Foveal Avascular Zone Measurements Research Articles

A Comparison of Optical Coherence Tomography Angiography Metrics and Artifacts on Scans of Different Sizes in Diabetic Macular Ischemia

Changes in the foveal avascular zone (FAZ) metrics over time are key outcome measures for clinical trials in diabetic macular ischemia (DMI). However, artifacts and automatically delineated FAZ measurements may influence the results. We aimed to compare the artifact frequency and FAZ metrics on 3 × 3 versus 6 × 6 mm optical coherence tomography angiography (OCTA) macular scans in patients with DMI. Prospective, comparative image quality analysis with 1-year follow-up. Patients with diabetic retinopathy (DR) were recruited if they presented with OCTA evidence of DMI, defined as an automated FAZ (aFAZ) ≥0.5 mm2 or parafoveal capillary nonperfusion (CNP) ≥1 quadrant if the aFAZ <0.5 mm2. Only those who had both size scans were included in the analysis. The types of artifacts and FAZ delineation errors were graded before manual correction. After excluding scans with poor quality, the aFAZ, corrected FAZ (cFAZ), whole image superficial vessel density (wiSVD), and whole image deep vessel density (wiDVD) were compared on both size scans. Fifty-seven patients (81 eyes) with paired OCTA 3 × 3 and 6 × 6 mm scans at baseline were included in the image quality analysis. The 6 × 6 mm scan presented with more severe motion artifact (P = .02). Conversely, the 3 × 3 mm scans were more susceptible to mild decentration (P = .009). After removing all the poor-quality images, 55 eyes with both size scans entered the longitudinal analysis. The 3 × 3 mm FAZ was significantly larger than the 6 × 6 mm FAZ using either aFAZ or cFAZ (both P < .05). In contrast, the 6 × 6 mm wiSVD and wiDVD were remarkably higher than those on the 3 × 3 mm scans (both P < .001). There was a steady increase in cFAZ over one year on both size scans (both P < .01). However, the 3 × 3 mm aFAZ decreased numerically at 52 weeks (P = .02). After reviewing all the scans, poor identification of parafoveal CNP was the most common reason for erroneous aFAZ delineation. In DMI, the FAZ metrics are best evaluated on the 3 × 3 scan due to better resolution. However, manual correction of the FAZ margin is needed. The frequency of artifacts and aFAZ delineation errors suggest that further technical refinement is required.

Vessel density, macula thickness and foveal avascular zone measurements in young African adults with moderate myopia: A pilot study.

The aim of this study was to investigate the association between macula thickness and vessel density in African myopic and emmetropic eyes through the use of Spectral Domain Optical Coherence Tomography (OCT). The study population comprised African adults aged 18-35 years old. The study was conducted at a University eye clinic located in Durban, South Africa. Purposive sampling was utilised to obtain 59 participants of whom 24 were myopes and 35 were emmetropes. Vessel density (VD), foveal avascular zone (FAZ) and retinal thickness (RT) were obtained using the Heidelberg Spectralis OCT with angiography. Thereafter, a multivariate linear regression was used to investigate associations between the spherical equivalent myopic refractive error and VD, FAZ and RT for the myopic group only. Myopic participants had a mean spherical equivalent (MSE) and standard deviation (SD) of -4.79 D (1.27) while the emmetropic group had an MSE (SD) of -0.32 D (0.46). Both superficial and deep VD were significantly decreased at the central fovea (radius (r) = 0.4 mm), peri-foveal (r = 1.10-1.45 mm) and para-foveal (r = 0.75-1.10 mm) sectors in myopes when compared with emmetropes. Myopes showed a significant reduction in RT in the inner retinal layer across the inferior and temporal zones of the peri-foveal region as well as the inferior and temporal zones of the para-foveal region when compared with emmetropes. A significantly smaller FAZ was found at both the superficial and deep vascular plexuses (p < 0.001). In African myopes, significant associations were not found between MSE and VD or FAZ and macula retinal thickness. Retinal vascular and thickness reduction may occur in young African adults with moderate myopia. A broad-based study targeting VD and IRT in African myopes is proposed to confirm preclinical myopic macula disruptions in adults of African ethnicity. OCT angiography should be considered when monitoring progressive myopia.

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

AimThe 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. MethodsThe 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. ResultsNo 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). ConclusionIn 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.

