disk during the early subacute stage may be the consequence of vasodilation due to nitric oxide release as compensation to mitochondrial impairment. Optic disk perfusion as measured by LSFG is a promising biomarker for LHON diagnosis and monitoring as well as an objective outcome measure for assessing response to therapies.

Choroidal thickness in patients with systemic arterial hypertension: a systematic review and meta-analysis

Background:

The global burden of hypertension is constantly increasing with adverse cardiovascular and ocular sequelae. The association between elevated blood pressure and choroidal thickness (CT), as assessed via optical coherence tomography (OCT), is poorly understood.

Objectives and Design:

Studies including hypertensive adults and normotensive controls undergoing OCT were evaluated for inclusion in this meta-analysis. The primary endpoint was CT difference between hypertensive and normotensive adults.

Data Sources and Methods:

We conducted a systematic review and after searching 1011 results from MEDLINE, ClinicalTrials.gov, medRxiv and Cochrane Library, six studies were deemed eligible and were pooled according to a random-effect model.

Results:

A statistically significant reduction in choroidal thickness was found in hypertensive adults ( n = 454) as compared with normotensive controls ( n = 365) [mean difference: −0.77; 95% confidence intervals: (−1.20, −0.34); p = 0.0004]. The main limitations of this meta-analysis are the relatively small population included and the high statistical heterogeneity ( I2 = 87%) among the various studies. Of note, after excluding one study the heterogeneity was markedly reduced.

Conclusion:

Choroidal thickness is reduced among hypertensive subjects compared with normotensive controls. This finding mandates further examination in the context of long-term clinical outcomes.

Investigation of the pathophysiology of the retina and choroid in Parkinson's disease by optical coherence tomography

Purpose

The pathology of Parkinson's disease (PD) is suspected to affect the retina and choroid. We investigated changes in the retina and choroid of patients with PD using optical coherence tomography.

Methods

We examined 14 patients with PD and 22 patients without PD. Patients without PD had no ophthalmic disease other than cataracts. In addition, it was also confirmed that there was no neurodegenerative disease. The retinal nerve fiber layer, ganglion cell layer + inner plexiform layer, and choroidal thickness were compared between both groups. Additionally, the choroidal image was divided into the choroid area, luminal area, and interstitial area using the binarization method, and the area of each region and the percentage of luminal area in the choroid area were analyzed.

Results

Patients with PD had a significantly thinner ganglion cell layer + inner plexiform layer compared to those without PD. The choroid area, luminal area, and interstitial area were significantly decreased in patients with PD compared to those without PD. Seven patients with PD who were successfully followed up showed decreased retinal nerve fiber layer and interstitial area after 3 years.

Conclusion

Autonomic nervous disorders and neurodegeneration in PD can cause thinning of the retina and choroid, as well as a reduction in the choroid area.

Relationship Between Changes in the Choroidal Structure and Blood Flow of the Macula After Trabeculectomy

Purpose

To elucidate the relationship between changes in the choroidal structure and blood flow of the macula after trabeculectomy.

Methods

A prospective study of 30 eyes of 30 patients with glaucoma who underwent trabeculectomy. Enhanced depth imaging optical coherence tomography with choroidal image binarization and laser speckle flowgraphy of the macula were performed at baseline and 1, 3, and 6 months postoperatively. Mixed-effects models with adjustment for confounders were used to analyze longitudinal changes in the mean choroidal thickness (mCT), mean choroidal vascular thickness (mCVT), mean choroidal interstitial thickness (mCIT), and mean blur rate (MBR).

Results

The decrease in the intraocular pressure (IOP; 45%–51%) and axial length (0.5%–0.8%) and the increase in ocular perfusion pressure (OPP; 34%–38%), mCT (16%–19%), mCVT (16%–20%), mCIT (17%–20%), and MBR (22%–25%) were significant at each postoperative time point (all P < 0.001). In the multivariate analysis, the mCVT changes were positively correlated with the OPP and MBR changes (P = 0.04 and P < 0.001, respectively), whereas the mCIT changes were negatively correlated with IOP changes (P = 0.005). The MBR changes correlated significantly with changes in mCVT but not mCIT (P < 0.001 and P = 0.39, respectively).

Conclusions

Thickness changes in the intraluminal and extraluminal parts of the choroid were closely associated with changes in blood flow and IOP, respectively, although both parts thickened comparably after IOP reduction by trabeculectomy.

Translational Relevance

The choroid reacts to IOP reduction differently between the intraluminal and extraluminal areas, blood flow dependence in the vascular area, and IOP dependence in the stromal area.

Diurnal Variation of Retinal Vessel Density in Healthy Human Eyes

PRECIS

A small increase in optic nerve head vessel density (VD), but not macular VD, in the evening compared with the morning is observed in healthy subjects.

PURPOSE

To evaluate the diurnal variation of the macular and optic nerve head (ONH) VD in healthy eyes as measured with optical coherence tomography angiography (OCT-A).

METHODS

In this prospective study of healthy individuals older than 18 years old, VD parameters, including macular whole image vessel density, parafoveal vessel density, ONH whole image vessel density, ONH whole image capillary density, circumpapillary vessel density (cpVD), and circumpapillary capillary density, were measured with OCT-A at 4 time points throughout the day (8 am, 12 pm, 4 pm, and 8 pm).

RESULTS

Twenty-nine healthy eyes were included from 15 subjects (mean age: 30.9 y). After adjustment for age and mean ocular perfusion pressure, a significant positive rate of change was found for cpVD (0.05%/h; P=0.027). In contrast, macular VD changes were not significantly different. When comparing morning (8 am and 12 pm) and evening (4 pm and 8 pm) measurements, there were small, but statistically significant, increases for all ONH measurements. The greatest increase was found for cpVD (0.58%; P=0.022). Significant but small increases in mean arterial pressure and mean ocular perfusion pressure were also observed.

CONCLUSIONS

There was a small increase in ONH VD, but not macular VD, in the evening compared with the morning in healthy human eyes. As the observed difference was within the measurement variability, our results suggest the timing of OCT-A examination does not affect retinal VD measurements.

Changes in pulse waveforms in response to intraocular pressure elevation determined by laser speckle flowgraphy in healthy subjects

Background

The influences of intraocular pressure (IOP) elevations on the pulse waveform in the optic nerve head (ONH) were evaluated using laser speckle flowgraphy (LSFG) in normal subjects.

Methods

This prospective cross-sectional study was conducted at the Nagoya University Hospital. An ophthalmodynamometer was pressed on the sclera to increase the IOP by 20 mmHg or 30 mmHg for 1 min (experiment 1, 16 subjects) and by 30 mmHg for 10 min (experiment 2, 10 subjects). The mean blur rate (MBR) and the eight pulse waveform parameters determined using LSFG were measured before, immediately after and during an IOP elevation, and after the IOP returned to the baseline pressure.

Results

A significant elevation in the IOP and a significant reduction in the ocular perfusion pressure (OPP) were found after applying the ophthalmodynamometer (both, P < 0.001). The blowout score (BOS) reduced significantly (P < 0.001), and the flow acceleration index (FAI; P < 0.01) and resistivity index (RI; P < 0.001) increased significantly immediately after increasing the IOP by 20 or 30 mmHg (experiment 1). The BOS reduced significantly (P < 0.001), and the FAI (P < 0.01) and RI (P < 0.001) increased significantly after the IOP elevation by 30 mmHg in both experiment 2 and 1. However, the BOS and RI recovered significantly at time 10 compared to that in time 0 (immediately after IOP elevation) during the 10-min IOP elevation (P < 0.001 and P = 0.008, respectively).

