Does collagen cross linking have any effect on retinal circulation in patients with keratoconus? An optical coherence tomography angiography (OCTA) study.

BACKGROUND: We aimed to employ Optical Coherence Tomography Angiography (OCTA) to comprehensively assess changes in the optic nerve head (ONH) and macular perfusion before and after the Corneal Collagen Cross-Linking (CCL) procedure in patients with keratoconus. METHODS: A total of 22 keratoconus patient's candidate for CCL procedures were included based on specific criteria, with meticulous exclusion criteria in place to minimize potential confounders. Participants underwent OCTA assessments of the ONH and macula using the Spectralis OCT (Heidelberg) before CCL, as well as at 1- and 3-months post-CCL. MATLAB software was utilized for image analysis. RESULTS: The mean age of the participants was 20.09 ± 6.11, including 59% male, and the mean intraocular pressure (IOP) before the surgery was 13.59 ± 2.85 mmHg. Peripapillary Retinal nerve fiber layer (ppRNFL) thickness and overall retinal thickness remained stable post-CCL. However, significant alterations were observed in macular vessel density, emphasizing regional variations in vascular response. For macular large vessel density (LVD), both superficial and deep vascular complex (SVC and DVC) demonstrated significant differences between before surgery and the 3 months post-surgery follow-up (p < 0.001 and p = 0.002, respectively). Optic nerve head markers demonstrated relative stability, except for changes in avascular complex density, which was 49.2 ± 2.2% before the surgery and decrease to 47.6 ± 1.7% three months after the operation (P-value = 0.005). CONCLUSION: While CCL appears to maintain the integrity of certain ocular structures, alterations in macular perfusion post-CCL suggest potential effects on retinal blood supply. Long-term monitoring is crucial to understand the implications of these changes, particularly in the context of conditions such as diabetes.

ASSOCIATION OF MACULAR STRUCTURE WITH MICROPERIMETRY SENSITIVITY FOLLOWING VITRECTOMY FOR PROLIFERATE DIABETIC RETINOPATHY.

PURPOSE: To evaluate macular sensitivity using microperimetry in patients with proliferate diabetic retinopathy following vitrectomy and to investigate the relationship between the sensitivity and foveal microstructures with optical coherence tomography/angiography. METHODS: Eighty-four eyes of 84 patients with proliferative diabetic retinopathy, who were indicated for vitrectomy, had no intraocular surgery history 3 months preoperatively, and were able to ensure fundus examination after the vitrectomy, were included. A logMAR best-corrected visual acuity, macular sensitivity of microperimetry, macular retinal thickness, and macular vessel perfusion using optical coherence tomography/angiography were examined at 1 week, 1 month, and 3 months postoperatively. RESULTS: The logMAR best-corrected visual acuity and mean macular sensitivity of patients with proliferative diabetic retinopathy improved postoperatively (P < 0.05). There was a significant correlation between best-corrected visual acuity and mean sensitivity (P < 0.05). Postoperative mean macular sensitivity was significantly correlated with outer retinal thickness in the 0 to 6 mm macular area (P < 0.05) and also significantly correlated with deep capillary plexus perfusion (P < 0.05). Fixation stability and mean macular sensitivity did not show any correlation with glycated hemoglobin, triglyceride, serum total cholesterol, carbamide, and creatinine and duration of diabetes mellitus (P > 0.05). CONCLUSION: Postoperative mean macular sensitivity was significantly correlated with outer retinal thickness and deep capillary plexus perfusion for patients with proliferative diabetic retinopathy. The authors found that the visual performance of patients can be evaluated by the outer retinal thickness and deep capillary plexus perfusion, so optical coherence tomography/angiography examination can be an important prognostic factor for visual performance in patients.Clinical Trial Registration: This trial is registered with the Chinese Clinical Trial Registry (http://www.chictr.org.cn; Registration No.: ChiCTR2100043399).

[Multimodal topographically oriented approach to the study of full-thickness macular holes]. / Mul'timodal'nyi topograficheski orientirovannyi podkhod k izucheniyu skvoznykh makulyarnykh razryvov.