Optical coherence tomography angiography in patients with bipolar disorder and major depressive disorder

BackgroundCerebral microvascular dysfunction is a promising area for research into the pathogenesis of major depressive disorder (MDD) and bipolar disorder (BD). Despite the scientific and clinical potential of studying microvascular dysfunction, progress in this area has long been hampered by the lack of methods to study microvessels intravitally. AimsThe aim of the present study was to search for potential optical coherence tomography (OCT) and OCT-angiography (OCTA) biomarkers of BD and MDD. MethodsOne hundred and five consecutive patients with a current depressive episode were enrolled in the study (39 – BD and 66 – MDD). In addition, forty-one generally healthy subjects were enrolled as a control group. Only the right eye was examined in all subjects. Structural OCT and OCTA scans with signal strength ≥7 were included. ResultsStructural OCT measurements showed no significant differences between the groups. OCTA measurements of foveal avascular zone (FAZ), area and skeleton density showed a decrease in the retinal capillary bed in BD patients, whereas OCTA values in MDD patients did not differ from the control group. Several significant differences were found between the BD and control groups. In the BD group, the FAZ of the deep capillary plexus was increased, reflecting a reduction in capillary perfusion in the central subfield of this plexus. ConclusionsOCTA measurements of FAZ, area and skeleton density showed a decrease in the retinal capillary bed in BD patients, whereas OCTA values in MDD patients did not differ from the control group.

Evaluation of Central and Peripheral Retinal Vascular Changes in the Fellow Eyes of Patients with Unilateral Retinal Vein Occlusions

To evaluate the subtle peripheral retinal and macular vascular changes in the fellow eyes of patients with unilateral retinal vein occlusion (RVO). This retrospective study included 53 patients with unilateral RVO and 44 age-matched controls. The frequency of peripheral retinal vascular pathologies in both eyes was evaluated using high quality ultra-wide field fluorescein angiography (UWFFA). Macular vascular density, flow area, and foveal avascular zone measurements from optical coherence tomography angiography (OCTA) were analyzed together with laser flare photometry values in patients and controls. Peripheral retinal vascular pathologies were detected on UWFFA in the fellow eyes of 36 (67.9%) patients. No significant central vascular pathologies were detected on OCTA and there was no significant difference in OCTA parameters between the fellow eyes and the controls. Flare values did not differ significantly between the control and the fellow eyes. Two thirds of the fellow eyes of unilateral RVO patients had subtle peripheral retinal vascular changes, while there was no significant microvascular change detected with OCTA in the macula. This suggests that vascular changes caused by systemic vascular disorders probably first start in the peripheral retina of the fellow eyes of patients with RVO.

Evaluation of macular choroidal and microvascular network changes by activity scores and serum antibodies in thyroid eye patients and healthy subjects.

To investigate the choroidal thickness and the microvascular network changes around the macula in thyroid eye disease (TED) patients at different stages and the relationship of those changes with risk factors, serum antibodies and the severity of TED. A total of 85 participants were enrolled. All participants underwent ophthalmology and endocrinology examinations. Subfoveal choroidal thickness (SFCT), superficial (s) and deep (d) foveal avascular zone (FAZ) area, mean (m) and central (c) superficial vascular density (SVD), deep vascular density (DVD) measurements of the enrolled cases were performed with Topcon swept source optical coherence tomography (OCT)/OCT angiography (OCTA) DRI OCT Triton. Multiple linear regression analysis was used to explore the associations between SFCT, FAZ area, SVD, DVD and the relevant factors of TED. Those with active TED patients had higher c-DVD and m-DVD levels (P<0.05), however there is no statistically significant difference in SFCT between active and stable TED patients. Among the serum antibodies, it was observed that s-FAZ and d-FAZ increased, c-SVD and m-SVD decreased in patients with high thyroid stimulating hormone-receptor autoantibodies (TRAB) level, whereas SFCT thickened in patients with high levels of both TRAB and human thyroglobulin (hTG). There was no significant difference in SFCT, FAZ, SVD and DVD measurement at gender, between hyperthyroid and euthyroid patients and among those with or without thyroid papillary carcinoma. The results show that both disease activation and serum antibodies differentially affect both superficial and deep retinal vascular density. It has also been shown that high serum antibody levels affect choroidal thickness independent of clinical activity.

