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Retinal vessel segmentation plays a significant role in the diagnosis and treatment of ophthalmological diseases. Recent studies have proved that deep learning can effectively segment the retinal vessel structure. However, the existing methods have difficulty in segmenting thin vessels, especially when the original image contains lesions. Based on generative adversarial network (GAN), this paper proposes a deep network with residual module and attention module (Deep Att-ResGAN). The network consists of four identical subnetworks. The output of each subnetwork is imported to the next subnetwork as contextual features that guide the segmentation. Firstly, the problems of the original image, namely, low contrast, uneven illumination, and data insufficiency, were solved through image enhancement and preprocessing. Next, an improved U-Net was adopted to serve as the generator, which stacks the residual and attention modules. These modules optimize the weight of the generator, and enhance the generalizability of the network. Further, the segmentation was refined iteratively by the discriminator, which contributes to the performance of vessel segmentation. Finally, comparative experiments were carried out on two public datasets: Digital Retinal Images for Vessel Extraction (DRIVE) and Structured Analysis of the Retina (STARE). The experimental results show that Deep Att-ResGAN outperformed the equivalent models like U-Net and GAN in most metrics. Our network achieved accuracy of 0.9565 and F1 of 0.829 on DRIVE, and accuracy of 0.9690 and F1 of 0.841 on STARE.

Aim: To evaluate retinal nerve fiber layer thickness, macular thickness and retinal vessel diameter by optical coherence tomography in patients with peripheral artery disease. Materials and Methods: 35 patients with a diagnosis of peripheral arterial disease (PAD) and 32 healthy individuals (control group) were included in the study. Retinal thickness (RT), choroidal thickness (CT) in enhanced depth imaging (EDI) mode, retinal nerve fiber layer (RNFL) thickness, retinal artery and vein diameters were measured with optical coherence tomography (OCT) device. Results: The mean age of the PAH group included in the study was 59.4±11.9 and the mean age of the control group was 55.5±5.3 years. A statistically significant difference was observed between the two groups in the values obtained from the CT in the subfoveal region of the EDI measured from three different regions and the nasal quadrant of the RNFL measured from 7 quadrants (p=0.03 and p=0.03, respectively). On the contrary, no statistically significant difference was observed in EDI and other measurements of RNFL, RT values, artery and vein diameters (p values were between 0.08-1.00). Conclusion: In patients with PAD, it is important to determine the RNFL and CT to be thinner. It can be a guide in more comprehensive studies in the future.

The purpose of this study was to investigate the association between the vertical position of the central retinal vessel (CRV) within the optic nerve head (ONH) and the site of visual field defects (VFDs) in glaucoma.Cross-sectional study.The vertical position of the CRV was identified in 134 glaucoma eyes and 61 normal eyes at the point at which CRV exited the lamina cribrosa (LC) onto the ONH surface, by using spectral-domain optical coherence tomography (exit position). The position was also identified at the entry point into the LC from the retrolaminar ONH region (entry position), which was little influenced by glaucomatous LC deformation, therefore close to the original position before the glaucoma development. Positions were compared among glaucoma eyes with different sites of VFDs, and between glaucoma and normal eyes.In glaucoma eyes, the entry position of the CRV was in the superior ONH region in 63.0% of eyes with superior VFDs and in the inferior ONH region in 97.8% of eyes with inferior VFDs (P.0001). The exit position exhibited a similar percentage. The vertical CRV positions were not significantly different between glaucoma and normal eyes, both at the entry and exit positions.Eyes with CRVs in the superior ONH region were significantly more likely to form VFDs in the superior hemifields and vice versa. The vertical position of the CRV was little altered by the development of glaucoma. The original position of the CRV before the development of glaucoma may influence regional susceptibility to glaucomatous stress and may be useful in predicting initial sites of VFDs.

Purpose To quantitatively investigate the role of deep capillary plexus (DCP) in patients affected by type 3 macular neovascularization (MNV), compared to patients with reticular pseudodrusen (RPD) eyes and healthy controls, using optical coherence tomography angiography (OCTA). Methods In this prospective observational study, a total of seventy-eight eyes of 78 patients were included. Group 1 consisted of 40 eyes of 40 patients with stage 1 of type 3 MNV (22 males, 18 females, mean age 73.7, SD ± 6.60) and group 2 included 38 eyes of 38 patients with RPD (17 males, 21 females, mean age 73.2, SD ± 4.55). The control group included 40 eyes of 40 healthy subjects (20 males, 20 females, mean age 71.4, SD ± 6.36 years). We evaluated the retinal vessel density (VD) of superficial capillary plexus (SCP) and deep capillary plexus (DCP) using OCTA. Results Patients with diagnosis of type 3 MNV showed statistically lower values of VD in DCP with respect to controls and to RPD group (p Conclusion OCTA provides a reproducible, non-invasive detailed quantitative analysis of retinal vascular features and changing in early-stage type 3 MNV patients, which allowed to shed the light on the main role of DCP ischemia in the development of type 3 MNV.

BACKGROUND To evaluate the ocular symptoms and findings of children diagnosed with Crimean-Congo hemorrhagic fever (CCHF). METHODS In this prospective study, children diagnosed with CCHF who underwent a complete ophthalmologic examination during the hospitalization period were included. RESULTS Twenty-four children with a mean age of 12.4 ± 3.6 years were included study. The most common ocular finding was conjunctival hyperemia and was observed in 50% of patients. Nine (37.4%) children had abnormalities in fundus examination. Two (8.3%) of them had dilated retinal veins, and 7 (29.1%) had tortuous retinal vessels. No significant difference was found between mild to moderate and severe disease groups in terms of ocular symptoms and ophthalmologic examination findings (P > 0.05, for all). CONCLUSIONS The increased retinal vessel tortuosity was detected as a fundus examination finding in children with CCHF. Both ophthalmologists and pediatricians should be aware of the various ocular manifestations of CCHF for rapid diagnosis and management.

