Optical Coherence Tomography Angiography Quantitative Assessment of Exercise-Induced Variations in Retinal Vascular Plexa of Healthy Subjects

Variation of retinal and choroidal microvascularization after an exercise stress test in patients with effort angina

PURPOSE

To describe retinal and choroidal vascular changes following an exercise stress test (ET) in patients with effort angina and to determine whether optical coherence tomography angiography (OCT-A) could play a role in the prediction of ischemic cardiac events.

METHODS

Prospective comparative study including patients with effort angina. All patients underwent OCT-A before and after an ET was performed. Blood flow, intercapillary spaces, and vessel density were analyzed in the superficial capillary plexus (SCP) and the deep capillary plexus (DCP). Vessel density in the choriocapillaris and the parameters of the central avascular zone (CAZ) were also analyzed.

RESULTS

Of the 38 eyes included in the study, a decrease in blood flow was found in 39.5% in the large SCP vessels, in 50% in the capillaris of the SCP, and in 81.6% in the DCP. An increase in intercapillary spaces was observed in the SCP in 68.4% of eyes and in the DCP in 55.3% of eyes. A statistically significant decrease in the DCP density was observed after an ET (p = 0.03). There were no significant modifications in the CAZ parameters, the SCP density, nor the choriocapillaris density. Patients with a positive ET had a decreased DCP density in 83.3%. Among patients with an increased DCP density, 92.85% had a negatif ET.

CONCLUSION

This pilot study suggests that DCP density significantly decreases after an ET. The DCP appears to be most affected in patients with effort angina. A larger trial is needed to further investigate these hypotheses.

OCTA quantitative assessment of exercise-induced variations and recovery in retinal microvasculature of healthy subjects with or without masks

PURPOSE

To investigate the impact of exercise and mask-wearing on retinal microvasculature using optical coherence tomography angiography (OCTA).

METHODS

A total of 30 healthy volunteers were enrolled and tasked with physical exercise to reach 75-80 % maximum heart rates. Swept-source OCTA was performed on the macular region and optic nerve head (ONH) in participants with no mask, surgical mask, or N95 mask at quiescent conditions (Step 1) and 0 min, 10 min, 20 min, and 30 min post-exercise (Steps 2-5, respectively). The functional vessel density (VD), including the superficial and deep plex (SP and DP) in the macular area and the superficial plex (SP), nerve fiber plex, and small vessels in the optic nerve head, were measured.

RESULTS

Under quiescent conditions, the functional VD of SP and DP exhibited significant reduction with surgical and N95 masks in the foveal area (P < 0.05). In step 2 (immediately after training) with or without masks, functional VD of SP and nerve fiber both showed significant reduction in the inside disc and peripapillary area, small functional VD of nerve fiber in the ONH showed significant reduction in peripapillary area (P < 0.05). These changes had been recovered in Step 5 (30 min post-exercise) in all groups (no-mask, surgical mask and N95 mask groups) (P > 0.05).

CONCLUSIONS

Mask-wearing and physical exercise reduce retinal functional VD in macular and ONH areas. The retinal vasoconstriction induced by exercise tends to recover after rest for approximately 30 min. Our research provides insights into mask-wearing and physical exercise's immediate retinal microvasculature effects, hinting at systemic microvascular changes.

Comparison of choroidal thickness, superficial and deep retinal vascular indices, and foveal avascular zones: Martial arts athletes vs healthy non-athletes

AIM

The study aims to compare choroidal thickness, deep and superficial retinal capillary plexuses, and foveal avascular zone (FAZ) parameters in elite martial arts athletes and a healthy sedentary control group.

METHODS

The study included martial arts athletes (32 individuals, 64 eyes) and healthy sedentary persons (43 individuals with healthy sedentary lifestyles, 86 eyes) aged 18-35 years. In this single non-repeated observational and cross-sectional study, choroidal thickness, superficial and deep retinal capillary plexuses, and FAZ measurements were measured using Swept-source optical coherence tomography angiography (SS-OCTA) and compared between groups.

RESULTS

No statistically significant differences were found (p > 0.05) in age, IOP, AL (axial length), and best-corrected visual acuity (BCVA) parameters between groups. There were no statistically significant differences between the groups in choroidal thickness, superficial and deep retinal capillary plexuses, and FAZ parameters determined by the OCTA method (p > 0.05).

CONCLUSION

In our study, we observed that the retinal and choroidal structures of martial art athletes and healthy sedentary individuals were similar. This observation implies that the putative microvascular effects on the choroid and retina in martial arts, especially those based on the anaerobic energy system, may reflect similar outcomes to those observed in individuals with sedentary lifestyles characterized by healthiness.

Decreased retinal capillary density as a beneficial response to 24-week high-speed circuit resistant training in healthy older adults

PURPOSE

To determine the changes in retinal microvascular density after a 24-week high-speed circuit resistance training program (HSCT) in healthy older adults.

METHODS

Thirty healthy older adults were recruited and randomly assigned to either a training group (HSCT) or a non-training (CON) group. Fifteen subjects (age 73.3 ± 7.76 yrs) in the HSCT group exercised three times per week on non-consecutive days for 24 weeks. Fifteen subjects in the CON group (age 72.2 ± 6.04 yrs) did not have formal physical training. Both eyes of each subject were imaged using optical coherence tomography angiography (OCTA) at baseline and at the 24-week follow-up. The vessel densities of the retinal vascular network (RVN), superficial vascular plexus (SVP), and deep vascular plexus (DVP) were measured.

RESULTS

There were no demographic differences between the study groups. There were significant decreases in the retinal vessel densities of RVN, SVP and DVP in the HSCT group (P < 0.05). However, there were no significant changes in all three vascular measurements in the CON group (P > 0.05), although the changes showed a decreasing trend. The decreased vessel densities were doubled in the HSCT group in comparison to the CON group. However, the differences between groups did not reach a significant level (P > 0.05).

CONCLUSIONS

This is the first study to reveal the decreased retinal vessel densities as a possible imaging marker for the beneficial effects of the 24-week HSCT program in older adults.

Meibomian Gland Probing Stimulates a Proliferative Epithelial Response Resulting in Duct Regeneration

Purpose

To demonstrate that the meibomian gland ductal basement membrane and basal epithelial cell layer are in continuity with and may derive from lid margin orifice-associated rete ridge epithelial/basement membrane structures (OARREBS) and to characterize changes in the distal duct microanatomy after meibomian gland probing (MGP) using in vivo confocal microscopy (IVCM).