Conclusions

In conclusion, the BOS, FAI, and RI of the pulse waveforms changed significantly with an acute elevation in the IOP. The change should be related to the larger difference between the maximum and minimum MBRs during the IOP elevation.

Carotid endarterectomy restores decreased vision due to chronic ocular ischemia

BACKGROUND

The therapeutic effect of carotid endarterectomy (CEA) on visual disturbance caused by chronic ocular ischemia due to carotid artery stenosis has not been validated. This prospective observational study aims to investigate whether CEA is associated with an increase in ocular blood flow (OBF) and postoperative visual improvement.

METHODS

In total, 41 patients with carotid artery stenosis treated by CEA between March 2015 and September 2018 were enrolled in this study. OBF was evaluated by laser speckle flowgraphy, which can measure the mean blur ratio (MBR) which is well correlated to the absolute retinal blood flow. Visual acuity was assessed before and after CEA by subjective improvement and objective visual assessment using CSV-1000, an instrument used to test contrast sensitivity.

RESULTS

OBF increased after CEA on the operated side (mean MBR 33.5 vs 38.2, p < 0.001) but not on the non-operated side (mean MBR 37.8 vs 37.5, p = 0.50). After CEA, 23 patients (56.1%) reported subjective visual improvement on the operated side. The mean CSV-1000 score among the patients with increased OBF after CEA (5.44 vs 5.88, p = 0.04) but not among those without increased OBF (5.48 vs 5.95, p = 0.09). The mean CSV-1000 scores increased significantly after CEA in 18 patients with decreased vision and decreased OBF (4.51 vs 5.37, p < 0.001), but not in the 23 patients without those (6.19 vs 6.31, p = 0.6).

CONCLUSION

CEA may successfully reverse visual dysfunction caused by chronic ocular ischemia due to carotid artery stenosis by increasing OBF.

Relationship between proteinuria and optical coherence tomographic features of the chorioretina in patients with pre-eclampsia

This retrospective study aimed to evaluate the correlation between ophthalmologic factors and proteinuria in patients with pre-eclampsia using swept-source optical coherence tomography (OCT) and OCT angiography. In total, 61 pregnant patients diagnosed with pre-eclampsia were recruited during their hospital stay. The authors investigated the relationship between urine protein–creatinine ratio (PCR) and chorioretinal measurements including choroidal thickness (CT), choroidal vascularity index (CVI), foveal avascular zone (FAZ), vascular density (VD), ganglion cell layer+ (GCL+) and GCL++. The associations between mean arterial pressure (MAP) and ophthalmologic factors were also evaluated. Central subfield CT of the right eye (p = 0.031) and paracentral CT of both eyes were related to higher PCR (≥1.35 mg/mg). A significant association with PCR after logarithm transformation was noted (r = 0.284, p = 0.026). Retinal measurements (FAZ, VD, GCL+ and GCL++) and CVI were not related with PCR. There was a positive association between MAP and PCR after logarithm transformation (r = 0.296, p = 0.021); however, chorioretinal factors were not related with MAP. In pregnant women with pre-eclampsia, CT using OCT is a novel factor that is correlated with PCR. Ocular structural alteration in patients with pre-eclampsia may be one of systemic vascular changes caused by pre-eclampsia rather than hypertension.

Retinal and choroidal vascularity changes in healthcare professionals wearing FFP3 respirators

PURPOSE

To evaluate short-term retinal and choroidal vascularity changes in the healthcare professionals after four hours of use filtering facepiece respirators (FFR).

MATERIALS AND METHODS

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.

RESULTS

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 (p = 0.018), MAP (p = 0.016), and MOPP (p = 0.007) when compared to base-line values. STV diameter (p = 0.019) and ITV diameter (p = 0.046) measurements were found significantly higher than baseline measurements. A significant increase in the choroidal vascularity was observed in the LA (p = 0.004) and TCA values (p = 0.043) after wearing the FFR for four hours.

CONCLUSION

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.

Changes in Choroidal Component Ratio and Circulation After Coffee Intake in Healthy Subjects

Purpose

The effects of coffee intake on the ratio of stromal and luminal components in the choroid and the underlying mechanism remain unclear. This prospective cross-sectional study aimed to explore how coffee intake affects the choroidal component ratio and circulation.

Methods

Forty-nine right eyes of healthy adult volunteers were evaluated as the coffee intake group. Thirty-two right eyes of healthy volunteers served as the control group. The participants consumed 185 mL of coffee or water, respectively, and the systemic hemodynamics, enhanced-depth imaging optical coherence tomographic (EDI-OCT) images, and foveal mean blur rate (MBR), an indicator of blood flow velocity, were recorded at baseline and after coffee or water intake. The EDI-OCT images were binarized using ImageJ software, and subfoveal choroidal thickness (SCT) and whole, luminal, and stromal choroidal areas were calculated.

Results

In the coffee intake group, significant decreases in SCT and luminal area peaked at 60 minutes after intake (both P < 0.001), whereas a significant increase in MBR peaked at 30 minutes (P < 0.001). No significant stromal area fluctuations were observed. SCT and luminal area fluctuations exhibited a significant positive correlation (r = 0.978, P < 0.001). Significant negative correlations of luminal area fluctuations with MBR fluctuations were observed by stepwise regression analysis (r = -0.220, P < 0.001). The control group exhibited no significant fluctuations.

Conclusions

Coffee-induced choroidal thinning may result mainly from a reduction in the choroidal vessel lumen, and this vessel lumen reduction correlated with an increased choroidal blood flow velocity after coffee intake. These coffee-induced changes in choroidal component ratio and circulation should be considered when evaluating choroids.

Evaluation of retinochoroidal tissues in third trimester pregnants: An optical coherence tomography angiography study

INTRODUCTION

The structural and vascular changes in the retina and choroid in women in the third trimester of pregnancy were analyzed using optical coherence tomography angiography (OCTA).

METHODS

Forty women in the third trimester of uncomplicated pregnancy and 40 age-matched healthy women were included. Vascular density (VD) in the superficial and deep capillary plexuses (SCP/DCP), foveal density (FD), and foveal avascular zone (FAZ) area and perimetry measured with OCTA, as well as OCT measurements of central macular thickness (CMT) and choroidal thickness (CT) were compared between the groups. Correlations between structural OCT parameters and vascular OCTA metrics were analyzed.

RESULTS

The mean gestational age was 34 (28-41) weeks. Mean age was comparable in the groups (p = 0.732). The pregnant women had significantly higher parafoveal DCP-VD (p = 0.015), FAZ area (p = 0.044), and FD (p = 0.002). Mean subfoveal CT was 21 µm higher in pregnant women but was not significant (p = 0.472). There was no difference in CMT (p = 0.448). FAZ metrics were positively correlated with CT in pregnants and with CMT in the control group (p < 0.05). Parafoveal VD was negatively correlated with CT in the control group (p < 0.05). After adjusting for CT and CMT, the significant difference in VD and FD persisted (p < 0.05), while the difference in FAZ area lost significance (p > 0.05).