We conducted this study to assess the effect of religious fasting on intraocular pressure (IOP) as well as retinal parameters and retinal thickness during Ramadan using optical coherence tomography angiography (OCTA) performed on a spectral domain device. All the participants ate a pre-dawn meal and drink, and then fasted for at least 15 hours. We assessed a total of 61 eyes from 31 healthy volunteers with a mean age of 32.87 ± 8.07. A significant decrease was found in the median IOP after fasting at 10.00 mmHg in comparison with the pre-fasting value of 12.00 mmHg (p

The purpose of this study was to evaluate the use of Fiji Image J application for digital fundus image analysis of retinal vessel diameter in diabetic retinopathy rat model. Male Sprague-Dawley rats, weighing 200-250 grams, were divided into two groups: normal and diabetic. The diabetes was induced by intraperitoneal (IP) injection of streptozotocin (STZ, 55 mg/kg body weight). Normal rats received IP citrate buffer. Fundus images were captured at week 0, 6 and 12 post-induction to observe changes in retinal veins and arteries. Images obtained were then analyzed using Fiji Image J software. Retinal venous diameter was increased in both groups at week 6 and 12 compared to baseline (p

Introduction: The aim of the study was to estimate the phenotype of retinal vessels using central retinal artery equivalent (CRAE), central retinal vein equivalent (CRVE), tortuosity, and fractal analysis in the unaffected contralateral eye of patients with central or branch retinal vein occlusion (CRVO or BRVO). Methods: Thirty-four patients suffering from CRVO, 15 suffering from BRVO, and 49 controlled matched subjects had a fundus image analyzed using the VAMPIRE software. The intraclass correlation coefficient and a Bland-Altman plot were done for the reproducibility study. Results: There was a lack of evidence of difference between the control group and the CRVO group for CRAE (p = 0.06), CRVE (p = 0.3), and arterio-venule ratio (AVR, p = 0.6). Contralateral eyes of CRVO exhibited a significantly higher arterial and minimum arterial tortuosity values (p = 0.012), as compared with control eyes. Contralateral eyes of patients with a history of BRVO had a significantly higher CRAE (p = 0.02), AVR (p = 0.006), and minimal arterial tortuosity (p = 0.05). Fractal analysis showed that contralateral eyes of BRVO had higher values of fractal parameters (D0a, p = 0.005). Conclusion: This study suggests that CVRO or BRVO is not triggered by the same retinal vascular phenotypes in the contralateral eye. The morphology of retinal vasculature may be associated with the occurrence of RVO, independently of known risk factors.

PURPOSE To compare the retinal vessel diameters of healthy eyes and active central serous chorioretinopathy (CSC) eyes, and to evaluate possible effect of retinal vessel diameter alterations on the pathogenesis of CSC. METHODS This retrospective study included 39 patients with CSC and 34 healthy individuals. Spectralis optical coherence tomography + HRA with an infrared reflectance image were used to evaluate structure of retinal vessels in the circular region around the optic disc. For each eye, vertical inner and outer diameters of the four major arteries and veins were measured using infrared reflectance images, and vessel wall thicknesses were also calculated based on inner and outer diameters. RESULTS The 304 vessels of the 39 active CSC eyes and 266 vessels of the 34 healthy eyes were used in the analyses. The mean venous wall thickness in active CSC eyes was significantly thicker than that in healthy eyes (40.0 ± 4.9 vs. 33.5 ± 4.1 μm, P = 0.001), whereas the mean venous inner diameter in active CSC eyes was significantly narrower (52.5 ± 9.7 vs. 61.3 ± 8.1 μm, P = 0.001). Also, the mean venous outer diameter was wider in CSC eyes, albeit not significantly (131.1 ± 7.0 vs. 128.5 ± 8.4 μm, P = 0.074). CONCLUSION Our results suggest that the alterations of retinal venous diameters may play a potential role in the pathogenesis of CSC in addition to alterations in choroidal thickness.

To investigate changes in the foveal avascular zone (FAZ) area and retinal vessel density (VD) in the macula of patients receiving multiple anti-vascular endothelial growth factor (VEGF) therapy for neovascular age-related macular degeneration (N-AMD).This study included 54 eyes of 54 treatment-naïve N-AMD patients. Thirty-three eyes were treated with intravitreal aflibercept injections, and 21 eyes were treated with intravitreal ranibizumab injections. Unaffected fellow eyes (54 eyes) were used as controls. All image scans were acquired after the macular architecture had recovered with drying up of the subretinal fluid/hemorrhage after treatment.Both the superficial and deep FAZ areas were significantly larger in the aflibercept group than in the control group. The VD was also significantly reduced in the aflibercept group.Prolonged and repeated anti-VEGF therapy may cause an increase in the FAZ area and a decrease in the VD in patients with N-AMD, indicating ischemic damage.

Hypertensive Retinopathy is an ocular disease that occurs due to the presence of hypertension in the body. Hypertensive Retinopathy is quantified using a parameter known as Arteriovenous Ratio. To ...

Retinal vessel tortuosity has been used in the diagnosis and management of different clinical situations. Notwithstanding, basic concepts, standards and tools of measurement, reliable normative data and clinical applications have many gaps or points of divergence. In this review we discuss triggering causes of retinal vessel tortuosity and resources used to assess and quantify it, as well as current limitations.

Purpose To investigate a possible microvascular component of poppers maculopathy (PMP) using optical coherence tomography angiography (OCTA). Methods Twelve patients suffering from poppers maculopathy were included. Health records, optical coherence tomography (OCT), and OCTA data was gathered and compared to a healthy control group (HC). PMP lesion type was determined by manifestation in OCT. OCTA-based evaluation of retinal vascular plexus and choriocapillaris (CC) was executed. Vessel density (VD) and vessel length density (VLD) in superficial and deep capillary plexus (SCP, DCP), as well as flow deficits (FD), within the foveal avascular zone (FAZ) in CC were assessed. Results Median age of PMP patients was 40 (min 24; max 64) years, all male. Eleven patients presented with ellipsoid zone-type lesions; one patient showed a vitelliform-type lesion. No qualitative microvascular changes between PMP patients and HC were identified. Quantitative values for VD and VLD of SCP and DCP did not differ in between the two groups. The analysis of FDs in CC showed no deviation from PMP patients to HC. Conclusions No vascular anomalies in qualitative and quantitative analysis in OCTA were detected in PMP patients. The constitution of the CC within FAZ of PMP patients does not differ from HC when assessed as FD.

BACKGROUND: The goal of the study was to determine the effect of different software versions on the measurement of retinal vessel densities using optical coherence tomography angiography (OCTA) in normal subjects. METHODS: Thirty-two eyes of eighteen healthy subjects were imaged using two OCTA devices: the Optovue RTVue and the Zeiss Cirrus. The macular 3 × 3 mm scan protocol was used. The images acquired using the Optovue OCTA device were exported using two different software versions in the system and compared to the images acquired through the Zeiss OCTA. In addition, the Optovue OCTA images were exported after manual adjustment of the segmentation boundaries according to the intraretinal layer definition. The densities of the superficial vascular plexus (SVP) and deep vascular plexus (DVP) were measured using fractal analysis by box-counting (Dbox). RESULTS: Both the vessel densities of the SVP and DVP acquired using the Optovue OCTA device were significantly different when compared to those from the Zeiss OCTA device (all, P < .05). No significant difference was found between the vessel densities of the SVP exported using both the new and old versions of Optovue (P > .05). However, the DVP exported using the new Optovue software version was significantly different compared to those exported using the old version (P < .05). The vessel densities of the SVP and DVP were related among the Optovue OCTA software versions and manual adjustment method (r ranged from 0.55 to 0.77; all P < .05). CONCLUSION: This is the first study to determine that different software versions with various intraretinal layer segmentation methods affect the vessel density measurements of the SVP and DVP.