Patients and Methods

Pre/post-MGP IVCM examinations were performed on upper lids. Thirty-six identical glands from 20 lids of 16 patients (49.24 ±17.11 y/o with 13:3 F:M) were identified, analyzed, and compared to control cases. Statistical analyses were performed using ImageJ software and IBM SPSS version 27. All MGPs were performed within 12 weeks of the initial examination. Post-MGP follow-up exams occurred at 5.03 ±4.48 months.

Results

Post-MGP images showed more superficially organized OARREBS with accelerated and more superficial basement membrane formation, and an average increase of 32.2%, 25.4%, 32.04%, 77.7%, and 81.3% in duct wall epithelial cell layers (DWECL) (p < 0.001, compared to control (CTC) p < 0.001), distal duct wall thickness (DWT) (p < 0.001, CTC p < 0.001), proximal DWT (p < 0.001, CTC p < 0.001), distal lumen area (p < 0.001, CTC p = 0.037), and proximal lumen area (p < 0.001, CTC p = 0.007), respectively. The increase in the distal DWT and lumen area correlated with the months of follow-up (p = 0.004 and p = 0.010, respectively). Immediate post-MGP imaging revealed the probe track confined to the ductal epithelial compartment.

Conclusion

MGP appears to stimulate a proliferative epithelial response characterized by an accelerated more superficial formation of ductal basement membrane with increased DWECL as well as DWT and lumen area at two separate duct foci. These findings suggest activation of lid margin meibomian gland precursor cells and confirm that MGP stimulates an epithelial regenerative phenomenon, not a fibrotic one.

Assessment of retinal and choroidal microcirculation after unilateral recession-resection surgery for horizontal strabismus by swept-source optical coherence tomography angiography

This study explored the possible hemodynamic changes of the retina and choroid after horizontal strabismus surgery using swept-source optical coherence tomography angiography (SS-OCTA). 32 eyes of 32 patients who underwent unilateral horizontal rectus muscle recession-resection surgery were included. SS-OCTA examinations were performed preoperatively and one week postoperatively. Several OCTA measurements were used, including vessel density (VD) of the superficial vascular complex (SVC), VD of the deep vascular complex (DVC), VD of the choriocapillaris (CC), choroidal vascular index (CVI) and choroidal thickness (CT). No significant change in VD of SVC, DVC, and CC was observed whereas CT increased significantly with CVI unchanged. Recession-resection surgery for horizontal strabismus seemed not to significantly influence the microcirculation of the retina and CC in the early postoperative period. However, choroidal thickening happened with a constant CVI probably due to the postoperative inflammation. Further studies are needed to investigate the long-term effects of unilateral recession-resection surgery for horizontal strabismus on the microcirculation of the retina and choroid.

Towards modifying the genetic predisposition for glaucoma: An overview of the contribution and interaction of genetic and environmental factors

Glaucoma, the leading cause of irreversible blindness worldwide, is a complex human disease, with both genetic and environmental determinants. The availability of large-scale, population-based cohorts and biobanks, combining genotyping and detailed phenotyping, has greatly accelerated research into the aetiology of glaucoma in recent years. Hypothesis-free genome-wide association studies have furthered our understanding of the complex genetic architecture underpinning the disease, while epidemiological studies have provided advances in the identification and characterisation of environmental risk factors. It is increasingly recognised that the combined effects of genetic and environmental factors may confer a disease risk that reflects a departure from the simple additive effect of the two. These gene-environment interactions have been implicated in a host of complex human diseases, including glaucoma, and have several important diagnostic and therapeutic implications for future clinical practice. Importantly, the ability to modify the risk associated with a particular genetic makeup promises to lead to personalised recommendations for glaucoma prevention, as well as novel treatment approaches in years to come. Here we provide an overview of genetic and environmental risk factors for glaucoma, as well as reviewing the evidence and discussing the implications of gene-environment interactions for the disease.

The Association of Physical Activity with Glaucoma and Related Traits in the UK Biobank

PURPOSE

To examine the association of physical activity (PA) with glaucoma and related traits, to assess whether genetic predisposition to glaucoma modified these associations, and to probe causal relationships using Mendelian randomization (MR).

DESIGN

Cross-sectional observational and gene-environment interaction analyses in the UK Biobank. Two-sample MR experiments using summary statistics from large genetic consortia.

PARTICIPANTS

UK Biobank participants with data on self-reported or accelerometer-derived PA and intraocular pressure (IOP; n = 94 206 and n = 27 777, respectively), macular inner retinal OCT measurements (n = 36 274 and n = 9991, respectively), and glaucoma status (n = 86 803 and n = 23 556, respectively).

METHODS

We evaluated multivariable-adjusted associations of self-reported (International Physical Activity Questionnaire) and accelerometer-derived PA with IOP and macular inner retinal OCT parameters using linear regression and with glaucoma status using logistic regression. For all outcomes, we examined gene-PA interactions using a polygenic risk score (PRS) that combined the effects of 2673 genetic variants associated with glaucoma.

MAIN OUTCOME MEASURES

Intraocular pressure, macular retinal nerve fiber layer (mRNFL) thickness, macular ganglion cell-inner plexiform layer (mGCIPL) thickness, and glaucoma status.

RESULTS

In multivariable-adjusted regression models, we found no association of PA level or time spent in PA with glaucoma status. Higher overall levels and greater time spent in higher levels of both self-reported and accelerometer-derived PA were associated positively with thicker mGCIPL (P < 0.001 for trend for each). Compared with the lowest quartile of PA, participants in the highest quartiles of accelerometer-derived moderate- and vigorous-intensity PA showed a thicker mGCIPL by +0.57 μm (P < 0.001) and +0.42 μm (P = 0.005). No association was found with mRNFL thickness. High overall level of self-reported PA was associated with a modestly higher IOP of +0.08 mmHg (P = 0.01), but this was not replicated in the accelerometry data. No associations were modified by a glaucoma PRS, and MR analyses did not support a causal relationship between PA and any glaucoma-related outcome.

CONCLUSIONS

Higher overall PA level and greater time spent in moderate and vigorous PA were not associated with glaucoma status but were associated with thicker mGCIPL. Associations with IOP were modest and inconsistent. Despite the well-documented acute reduction in IOP after PA, we found no evidence that high levels of habitual PA are associated with glaucoma status or IOP in the general population.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Improvement of Retinal Capillary Function After High-Speed Circuit Resistance Training in Healthy Older Adults

BACKGROUND

To determine the retinal capillary function (RCF, the efficiency of blood flow transferring in the capillary network) and its relation to cognitive function in healthy older people without known cognitive impairment following an 8-week high-speed circuit resistance training program (HSCT).