CONCLUSIONS

Considering the effects of the probable covariant factors CMT and CT, systemic changes in pregnant women in their third trimester may cause an increase in VD in the macula and parafoveal DCP.

Are choriocapillaris flow void features robust to diurnal variations? A swept-source optical coherence tomography angiography (OCTA) study

We evaluated the impact of diurnal variation on choroidal and retinal microvasculature and structural measurements using a swept-source optical coherence tomography angiography machine (SS-OCTA; PLEX Elite 9,000, Carl Zeiss Meditec, Inc., Dublin, USA). Fourteen participants who were without ocular diseases underwent SS-OCTA imaging using 3 × 3-mm² macular scan pattern on two separate days at five time points. Choriocapillaris flow voids were generated to determine its density (percentage), size (μm) and numbers. Perfusion densities of the large superficial vessels, as well as capillaries on superficial and deep vascular plexuses were generated from retinal angiograms. Subfoveal choroidal and retinal thicknesses were manually measured. Repeated-measures ANOVA was used to investigate the impact of diurnal variation on choroidal and retinal measurements. There was no observable diurnal pattern for any of the flow void features, in terms of the density, size and numbers. There was a significant diurnal pattern observed in the choroidal thickness, where it decreased progressively during the day (P < 0.005). As opposed to sub-foveal choroidal thickness, there does not appear to be significant diurnal variation in choriocapillaris flow voids in normal individuals. This suggests that alterations of choriocapillaris flow deficit seen in pathological eyes will not be confounded by the diurnal fluctuation.

Evaluating diurnal variations in retinal perfusion using optical coherence tomography angiography

Background

Optical coherence tomography angiography (OCTA) is a non-invasive tool for imaging and quantifying the retinal and choroidal vasculature as well as perfusion state in healthy eyes. Choroidal perfusion is subject to diurnal variation, showing lowest perfusion in the morning and highest in the afternoon. In this index study, OCTA was used to investigate diurnal changes of the retinal perfusion in healthy adult eyes and to identify impacting factors since retinal perfusion is known to be mainly determined by autoregulatory mechanisms.

Methods

A prospective study was conducted on healthy volunteers, each of whom underwent repeated measurements of mean arterial pressure (MAP), intraocular pressure (IOP), macular volume (MV), subfoveal choroidal thickness (SFCT), foveal avascular zone (FAZ) and retinal perfusion of the superficial capillary plexus (SCP), deep capillary plexus (DCP) and full retina (FR) slab at 7 a.m. and 4 p.m. Possible influence of MAP or IOP on the retinal perfusion was evaluated.

Results

A total of 22 eyes of 22 participants (mean age 55.91 ± 14.84) were analysed. Significant diurnal changes from 7 a.m. to 4 p.m. were observed for MAP (p < 0.001) and SFCT (p = 0.017). The perfusion of SCP, DCP and FR as well as the size of the FAZ and the MV did not show significant fluctuation during the day. No significant correlation between MAP or IOP and retinal perfusion values were detectable.

Conclusion

OCTA-based analysis of the retina in healthy adults demonstrated a steady perfusion of both plexus during the day, independently of changes in MAP. These findings support the theory of autoregulatory mechanisms of the retinal blood flow.

Diurnal variation in subfoveal and peripapillary choroidal vascularity index in healthy eyes

Purpose

To report the diurnal variation in choroidal vascularity index (CVI) in subfoveal (SF-CVI) and peripapillary area in healthy eyes.

Methods

The study was a cross-sectional study including 12 healthy subjects. Swept-source optical coherence tomography scans were taken at 9 am, 11 am, 1 pm, 3 pm, and 5 pm. Subfoveal choroidal thickness (SFCT) and CVI were calculated using automated segmentation techniques and previously validated algorithms. Systemic parameters including systolic blood pressure (SBP), diastolic blood pressure, mean arterial pressure, and mean ocular perfusion pressure were calculated and correlated with SFCT and CVI.

Results

A total of 12 eyes (right eye) of 12 patients (mean age: 26 ± 3.77 years) were analyzed. The mean (±standard deviation) amplitude of SFCT and SF-CVI variation was 35.91 ± 14.8 μm (range, 15-69 μm) and 0.05 ± 0.02 (range, 0.02-0.08). The mean CVI showed a significant diurnal variation in the temporal quadrant of the peripapillary region (P = 0.02).

Conclusion

SFCT and SF-CVI showed a significant diurnal variation in amplitude (peak-trough analysis) and SF-CVI correlated well with SBP suggestive of a direct influence of blood pressure on choroidal vascularity. The mean peripapillary CVI in the temporal quadrant also showed a significant diurnal variation with no significant change in other quadrants.

Subfoveal Choroidal Thickness in Pre-eclampsia

SIGNIFICANCE

To our knowledge, this is the first time a study looking at the association between subfoveal choroidal thickness (SFCT) and the parameters affecting the severity of pre-eclampsia has been reported. We provide evidence that SFCT is thicker in pre-eclamptic (PE) patients and speculate on the possible causes.

PURPOSE

The purposes of this study were to compare SFCT in PE, normal pregnant, and nonpregnant women using spectral domain optical coherence tomography and to correlate SFCT with severity of pre-eclampsia.

METHODS

A cross-sectional, observational study was performed. A total of 150 participants were divided into three groups: group 1 (50 PE women), group 2 (50 normal pregnant women), and group 3 (50 nonpregnant healthy women). Subfoveal choroidal thickness was measured using spectral domain optical coherence tomography. Other parameters including mean arterial blood pressure (MABP), central corneal thickness, macular thickness, IOP, ocular perfusion pressure (OPP), and urine protein-to-creatinine ratio were also measured. ANOVA and Pearson correlation analysis were used to look at differences between the groups. P < .05 was considered as statistically significant.

RESULTS

The MABP was higher in group 1 than in groups 2 and 3 (103.0 ± 12.9 vs. 83.2 ± 9.8 vs. 89.5 ± 7.2 mmHg, respectively; all P < .001). The SFCT of the PE group was higher than in groups 2 and 3 (370.7 ± 23.8 vs. 344.5 ± 30.8 vs. 315.8 ± 49.9 μm, respectively; all P < .001). There were no statistically significant differences in central corneal thickness, macular thickness, or IOP between the PE and healthy pregnant groups (all P > .05). The OPP was greater in PE patients (52.8 ± 8.5 vs. 41.9 ± 6.9 vs. 43.4 ± 5.2 mmHg, respectively; both P < .001). The SFCT was positively correlated with MABP (r = 0.464, P < .001), OPP (r = 0.495, P < .001), and urine protein-to-creatinine ratio (r = 0.635, P < .001) in the PE group.

CONCLUSIONS

Subfoveal choroidal thickness is higher in pre-eclampsia and is proportional to established markers of severity of the condition. This parameter might serve as a novel predictive marker for the severity of pre-eclampsia.

Assessment of Choroidal Neovascularization Perfusion: A Pilot Study With Laser Speckle Flowgraphy

Purpose

The purpose of this study was to quantify perfusion in the area of choroidal neovascularization (CNV) using laser speckle flowgraphy (LSFG) before and after intravitreal anti-vascular endothelial growth factor (VEGF) injection.