To evaluate retinal vessel quantity within various retinal structural layers using optical coherence tomography angiography (OCTA). In this IRB-approved study, 22 normal eyes (from 22 subjects) were imaged using the Spectralis OCT2, with a 15 × 15 degree OCTA scan centered on fovea and two additional 15 × 5 degree OCTA scans, displaced temporally and nasally by 15 degrees along the fovea-Bruch’s membrane opening (BMO) axis. Following projection artifact removal (PAR), vessel quantity (i.e., amount of flow signal) within each retinal nuclear and plexiform layer was assessed across the scan and was plotted as a vessel quantity profile over this fovea-BMO axis. Vessel quantity was correlated against the retinal layer thickness at the corresponding locations using the Spearman correlation. For the nerve fiber layer (NFL), the vessel quantity was highest nasally and declined towards the fovea and was near zero temporal to the fovea with or without PAR. For all other retinal layers, the retinal vessel quantities were greatest in the parafoveal retina, peaking approximately 5 degrees from the foveal center. Before PAR, the parafoveal vessel quantity was highest in the inner plexiform layer (IPL). Following PAR, the vessel quantity in the IPL decreased but was relatively unchanged in the other layers. The vessel quantity correlated moderately well with retinal layer thickness (r = 0.432 to 0.511; P < 0.05 among the various layers). Retinal vessel quantity varies significantly among the various structural layers, with significant regional variability. Projection artifact can significantly impact retinal vessel quantity in the deeper layers, but the effect appears to be most pronounced in the IPL.

The success of surgical treatment for idiopathic epiretinal membrane (ERM) is measured by postoperative best-corrected visual acuity (BCVA), metamorphopsia, and foveal retinal sensitivity (RS).This study searched for predictive biomarkers of surgical success by determining the association between foveal RS and various aspects of vessel density (VD) in the fovea of patients with ERM. The study examined 25 eyes of 25 patients with ERM who underwent 27-gauge microincision vitrectomy surgery (MIVS). RS was measured with microperimetry (MP-3; NIDEK) at four central points in the fovea with an interpoint distance of 2°. VD was measured with SD-OCT (RS 3000; NIDEK) within the 1-mm2 square defined by the 4 RS points at various depths, including the superficial and deep retinal capillary plexus (SCP and DCP, respectively). Though VD did not change throughout the follow-up period, BCVA and RS significantly improved 1 and 3 months after surgery, respectively (both P

Background/imsTo compare the retinal vessel diameter measurements obtained from the swept-source optical coherence tomography angiography (OCTA; Plex Elite 9000, Carl Zeiss Meditec, USA) and adaptive optics ophthalmoscope (AOO; RTX1, Imagine Eyes, France).MethodsFifteen healthy subjects, 67% women, mean age (SD) 30.87 (6.19) years, were imaged using OCTA and AOO by a single experienced operator on the same day. Each eye was scanned using two OCTA protocols (3×3 mm2 and 9×9 mm2) and two to five AOO scans (1.2×1.2 mm2). The OCTA and AOO scans were scaled to the same pixel resolution. Two independent graders measured the vessel diameter at the same location on the region-of-interest in the three coregistered scans. Differences in vessel diameter measurements between the scans were assessed.ResultsThe inter-rater agreement was excellent for vessel diameter measurement in both OCTA protocols (ICC=0.92) and AOO (ICC=0.98). The measured vessel diameter was widest from the OCTA 3×3 mm2 (55.2±16.3 µm), followed by OCTA 9×9 mm2 (54.7±14.3 µm) and narrowest by the AOO (50.5±15.6 µm; p2: mean difference Δ=4.7 µm, p2: Δ=4.2 µm, p45 µm, it appeared to be larger in OCTA 3×3 mm2 scan than the 9×9 mm2 scan (Δ=1.9 µm; p=0.005), while vessels 2 scan (Δ=−1.3 µm; p=0.009)ConclusionsThe diameter of retinal vessels measured from OCTA scans were generally wider than that obtained from AOO scans. Different OCTA scan protocols may affect the vessel diameter measurements. This needs to be considered when OCTA measures such as vessel density are calculated.

Purpose: To evaluate choroidal structural changes occurring over time in geographic atrophy (GA) secondary to age-related macular degeneration using choroidal vascularity index (CVI). Methods: Enhanced-depth imaging optical coherence tomography scans of 34 patients with GA and 32 control subjects were retrospectively analyzed. Data were collected at baseline and after a mean follow-up of 18.3 ± 8.3 months. Choroidal images were binarized using the ImageJ software, and the luminal area and stromal area were segmented. Cho- roidal vascularity index was defined as the ratio of luminal area to total choroid area. Results: Patients with GA showed significantly lower values of CVI, total choroid area, luminal area, and subfoveal choroidal thickness compared to control subjects (65.83 ± 3.95 vs. 69.33 ± 3.11, P , 0.001; 0.400 ± 0.239 mm2 vs. 0.491 ± 0.132, P = 0.006; 0.263 ± 0.152 mm2 vs. 0.340 ± 0.094, P = 0.002; 185.2 ± 79.8 mm vs. 216.8 ± 58.8 mm, P = 0.036, respectively). Best-corrected visual acuity was significantly correlated only with choroidal thickness (R = 20.509; P = 0.002). During the follow-up period in patients with GA, sub- foveal choroidal thickness decreased from 185.2 ± 79.8 to 152.2 ± 73.1 (P = 0.001), stromal area increased from 0.138 ± 0.090 mm2 to 0.156 ± 0.068 (P = 0.028), and CVI decreased from 65.83 ± 3.95 to 62.24 ± 3.63 (P , 0.001). Conclusion: This study showed for the first time that CVI is reduced in patients with GA, and that this metric further worsened during the follow-up period.