METHODS

Eleven subjects in the HSCT group and 7 age-matched nontraining controls (CON) were recruited. The HSCT group trained 3 times per week for 8 weeks, whereas CON performed no formal training. One eye of each subject from both groups was imaged at baseline and 8-week follow-up. Retinal blood flow (RBF) was measured using a retinal function imager, and retinal capillary density (RCD, expressed as fractal dimension Dbox) was measured using optical coherence tomography angiography. RCF was defined as the ratio of RBF to RCD. Cognitive function was assessed during both visits using the NIH Toolbox Fluid Cognition Battery.

RESULTS

RCF was 2.07 ± 0.64 nL⋅s -1 ·Dbox -1 (mean ± SD) at baseline, and significantly increased to 2.59 ± 0.54 nL⋅s -1 ·Dbox -1 after training ( P = 0.0003) in the HSCT group, reflecting an increase of 25%. The changes of RBF were not related to the changes of RCD in the HSCT group (r = -0.18, P = 0.59). There was no significant change of RCF in the CON group ( P = 0.58). In the HSCT group, the Pattern Comparison Processing Speed Test and Fluid Cognition Composite Score were significantly increased after HSCT ( P = 0.01). Furthermore, the changes in Flanker Inhibitory Control and Attention Test (FLNK) were positively correlated to increases in RCF (r = 0.77, P = 0.005).

CONCLUSIONS

This is the first prospective study to demonstrate that the increased RCF after HSCT was related to improved cognition in cognitively normal older adults.

Optic disc and retinal vascular features in first 6 years of Chinese children

Purpose

Retinal microvasculature plays an important role in children's fundus lesions and even in their later life. However, little was known on the features of normal retina in early life. The purpose of this study was to explore the normal retinal features in the first 6 years of life and provide information for future research.

Methods

Children, aged from birth to 6 years old and diagnosed with various unilateral ocular diseases were included. Venous phase fundus fluorescein angiography images with the optic disc at the center were collected. Based on the ResUNet convolutional neural network, optic disc and retinal vascular features in the posterior retina were computed automatically.

Results

A total of 146 normal eyes of 146 children were included. Among different age groups, no changes were shown in the optic disc diameter (y = -0.00002x + 1.362, R² = 0.025, p = 0.058). Retinal vessel density and fractal dimension are linearly and strongly correlated (r = 0.979, p < 0.001). Older children had smaller value of fractal dimension (y = -0.000026x + 1.549, R²= 0.075, p = 0.001) and narrower vascular caliber if they were less than 3 years old (y = -0.008x + 84.861, R²= 0.205, p < 0.001). No differences were in the density (y = -0.000007x + 0.134, R²= 0.023, p = 0.067) and the curvature of retinal vessels (lnC = -0.00001x - 4.657, R²= 0.001, p = 0.667).

Conclusions

Age and gender did not impact the optic disc diameter, vessel density, and vessel curvature significantly in this group of children. Trends of decreased vessel caliber in the first 3 years of life and decreased vessel complexity with age were observed. The structural characteristics provide information for future research to better understand the developmental origin of the healthy and diseased retina.

The Assessment of Acute Chorioretinal Changes Due to Intensive Physical Exercise in Senior Elite Athletes

Regular physical exercise is known to lower the incidence of age-related eye diseases. We aimed to assess the acute chorioretinal alterations in older adults following intense physical strain. Seventeen senior elite athletes were recruited who underwent an aerobic exercise on a cycle ergometer and macular scanning by optical coherence tomography. A significant thinning of the entire retina was observed 1 min after exercise, followed by a thickening at 5 min, after which the thickness returned to baseline. This trend was similar in almost every single retinal layer, although a significant change was observed only in the inner retina. Choroidal thickness changes were neither significant nor did they correlate with the thickness changes of intraretinal layers. The mechanism of how these immediate retinal changes chronically impact age-related sight-threatening pathologies that, in turn, result in a substantially reduced quality of life warrants further investigation on nontrained older adults as well.

Association of Physical Activity with Retinal Thickness and Vascular Structure in Elderly Chinese Population

INTRODUCTION

We aimed to assess the association of physical activity (PA) with retinal thickness and vascular structure in an elderly Chinese population.

METHODS

This study enrolled 220 retirees aged 50 years and above from Tianjin University of Sport, China. PA data gathered through the International Physical Activity Questionnaires were computed for metabolic equivalent of task-minutes per week. All participants underwent full ophthalmic examination including optical coherence tomography angiography. Multiple linear regression analyses were used to evaluate the association of PA with retinal thickness and vascular structure.

RESULTS

A high amount of total PA was associated with smaller size of foveal avascular zone (FAZ) (high vs. low: area, β = -0.04; circumference β = -0.14) and greater central vessel density (VD) (β = 1.04) and perfusion density (PD) (β = 0.02). For domain-specific PA, participants with high and moderate recreational PA levels were found to have greater central VDs and PDs. Nonleisure activities demonstrated negative relationship with FAZ perimeter ratio (moderate vs. low: β = -0.08; high vs. low: β = -0.13) and, counter-intuitively, negative relation with VDs measured at the inner (high vs. low: β = -0.98) and outer retinal layers (high vs. low: β = -0.38). Additionally, higher levels of total PA were related to increased macular fovea thickness and average thickness of retinal nerve fiber layer.

CONCLUSIONS

High PA level, particularly recreational PA, was associated with smaller FAZ and greater VD and PD in senior adults. Nonleisure-time PA might not confer the same health benefits as leisure-time PA. Our data support a possible protective role of recreational PA in the retina against microvascular changes.

Effects of Exercise on Optic Nerve and Macular Perfusion in Glaucoma and Normal Subjects

PRCIS

Using optical coherence tomography angiography, we only found an increase in the blood flow in regional macular without significant changes in the optic disc in patients with glaucoma after a moderate exercise regime.

PURPOSE

To investigate the effect of moderate exercise on optic nerve and macular perfusion in glaucoma patients.

METHODS

Overall, 25 eyes of 25 patients with primary open-angle glaucoma and 22 eyes of 22 normal subjects were included in the glaucoma and control groups, respectively. Foveal avascular zone parameters, whole and regional vessel density in the superficial layer of macula, vessel densities in the radial peripapillary capillary (RPC) layer of the optic nerve head, intraocular pressure, and cardiovascular parameters were measured using optical coherence tomography angiography before, immediately after, and 30 minutes after a 20-minute run at moderate speed.