Methods

Retrospective case series. Fifteen eyes of 15 patients with treatment-naïve CNV due to age-related macular degeneration (AMD) and with available LSFG images were included. The main outcome was the mean blur rate (MBR) quantified as a measure of perfusion within the CNV area observed on indocyanine green angiography. Twelve patients had available longitudinal data until one month after the injection, used to evaluate changes in perfusion, central macular thickness (CMT), visual acuity, and ocular perfusion pressure. Reproducibility of LSFG measurements was investigated at each time point from two images taken within five minutes.

Results

Intraclass correlation coefficients for LSFG measurements were higher than 0.8 indicating excellent reproducibility. There was a significant decrease in perfusion after one week (-26.4 ± 14.4%; P = 0.027), whereas, after one month, perfusion was no longer significantly different from baseline (P = 0.121). CMT showed a progressive decrease over the follow-up period. Changes in perfusion were strongly correlated with changes in CMT after one week, but not thereafter.

Conclusions

This pilot study suggests a method to select a region in the CNV area to quantify perfusion using LSFG. MBR could represent a parameter possibly related to regrowth of the CNV after anti-VEGF treatment. Large-scale studies are needed to assess the usefulness of LSFG in defining re-treatment criteria for neovascular AMD.

Translational Relevance

LSFG technology to quantify perfusion could provide useful biomarkers for therapeutic management of CNV.

Changes in choroidal blood flow velocity in patients diagnosed with central serous chorioretinopathy during follow-up for pachychoroid pigment epitheliopathy

Purpose

To evaluate chronological changes in choroidal blood flow velocity in two patients with pachychoroid pigment epitheliopathy (PPE) and central serous chorioretinopathy (CSC) in the same eye.

Observations

Two males aged 36 and 43 years old with PPE were diagnosed with CSC in the same eyes during follow-up. Using laser speckle flowgraphy, the macular mean blur rate (MBR), an index of relative blood flow velocity, was sequentially evaluated in the affected and unaffected eyes. In the affected eye, the macular MBR values at the onset of PPE and CSC were higher, at 25% and 33% in Case 1 and 21% and 51% in Case 2, respectively, than those on PPE regression; but the same trends were not observed in their fellow eyes. The increases in MBR changing rates were 1.3 and 2.5 times higher in Cases 1 and 2, respectively, at the onset of CSC than those at the onset of PPE.

Conclusion and importance

In the affected eyes, the rates of MBR change increased at the alternate onsets of PPE and CSC. The increased MBR changing rates were 1.3-2.5 times higher at the onset of CSC than those at the onset of PPE. Our data suggest that choroidal hyperperfusion is involved in the pathogenesis of both diseases and that its severity may differ between CSC and PPE. These results may support the hypothesis that PPE and CSC clinically overlap and have a common pathogenic background.

Correlation between blood flow on optic nerve head and structural and functional changes in eyes with glaucoma

The purpose of this study was to determine the significance of the correlations between blood flow on the optic nerve head (ONH) using the mean blur rate (MBR) determined by laser speckle flowgraphy and the visual field loss determined by perimetry and the structural alterations by optical coherence tomography in eyes solely with open-angle glaucoma. There were significant differences in the circumpapillary retinal nerve fiber layer thickness (cpRNFLT), and the MBR-tissue, at the different stages of glaucoma (ANOVA, P < 0.001). Univariate linear regression analyses indicated that the mean deviations (MD) were significantly correlated with both the MBR-tissue (r = 0.661, P < 0.001) and the cpRNFLT (r = 0.279, P = 0.005). Logistic regression analyses showed that the MD was significantly correlated with the MBR-tissue (P < 0.001) and the cpRNFLT (P < 0.001). The MBR-tissue was found to be the factor that can best predict the MD based on the Akaike information criteria (P < 0.001). Stepwise multiple logistic regression analyses showed that the MBR-tissue and the cpRNFLT were both risk factors that were significantly associated with the MD (Odds ratio;1.25 and 1.07, P < 0.001 and P < 0.001, respectively). These results indicate that the MBR-tissue was as important as the structural values in diagnosing and determining the prognosis of glaucoma.

Evaluating diurnal changes in choroidal sublayer perfusion using optical coherence tomography angiography

PURPOSE

To investigate diurnal changes of choroidal sublayer perfusion in normal eyes and to identify influencing factors using optical coherence tomography angiography (OCTA).

METHODS

A prospective study was conducted on healthy volunteers, each of whom underwent repeated measurements of subfoveal choroidal thickness (SFCT) via enhanced depth imaging (EDI) optical coherence tomography (OCT) as well as perfusion of choroidal vascular sublayers using OCTA at 7 a.m., 12 p.m., 4 p.m. and 8 p.m. Possible interactions between diurnal variations and other factors, such as mean arterial pressure (MAP), gender and age, were evaluated.

RESULTS

A total of 22 eyes from 22 participants were analysed. Mean age of participants was 56 years. A significant pattern of diurnal variation was observed for SFCT (p < 0.001) as well as perfusion of Sattler's layer (SLP; p = 0.009) and Haller's layer (HLP; p = 0.003). SFCT demonstrated a linear decrease, being thicker in the morning (348 μm) and thinner in the evening (310 μm). Both, SLP and HLP showed a quadratic relation to time of day, increasing from morning (64% and 76%) to afternoon (66% and 77%), before decreasing again in the evening (64% and 76%). HLP changes were significantly associated with fluctuations of MAP (B = 0.0007; CI 0.0001-0.0014; p = 0.047). No significant differences with regard to gender were detectable. However, older participants (≥60 years) had fewer diurnal changes (p = 0.042).

CONCLUSION

Optical coherence tomography angiography-based analysis of choroidal sublayer perfusion demonstrated significant diurnal variations. Therefore, it is important to account for time of day, when comparing longitudinal OCTA data.

Pulse Waveform Analysis of the Ocular Blood Flow Using Laser Speckle Flowgraphy before and after Glaucoma Treatment

Although reduction in intraocular pressure (IOP) is the principle of glaucoma treatment, impaired ocular blood flow is believed to play a role in the progression of glaucoma. This study evaluated the effect of glaucoma treatment on pulse waveforms for optic nerve head (ONH) microcirculation in patients with glaucoma. Fifty-one subjects were included on the basis of the glaucoma treatment administered, which involved instillation of prostaglandin (PG) analogs (PG group; n = 28) or trabeculectomy (trabeculectomy group; n = 23). ONH blood flow, represented by the mean blur rate (MBR_T) and pulse waveforms, was measured using laser speckle flowgraphy before and 1 and 3 months after treatment. Three months after treatment, IOP exhibited a significant decrease (p < 0.05). Although there was no significant change in MBR_T after treatment, the acceleration time index (ATI) significantly decreased (p=0.034) in the PG group. In the trabeculectomy group, there was no significant change in the MBR_T after treatment, while fluctuation (p=0.019) and blowout score (BOS) (p=0.036) exhibited significant decrease and increase, respectively. Multiple regression analysis showed that mean deviation was significantly associated with the rate of change in the BOS (p=0.013), age was a significant contributing factor for the rate of change in fluctuation in the trabeculectomy group, reflection was significantly associated with the ATI (p=0.037) in the in the PG group. Both glaucoma treatments can change the pulse waveforms, with MBR_T remaining unchanged, and IOP reduction owing to the treatment may contribute to stable blood flow in the tissue area of the ONH. As impaired ocular blood flow plays a role in the progression of glaucomatous damage, it would be beneficial if glaucoma treatment could improve the stability of ONH microcirculation.