Cannabis appears to have vascular effects that may have implications for cerebrovascular function, but no studies have directly visualized the microvasculature in living cannabis users. The current study used retinal imaging, a tool taken from ophthalmology, to visualize the small retinal microvessels in cannabis users. We compared retinal arteriolar (small arteries) and venular (small veins) diameters in 55 frequent cannabis users and 51 comparison individuals with a mean age of 19.25 years (SD = 2.43). Results indicated that mean arteriolar diameter was statistically significantly wider for cannabis users (M = 157.98, SE = 1.42) than for comparison individuals (M = 153.56, SE = 1.46; F(1,103) = 4.67, p = .033), even after controlling for a variety of covariates and after excluding from analyses cannabis users who had used cannabis in the past 24 h. There was no statistically significant difference in retinal venular diameter between cannabis users and comparison individuals. Findings suggest that frequent cannabis use is associated with wider retinal arterioles, which might represent a residual vasodilatory effect of recent cannabis use or impaired autoregulation resulting from chronic cannabis use. Retinal imaging is a non-invasive, cost-effective tool for visualizing the microvasculature in living individuals and can be combined, in future research, with neuroimaging and other measures of retinal vascular function to better understand the acute and longer-term effects of cannabis use on the microvasculature.

PurposeAlthough the choroid contributes to the pathogenesis of age-related macular degeneration (AMD), the role of retinal perfusion is unclear. We sought to compare retinal vascular measurements between eyes with nonexudative and exudative AMD using optical coherence tomography angiography (OCT-A).DesignRetrospective, cross-sectional study.MethodsOCT-A images were analyzed from 310 eyes of 182 patients (mean age ± standard deviation [SD], 78.8 ± 8.8 years) with nonexudative (54.2%) and exudative (45.8%) AMD to measure retinal vessel density (VD) from the superficial capillary plexus in the foveal, parafoveal, and full macular regions and foveal avascular zone (FAZ) area, perimeter, and circularity. Multivariate regressions were used to compare nonexudative and exudative AMD eyes and the impact of anti-vascular endothelial growth factor (anti-VEGF) treatments or geographic atrophy (GA).ResultsIn eyes with AMD, VD decreases with age in the foveal (β=-0.211, P < .001), parafoveal (β=-0.305, P < .001), and full macular regions (β=-0.295, P < .001). Eyes with exudative AMD demonstrated lower VD, especially in the parafoveal (29.8% ± 6.3% vs 33.0% ± 5.7%, P < .001) and full regions (27.9% ± 6.2% vs 31.2% ± 5.5%, P < .001) compared with nonexudative AMD. There were no differences in FAZ area, perimeter, or circularity between the 2 groups (P= .503-.907). In eyes with exudative AMD, previous anti-VEGF treatments did not impact retinal vascular measurements (P= .324-.986). Nonexudative AMD severity and presence of central GA also impacted retinal VD and FAZ morphology.ConclusionsRetinal VD is decreased in eyes with exudative AMD compared with nonexudative AMD but is unaffected by anti-VEGF treatments, suggesting a retinal vascular contribution to the pathogenesis of AMD.

The aim of this study is to evaluate the retinal microvascular density in SLE patients using optical coherence tomography angiography (OCTA) and to correlate vascular density with the disease activity and damage risk. Twenty eyes of 20 SLE patients were compared with 20 eyes of normal subjects. The retinal capillary plexuses were examined by OCTA. The disease activity and damage risk were evaluated by the SLEDAI-2 K and SLICC/ACR SDI scoring systems. No difference was found between SLE patients’ central foveal thickness (CFT) and foveal avascular zone (FAZ) area and the normal (P > 0.05). SLE patients had slightly lower superficial vessel densities than normal in the upper and lower macular regions (P 0.05). In the deep plexus, vessel density loss was detected in all sectors (P

AIM: To compare the qualitative and quantitative features among untreated polypoidal choroidal vasculopathy (PCV), neovascular age-related macular degeneration (nv-AMD) and central serous chorioretinopathy (CSC) using optical coherence tomography (OCT) and OCT angiography (OCTA). METHODS: This retrospective study included 16 eyes with thin-choroid PCV, 18 eyes with thick-choroid PCV, 16 eyes with nv-AMD and 17 eyes with CSC, respectively. The indicators were obtained by OCT and OCTA. RESULTS: Sub-foveal choroidal thickness (SFCT) in CSC was thicker compared to other groups (all P

PURPOSE: To compare retinal vessel density in eyes with geographic atrophy (GA) secondary to age-related macular degeneration (AMD) to age-matched healthy eyes using projection-resolved optical coherence tomography angiography (PR-OCTA). DESIGN: Prospective cross-sectional study. METHODS: Study participants underwent macular 3×3-mm OCTA scans with spectral domain OCTA. Reflectance-compensated retinal vessel densities were calculated on projection-resolved superficial vascular complex (SVC), intermediate capillary plexus (ICP), and deep capillary plexus (DCP). Quantitative analysis using normalized deviation compared the retinal vessel density in GA regions, 500 μm GA rim regions, and non-GA regions to similar macular locations in control eyes. RESULTS: Ten eyes with GA and 10 control eyes were studied. Eyes with GA had significantly lower vessel density in the SVC (54.8±2.4% vs. 60.8±3.1%, P