Effects of COVID-19 infection on retinal vascular density and choroidal thickness measured by optical coherence tomography angiography

AimThe present study evaluates the possible effects of COVID-19 on choroid thickness, the Foveal Avascular Zone (FAZ) and retinal vascular indices in the same individuals who had Optical Coherence Tomography (OCT) and Optical Coherence Tomography Angiography (OCTA) data prior to the COVID-19 pandemic. MethodsThe OCT and OCTA images of the same individuals with no known ophthalmic pathology who developed a COVID-19 infection were obtained were retrieved retrospectively from the database and compared with the repeated images of OCT and OCTA images 1–2 months after COVID-19 infection. ResultsEighty eyes of 40 patients (26 female [65%], 14 male [35%]) who had developed a prior Covid-19 infection were included in the study. When comparing the measurements of the same participants before and after Covid-19 infection, no significant difference was detected in the mean average choroidal thicknesses (p=0.998), average superficial (p=0.425) and deep (p=0.333) retinal vascular densities, and superficial (p=0.991) and deep (p=0.075) FAZ measurements. ConclusionsNo significant effect of COVID-19 on choroid thickness, FAZ or retinal vascular densities was noted in the present study, although there are some studies in literature with equivocal results.

Relationship between nonperfusion area from widefield optical coherence tomography angiography and macular vascular parameters in diabetic retinopathy

PurposeTo evaluate the relationship between the nonperfusion area (NPA) from widefield optical coherence tomography angiography (OCTA) and macular vascular parameters in diabetic retinopathy (DR).MethodsIn total, 51 eyes from 51 patients with proliferative DR (PDR) or moderate/severe non-PDR were included. Widefield OCTA using the Zeiss Plex Elite 9000 was performed. A semi-automatic algorithm calculated the percentages of the NPA within the total image. Macular OCTA (3 × 3 mm and 6 × 6 mm area) was scanned using the RTVue-XR Avanti. Vessel density (VD) was automatically separated into the superficial (SCP) and deep capillary plexus (DCP), and foveal avascular zone (FAZ) measurements were computed according to the parafoveal (1–3 mm) and perifoveal (3–6 mm) regions.ResultsA negative correlation was found between the average VD of the SCP and DCP obtained 3 × 3 mm and 6 × 6 mm area and the NPA. Multiple regression analysis revealed that the temporal–perifoveal region most negatively correlated with the NPA (r = − 0.55, p < 0.0001). No correlation was found between FAZ measurements and DR severity (area, p = 0.07; perimeter, p = 0.13).ConclusionDiabetic macular nonperfusion was significantly associated with the NPA from widefield OCTA. In particular, the temporal–perifoveal DCP disorder may be a sensitive indicator of wide NPA.

Optical coherence tomography angiography in birdshot chorioretinopathy.

To describe the retinal vascular changes in birdshot chorioretinopathy (BSCR) using optical coherence tomography angiography (OCTA) and to compare them with changes in macular thickness. In this multicenter study, patients with a diagnosis of BSCR and a positive HLA-A29 underwent fluorescein angiography, spectral domain optical coherence tomography (SD-OCT), and OCTA. The foveal avascular zone (FAZ) and the area of capillary non-perfusion were manually measured by two examiners in fluorescein angiography (FA) and 3 × 3-mm OCTA images of the superficial retinal layer. These measurements were compared to central retinal thickness. To calculate normal capillary density, we collected data from 22 controls who had OCTA performed on one visit only. A total of 44 eyes with BSCR were enrolled. The mean automated parafoveal superficial capillary density in BSCR eyes was 0.47 ± 0.03. The differences between the foveal capillary density of BSCR patients and healthy subjects were statistically significant (P < 0.001). The mean area of FAZ manually measured on the 3 × 3 mm unsegmented OCTA images was larger in eyes with BSCR (1.34 ± 0.41 mm2; P < 0.0001). Measurement of FAZ area showed good interobserver (κ 0.88) and intraobserver repeatability (κ 0.79) on OCTA images. The intraclass correlation coefficient for FAZ measurements on FA between the two observers was 0.48. The OCT retinal thickness maps of all BSCR eyes demonstrated statistically significant thinning compared to those of control subjects (P < 0.01). Our study demonstrates the potential contribution of OCTA as a new non-invasive imaging technology that monitors disease activity in BSCR patients.