Waveform analysis of human retinal and choroidal blood flow with laser Doppler holography

Laser Doppler holography was introduced as a full-field imaging technique to measure blood flow in the retina and choroid with an as yet unrivaled temporal resolution. We here investigate separating the different contributions to the power Doppler signal in order to isolate the flow waveforms of vessels in the posterior pole of the human eye. Distinct flow behaviors are found in retinal arteries and veins with seemingly interrelated waveforms. We demonstrate a full field mapping of the local resistivity index, and the possibility to perform unambiguous identification of retinal arteries and veins on the basis of their systolodiastolic variations. Finally we investigate the arterial flow waveforms in the retina and choroid and find synchronous and similar waveforms, although with a lower pulsatility in choroidal arteries. This work demonstrates the potential held by laser Doppler holography to study ocular hemodynamics in healthy and diseased eyes.

Diurnal variations in flow density measured using optical coherence tomography angiography and the impact of heart rate, mean arterial pressure and intraocular pressure on flow density in primary open-angle glaucoma patients

PURPOSE

To determine the diurnal variations in peripapillary and macular flow density (FD), as measured using optical coherence tomography angiography (OCTA) and to elaborate on the relationship between diurnal FD, circulatory parameters and intraocular pressure (IOP) variations in primary open-angle glaucoma (POAG).

METHODS

Forty eyes of 40 POAG patients were drawn into this cross-sectional study. The retinal microvasculature of the macula (superficial and deep layers) and optic nerve [radial peripapillary capillary (RPC)] was examined by OCTA (AngioVue^® , Optovue). Optical coherence tomography angiography (OCTA) measurements were conducted at 08:00, 11:00, 15:00 and 20:00 over the course of two consecutive days. Intraocular pressure (IOP) and circulatory parameters were assessed accordingly. Diurnal variations in FD were analysed using linear mixed models.

RESULTS

While superficial macular FD and RPC FD revealed not to be affected by diurnal variations (p = 0.492, p = 0.319), FD in the deep layer of the macula increased throughout the day (p < 0.001). Superficial macular FD was influenced significantly by mean arterial pressure (MAP) (p = 0.006) and heart rate (HR) (p = 0.033), whereas FD in the RPC layer was significantly affected by HR (p = 0.010). No statistically significant effect of IOP fluctuations on FD was observed.

CONCLUSION

This study shows diurnal fluctuations of deep macular FD measured by OCTA and outlines the relationship between FD and hemodynamic parameters (MAP/HR) in POAG patients.

Evaluation of blood flow on optic nerve head after pattern scan and conventional laser panretinal photocoagulation

To evaluate the changes in the blood flow on retina and the optic nerve head (ONH) after conventional laser treatment and to compare it to that after patterned scanning laser (PASCAL) treatment in patients with severe nonproliferative diabetic retinopathy (S-NPDR).In this prospective, cross-sectional study, the blood flow on retina and the ONH was assessed by laser speckle flowgraphy using the mean blur rate (MBR) in 39 eyes with S-NPDR before, 1, 4, 8, 12 weeks after panretinal photocoagulation (PRP). Of 39 eyes, 17eyes with 17 patients treated by conventional laser and 22 eyes with 22 patients treated by PASCAL.The mean age was 55.5 ± 11.5 years in the conventional laser group, 55.6 ± 11.8 years in the PASCAL group. The MBR-vessel, which can be dominantly expressed as retinal blood flow, was significantly reduced after PRP treated by conventional laser (P < .001), but did not change after PRP treated by PASCAL. The ratio of MBR-vessel to the baseline was significantly lower in the conventional laser group only at Week 1 (P = .045). The MBR-tissue, which can be dominantly expressed as the ONH blood flow, did not significantly change after PRP in the both group. The multiple stepwise regression analysis revealed that the laser burns was an independent factor significantly correlated with the ratio of MBR-vessel at Week 1 to the baseline (β = -0.550, P = .012).The retinal blood flow was significantly reduced during the 12 weeks only after completion of PRP by conventional laser treatment. Our results indicate that short pulse on PRP treatment performed by the PASCAL would not significantly reduce the retinal blood flow.

Choroidal thickness in thyroid-associated orbitopathy

IMPORTANCE

To investigate the choroidal thickness (CT) in patients with thyroid-associated orbitopathy (TAO).

BACKGROUND

To compare CT of TAO patients and healthy subjects.

DESIGN

Prospective cross-sectional study in a public hospital.

PARTICIPANTS

One hundred and four eyes of 52 TAO patients and 52 eyes of 26 healthy subjects.

METHODS

CT was measured with enhanced-depth imaging optical coherence tomography (EDI-OCT) at the subfoveal, macular and peripapillary regions. Multivariate linear regression was used to evaluate the associations of subfoveal CT with systemic and ocular variables among TAO eyes.

MAIN OUTCOME MEASURES

CT of both groups.

RESULTS

CT of eyes with TAO was significantly increased at the subfoveal region, 1 and 2 mm from the fovea nasally, temporally and superiorly, and 1 mm inferior to the fovea (all P < .05). No significant difference was found in CT at 2 mm inferior to the fovea (P = .094) and all four quadrants of the peripapillary region (superior, P = .096; nasal, P = .732; inferior, P = .179; temporal, P = .052). Among TAO eyes, thinner subfoveal choroid was associated with worsening exophthalmos (P = .043), poorer visual acuity (P = .017), increasing age (P = .040) and axial length (P < .001). There was no association between CT and clinical activity score (P = .239).

CONCLUSIONS AND RELEVANCE

TAO patients showed thicker choroid than controls over the macula, but not the peripapillary regions. Thinner subfoveal choroid was associated with worsening exophthalmos and poorer vision. EDI-OCT can monitor choroidal vascular changes associated with TAO and its complications.

Diurnal change of retinal vessel density and mean ocular perfusion pressure in patients with open-angle glaucoma

Purpose

To investigate, in primary open-angle glaucoma (POAG) and healthy subjects, the pattern and magnitude of diurnal variation in optical coherence tomography angiography (OCTA) retinal vessel density (RVD).

Design

Prospective, observational cross-sectional study.

Participants

A prospective study was conducted on 20POAG patients and 19 healthy subjects.

Methods

Peripapillary/macular RVD (using swept-source OCTA), intraocular pressure (IOP), and systemic blood pressure (BP) were measured five times a day (8 a.m., 11 a.m., 2 p.m.,5 p.m. and 8 p.m.). The magnitudes and patterns of diurnal changes in RVD, diastolic BP, and mean ocular-perfusion pressure (MOPP) were analyzed and compared between the POAG patients and the healthy subjects.

Main outcome measures

The patterns and magnitudes of diurnal RVD change in OCTA.

Results

Intra-visit repeatability (0.755–0.943) and inter-visit reproducibility (0.843–0.986) for the RVD measurements showed excellent reliability. In the POAG patients, the magnitude of diurnal change in peripapillary RVD (9.71±7.04%) and macular RVD (7.22±4.73%) were significantly greater than that in the healthy group (5.73±3.85%, P = 0.013 and 5.51±3.45%, P = 0.042, respectively). The magnitudes of diurnal variations of IOP and MOPP in the POAG group likewise were greater than those in the healthy group (P = 0.003 and 0.039). As for the patterns of diurnal RVD change, interestingly, at 8 p.m., the macular RVD of the healthy group increased to the highest level (44.12±2.95%) while that of the POAG group decreased to the lowest level (40.41±2.54%).