Multiple approaches for quantifying parameters such as vessel density (VD) and vessel length density (VLD) in optical coherence tomography angiography (OCTA) en-face segmentations are currently available. While it is common knowledge that data gathered from different methods should not be directly compared to each other, a comparison of the different methods can help to further the understanding of differences between different methods of measurement. Here we compare a common method of semiautomatically quantifying VD and VLD with an automated method supplied by the manufacturer of an OCTA device and report on differences in performance in order to probe for and highlight differences in values gathered by both methods.OCTA was performed using the swept source PLEX Elite 9000 device, software version 2.0.1.47652 (Carl Zeiss Meditec Inc., Dublin, CA, USA). Scans of 3 mm × 3 mm from healthy volunteers centred on the fovea were acquired by a well-trained certified ophthalmologist. Scans with a signal strength of 8 out of 10 or higher were included. Quantitative parameters of the 3 mm × 3 mm cube scans were automatically generated and segmented into superficial capillary plexus (SCP) and deep capillary plexus (DCP) layers using layer segmentation produced by the instrument software and prototype analysis VD quantification software (Macular Density v.0.7.1, ARI Network Hub, Carl Zeiss Meditec Inc., Dublin, CA, USA) supplied by the manufacturer. An alternative approach of quantitative analysis of VD and VLD was performed manually with ImageJ (National Institutes of Health, Bethesda, Maryland, USA), as previously reported. VD was assessed as the ratio of the retinal area occupied by vessels. VDL was measured as the total length of the skeletonised vessels using 1-pixel centre line extraction of the blood vessels.We report differences in standard deviation (SD) in OCTA parameters obtained using different methods. The standard deviation of VD and VLD measurements was statistically significantly different in VD of 3 mm × 3 mm DCP (p = 0.009), VLD of 3 mm × 3 mm SCP (p = 0.000), and VLD of 3 mm × 3 mm DCP (p = 0.021). No statistically significant differences were found in VD of 3 mm × 3 mm SCP (p = 0.128) or VLD of 3 mm × 3 mm SCP (p = 0.107).As expected, we were able to demonstrate significant differences in quantitative OCTA parameters gathered from the same images using different methods of quantification. Values gathered using different methods are not interchangeable. In scientific studies and in situations where long-term follow-up is necessary, the same device and the same method of quantification should be used to maintain retrospective comparability of measurements.Mehrere Ansätze zur Quantifizierung von Parametern wie Vessel Density (VD) und Vessel Length Density (VLD) in der optischen Kohärenztomografieangiografie (OCTA) sind derzeit verfügbar. Es ist ebenfalls bekannt, dass Daten, die mit verschiedenen Methoden erhoben wurden, nicht direkt miteinander vergleichbar sind. Diese Studie exploriert Unterschiede der verschiedenen Methoden, um zu einem besseren Verständnis der unterschiedlichen Messmethoden zu führen. Sie vergleicht eine gängige Methode zur halbautomatischen Bestimmung von VD und VLD mit einer automatischen Methode, welche vom Hersteller eines OCTA-Geräts bereitgestellt wird und berichtet über Unterschiede der mit den beiden Methoden ermittelten Werte.Die OCTA-Aufnahmen wurden mit dem Swept Source PLEX Elite 9000, Softwareversion 2.0.1.47652 (Carl Zeiss Meditec Inc., Dublin, CA, USA) akquiriert. Scans von 3 mm × 3 mm von gesunden Probanden, zentriert auf die Fovea, wurden von einem geschulten Ophthalmologen erstellt. Scans mit einer Signalstärke von 8 von 10 oder höher wurden eingeschlossen. Quantitative Parameter der 3 mm × 3 mm-Scans wurden automatisch für den oberflächlichen Kapillarplexus (SCP) und tiefen Kapillarplexus (DCP) erstellt. Die Segmentierung wurde durch die geräteherstellereigene Software (Macular Density v.0.7.1, ARI Network Hub, Carl Zeiss Meditec Inc., Dublin, CA, USA) vorgenommen. Diese Software generiert auch VD- und VLD-Werte für den SCP und DCP. Ein alternativer Ansatz der quantitativen Analyse von VD und VLD wurde manuell mit ImageJ (National Institutes of Health, Bethesda, Maryland, USA) durchgeführt, wie bereits in anderen Publikationen berichtet.Wir berichten über Unterschiede in der Standardabweichung (SD) der OCTA-Parameter der unterschiedlichen Methoden. Die Standardabweichung der VD- und VLD-Messungen war statistisch signifikant unterschiedlich bei der VD von 3 mm × 3 mm des DCP (p = 0,009), bei der VLD von 3 mm × 3 mm des SCP (p = 0,000) und bei der VLD von 3 mm × 3 mm des DCP (p = 0,021). Keine statistisch signifikanten Unterschiede wurden bei der VD von 3 mm × 3 mm des SCP (p = 0,128) oder bei der VLD von 3 mm × 3 mm des SCP (p = 0,107) entdeckt.Wie erwartet, konnten wir signifikante Unterschiede in den quantitativen OCTA-Parametern nachweisen, die aus denselben Bildern, aber mit unterschiedlichen Quantifizierungsmethoden gewonnen wurden. Die mit verschiedenen Methoden ermittelten Werte sind nicht austauschbar. In wissenschaftlichen Studien und in Situationen, in denen langfristig wiederholt Messungen durchgeführt werden, sollte dasselbe Gerät und dieselbe Quantifizierungsmethode verwendet werden, um die retrospektive Vergleichbarkeit der Messungen zu gewährleisten.

OBJECTIVES: The examination of retinal microvascular abnormalities through fundus photography is currently the best available non-invasive technique for assessment of cerebral vascular status. Several studies in the last decade have reported higher incidences of adverse cerebrovascular events in Schizophrenia (SCZ) and bipolar disorder (BD). However, retinal microvasculature abnormalities in SCZ and BD have remained under-explored, and no study has compared this aspect of SCZ and BD till date.METHODS: Retinal Images of 100 SCZ patients, BD patients, and healthy volunteers each were acquired by trained individuals using a non-mydriatic camera with a 40-degree field of view. The retinal images were quantified using a valid semi-automated method. The average of left and right eye diameters of the venules and arterioles passing through the extended zone between 0.5 and 2 disc diameters from the optic disc were calculated.RESULTS: The groups differed significantly with respect to average diameters of both retinal venules (P < 0.001) and retinal arterioles (P < 0.001), after controlling for age and sex. Both SCZ and BD patients had significantly narrower arterioles and wider venules compared to HV. There were also significant differences between SCZ and BD patients; patients with BD had narrower arterioles and wider venules.CONCLUSION: Considering the affordability and easy accessibility of the investigative procedure, retinal microvascular examination could serve as a potential screening tool to identify individuals at risk for adverse cerebrovascular events. The findings of the current study also provide a strong rationale for further systematic examination of retinal vascular abnormalities in SCZ and BD.

Purpose The aim of this case control study was to evaluate the prognostic value of automatically quantified retinal vessel tortuosity from fundus images and vessel density from OCT-A in Fabry disease and to evaluate the correlation of these with systemic disease parameters. Methods Automatically quantified perimacular retinal vessel tortuosity (MONA REVA software), acquired by fundus imaging, and perifoveal retinal vessel density, acquired by optic coherence tomography angiography (OCT-A) were compared between 26 FD patients and 26 controls. Gender and FD phenotype were analyzed to the obtained retinovascular data and correlated to the Mainz severity score index (MSSI) and plasma lyso-Gb3. Results Automatically quantified retinal vessel tortuosity indices of FD patients were significantly lower, reflecting an increased vessel tortuosity, compared to controls (p = 0.008). Males with a classical phenotype showed significantly lower retinal vessel tortuosity indices compared to males with an oligosymptomatic phenotype and females with a classical or oligosymptomatic phenotype (p p p p Conclusion We advocate fundus imaging based automatically quantified retinal vessel tortuosity index over OCT-A imaging as it is a quick, non-invasive, easily assessable, objective and reproducible marker.