RESULTS

In the glaucoma group, macular superficial vessel density of the whole image, parafovea, and superior and nasal regions were higher after 30 minutes of rest (44.049±5.704, 47.238±5.741, 48.692±6.648, 47.852±5.078) than immediately after exercise(43.229±5.867, 46.334±5.984, 47.840±6.895, 46.793±5.238, P<0.05). The vessel density in the temporal and nasal regions was higher 30 minutes after exercise (45.105±5.512, 47.852±5.078) than before exercise (44.265±5.803 and 46.750±5.639, P<0.05). The intraocular pressure decreased immediately after exercise (14.20±2.51 and 14.51±2.96 mmHg for glaucoma and controls, respectively) but was restored after 30 minutes of rest (15.84±3.57 mmHg for glaucoma and 16.50±2.25 mmHg for controls) in both groups (P<0.001). Cardiovascular parameters were similar in both groups.

CONCLUSION

Moderate physical exercise for 20 minutes increased blood flow in the macula region without significant change to the optic nerve and lowered intraocular pressure in glaucoma and normal subjects. The benefit of these findings to glaucoma patients needs further study.

The assessment of acute chorioretinal changes due to intensive physical exercise in young adults

Purpose

There is abundant evidence on the benefits of physical activity on cardiovascular health. However, there are only few data on the acute effects of physical exercise on the retina and choroid. Our aim was the in vivo examination of chorioretinal alterations following short intense physical activity by spectral domain optical coherence tomography (SD-OCT).

Methods

Twenty-one eyes of 21 healthy, young subjects (mean age 22.5 ± 4.1 years, 15 males and 6 females) were recruited. Macular scanning with a SD-OCT was performed before and following a vita maxima-type physical strain exercise on a rowing ergometer until complete fatigue. Follow-up OCT scans were performed 1, 5, 15, 30 and 60 minutes following the exercise. The OCT images were exported and analyzed using our custom-built OCTRIMA 3D software and the thickness of 7 retinal layers was calculated, along with semi-automated measurement of the choroidal thickness. One-way ANOVA analysis was performed followed by Dunnett post hoc test for the thickness change compared to baseline and the correlation between performance and thickness change has also been calculated. The level of significance was set at 0.001.

Results

We observed a significant thinning of the total retina 1 minute post-exercise (-7.3 ± 0.6 μm, p < 0.001) which was followed by a significant thickening by 5 and 15 minutes (+3.6 ± 0.6 μm and +4.0 ± 0.6 μm, respectively, both p <0.001). Post-exercise retinal thickness returned to baseline by 30 minutes. This trend was present throughout the most layers of the retina, with significant changes in the ganglion cell–inner plexiform layer complex, (-1.3 ± 0.1 μm, +0.6 ± 0.1 μm and +0.7 ± 0.1 μm, respectively, p <0.001 for all), in the inner nuclear layer at 1 and 5 minutes (-0.8 ± 0.1 μm and +0.8 ± 0.1 μm, respectively, p <0.001 for both), in the outer nuclear layer–photoreceptor inner segment complex at 5 minute (+2.3 ± 0.4 μm, p <0.001 for all) and in the interdigitation zone–retinal pigment epithelium complex at 1 and 15 minutes (-3.3 ± 0.4 μm and +1.8 ± 0.4 μm, respectively, p <0.001 for both). There was no significant change in choroidal thickness; however, we could detect a tendency towards thinning at 1, 15, and 30 minutes following exercise. The observed changes in thickness change did not correlate with performance. Similar trends were observed in both professional and amateur sportsmen (n = 15 and n = 6, respectively). The absolute changes in choroidal thickness did not show any correlation with the thickness changes of the intraretinal layers.

Conclusions

Our study implies that in young adults, intense physical exercise has an acute effect on the granular layers of the retina, resulting in thinning followed by rebound thickening before normalization. We could not identify any clear correlation with either choroidal changes or performance that might explain our observations, and hence the exact mechanism warrants further clarification. We believe that a combination of vascular and mechanic changes is behind the observed trends.

Choroidal Vascularity Index Changes After Exercise in Patients With Glaucoma

Purpose: To investigate the changes in choroidal vascular structures after exercise in patients with glaucoma using an image binarisation algorithm with enhanced-depth imaging optical coherence tomography.

Methods: Thirty-four eyes of 19 patients with primary open-angle glaucoma and 40 eyes of 20 normal subjects were included in the glaucoma and control groups, respectively. All subjects were evaluated before, immediately after, and 30 min after 20-min running at moderate speed. The subfoveal choroidal area was segmented into the luminal area (LA) and stromal area (SA), and the choroidal vascularity index (CVI) was measured by calculating the ratio of LA to the total choroidal area (TCA). The mean intraocular pressure (IOP), subfoveal choroidal thickness, CVI, SA, CA, and TCA were compared within and between both groups. The correlation between CVI, IOP, and other vascular indexes was investigated.

Results: In the glaucoma group, a significantly lower CVI was found immediately after exercise and recovered 30 min after exercise. Higher TCA and LA levels were demonstrated 30 min after exercise compared to immediately after exercise. In both groups, IOP decreased immediately after exercise but was restored after a 30-min rest. In the glaucoma group, there was a higher correlation between CVI and other choroidal vascular parameters than in the control group. There was no difference in IOP or choroidal parameters between the groups at different time points.

Conclusion: In patients with glaucoma, CVI decreased significantly immediately after exercise, indicating that the choroidal layer is affected by exercise and an unhealthy vascular regulatory mechanism.

Optical coherence tomography angiography changes in cardiovascular systemic diseases and risk factors: A Review

Cardiovascular (CV) disease (CVD) is the main cause of death around the world, and assessing a patient's CV risk factors (CVRF) can play a major role in its prevention. Since it has been shown that retinal vascular alterations may reflect several systemic processes such as CVRF, we conducted a systematic review in order to summarize which ocular microvasculature changes can be found using Optical Coherence Tomography Angiography (OCTA) in patients without ocular diseases and with systemic pathologies/conditions that affect the CV system when compared to healthy subjects. We searched on online databases, namely PubMed, Scopus, Cochrane and Web of Science, and obtained additional studies through citation tracking. Case reports and review articles were excluded. A total of 47 articles were included in our review. We describe that patients with hypertension, diabetes mellitus, kidney disease, preeclampsia, coronary artery disease, carotid artery stenosis and obstructive sleep apnoea syndrome have, in general, lower retinal and choroidal Vessel Density (VD) and Length (VL), as well as an increased foveal avascular zone area and perimeter. Additionally, several characteristics and/or conditions in healthy subjects, such as smoking status, hyper or hypoxia conditions, race, among others, are also related to ocular vascular changes and should be accounted for. We concluded that OCTA could be a useful tool to assess a patient's CV risk profile in a non-invasive way, possibly integrating the diagnostic and prognostic algorithms of the most prevalent CV diseases in the future.