Conclusions

In POAG eyes, diurnal change of IOP, MOPP and RVD was significantly greater than in the healthy eyes. These findings suggest that diurnal RVD changes might reflect the hemodynamic variation of POAG.

Evaluation of optic nerve head blood flow in response to increase of intraocular pressure

The time course of the changes in the optic nerve head (ONH) blood flow in response to changes in the ocular perfusion pressure (OPP) induced by an artificial elevation of the intraocular pressure (IOP) has not been determined. We measured the blood flow, represented by the mean blur rate (MBR), on the ONH determined by laser speckle flowgraphy. The MBR was determined before, during, and after the IOP was elevated by 20 or 30 mmHg by pressure applied on the eye by an ophthalmodynamometer in a total of 27 healthy eyes. For an IOP elevation of 20 mmHg, the percentage reduction in the MBR-vessel was −24.7%, and in the MBR-tissue was −16.0% (P < 0.001). For an IOP elevation of 30 mmHg, the percentage reduction of the MBR-vessel was −35.3% and the MBR-tissue was −24.7% (P < 0.001). During the 30 mmHg IOP elevation for 10 minutes, both the MBR-vessel and MBR-tissue began returning to the baseline level from 1 minute after the beginning of the IOP elevation (P < 0.01, P < 0.05, respectively) and continued returning during the 10 minutes IOP elevation (P < 0.001, P < 0.01, respectively). We conclude that the ONH can autoregulate its blood flow in response to experimental changes in OPP induced by IOP elevations.

Diurnal variation of choriocapillaris vessel flow density in normal subjects measured using optical coherence tomography angiography

Background

Vessel flow density (VFD) may provide important information regarding perfusion status. Diurnal variation in VFD of choriocapillaris has not been reported in literature. In the index study, optical coherence tomography angiography (OCTA) was used to assess the diurnal variation of the VFD in the choriocapillaris of subjects with no known ocular disease.

Methods

Fifty eyes with no known ocular disease (25 subjects) were included. OCTA images were acquired using AngioVue (Optovue, Fremont, CA, USA) at two different time points on a single day: 9:00 AM and 6:00 PM. Macular cube scan protocol (3 × 3 mm) centered on the fovea was used. Automatic segmentation of the retinal layers and choriocapillaris was performed using ReVue software, which was also used to measure the choriocapillaris VFD. Horizontal line scan passing through fovea was obtained by the device at both time points to measure the subfoveal choroidal thickness (CT). Linear measurement tool of software was used to measure subfoveal CT according to a standardized reproducible method. Wilcoxon signed-rank test was used to assess the differences in choriocapillaris VFD and subfoveal CT at the two time points. Correlation between change in choriocapillaris VFD and subfoveal CT at the two time points was assessed using the Pearson correlation coefficient (r).

Results

The mean age of the subjects was 31.96 ± 11.23 years. Choriocapillaris VFD was significantly higher at 9:00 AM compared to 6:00 PM (P < 0.0001) with mean choriocapillaris VFD of 68.74 ± 4.80% at 9:00 AM and 67.57 ± 5.41% at 6:00 PM, with a mean diurnal amplitude of 1.17%. Mean subfoveal CT was 287.74 ± 61.51 µm at 9:00 AM and 270.06 ± 60.73 µm at 6:00 PM. Subfoveal CT was also significantly higher at 9:00 AM compared to 6:00 PM (P < 0.0001) with a mean diurnal amplitude of 17.68 µm. Change in choriocapillaris VFD correlated with change in subfoveal CT (r = 0.87, P < 0.001).

Conclusion

OCTA demonstrated significant diurnal change in choriocapillaris VFD in subjects without any ocular disease with VFD being higher in the morning and lower in the evening. Decrease in choriocapillaris VFD in the evening correlated with a reduction in subfoveal CT.

Repeatability of Arterial Spin Labeling MRI in Measuring Blood Perfusion in the Human Eye

BACKGROUND

Quantifying blood perfusion in ocular tissues is challenging, partly because the majority of the blood is carried by the choroid, which is difficult to visualize because it is located between the retina and sclera.

PURPOSE/HYPOTHESIS

To evaluate the intra- and interday repeatability of MRI measures of chorio-retinal blood perfusion.

STUDY TYPE

Prospective, cross-sectional, observational study.

POPULATION

Twenty young healthy adults (six male, age: 25 ± 5 years) scanned twice within a single session repeated at the same time of day on 2 days.

FIELD STRENGTH/SEQUENCE

Arterial spin labeling (ASL) MRI at 3.0T using pseudocontinuous ASL (PCASL) labeling scheme and a 3D turbo-gradient-spin-echo (TGSE) acquisition, including axial T₂ -weighted structural images using a 2D turbo-spin-echo (TSE) sequence.

ASSESSMENTS

Region-of-interest analysis for assessment of chorio-retinal blood perfusion.

STATISTICAL TESTS

Intra- and interday repeatability of measures analyzed using intraclass correlation coefficients (ICC), Pearson's correlation analysis, paired t-tests, and Bland-Altman plots.

RESULTS

The mean chorio-retinal perfusion was 77.86 (standard deviation [SD] = 29.80) ml/100ml/min. Perfusion measurements correlated strongly within a single session (r = 0.95, 95% confidence interval [CI] [0.880-0.980], P < 0.001) and between the two sessions based on a single run (r = 0.80 [0.582-0.913], P < 0.001), and two runs (r = 0.80 [0.479-0.918], P < 0.001). There were mean differences of 2.69 [16.85 to -22.23] ml/100ml/min for intraday measures, -7.44 [27.45 to -42.32] ml/100ml/min for single-run interday measures, and 5.73 [28.71 to -40.17] ml/100ml/min for two-run interday measures, but none were significant (all P > 0.05).

DATA CONCLUSION

Quantitative ASL-MRI measurements of chorio-retinal blood perfusion showed high intra- and interday repeatability. The ASL-MRI technique provides reliable measures of chorio-retinal perfusion in vivo.

LEVEL OF EVIDENCE

1 Technical Efficacy Stage: 2 J. Magn. Reson. Imaging 2019;49:966-974.

A randomized clinical trial evaluating choroidal blood flow and morphology after conventional and pattern scan laser panretinal photocoagulation

We prospectively investigated the changes in choroidal blood flow and morphology after panretinal photocoagulation (PRP) in 39 eyes with severe nonproliferative diabetic retinopathy (S-NPDR). Seventeen eyes underwent PRP by conventional laser and 22 eyes underwent pattern scan laser (PASCAL). The choroidal blood flow was assessed by laser speckle flowgraphy, and the subfoveal choroidal thickness (SFCT) was measured with optical coherence tomography before and 1, 4, 8, and 12 weeks after the two types of PRP treatments. The choroidal mean blur rate (MBR) at the macular region was significantly reduced to 86.4% of the baseline level in the conventional laser group and 85.7% in the PASCAL group at Week 12 (P = 0.001, P < 0.001, respectively). The SFCT was significantly increased at 1 week following PRP but it was significantly reduced at Week 8 (P = 0.001, P < 0.001, respectively) in both groups. The differences in the ratio of the MBR and the SFCT was not significant between the conventional laser and PASCAL groups at any time after PRP. The results suggest that appropriate PRP treatments even by the PASCAL method will reduce the choroidal blood flow and the choroidal morphological components.