PURPOSE: This cross-sectional study investigates the association between retinal vessel complexity and age and studies the effects of cardiovascular health determinants. METHODS: Retinal vessel complexity was assessed by calculating the box-counting fractal dimension (Df ) from digital fundus photographs of 850 subjects (3-97 years). All photographs were labelled as 'non-pathological' by the treating ophthalmologist. RESULTS: Statistical models showed a significantly decreasing relationship between age and Df (linear: R-squared = 0.1897, p

SIGNIFICANCE Commercially available platforms show good agreement in clinical outcomes for retinal vessel caliber measurements, despite differing absolute values. Tighter agreement is observed when right and left eye data are averaged, suggesting an approach suitable for clinical practice. PURPOSE The purpose of this study was to compare the retinal vessel caliber measurements generated by different commercially available platforms and their associations with systemic blood pressure and age. METHODS A total of 209 participants were recruited from a UK optometric practice. After a routine eye examination, participants had disc-centered retinal photographs and systemic blood pressure taken. Retinal vessel calibers (central retinal artery equivalent, central retinal vein equivalent, and arteriovenous ratio) were calculated using both MONA REVA and VesselMap. RESULTS An inverse Pearson correlation was observed between central retinal artery equivalent and mean arterial blood pressure on both platforms (r = -0.275 [P ≤ .001] and r = -0.388 [P ≤ .001] for MONA REVA and VesselMap, respectively); this correlation was also observed with arteriovenous ratio and blood pressure. An inverse correlation was observed between central retinal artery equivalent and age (r = -0.362 [P ≤ .001] and r = -0.404 [P ≤ .001] for MONA REVA and VesselMap, respectively); this was also seen between central retinal vein equivalent and age (r = -0.322 [P ≤ .001] and r = -0.369 [P ≤ .001]). Arteriovenous ratio remained independent from age for both platforms. Bland-Altman plots demonstrated good agreement between the platforms for all three variables. CONCLUSIONS Although absolute caliber measurements differed between the platforms, the correlations observed were of similar magnitudes, with good agreement between the two platforms. Tighter spaced limits of agreement were observed when right and left eye data were averaged for each subject. In the absence of localized ocular pathology, this approach should be used.

Purpose: To analyze changes in the anterior segment, retinal vessel density, and choroidal thickness (ChT) after orthokeratology (Ortho-K).Methods: Myopic children were enrolled from Ruijin Hospital, Shanghai, China. Ortho-K lenses and single-vision spectacles were fitted for myopia correction. Ocular measurements were taken at baseline and 6 months, including axial length (AL), central corneal thickness (CCT), anterior chamber depth (ACD), lens thickness (LT), white to white (WTW), ChT, macular vessel density (MVD), and optic disc vessel density (OVD).Results: Seventy-six patients were enrolled in this study, including 40 in the Ortho-K group and 36 in the control group. At baseline, no parameters between the two groups were statistically different. After 6 months, changes in CCT and ACD decreased in the Ortho-K group compared with those in the control group (p < 0.05); LT and ChT in the Ortho-K group were thicker than those in the control group (p < 0.05), while there was no difference in MVD and OVD compared with those in the control group (p > 0.05). There were moderate positive correlations between ChT and LT and between ChT and OVD in the Ortho-K group (p < 0.05).Conclusion: The changes in the anterior and posterior segments of the eye after Ortho-K lens wearing suggest that the human eye has a powerful compensatory effect on the imposed defocus.

Background: This study compares the change of retinal vessel density (VD) after pan-retinal photocoagulation (PRP) and intravitreal conbercept (IVC) treatment in proliferative diabetic retinopathy (PDR) eyes with optical coherence tomography angiography (OCTA). Methods: A total of 55 treatment-naïve PDR eyes were included in this retrospective study. Of these, 29 eyes were divided into a PRP group, and 26 eyes were divided into an IVC group based on the treatment they received. OCTA was performed to measure macular and papillary VD at each follow-up in both groups. Results: The macular VD for superficial capillary plexus (SCP), deep capillary plexus (DCP), choriocapillaris (CC) and papillary VD for radial peripapillary capillary (RPC) between the two groups demonstrated no significant difference at baseline and month 12 (p &gt, 0.05). The paired t-test results showed that the macular VD for SCP, DCP, CC and papillary VD for the RPC at month 12 did not differ to the baseline in each group (p &gt, 0.05). Conclusions: During the 12-month follow-up, there was no significant change of macular and papillary VD between the PRP and IVC treatment in PDR eyes. Additionally, compared to the baseline, there were no significant changes of macular and papillary VD after either the PRP or IVC treatment. Considering the decrease in VD as DR progress, both treatments have potential protection of macular and papillary VD loss in PDR.

The study aimed at a quantitative evaluation of macular vasculature after primary repair of rhegmatogenous retinal detachment (RRD) in correlation with the elapsed postoperative time. Optical coherence tomography angiography (OCT-A) was performed in 66 eyes of 33 patients in a retrospective case-control study: superficial and deep retinal vessel density (VD) of the whole image, fovea, parafovea, non-flow area, and foveal avascular zone (FAZ) were measured. Data of eyes with RRD were compared to the healthy fellow eyes in 3 groups according to the elapsed time after surgery: RD1: 6–12 months (n = 10), RD2: 1–2 years (n = 10), and RD3: 2–10 years (n = 13). In RD1 VD was significantly lower in the superficial parafoveal, deep parafoveal, and deep whole area compared to the fellow eyes. In RD3 VD was significantly lower in the superficial fovea, parafovea, whole image, and deep fovea, the non-flow area was significantly enlarged. OCT-A demonstrated a significant reduction in the superficial and deep regions of the macular vasculature after the repair of RRD. The deep area is more affected in the early postoperative period and the superficial region and the extent of the non-flow area are more involved after a longer postoperative time.

(1) Background: Topical antiglaucoma medications may alter the microcirculation in the optic nerve head. We aimed to evaluate the changes in retinal vessel density (VD) on optical coherence tomography angiography (OCTA) in patients with newly diagnosed normal-tension glaucoma (NTG) treated with a topical beta-blocker. (2) Methods: This study included 80 patients diagnosed with NTG not using systemic medication, who received topical carteolol treatment between December 2019 and November 2020. We studied the changes in the OCTA VD/signal strength index (SSI) after the 6-month treatment period and determined the predictive factors affecting the changes in VD/SSI. (3) Results: After the 6-month treatment period, the peripapillary VD increased in 40 patients but decreased in the other 40 patients. The univariate and multivariate analyses revealed that old age and hypertension were significant factors associated with a VD/SSI decrease after carteolol treatment. Moreover, high baseline peripapillary, superficial, and deep macular VDs were significantly associated with the VD decrease after carteolol treatment. (4) Conclusions: Carteolol treatment could increase or decrease the VD in patients with NTG. The baseline VD, age, and hypertension could affect these VD changes. Patients with NTG and higher baseline peripapillary or macular VD, older age, and hypertension are more likely to have a decreased VD after carteolol treatment.