IDIOPATHIC FOVEAL HYPOPLASIA: Quantitative Analysis Using Optical Coherence Tomography Angiography

PURPOSE

To evaluate vascular density (VD), fractal dimension, and skeletal density on optical coherence tomography angiography in eyes with idiopathic foveal hypoplasia (IFH).

METHODS

Patients presenting with IFH to Creteil University Eye Clinic between January 2015 and October 2018 and age-matched healthy controls were retrospectively evaluated. Vascular density, skeletal density, and fractal dimension analyses were computed on optical coherence tomography angiography superficial capillary plexa (SCP) and deep capillary plexa (DCP) images on the whole image using a custom algorithm. Vascular density on the central 1 mm and the peripheral 8 mm for the two groups was performed.

RESULTS

Thirty-six eyes of 21 patients (18 eyes with IFH and 18 control eyes) were included. A decrease of VD at the level of the SCP and DCP was found in eyes with IFH compared with healthy control eyes (P = 0.005 for VD at the level of the SCP and P = 0.003 for VD at the level of the DCP, respectively). On the central 1 mm, VD was decreased in healthy eyes (32.3% ± 4.8) at the level of the SCP compared to IFH eyes (55.6% ± 46.3) (P < 0.001). Skeletal density was decreased in IFH eyes in both SCP and DCP (P =< 0.001). Fractal dimension was lower in IFH eyes in both SCP and DCP (P < 0.001).

CONCLUSION

Vascular density, skeletal density, and fractal dimension are reduced at the level of SCP and DCP in patients with IFH compared with controls, reflecting a particular anatomical and vascular organization. Quantitative analysis using optical coherence tomography angiography could help to evaluate the severity of IFH.

Evaluation of the effect of high-intensity interval training on macular microcirculation via swept-source optical coherence tomography angiography in young football players

Purpose:

This study was conducted to evaluate the effect of high intensity interval training (HIIT) on macular microcirculation, measured by swept source optical coherence tomography angiography (ss OCTA) in young football players.

Methods:

Football players between 18–20 years old were included. After a detailed ophthalmological examination, physiological parameters, including height, body weight, body fat, systemic blood pressure, hematocrit values, oxygen saturation, and heart rate, were recorded. Intraocular pressure and ss OCTA parameters were measured one day before and the day after the high intensity interval training program using DRI OCT Triton (Topcon, Tokyo, Japan) between 11:00 am and 1:00 pm.

Results:

Fifteen participants completed the study. All were males with a mean age of 18.1 ± 0.4 years. Systolic and diastolic blood pressure and oxygen saturation did not change significantly (P > 0.05), while hematocrit levels increased remarkably (P = 0.049) after the HIIT program. Heart rates and intraocular pressure decreased (P = 0.003, P = 0.017, respectively). There was a significant increase in the central vessel density in deep capillary plexus (before: 18.7 ± 3.8%, after: 21.1 ± 4.5%) and central vessel density in choriocapillaris (before: 54.5 ± 2.8%, after 56.9 ± 2.2%) (P = 0.02, P = 0.02, respectively), although no changes were observed in other ss OCTA or in the central macular thickness and subfoveal choroidal thickness.

Conclusion:

A 6 week, high intensity interval training program with three exercise sessions per week seems not to alter mean superficial vascular densities, deep foveal avascular zone, and superficial foveal avascular zones, central macular thickness, or subfoveal choroidal thickness, while the central deep vascular density and central choriocapillaris vascular density increased remarkably among ss OCTA parameters.

Evaluation of the Macular and Choroidal Perfusion in Healthy Turkish Population Using Optical Coherence Tomography Angiography

PURPOSE

To investigate the effect of age- and sex-related differences on macular and choroidal perfusion in healthy Turkish individuals by optical coherence tomography angiography (OCTA).

METHODS

Two hundred-eight eyes of 116 healthy Turkish individuals (60 females and 56 males, mean age 40.35 ± 12.64 years) were included in this study. OCTA was performed on a 3 × 3-mm region on the macula. The superficial macula wholeimage vessel density (wiVD), foveal VD and parafoveal VD vessel density, foveal avascular zone (FAZ) as well as choriocapillaris flow index (CFI) were quantified.

RESULTS

The mean vessel density was 53.1% ± 2.8% in superficial macula wiVD, 31.7% ± 6.9% in superficial foveal VD and 55.2% ± 3.4% in superficial parafoveal VD for 3 × 3-mm OCTA images. Analysis of 3 × 3-mm scan has revealed a mean value of FAZ area was 0.313 ± 0.112 mm2. The mean CFI for 3 × 3-mm scan was 1.937 ± 0.059. A significant decrease was observed in the mean values of wiVD, parafoveal VD and CFI with age (p &lt; 0.001, p = 0.001, and p &lt; 0.001, respectively), with average yearly reductions of 0.3%, 0.4% and 0.4%, respectively. However, there was no correlation between age and foveal VD (p &gt; 0.05). The FAZ area has shown an age-dependent annual increment, showing an average of 1.26%. The parafoveal VD and FAZ area were significantly higher in females than males (p = 0.027 and p = 0.015, respectively) while other parameters seemed similar (p &gt; 0.05 for all).

CONCLUSIONS

Our results suggest that age- and sex-related variations were effective on macular and choroidal perfusion. These normative values obtained using OCTA may be clinically useful to the evaluation of retinal and choroidal disorders.

Retina Vascular Perfusion Dynamics During Exercise With and Without Face Masks in Healthy Young Adults: An OCT Angiography Study

Purpose

To determine possible impacts on retinal microvasculature in healthy young adults during exercise with a face mask, using optical coherence tomography angiography (OCTA).

Methods

Twenty-three healthy participants (23 eyes, 17 women and 6 men) performed the incremental continuous running test (ICRT) with different masks. OCTA of the macula and optic nerve head were performed before and after ICRT to detect changes in retinal vessel density (VD). All participants were in groups A, B, and C (before ICRT) and groups A′, B′, and C′ (after ICRT), which comprised data from volunteers without a mask, with a surgical mask, and with an N95 mask, respectively.

Results

Before ICRT, group C showed significantly reduced VD in the superficial plexus (SP), except foveal VD, compared with group A (P < 0.05). After ICRT, groups B′ and C′ showed significantly shorter maximum running time, lower oxygen saturation, and lower perifoveal VD of SP compared with group A′ (P < 0.05).

Conclusions

Use of an N95 mask reduced VD in SP even under quiescent conditions, which might have clinical implications for protecting healthy workers and indoor manual labor workers from potential risks of retinal damage due to long-term mask use. Moreover, mask use while exercising might lead to attenuated exercise ability and lower VD in SP, which should be investigated in additional studies.