Retinal capillary and choriocapillaris assessment using a beam modifier optical coherence tomography angiography module to increase lateral optical resolution.

To assess a new optical coherence tomography angiography (OCTA) technology and its contribution to retinal vascularization and choriocapillaris (CC) exploration. A new module, named "Beam expander" (BE), which increases the lateral resolution of OCTA, was used in combination with a prototype software in the PLEX® Elite 9000 Swept-Source OCT instrument (ZEISS, Dublin, CA). This prospective study involved 22 healthy subjects imaged with and without BE. Qualitative analysis of superficial capillary plexus (SCP), deep capillary complex (DCC) retinal and CC angiograms were performed. Perfusion density (PD), vessel density (VD), and foveal avascular zone (FAZ) measurements were also compared. Qualitative analysis of single SCP and DCC retinal angiograms acquired with BE showed significantly better vessel sharpness (respectively, p = 0.0002, and p<0.0001), and greater peripheral image quality (p = 0.028 and p = 0.007) compared to standard OCTA images. Mean VD of whole retina single scans was significantly higher for BE angiograms compared to classic angiograms (28.16 ±1.29 mm-1 and 23.36 ±0.92 mm-1, respectively, p<0.0001). Repeatability of VD, PD and FAZ raw size were found to be similar between the two methods (intraclass correlation coefficient: 0.671, 0.604 and 0.994 with BE versus 0.764, 0.638 and 0.990 without BE). CC image quality was found to be significantly superior with BE, and flow deficits were more visible in all BE scans compared to standard scans. An increase in lateral resolution of the OCT beam resulted in higher quality of retinal and choriocapillaris OCTA images in healthy subjects. These results provide significant insights into the future OCTA imaging enhancements.

Quantitative Measurements of Macular and Optic Nerve Head Blood Flow Parameters Following Cataract Surgery in Eye Department, Red Cross Tertiary General Hospital, Athens, Greece

Objective: To evaluate the effect of uncomplicated cataract surgery on macular and optic nerve head blood flow with Optical Coherence Tomography Angiography (OCT-A). Retinal vascular changes and macular vessel remodeling following cataract surgery is an area of interest, as the effect, cause and duration of such changes remain debatable.&#x0D; Setting: Eye Department, Red Cross Tertiary General Hospital, Athens, Greece.&#x0D; Methods: In this study, we recruited cataract surgery candidates who had regular post operative visits and underwent longitudinal OCT-A examinations before and after surgery.&#x0D; Results: Macular vessel density increased in the post operative visits both in the superficial (SCP) and deep capillary network (DCP) (P&lt;0.001) and showed a persistent effect over 3 months follow-up. Macular thickness increased over the first postoperative month, but returned to preoperative values at 3 months. Foveal avascular zone (FAZ) measurements and vessel density at radial peripapillary capillaries (RPC) were unaffected.&#x0D; Conclusions: OCT-A enables a quantitative analysis of blood flow by regular patient monitoring. In this study, we found that after cataract surgery, macular blood flow increased significantly. The reason for this could be attributed to post operative inflammatory process or vascular remodeling due to change in retinal metabolic demands.

Early effects of inactivated (CoronaVac) SARS-CoV-2 vaccine on retrobulbar vascular blood flow and retinal vascular density

AimsWe aimed to investigate the early effects of inactivated SARS-CoV-2 vaccine on retrobulbar vascular blood flow and retinal vascular density in healthy subjects. MethodsThirty-four eyes of 34 healthy volunteers who received the CoronaVac (Sinovac Life Sciences, China) were included in this prospective study. Resistive index (RI), pulsatility index (PI) and peak systolic velocity (PSV) of the ophthalmic artery (OA), central retinal artery (CRA), and the temporal and nasal posterior ciliary arteries (PCA) were evaluated with color Doppler ultrasonography (CDUS) before vaccination, at the 2nd and 4th weeks after vaccination. Superficial capillary plexus (SCP) and deep capillary plexus (DCP) vessel density (VD), foveal avascular zone (FAZ), and choriocapillaris blood flow (CCF) measurements were made using optical coherence tomography angiography (OCTA). ResultsWhen compared to the pre-vaccination values, there was no significant change in OA-PSV, temporal-nasal PCA-PSV, CRA-EDV, temporal-nasal PCA-EDV at 2nd and 4th weeks after vaccination. However statistically significant reductions were found in the OA-RI, OA-PI, CRA-RI, CRA-PI, temporal-nasal PCA-RI, temporal-nasal PCA-PI values, CRA-PSV at post-vaccination 2nd week (p<0.05 for all). While there was sustained reduction in OA-RI, OA-PI, CRA-PSV, and nasal PCA-RI values at 4th week after vaccination, the change in CRA-RI, CRA-PI, temporal PCA-RI, temporal-nasal PCA-PI values were not significant compared to pre-vaccination values. There was no statistically significant difference in the SCP-VD, DCP-VD, FAZ and CCF measurements. ConclusionsOur findings demonstrating that CoronaVac vaccine did not affect retinal vascular density in the early period, but it caused alterations in the retrobulbar blood flow.