Purpose: To investigate the changes in the retinal vessels (RVs) in different sectors in patients with primary open-angle glaucoma (POAG), and their possible correlations with retinal nerve fiber layer thickness (RNFLT) and visual-field defects in the temporal parapapillary region.Methods: The RV diameters, RNFLTs, and visual-field parameters were measured. The temporal parapapillary region was divided into the temporal (T, 315°-45°), temporal superior (TS, 45°-90°), and temporal inferior sectors (TI, 270°-315°). The changes in the RV diameters in each sector were determined, and their relationships with RNFLT, the mean deviation (MD), and visual field sensitivity (VFS) were examined.Results: Fifty POAG patients (50 eyes) and 50 healthy subjects (50 eyes) were included. Compared with the healthy subjects, the POAG group had a significantly smaller accumulated parapapillary RV diameter (P < 0.001), which was positively correlated with the MD and RNFLT. When the different temporal sectors were examined, the accumulated RV diameters were significantly smaller in the POAG group than in the healthy controls in the TI and T sectors, but not in the TS sector. The accumulated diameters in the TI and T sectors were correlated with the corresponding RNFLTs (all P < 0.05), but only the accumulated diameter in the TI sector was correlated with the VFS.Conclusions: In POAG, the changes in the RVs differed between different temporal sectors, with the most prominent changes occurring in the TI and T sectors.

Purpose/Aim of this study: Retinal vessel caliber is an independent risk marker of cardiovascular disease risk. However, variable mechanical delays in capturing retinal photographs and cardiac cycl...

Purpose: The aim of this study was to measure retinal vessel diameter using spectral domain optical coherence tomography (SD-OCT), and to compare patients with unilateral pseudoexfoliation syndrome (PEX) with controls.Materials and Methods: 40 patients with pseudoexfoliation material (40+) eyes and (40-) eyes and 32 healthy controls was included study. Observation of pseudoexfoliative material on the anterior lens capsule or pupillar margin in one or both eyes was set as the diagnostic criteria for PEX. The diameter of superior temporal vein, inferior temporal vein; superior temporal artery and inferior temporal artery were measured by SD-OCT device.Results: when PEX (+) eyes were compared with PEX (-) eyes, a significant decrease was noted in vertical diameter of the arteries, as in the superior nasal artery. In PEX (+) patients the diameter of vascular structures was significantly decreased.Conclusion: We report a relationship between PEX and retinal vessel diameter. Vascular narrowing in the contralateral eye was also seen. Thus detection of this narrowing in the non-PEX eye vessels might be important for diagnosis and prevention of early glaucoma.

Purpose: Familial retinal arteriolar tortuosity (FRAT) is a rare autosomal dominant disorder that is characterized by tortuosity of the second and higher order retinal arterioles. We implement swept-source optical coherence tomography angiography (SS-OCTA) to quantify vessel tortuosity in patients with FRAT. We hypothesize that patients with FRAT will have higher retinal arteriole tortuosity when compared to controls. Methods: Patients were scanned with a SS-OCTA device (Plex Elite 9000, Carl Zeiss Meditec, Dublin, CA). Images of a 12 × 12 mm2 area centered on the fovea were processed, and retinal vessels >23.5 μm in diameter were identified. An automatic tortuosity measurement program written in MATLAB was used to assess vessel tortuosity. Branch points in the vessels were detected and used to separate the vasculature into individual segments. The tortuosity was measured by calculating the arc-chord ratio of each vessel segment, where a minimum value of 1 indicated a straight vessel and higher values corresponded to increasing tortuosity. Results: Two patients (4 eyes) with a known history of FRAT and six controls (12 eyes) were enrolled in the study. The mean tortuosity of all vessel segments (MTVS) in scans of FRAT eyes was on average 1.1244 [range: 1.1044–1.1438] while for control eyes it was 1.0818 [range: 1.0746–1.0872]. Average MTVS of FRAT eyes was significantly higher compared to control eyes (p = 0.03). Conclusions and Importance: Our results are consistent with the hypothesis that patients with FRAT have higher objective measurements of tortuosity compared to controls. Broader applications of this method may be of benefit in other retinal diseases with changes in retinal vessel configuration. Keywords: Familial retinal arteriolar tortuosity, Vascular tortuosity, OCT angiography

Purpose: To evaluate the effects of intravitreal aflibercept (IVA) treatment on retinal vein parameters and choroidal thickness used in the treatment of diabetic macular oedema (DME).Method...

Purpose To evaluate the dynamic range of peripapillary retinal vessel density (ppVD) for predicting the severity of visual field (VF) damage in comparison with that of circumpapillary retinal nerve fiber layer thickness (cpRNFLT) in primary open-angle glaucoma (POAG) patients and to determine the severity of VF damage below which progressive VF loss becomes undetectable based on either ppVD or cpRNFLT. Design Cross-sectional study. Participants One hundred thirty-three POAG patients having ppVD, cpRNFLT, and VF sensitivity (VFS) measurements evaluated using OCT angiography, spectral-domain OCT, and standard automated perimetry, respectively. Methods Correlations between ppVD and VFS (vessel–function) and between cpRNFLT and VFS (structure–function) were assessed using both linear and fractional polynomial (FP) models. Davies' test was used to determine the breakpoints for VFS below which progressive VF loss became undetectable based on ppVD or cpRNFLT. Main Outcome Measures Comparison of the vessel–function and structure–function correlations, and the VFS breakpoints in each correlation. Results Both ppVD and cpRNFLT exhibited significant linear correlations with VFS globally. In the temporal–superior, temporal, and temporal–inferior sectors, the correlations were explained better by the FP model than by the linear model for both ppVD (P ≤ 0.009) and cpRNFLT (P ≤ 0.008). The breakpoints for VFS in the vessel–function and structure–function correlations were –8.28 dB and –6.41 dB, respectively, in the temporal–superior sector, –11.83 dB and –8.42 dB, respectively, in the temporal sector, and –7.92 dB and –6.28 dB, respectively, in the temporal–inferior sector. Conclusions The sectoral ppVD exhibits curvilinear correlations with VFS and has significant breakpoints below which the VFS decline becomes undetectable. The VFS breakpoints were lower for ppVD than for cpRNFLT, indicating that the dynamic range of ppVD is potentially larger for detecting more advanced VF damage.