REPEATABILITY OF AUTOMATED VESSEL DENSITY AND SUPERFICIAL AND DEEP FOVEAL AVASCULAR ZONE AREA MEASUREMENTS USING OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY: Diurnal Findings

PURPOSE

To evaluate the repeatability of vessel density and superficial and deep foveal avascular zone measurements using optical coherence tomography angiography, and to specify a diurnal change range.

METHODS

Forty-six eyes of 25 healthy individuals were included. Optical coherence tomography angiography measurements were planned for three consecutive sessions, with 3 hours in between them. AngioVue software of the RTVue XR Avanti was used. Superficial and deep retinal layer vessel density values, including the whole retina, fovea, and each parafoveal zone, were obtained from the software. The intraclass correlation, coefficient of variation, and coefficient of repeatability were calculated for each parameter.

RESULTS

The whole image intraclass correlation value was 0.81 for the superficial and 0.86 for the deep layer among the three consecutive sessions. The smallest real difference (coefficient of repeatability) value of whole image measurements was 7.72% for the superficial and 9.84% for the deep retinal layer. Foveal avascular zone area intraclass correlation value was 0.97 for the superficial and 0.83 for the deep retinal layer.

CONCLUSION

The optical coherence tomography angiography analysis provides quantitative data about the retinal microvasculature, which could be used to distinguish between normal and pathology. Changes in superficial vessel density >8% and deep vessel density >10% may be considered as real clinical change rather than variation.

Pulse waveform analysis on temporal changes in ocular blood flow due to caffeine intake: a comparative study between habitual and non-habitual groups

PURPOSE

To evaluate and compare the temporal changes in pulse waveform parameters of ocular blood flow (OBF) between non-habitual and habitual groups due to caffeine intake.

METHOD

This study was conducted on 19 healthy subjects (non-habitual 8; habitual 11), non-smoking and between 21 and 30 years of age. Using laser speckle flowgraphy (LSFG), three areas of optical nerve head were analyzed which are vessel, tissue, and overall, each with ten pulse waveform parameters, namely mean blur rate (MBR), fluctuation, skew, blowout score (BOS), blowout time (BOT), rising rate, falling rate, flow acceleration index (FAI), acceleration time index (ATI), and resistive index (RI). Two-way mixed ANOVA was used to determine the difference between every two groups where p < 0.05 is considered significant.

RESULT

There were significant differences between the two groups in several ocular pulse waveform parameters, namely MBR (overall, vessel, tissue), BOT (overall), rising rate (overall), and falling rate (vessel), all with p < 0.05. In addition, the ocular pulse waveform parameters, i.e., MBR (overall), skew (tissue), and BOT (tissue) showed significant temporal changes within the non-habitual group, but not within the habitual group. The temporal changes in parameters MBR (vessel, tissue), skew (overall, vessel), BOT (overall, vessel), rising rate (overall), falling rate (overall, vessel), and FAI (tissue) were significant for both groups (habitual and non-habitual) in response to caffeine intake.

CONCLUSION

The experiment results demonstrated caffeine does modulate OBF significantly and response differently in non-habitual and habitual groups. Among all ten parameters, MBR and BOT were identified as the suitable biomarkers to differentiate between the two groups.

Choroidal Thickness in Women with Uncomplicated Pregnancy: Literature Review

Pregnancy is a time when many changes occur in a woman's body. The goal of these changes is the provision of optimum conditions for the development of the foetus. Pregnancy also affects eye physiology. Well recognized physiological changes include a reduced corneal sensitivity, an increase in its central thickness and curvature, and a decrease in intraocular pressure. The association between choroidal thickness and pregnancy is not clear. Haemodynamic and hormonal changes taking place during pregnancy and the question of whether these changes are reflected by choroidal thickness are especially important. It is assumed that the choroid, which is one of the most highly vascularized tissues characterized by the highest blood flow to tissue volume ratio in the whole body, should respond by an increase in its thickness to an increase in blood flow and drop in the value of peripheral resistance. Measurement of choroidal thickness using enhanced depth imaging optical coherence tomography (EDI-OCT) in women with uncomplicated pregnancy provides important information concerning the effects of physiological changes in the eye.

Diurnal variation of pulse waveform parameters determined by laser speckle flowgraphy on the optic nerve head in healthy subjects

To investigate the diurnal variation of the pulse waveform parameters determined by laser speckle flowgraphy (LSFG) on the optic nerve head (ONH) in healthy subjects.This prospective cross sectional study was conducted at Nagoya University Hospital. We studied 13 healthy volunteers whose mean age was 33.5 ± 7.6 years. Eight pulse waveform parameters on the ONH were determined by LSFG (LSFG-NAVI) every 3 hours from 6 AM to 12 PM. The intraocular pressure (IOP), systolic (SBP) and diastolic (DBP) blood pressure, and heart rate (HR) in the brachial artery were also recorded. We evaluated the diurnal variations of the parameters and compared the pulse waveform parameters to the other parameters using a linear mixed model.Of the 8 parameters, skew (P < .001), blow out score (BOS, P < .001), blow out time (BOT, P = .028), rising rate (P < .001), falling rate (P < .001), resistivity index (P < .001) had a significant diurnal fluctuation. In addition, IOP (P < .001), SBP (P = .005), DBP (P = .001), and HR (P < .001) had significant diurnal fluctuations. The BOS and resistivity index were significantly correlated with the HR (P = .009, P = .012, respectively), and the BOT were significantly correlated with the DBP and mean ocular perfusion pressure (P = .042, P = .041, respectively).We found that there was significant diurnal variation in 6 waveform parameters on the ONH in LSFG. We believe that our results highlighting diurnal variations in these waveform parameters need to be considered when interpreting pulse waveform parameter data and in understanding the precise underlying mechanism of ocular diseases such as diabetic retinopathy, retinal vein occlusion, and glaucoma.

Change in choroidal blood flow and choroidal morphology due to segmental scleral buckling in eyes with rhegmatogenous retinal detachment

Although scleral buckling is a well-established surgical treatment for rhegmatogenous retinal detachment (RRD), the procedure can reportedly cause problems in the ocular circulation. Segmental scleral bucking without a concomitant encircling procedure was performed on 46 eyes with successfully reattached macula-on RRD. Choroidal blood flow was assessed using laser speckle flowgraphy. Spectral-domain optical coherence tomography was used to image macular regions, to measure the subfoveal choroidal thickness (SFCT), and to calculate the luminal and the stromal areas by the binarization method preoperatively and 1, 4, 8 and 12 weeks postoperatively. Choroidal mean blur rate at the macula did not significantly change, while that at the buckle and unbuckle side significantly reduced at 8 weeks postoperatively in the operated eye (P = 0.007 and P = 0.017, respectively). The SFCT and the luminal area increased temporarily 1 week following surgery in the operated eye (P < 0.001). The trend of SFCT with time coincided with that of the luminal area (P < 0.001). Venous drainage obstruction induced by compression force of scleral buckling leads to SFCT thickening in the acute postoperative phase. The macular choroidal blood flow might be less susceptible because the blood flow at the macula, in contrast to the other areas, does not change following segmental scleral buckling.

The Effect of Change in Intraocular Pressure on Choroidal Structure in Glaucomatous Eyes

Purpose

Choroidal thickness increases linearly with intraocular pressure (IOP) lowering. We studied the relationship between the change in size of the choroidal vasculature and IOP lowering after glaucoma procedures.