Translational Relevance

Retina vascular perfusion dynamics could be monitored in vivo by OCTA, which would be valuable to study physiologic retinal blood flow redistribution and potential impacts on retinal vascular perfusion during exercise with face masks.

Retinal and choroidal blood flow variations after an endurance exercise: A real-life pilot study at the Paris Marathon

OBJECTIVES

To collect information about the retinal blood flow variations and other choroidal and retinal parameters during a prolonged effort such as marathon running.

DESIGN

Non-randomized prospective cohort study.

METHODS

Patients were recruited through an information campaign at the Rothschild Foundation Hospital (Paris, France). A first visit (V1) was planned in the month before the marathon. All participants underwent blood pressure measurement, fundus photography, spectral domain-optical coherence tomography (SD-OCT) and OCT-angiography (OCT-A). A second visit (V2) was scheduled within one hour of crossing the finish line. The same tests were repeated, using the same equipment.

RESULTS

Of the 31 runners who were included, 29 finished the marathon and attended V2. At baseline, various ophthalmological abnormalities were found in 45.2% of the 58 eyes, among which almost a third concerned the optic nerve and a quarter the pachychoroid spectrum. A significant decrease in retinal vascular plexus density was found between V1 and V2 (p<0.01). While median macular and retinal nerve fiber layer (RNFL) thicknesses significantly increased after the marathon (p<0.01), median choroidal thickness significantly decreased (p<0.01). Both systolic and diastolic blood pressures significantly decreased (p<0.01 and p=0.021 respectively).

CONCLUSIONS

Prolonged physical effort impacts the structure and vascularization of the retina and the choroid. Hypoxia and dehydration due to such an effort may induce a low ocular blood flow rate resulting in a choroidal thinning, contrasting with a transient subclinical ischemic edema of the inner retina and optic nerve head.

CLINICAL TRIAL REGISTRATION NUMBER

NCT03864380.

[Optical coherence tomography angiography and cardiovascular diseases. An overview of the current knowledge]

Hintergrund

Kardiovaskuläre Erkrankungen (KVE) sind die Haupttodesursache weltweit. Die Beobachtbarkeit von Veränderungen der retinalen Gefäße im Zusammenhang mit KVE mittels Fundoskopie ist schon seit Langem bekannt. Ein neuartiges Verfahren zur nichtinvasiven und detaillierten Darstellung und Quantifizierung der retinalen und papillären Gefäße stellt die optische Kohärenztomographie-Angiographie (OCT-A) dar. Durch die OCT‑A ist es möglich, Gefäßveränderungen einfach und gut reproduzierbar zu visualisieren, weswegen ihr Einsatz nicht nur auf augenärztliche Fragestellungen beschränkt ist. In den vergangenen Jahren sind einige experimentelle und klinische Studien zur Darstellbarkeit und Quantifizierung von Gefäßveränderungen durch die OCT‑A bei Erkrankungen des kardiovaskulären Spektrums publiziert worden. In der vorliegenden Übersicht werden die wichtigsten Erkenntnisse aus diesen Studien zusammengefasst.

Methoden

Grundlage dieser Arbeit bilden eine umfassende selektive Literaturrecherche und die Darstellung eigener Daten.

Ergebnisse

Mittlerweile liegen zu vielen Erkrankungen des kardiovaskulären Spektrums OCT-A-Studien vor, die verdeutlichen, dass systemische Gefäßerkrankungen mit Veränderungen der retinalen Mikrozirkulation verbunden sind. Mit der OCT‑A können diese Veränderungen visualisiert und reproduzierbar quantifiziert werden. Oftmals ist es möglich, subklinische Veränderungen aufzuzeigen, bevor die zugrunde liegende Erkrankung anderweitig messbare Veränderungen oder für den Patienten merkbare Symptome verursacht.

Schlussfolgerung

Die OCT‑A ist eine vielversprechende Bildgebungsmethode auf dem Gebiet der KVE in Wissenschaft und klinischer Anwendung. Sie kann zur Diagnostik und Quantifizierung retinaler Gefäßveränderungen eingesetzt werden. Weitere Studien werden zeigen, ob die OCT‑A bei der Einschätzung des individuellen kardiovaskulären Risikoprofils helfen kann.

Retinal applications of swept source optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA)

The advent of optical coherence tomography (OCT) revolutionized both clinical assessment and research of vitreoretinal conditions. Since then, extraordinary advances have been made in this imaging technology, including the relatively recent development of swept-source OCT (SS-OCT). SS-OCT enables a fast scan rate and utilizes a tunable swept laser, thus enabling the incorporation of longer wavelengths than conventional spectral-domain devices. These features enable imaging of larger areas with reduced motion artifact, and a better visualization of the choroidal vasculature, respectively. Building on the principles of OCT, swept-source OCT has also been applied to OCT angiography (SS-OCTA), thus enabling a non-invasive in depth-resolved imaging of the retinal and choroidal microvasculature. Despite their advantages, the widespread use of SS-OCT and SS-OCTA remains relatively limited. In this review, we summarize the technical details, advantages and limitations of SS-OCT and SS-OCTA, with a particular emphasis on their relevance for the study of retinal conditions. Additionally, we comprehensively review relevant studies performed to date to the study of retinal health and disease, and highlight current gaps in knowledge and opportunities to take advantage of swept source technology to improve our current understanding of many medical and surgical chorioretinal conditions. We anticipate that SS-OCT and SS-OCTA will continue to evolve rapidly, contributing to a paradigm shift to more widespread adoption of new imaging technology to clinical practice.

Effects of physical exercise on macular vessel density and choroidal thickness in children

We used swept-source (SS) optical coherence tomography (OCT) and OCT angiography (OCTA) to investigate the effects of moderate physical exercise on retinal and choroidal vessel densities (VDs) and thicknesses in children. One eye in each of 40 myopic children (mean age, 11.70 years) and 18 emmetropic children (mean age, 11.06 years) were included. SS-OCT 6 × 6-mm radial scans and SS-OCTA 3 × 3-mm images were centered on the macula. Heart rate (HR), systolic and diastolic blood pressure, and intraocular pressure (IOP) were recorded before and immediately after a 20-min stationary cycling exercise and after a 30-min rest. The subfoveal choroidal thickness (SFCT), choroidal thickness (CT), and VD at the superficial and deep retinal layers, choriocapillaris, and deeper choroidal vessels were determined. SFCT and CT were significantly lower at all locations immediately after exercise (p < 0.001) and did not fully recover after rest (p < 0.05). VD was lower in the deep retinal layer after exercise (p = 0.02) and higher in the superficial layer after rest (p = 0.03) in myopic eyes while it was higher in the superficial (p < 0.01) and deep layer (p < 0.01) after rest in emmetropic eyes. No significant exercise-related changes in the superficial retinal VD, choroidal VD, or IOP were observed. ΔCT% and ΔSFCT% were significantly correlated with increases in HR in myopic group (p = 0.04 and p = 0.03, respectively). Exercise increased retinal VD after rest in emmetropic eyes, and caused significant CT thinning that lasted for at least 30 min in both emmetropic and myopic eyes.