Associations between body mass index and choroidal thickness, superficial and deep retinal vascular indices, and foveal avascular zone measured by OCTA

AimThe present study explores the effects of Body Mass Index (BMI) on choroidal thickness, the deep and superficial retinal capillary plexuses, and the foveal avascular zone (FAZ). MethodsThe subjects in this prospective study were divided into five groups based on their calculated BMI. Choroidal thickness, superficial and deep retinal capillary plexuses, and FAZ were measured using enhance depth imaging (EDI) and optical coherence tomography angiography (OCTA). The groups were then compared and correlations with BMI were evaluated. ResultsThe study included 210 eyes of 105 subjects. The comparison of the BMI groups revealed a significant decrease in the mean choroidal thicknesses in the obese groups (p = 0.001), and a significant negative correlation between BMI and mean choroidal thickness (p = 0.02). The results of the analysis of the mean superficial and deep retinal capillary plexuses did not differ between the groups (p = 0.089, p = 0.808 respectively), while the deep FAZ measurements revealed a significant decrease in the obese groups (p = 0.003). ConclusionChoroidal thickness and deep FAZ are significantly negatively correlated with BMI, suggesting potential choroidal and retinal microvascular effects of obesity.

Long-Term Retinal Vascular Changes in Age-Related Macular Degeneration Measured Using Optical Coherence Tomography Angiography.

To determine if age-related macular degeneration (AMD) status affects longitudinal retinal vessel changes. Retrospective, cohort study of 125 eyes (75 patients) with AMD, following retinal vessel density (VD) and foveal avascular zone (FAZ) measurements using optical coherence tomography angiography (OCT-A) over 24 months. FAZ area (<i>P</i> &lt; .001) and perimeter (<i>P</i> &lt; .001) increased over 2 years, with no difference between nonexudative and exudative AMD (<i>P</i> = .134-.976). Eyes with geographic atrophy (GA) showed greater progressive VD loss (<i>P</i> = .023-.038), and greater increase in FAZ area (<i>P</i> = .044) and perimeter (<i>P</i> = .040) compared to eyes without GA. Neither baseline nor 2-year change in vascular parameters were associated with choroidal neovascularization (CNV) or GA incidence in nonexudative AMD, or anti-VEGF injection frequency in exudative AMD (<i>P</i> = .070-.952). AMD eyes with GA undergo more rapid loss of retinal vessel density and FAZ enlargement over 2 years, suggesting a relationship between the retinal vasculature and AMD pathophysiology. <b>[<i>Ophthalmic Surg Lasers Imaging Retina</i> 2022;53:529-536.]</b>.

Reproducibility of macular perfusion parameters in non-proliferative diabetic retinopathy patients by two different OCTA sweep modes.

To assess the reproducibility of macular perfusion parameters in non-proliferative diabetic retinopathy (NPDR) patients measured by different examiners and two different sweep modes of optical coherence tomography angiography (OCTA). Ninety-eight (98 eyes) patients with NPDR were included in this study. All participates were performed three times using Cirrus OCTA with Angiography 3×3 mm2 and 6×6 mm2 sweep mode by two examiners. The macular foveal avascular zone (FAZ) and vessel density (VD) in the superficial retinal layer (SRL) were measured. The reproducibility of the measurements was evaluated with intraclass correlation coefficients (ICC) and coefficient of variation (CoV). The intra-mode ICCs of Angiography 3×3 mm2 and 6×6 mm2 sweep mode were 0.957 to 0.959 and 0.964 to 0.977, respectively; and the inter-mode ICCs were 0.962 to 0.970. The intra-examiner ICCs of macular perfusion parameters were >0.950; and the inter-examiner ICCs were 0.928 to 0.969. All CoVs were <1.0%. Cirrus OCTA can measure macular perfusion parameters in NPDR patients with excellent reproducibility. The measurements of FAZ and VD in the SRL determined by Angiography 3×3 mm2 and 6×6 mm2 sweep mode are highly consistent and both sweep modes are suitable for macular perfusion parameters measurement.