Methods

Thirty eyes of twenty-nine patients were examined pre- and postoperatively for up to 6 months with standard clinical assessment, enhanced depth imaging spectral-domain optical coherence tomography (OCT), and axial length measurement. Each enhanced depth imaging spectral-domain OCT image was analyzed using three separate methods to determine the choroidal thickness, choroidal vessel thickness, choroidal interstitial thickness, large choroidal vessel layer thickness, medium choroidal vessel layer thickness, and light-dark ratio. Bivariate linear regression analysis was completed with largest change in IOP as the independent variable. The dependent variables included choroidal thickness, choroidal vessel thickness, and choroidal interstitial thickness, at the largest change in IOP. Multivariable regression analysis using a generalized estimating equation to account for multiple measurements per eye was also completed.

Results

Mean choroidal vessel thickness increases 1.5 μm for every 1 mm Hg decrease in IOP (P < 0.0001; 95% confidence interval [CI], 0.8, 2.1) and choroidal interstitial thickness increases 1.3 μm for every 1 mm Hg change in IOP (P < 0.0001; 95% CI, 0.8, 1.8). There was no significant association between change in IOP and change in large choroidal vessel layer temporally (P = 0.13), nasally (P = 0.20), or subfoveally (P = 0.18). There was also no association between IOP and the light-dark ratio (P = 0.16).

Conclusions

The increase in choroidal thickness at lower IOP is associated with approximately equal increases in its intravascular and extravascular compartments.

Melanopsin Phototransduction Contributes to Light-Evoked Choroidal Expansion and Rod L-Type Calcium Channel Function In Vivo

Purpose

In humans, rodents, and pigeons, the dark → light transition signals nonretinal brain tissue to increase choroidal thickness, a major control element of choroidal blood flow, and thus of photoreceptor and retinal pigment epithelium function. However, it is unclear which photopigments in the retina relay the light signal to the brain. Here, we test the hypothesis that melanopsin (Opn4)-regulated phototransduction modulates light-evoked choroidal thickness expansion in mice.

Methods

Two-month-old C57Bl/6 wild-type (B6), 4- to 5-month-old C57Bl/6/129S6 wild-type (B6 + S6), and 2-month-old melanopsin knockout (Opn4^−/−) on a B6 + S6 background were studied. Retinal anatomy was evaluated in vivo by optical coherence tomography and MRI. Choroidal thickness in dark and light were measured by diffusion-weighted MRI. Rod cell L-type calcium channel (LTCC) function in dark and light (manganese-enhanced MRI [MEMRI]) was also measured.

Results

Opn4^−/− mice did not show the light-evoked expansion of choroidal thickness observed in B6 and B6 + S6 controls. Additionally, Opn4^−/− mice had lower than normal rod cell and inner retinal LTCC function in the dark but not in the light. These deficits were not due to structural abnormalities because retinal laminar architecture and thickness, and choroidal thickness in the Opn4^−/− mice were similar to controls.

Conclusions

First time evidence is provided that melanopsin phototransduction contributes to dark → light control of murine choroidal thickness. The data also highlight a contribution in vivo of melanopsin phototransduction to rod cell and inner retinal depolarization in the dark.

Enhanced Depth Imaging Optical Coherence Tomography: A New Way Measuring Choroidal Thickness in Pregnant Women

The body changes markedly during pregnancy; each system behaves differently from a nonpregnant state. As the eyes are the only windows to see directly what is going on in the internal environment, more and more researches have been done to explain the association between ocular changes and the physiological and pathological changes during pregnancy. The choroid is one of the critical parts of the eye, providing nutrition. And abnormal choroid may result in ocular dysfunction and visual problems. As the optical coherence tomography develops, a rapid, direct, noninvasive, and nontoxic way is available to obtain the choroid situation of pregnant women, which may explain the mechanism of pregnancy-related eye diseases. This review would summarize relevant original articles published from January 1, 2008 to December 1, 2016 to assess the changes of choroidal thickness (CT) with enhanced depth imaging optical coherence tomography (EDI-OCT) during pregnancy. And the relationship between choroidal thickness changes and pregnancy remains uncertain. To our knowledge, this is the first review of EDI-OCT in assessing the choroidal thickness of the pregnant women.

Ocular Blood Flow Measurements in Healthy White Subjects Using Laser Speckle Flowgraphy

Purpose

To assess the feasibility and reliability of Laser Speckle Flowgraphy (LSFG) to measure ocular perfusion in a sample of healthy white subjects and to elucidate the age-dependence of the parameters obtained.

Methods

This cross-sectional study included 80 eyes of 80 healthy, non-smoking white subjects of Western European descent between 19 and 79 years of age. A commercial LSFG instrument was applied to measure ocular blood flow at the optic nerve head (ONH) three successive times before and after pharmacological pupil dilation. The mean blur rate (MBR), a measure of relative blood flow velocity, was obtained for different regions of the ONH. Eight parameters of ocular perfusion derived from the pulse-waveform analysis of MBR including blowout time (BOT) and falling rate (FR) were also recorded.

Results

Artifact-free LSFG images meeting the quality criteria for automated image analysis were obtainable in 93.8% without pupil dilation and in 98.8% with pharmacological pupil dilation. Measurements of MBR showed excellent repeatability with intraclass correlation coefficients ≥ 0.937 and were barely affected by pupil dilation. The majority of pulse-waveform derived variables exhibited equally high repeatability. MBR-related blood flow indices exhibited significant age dependence (p<0.001). FR (r = 0.747, p<0.001) and BOT (r = -0.714, p<0.001) most strongly correlated with age.

Conclusions

LSFG represents a reliable method for the quantitative assessment of ocular blood flow in white subjects. Our data affirms that the LSFG-derived variables FR and BOT may be useful biomarkers for age-related changes in ocular perfusion.

Ocular biometry by computed tomography in different dog breeds

OBJECTIVE

To (i) correlate B-mode ocular ultrasound (US) and computed tomography (CT) (prospective pilot study), (ii) establish a reliable method to measure the normal canine eye using CT, (iii) establish a reference guide for some dog breeds, (iv) compare eye size between different breeds and breed groups, and (v) investigate the correlation between eye dimensions and body weight, gender, and skull type (retrospective study).

PROCEDURE

B-mode US and CT were performed on ten sheep cadaveric eyes. CT biometry involved 100 adult pure-bred dogs with nonocular and nonorbital disease, representing eleven breeds. Eye length, width, and height were each measured in two of three planes (horizontal, sagittal, and equatorial).

RESULTS

B-mode US and CT measurements of sheep cadaveric eyes correlated well (0.70-0.71). The shape of the canine eye was found to be akin to an oblate spheroid (a flattened sphere). A reference guide was established for eleven breeds. Eyes of large breed dogs were significantly larger than those of medium and small breed dogs (P < 0.01), and eyes of medium breed dogs were significantly larger than those of small breed dogs (P < 0.01). Eye size correlated with body weight (0.74-0.82) but not gender or skull type.

CONCLUSIONS

Computed tomography is a suitable method for biometry of the canine eye, and a reference guide was established for eleven breeds. Eye size correlated with breed size and body weight. Because correlation between B-mode US and CT was shown, the obtained values can be applied in the clinical setting, for example, for the diagnosis of microphthalmos and buphthalmos.