Retinal Vascular Reactivity in Type 1 Diabetes Patients Without Retinopathy Using Optical Coherence Tomography Angiography

Purpose

We hypothesize that patients with type 1 diabetes (T1D) may have abnormal retinal vascular responses before diabetic retinopathy (DR) is clinically evident. Optical coherence tomography angiography (OCTA) was used to dynamically assess the retinal microvasculature of diabetic patients with no clinically visible retinopathy.

Methods

Controlled nonrandomized interventional study. The studied population included 48 eyes of 24 T1D patients and 24 demographically similar healthy volunteers. A commercial OCTA device (AngioVue) was used, and two tests were applied: (1) the hypoxia challenge test (HCT) and (2) the handgrip test to induce a vasodilatory or vasoconstrictive response, respectively. The HCT is a standardized test that creates a mild hypoxic environment equivalent to a flight cabin. The handgrip test (i.e., isometric exercise) induces a sympathetic autonomic response. Changes in the parafoveal superficial and deep capillary plexuses in both tests were compared in each group. Systemic cardiovascular responses were also comparatively evaluated.

Results

In the control cohort, the vessel density of the median parafoveal superficial and deep plexuses increased during hypoxia (F_1,23 = 15.69, P < 0.001 and F_1,23 = 16.26, P < 0.001, respectively). In the T1D group, this physiological response was not observed in either the superficial or the deep retinal plexuses. Isometric exercise elicited a significant decrease in vessel density in both superficial and deep plexuses in the control group (F_1,23 = 27.37, P < 0.0001 and F_1,23 = 27.90, P < 0.0001, respectively). In the T1D group, this response was noted only in the deep plexus (F_1,23 = 11.04, P < 0.01).

Conclusions

Our work suggests there is an early impairment of the physiological retinal vascular response in patients with T1D without clinical diabetic retinopathy.

Quantitative deep vascular complex analysis of different AMD stages on optical coherence tomography angiography

Aims:

To investigate alterations in deep retinal vascular complex (DVC) in patients with non-neovascular intermediate AMD (iAMD), treatment-naïve quiescent macular neovascularization (qMNV), exudative AMD (eAMD) by means of OCT angiography (OCTA).

Methods:

Patients with iAMD, qMNV, eAMD and healthy controls presenting in the Department of Ophthalmology of the Centre Hospitalier Intercommunal de Créteil between January 2016 and January 2018, were retrospectively included. 3 × 3-mm OCTA (AngioVue RTVue XR Avanti) perfusion density (PD) of DVC was computed in all groups at baseline and follow up (12.0 ± 1.1 months).

Results:

A total of 46 eyes of 45 patients were enrolled: 11/46 iAMD, 10/46 qMNV, 13/46 eAMD, 12/46 control eyes. PD showed a significant decrease during follow-up in qMNV ( p = 0.0059) and iAMD ( p = 0.0076) eyes. PD in eAMD and healthy controls didn’t show significant changes.

Conclusion:

PD decreases at the level of DVC in eyes with qMNV and iAMD, while in eAMD eyes, PD is stable throughout follow up, suggesting that repeated anti-vascular endothelial growth factor (VEGF) injections do not impact on the DVC PD.

Characterization of retinal microvasculature and its relations to cognitive function in older people after circuit resistance training

PURPOSE

To characterize the changes of retinal microvascular density and their relations to cognitive function in the healthy older people without known cognitive impairment after an 8-week high-speed circuit resistance training program (HSCT).

METHODS

Twenty cognitively normal older people were recruited and randomly assigned to either the HSCT group or control group (CON). Twelve subjects (age 70.8 ± 5.8 yrs) in the HSCT group trained three times per week for 8 weeks. Eight subjects in the CON group (age 71.8 ± 4.8 yrs) did not perform formal training. Both eyes of each subject were imaged using optical coherence tomography angiography (OCTA) at baseline and at 8-week follow-up. The densities of the retinal vascular network (RVN), superficial vascular plexus (SVP), and deep vascular plexus (DVP) were measured. In addition, their cognitive functions were tested using the NIH toolbox.

RESULTS

There were significant increases in pattern comparison processing speed (PAT, P = 0.02) and fluid composite score (FCS, P = 0.005) at the follow-up in the HSCT group. Although the vessel densities did not differ between visits in either group, the variation (i.e., change) in retinal vessel density of SVP was negatively related to the changes of FCS (r = -0.54, P = 0.007) and the List Sorting Working Memory test (r = -0.43, P = 0.039) in the HSCT group.

CONCLUSIONS

This is the first study to reveal that the individual response of the SVD was related to the improvement in the cognition in cognitively normal older people after HSCT.

Retinal Nonperfusion in Proliferative Diabetic Retinopathy Before and After Panretinal Photocoagulation Assessed by Widefield OCT Angiography

PURPOSE

Widefield swept source optical coherence tomography angiography (WF SS-OCTA) imaging was compared with ultra-widefield (UWF) fluorescein angiography (FA) imaging to better understand changes in retinal nonperfusion before and after panretinal photocoagulation (PRP) in treatment-naïve eyes with proliferative diabetic retinopathy (PDR).

DESIGN

Prospective, observational, consecutive case series.

METHODS

Participants with treatment-naïve PDR were imaged using the SS-OCTA 12- × 12-mm scan pattern at baseline and at 1 week, 1 month, and 3 months after PRP. UWF FA was obtained at baseline and 3 months after PRP. Selected eyes were imaged using 5 SS-OCTA 12- × 12-mm scans to create a posterior pole montage, and 5 eyes also underwent SS-OCTA imaging at 6 months and 1 year. Areas of retinal nonperfusion (RNP) were drawn independently by 2 masked graders, and analysis of variance (ANOVA) tests were used to compare areas of RNP over time. Main outcome measurements consisted of areas and boundaries of RNP visualized using WF SS-OCTA and UWF FA.

RESULTS

From January 2018 through January 2019, WF SS-OCTA was performed on 20 eyes with treatment-naïve PDR from 15 patients. Areas of RNP identified on UWF FA images co-localized with RNP areas visualized on WF SS-OCTA images. There were no statistically significant changes in RNP area on WF SS-OCTA images through 3 months after PRP. Even eyes that were severely ischemic at baseline had no significant changes in RNP area 1 year after PRP.