Optical coherence tomography angiography biomarkers of microvascular alterations in RVCL-S.

BackgroundThe brain and retina share many neuronal and vasculature characteristics. We investigated the retinal microvasculature in patients with a monogenic vasculopathy using optical coherence tomography angiography (OCTA). OCT-A is a novel precise non-invasive imaging method that may provide biomarkers suitable for diagnosis and follow-up of small vessel diseases.MethodsIn this exploratory cross-sectional study, eleven RVCL-S patients and eleven age-matched healthy control participants were included. The size of the foveal avascular zone (FAZ) and the vascular density of the superficial capillary networks in the retina were measured by OCT-A.ResultsThe symptomatic and presymptomatic patients showed significantly lower vascular density values than controls in the foveal region [median (IQR) 18.2% (15.8–18.6) vs. 24.4% (21.5–26.8) (p < 0.001), 29.8% (29.6–30.8) vs. 33.2% (32.0–33.6) (p = 0.002), respectively]. The FAZ was significantly larger in the symptomatic RVCL-S patients than in the control group [13,416 square pixels [7,529–22,860] vs. 1,405 square pixels [1,344–2,470] (p < 0.001)]. No significant difference was identified in measurements of FAZ comparing presymptomatic and controls.ConclusionOur findings with OCT-A demonstrated that RVCL-S causes an increase in the size of the FAZ in symptomatic RVCL-S patients compared to healthy participants. Moreover, there is a decrease in vessel density in the superficial capillary networks in both symptomatic and presymptomatic patients. In the future, newly developed precise objective instruments such as OCT (-A) may provide important tools in determining disease activity for follow up of common small vessel diseases.

Optical coherence tomography angiography in patients with euthymic bipolar disorder

ObjectiveThe number of studies conducted on the evaluation of retinal microvascularity in patients with Bipolar Disorder (BD) is very few. Therefore, in the present study it was aimed to provide a significant diagnostic support and to better understand the relationship between BD and vascular changes by making vascular measurements with Optical Coherence Tomography Angiography (OCTA). MethodThe statistical analysis was performed by comparing OCTA measurements of 48 eyes of 48 euthymic patients followed up with a diagnosis of BD and in remission for at least 6 months, and 45 eyes of 45 age-matched healthy volunteers in the control group. Among the OCTA measurements compared were retinal vessel density analysis, foveal avascular zone measurements, retinal nerve fiber layer, radial peripapillary capillary plexus, ganglion cell-inner plexiform layer values. ResultsIn the multivariate regression model, such variables as nasal quadrant of retinal nerve fiber layer, inferior and nasal quadrants of radial peripapillary capillary plexus and superficial vessel density variables were determined to have a significant and independent effect in differentiating patients with BD from the participants in the healthy control group. ConclusionIn the present study, for the first time, the OCTA method was used to compare both retinal neurodegeneration and vascularization measurements in those in the BD and the healthy groups. That the effects of drugs other than mood stabilizers were not taken into account is among the limitations of our study.

Reproducibility and Reliability of Spectralis II OCT Angiography Vascular Measurements.

Purpose: to investigate the reproducibility and reliability of OCT-A vascular measurements using Heidelberg Spectralis II OCT-A. Methods: a prospective study involving a single eye of patients aged 18 or older with no ocular disease. In order to investigate the reliability of the first and second OCT-A scans, the coefficient of variation of the foveal avascular zone (FAZ) and the vessel density (VD) in the superficial (SCP), intermediate (ICP) and deep capillary plexus (DCP) were calculated. Results: A total of 75 eyes were included in the study. The mean FAZ in the first and second scan was 0.36 × 0.13 mm2 and 0.37 × 0.12 mm2, respectively, in the SCP, 0.23 × 0.10 mm2 and 0.23 × 0.09 mm2 in the ICP, and 0.42 × 0.11 mm2 and 0.43 × 0.12 mm2 in the DCP. The overall VD was 36.05 × 9.01 and 35.33 × 9.92 at the first and second scan, respectively, in the SCP, 21.87 × 5.00 and 21.32 × 5.56 in the ICP, and 23.84 × 6.53 and 23.20 × 6.83 in the DCP. No statistically significant differences in FAZ measurements and VD in all sectors of each capillary plexus were observed between the first and second scan (p > 0.05). Conclusion: our study demonstrated the good reproducibility and reliability of OCT-A vascular measurements in the analysis of the FAZ and the quantification of VD in each capillary plexus of the retina.