Diabetic retinopathy is a disease in diabetic patients that affects the eye. It happens due to damage in the blood vessels of the light-sensitive tissues at the retina. In non-proliferative diabetic retinopathy, tiny changes occur in the blood vessels of the eye. Non-proliferative diabetic retinopathy can trigger macular edema or macular ischemia. In this study proposes the retinal vessel segmentation and vessel quantization on the DRIVE database which is publicly available. The experimental results express the retinal vessel can be effectively detected and segmented.

Background To investigate the repeatability of superficial retinal vessel density measurements in healthy eyes with long axial length (AL) using optical coherence tomography angiography (OCTA). Methods There were 60 eyes of 31 volunteers enrolled in this cross-sectional observational study. All subjects underwent OCTA, AL and refraction test. The enrolled eyes were divided into the long AL group (26 mm ≤ AL

ZusammenfassungMit modernen nicht invasiven bildgebenden Verfahren lassen sich anhand der Fundusfotografie bzw. der optischen Verfilmung Aspekte der funktionellen und strukturellen retinalen Gefäßveränderungen objektiv untersuchen. Der Zustand und das Verhalten retinaler Gefäße beeinflussen im prä-, post- und kapillaren Bereich den Blutfluss und strömungsbedingte Stoffwechselverhältnisse passiv und aktiv über den Gefäßdurchmesser. Retinale Gefäße gleichen von Aufbau und Funktion den zerebralen Gefäßen und spiegeln den Zustand der Mikrozirkulation wider. Mithilfe von aus den Gefäßweiten berechneten Biomarkern soll eine Aussage über die Prognose von systemischen vaskulär bedingten Erkrankungen getroffen werden. Die statische retinale Gefäßanalyse befasst sich mit der Untersuchung des Zustandes der prä- und postkapillaren Gefäßdurchmesser der retinalen Mikrozirkulation anhand einer optischen Fundusaufnahme. Bei der dynamischen retinalen Gefäßanalyse wird der Längsschnitt eines retinalen Gefäßes nicht invasiv funktionell und strukturell über einen Zeitraum vor, während und nach einer spezifischen vaskulären Stimulation untersucht. Die genaue Methodologie der Auswertung und die Bezeichnung der Parameter variieren bei unterschiedlichen Ansätzen. Mittels retinaler Gefäßanalyse wurden bislang mehrere klinische Querschnitts- und Interventionsstudien in der Augenheilkunde und anderen Fachgebieten, inkl. Kardiologie, Neurologie, Neurochirurgie, Nephrologie, Gynäkologie, Sportmedizin, Diabetologie, Hypertensiologie usw. durchgeführt. Mit der statischen retinalen Gefäßanalyse steht eine kostengünstige, reproduzierbare, nicht invasive Screeningtechnik zur Verfügung, um eine prognostische Aussage über die Gefäßgesundheit eines individuellen Patienten zu treffen. Die dynamische retinale Gefäßanalyse besitzt ein weiteres diagnostisches Anwendungsspektrum als die statische, da sie das Verhalten retinaler Gefäße zeitkontinuierlich untersucht. Die Evaluation vaskulärer Erkrankungen sowie zerebro- bzw. kardiovaskulärer Morbidität und Mortalität mittels mehrerer methodologischer Modalitäten retinaler Gefäßanalyse mit ihren jeweiligen quantitativen Biomarkern bietet eine zukunftsträchtige diagnostische Perspektive. Die interdisziplinäre klinische Anwendung dieser vaskulären Biomarker gewinnt zunehmend an Bedeutung, sowohl in der Augenheilkunde als auch in anderen Fachgebieten.

In mild or moderate retinopathy of prematurity (ROP), retinal vessels undergo obliteration, proliferation, and regression. Despite complete regression of vessel abnormalities, a variety of visual impairments have been reported. Rodent oxygen-induced retinopathy (OIR) is widely used as a model to study ROP. However, the long-term changes of OIR model remain unclear. The aim of this study is to examine long term changes of retinal vessel and visual function in a rodent OIR model resembling human mild or moderate ROP. In this study, after subjecting the animals to 80% oxygen (O2) for 5–7 d, the retinal vessel density at postnatal day 12 (P12) was approximately 30% lower than that in the age-matched control, but this difference was not significant between the groups. Vessel abnormalities, such as vessel tortuosity, neovascular tufts, and the number of vessels protruding into the vitreous, peaked between P17 and P20. Despite the regression of many abnormalities, vessel density in the OIR group was 36% and 32% lower than that in the control animals at 6 weeks and 4 months, respectively. The visual acuity and contrast sensitivity were impaired in the OIR group when measured at 2, 3 and 4 months. Therefore, the rodent OIR model exhibited long-lasting reduction in retinal vessel density and visual impairments, similar to those observed in mild or moderate human ROP. This study suggests that the rodent OIR model can be used to explore possible interventions for mild and moderate human ROP.

Purpose: To assess the agreement between Line 3–5 raster scan mode and circular scan mode for measuring retinal vessel diameter, and to analyze the influence of scanning distance on retinal vessel ...

Purpose We aimed to investigate the reactivity of retinal vessels to a flickering stimulus in patients with age-related macular degeneration (AMD) and healthy participants. We also assessed whether the parameters of retinal vessels are dependent on genetic predisposition. Methods A total of 354 patients with AMD and 121 controls were recruited for the study. All participants underwent thorough ophthalmologic examination and static and dynamic retinal vessel analysis. AMD risk polymorphisms were genotyped in the CFH and ARMS2 genes. Results We found no differences between the AMD group and controls in central retinal arteriolar equivalent (CRAE), central retinal venular equivalent (CRVE), arteriovenous ratio (AVR), dynamic analysis of arteries (DAAs), or dynamic analysis of veins (DAVs). Eyes with early AMD presented with significantly higher AVR values than eyes with late AMD. In the AMD group, DAA correlated positively with both choroidal thickness (Rs = 0.14, P = 0.00096) and choroidal volume (Rs = 0.23, P < 0.0001), and no such associations were observed in the controls. We found significantly lower DAA (1.47 ± 1.50) in TT homozygotes for the ARMS2 A69S polymorphism in comparison with GG homozygotes (2.38 ± 1.79) and patients with GG + GT genotypes (2.28 ± 1.84). We also observed less prominent DAV (3.24 ± 1.71) in patients with TC + CC genotypes in the CFH Y402H polymorphism compared with TT homozygotes (3.83 ± 1.68). Conclusions Our findings suggest that retinal microcirculation appears to be associated with the genetic background, choroidal parameters, and clinical features of the patients with AMD.