CONCLUSIONS

RNP in PDR can be identified at baseline and imaged serially after PRP using WF SS-OCTA. Retinal perfusion in PDR does not change significantly after PRP. The ability of WF SS-OCTA to longitudinally evaluate RNP areas provides additional justification for adopting WF SS-OCTA as the sole imaging modality for clinical management of PDR.

Asymmetry analysis of macular optical coherence tomography angiography in patients with glaucoma and healthy subjects

BACKGROUND/AIMS

Quantitative analysis of optical coherence tomography angiography (OCT-A) images requires a reproducible approach that accounts for sectoral loss. The objective of this study was to determine whether an index that accounts for both global (perfusion density, PD) and asymmetric loss of perfusion, rather than PD alone, more reliably measures loss of perfusion in patients with glaucoma.

METHODS

We analysed macular OCT-A scans of 95 glaucoma patients and 59 control subjects. Two-dimensional projection images corresponding to the superficial vascular plexus were exported and analyses performed to calculate global PD and image asymmetry. An unsigned perfusion asymmetry index (PAI) that included PD and asymmetry (with 1:1 wt) was calculated. Perfusion density and PAI were compared with 10-2 visual field mean deviation and ganglion cell layer (GCL) thickness.

RESULTS

Median (IQR) visual field mean deviation was -1.73 (-3.76, 0.30) dB for the glaucoma group and 0.67 (0.16, 1.18) dB for the control group. The strength of the correlation with mean deviation was stronger for PAI (r=0.47), compared with PD (r=0.35), whereas with GCL thickness they were comparable (r=0.45 and 0.43, respectively). Compared with controls, mean PD was 12% lower in patients with glaucoma (0.27 vs 0.30), while PAI was 17% lower (0.40 vs 0.48). However, diagnostic accuracy of either PD or PAI was worse than GCL thickness.

CONCLUSIONS

While PAI yielded better correlation with mean deviation and GCL thickness, and a slightly improved separation between patients with glaucoma and healthy controls, diagnostic accuracy was inferior compared with GCL thickness.

Quantitative assessment of the effect of acute anaerobic exercise on macular perfusion via swept-source optical coherence tomography angiography in young football players

AIM

To evaluate the effect of acute anaerobic exercise on macular perfusion measured by swept-source optical coherence tomography angiography (SS-OCTA) in young football players.

MATERIALS AND METHODS

Football players with ages between 18 and 20 years were included into the study. After a detailed ophthalmological examination, physiological parameters including height (cm), body weight (kg), body fat percentage (%), systemic blood pressure (BP) (mmHg), hematocrit values (%), oxygen saturation pO₂ (%) and heart rate (bpm) were recorded. Intraocular pressure (IOP) (mmHg) and SS-OCTA using DRI OCT Triton (Topcon, Tokyo, Japan) were measured immediately before and after Wingate test.

RESULTS

Out of 20, 16 participants completed the study. All participants were males with a mean age of 18.12 ± .34 years. Systolic BP, hematocrit and heart rate increased, while pO₂ and IOP decreased remarkably after Wingate test (p < .01). After anaerobic exercise, there was an increase in mean FAZ area in superficial capillary plexus (FAZs) which was not significant (p = .13), while decrease in FAZ area in deep capillary plexus (FAZd) (mm²) was remarkable (p = .04). No changes were observed in mean vessel density (VD) (%) in superficial capillary plexus (VDs), deep capillary plexus (VDd), choriocapillaris (VDcc), central macular thickness (CMT) (μm) and subfoveal choroidal thickness (SFCT) (μm) after Wingate test (p > .05). FAZd and some of the VD parameters showed a significant correlation with BP (p < .05).

CONCLUSION

Acute anaerobic exercise seems not to alter either mean VD in retina and choroid or CMT and SFCT. Among OCTA parameters, only FAZd decreased remarkably.

Quantitative optical coherence tomography angiography: A review

As a new optical coherence tomography (OCT) modality, OCT angiography (OCTA) provides a noninvasive method to detect microvascular distortions correlated with eye conditions. By providing unparalleled capability to differentiate individual plexus layers in the retina, OCTA has demonstrated its excellence in clinical management of diabetic retinopathy, glaucoma, sickle cell retinopathy, diabetic macular edema, and other eye diseases. Quantitative OCTA analysis of retinal and choroidal vasculatures is essential to standardize objective interpretations of clinical outcome. Quantitative features, including blood vessel tortuosity, blood vessel caliber, blood vessel density, vessel perimeter index, fovea avascular zone area, fovea avascular zone contour irregularity, vessel branching coefficient, vessel branching angle, branching width ratio, and choroidal vascular analysis have been established for objective OCTA assessment. Moreover, differential artery–vein analysis has been recently demonstrated to improve OCTA performance for objective detection and classification of eye diseases. In this review, technical rationales and clinical applications of these quantitative OCTA features are summarized, and future prospects for using these quantitative OCTA features for artificial intelligence classification of eye conditions are discussed.

Influence of cardiac hemodynamic variables on retinal vessel density measurement on optical coherence tomography angiography in patients with myocardial infarction

INTRODUCTION

Quantitative measurements of retinal microvasculature by optical coherence tomography angiography (OCT-A) have been used to assess cardiovascular risk profile. However, to date, there are no studies focusing on OCT-A imaging in the setting of the altered hemodynamic status found in high-risk cardiovascular patients.

METHODS

To determine the potential association between retinal vascular density on OCT-A and a comprehensive battery of hemodynamic variables in patients with myocardial infarction (MI) using data from the acute phase and at 3 months follow-up after cardiac rehabilitation. This prospective longitudinal study included patients who presented with MI in the cardiology intensive care unit at Dijon University Hospital. Main outcomes and measurements were retinal vessel density on OCT-A, hemodynamic status based on left ventricular ejection fraction (LVEF), and indexed cardiac output during the acute phase of myocardial infarction and at 3 months follow-up.

RESULTS

Overall, 30 patients were included in this pilot study. The median (IQR) age was 64 years (55-71) with 87% men. At admission, the mean (SD) LVEF was 53% (11), and the mean indexed cardiac output was 2.70 (0.83) L/min/m². On OCT-A, the mean inner retinal vascular density was 19.09 (2.80) mm^-1. No significant association was found between retinal vascular density and hemodynamic variables.

CONCLUSION

We found no significant association between retinal vascular density on OCT-A and hemodynamic variables in the acute phase of a myocardial infarction or after 3 months of cardiac rehabilitation. Therefore, OCT-A findings do not seem to be influenced by the hemodynamic changes associated with myocardial infarction.