Changes in retinal vessel and retinal layer thickness after cross-linking in keratoconus via swept-source OCT angiography.

To analyze the postoperative foveal avascular zone (FAZ) area, superficial capillary plexus (SCP), deep capillary plexus (DCP) vascular densities (VD), and retinal layers after cross-linking (CXL) for keratoconus treatment. Twenty-seven eyes with cross-linking treatment for keratoconus were included in the study. Foveal avascular zone (FAZ) area, SCP VD, DCP VD, and retinal layers were evaluated by using optical coherence tomography angiography (OCTA). OCTA measurements were made at preoperative, first week, and first and sixth months after the surgery. In addition, corneal topography measurements were also made. Although there was a decrease in corneal thickness in the follow-up of the patients, there was no significant difference in axial length and anterior chamber depth. There was no significant difference in full retinal thickness in the foveal and parafoveal areas. While there was a significant increase in retinal nerve fiber layer (RNFL) thickness in the foveal area (p = 0.032, p = 0.015, p = 0.017; preoperative values compared to first week, first month, and sixth month respectively), there was a decrease in ganglion cell layer (GCL) thickness in the parafoveal area in the postoperative sixth month (p = 0.028). There was no difference in FAZ measurements. In the parafoveal area, a decrease was observed in SCP VD in the sixth-month control (p = 0.019). There was a significant increase in DCP VD in the foveal area (p = 0.008, p = 0.043, p = 0.040). The preoperative mean CDVA (corrected distance visual acuity) was 0.37 ± 0.16 logMAR and postoperative sixth month mean CDVA was 0.39 ± 0.15. There was no significant difference in visual acuity(p = 0.71). Keratoconus patients successfully treated with CXL had significant changes in retinal layers and vessel density in the superficial and deep retinal plexus.

Effect of Mydriatic Administration on Retinal Hemodynamics in Glaucoma: An Optical Coherence Tomography Angiography Study.

Pupillary dilation with 0.5% tropicamide and 2.5% phenylephrine resulted in a statistically significant decrease in foveal avascular zone (FAZ) metrics in glaucoma eyes. This observation emphasizes the critical role of pupillary status in interpreting glaucomatous vascular alterations detected by optical coherence tomography angiography (OCTA). The purpose of this study was to evaluate the influence of mydriatic eye drops on OCTA parameters in patients with primary open angle glaucoma (POAG). A total of 20 POAG eyes and 20 control eyes were recruited in the study. The imaging area on the fundus was visualized by AngioPlex (Cirrus 5000 HD-OCT) using en face view of 3×3 mm and 6×6 mm preview scans. Images were generated before and after the instillation of topical 0.5% tropicamide and 2.5% phenylephrine. Optic nerve head (ONH) perfusion, ONH flux index, macular perfusion density, macular vessel density, and FAZ measurements were consecutively obtained for each session. Differences between the predilation and postdilation measurements were evaluated in POAG patients and controls. POAG eyes showed a statistically significant decrease in the FAZ area from a mean of 0.29-0.25 mm 2 ( P =0.037) and FAZ perimeter from a mean of 2.27-2.09 mm ( P =0.045) in the OCTA 6×6 mm scan area after tropicamide/phenylephrine instillation. Predilation and postdilation measurements of ONH perfusion and ONH flux index were significantly lower in the glaucoma group compared with controls ( P <0.05, for all). Topical pupillary dilation with 0.5% tropicamide and 2.5% phenylephrine results in a statistically significant reduction in the FAZ area and FAZ perimeter in POAG eyes. Further OCTA studies are needed for the diagnostic value of vascular changes due to pupil dilation in glaucoma.