PURPOSE: This article studies the relationship between structural changes according to the findings of optical coherence tomography (OCT) and OCT angiography (OCTA), microperimetry (MP), multifocal electroretinography (mfERG) parameters in topographically corresponding areas of the macular region in idiopathic full-thickness macular holes (FTMH). MATERIAL AND METHODS: OCT, OCTA, MP and mfERG were performed in 14 eyes with FTMH stages I-IV according to Gass. In 13 points at a distance of 0-2.5°, 2.5-5.0°, and 5.0-10.0° from the fixation point, the light sensitivity (LS), amplitude and latency of the P1 component were compared with the size of the hole, the area of cystic changes (CC) at the level of the inner nuclear layer (INL) and the outer plexiform layer and Henle fiber layer complex (OPL+HFL), vessel density in the superficial and deep capillary plexus (SCP and DCP). RESULTS: LS and P1 component amplitude were significantly reduced at a distance of up to 5.0° from the fixation point. LS correlates with the apical and basal diameter of the hole (R> -0.53), the area of CC in the INL (R> -0.62) and the OPL+HFL complex (R> -0.55), the density of vessels in the SCP at a distance of up to 2.5° from the fixation point (R>0.51) and in the DCP at a distance of up to 5° from the fixation point (R>0.49). The P1 amplitude correlates with the basal diameter of the hole (R= -0.38), the area of CC in the INL and the OPL+HFL complex (R> -0.33) and vessel density in the SCP (R=0.37) at a distance of up to 2.5° from the fixation point, as well as vessel density in the DCP at a distance of up to 5° from the fixation point (R=0.47). Vessel density in the DCP is significantly lower in the presence of CC in the retina (p<0.001). CONCLUSION: In FTMH, there is a relationship between bioelectrical activity and LS, and structural disorders, capillary perfusion in different layers of the retina. A multimodal topographically oriented approach allows studying the relationship between structural and functional parameters in individual points of the retina and can be used in monitoring of FTMH after surgical treatment.

Reduced macular thickness and vascular density in abnormal glucose metabolism patients: A meta-analysis of optical coherence tomography (OCT) and OCT angiography studies.

BACKGROUND: Alterations in macular thickness and vascular density before clinically visible diabetic retinopathy (DR) remain inconclusive. This study aimed to determine whether retinal manifestations in abnormal glucose metabolism (AGM) patients differ from those in the healthy individuals. METHODS: PubMed, Embase, and Web of Science were searched between 2000 and 2021. The eligibility criteria were AGM patients without DR. Primary and secondary outcomes measured by optical coherence tomography (OCT) and OCT angiography (OCTA) were analyzed and expressed as standardized mean differences (SMDs) with 95% confidence intervals (CIs). A random-effects model was used in the data synthesis. The potential publication bias for the variables was evaluated using Egger's test. RESULTS: A total of 86 observational studies involving 13,773 participants and 15,416 eyes were included. OCT revealed that compared to healthy controls, the total macular thickness of AGM patients was thinner, including the thickness of fovea (-0.24, 95% CI [-0.39, -0.08]; P  = 0.002, I2  = 87.7%), all regions of parafovea (-0.32, 95% CI [-0.54, -0.11]; P  = 0.003; I2  = 71.7%) and the four quadrants of perifovea; the thickness of peripapillary retinal nerve fiber layer (pRNFL), macular retinal nerve fiber layer (mRNFL), and ganglion cell layer (GCL) also decreased. OCTA indicated that the superficial and deep vascular density decreased, the foveal avascular zone (FAZ) area enlarged, and the acircularity index (AI) reduced in AGM individuals. CONCLUSIONS: Retinal thinning and microvascular lesions have occurred before the advent of clinically detectable DR; OCT and OCTA may have the potential to detect these preclinical changes. REGISTRATION: PROSPERO; http://www.crd.york.ac.uk/prospero/ ; No. CRD42021269885.

Contribution of systemic factors on macular vessel density: a sex-specific population-based study.

PURPOSE: To evaluate the influence of systemic factors on macular vessel density in quantitative Optical Coherence Tomography Angiography (OCTA) by sex. STUDY DESIGN: A cross-sectional study. METHODS: A total of 2018 adults were recruited in this study. Participants were excluded (n=964) due to missing data, eye-related problems, or low OCTA scan quality. Macular vessel densities were measured with OCTA using split-spectrum amplitude decorrelation angiography algorithm. Only the data from the right eyes were selected for analysis. Multivariable linear regression analysis was performed to determine the associations between macular vessel density and obesity-related systemic factors in each gender group. RESULTS: The right eyes of 1054 participants (59.6% women) were enrolled. Men had significantly higher obesity parameters and associated risk factors. In multivariable linear regression analysis in men, older age and type 2 diabetes mellitus were independently associated with lower superficial retinal vessel density (ß = -0.37, p = 0.002; ß = -1.22, p = 0.03) and deep retinal vessel density, respectively (ß = -0.66, p < 0.001; ß = -1.76, p = 0.02); positive association was also observed between body mass index (BMI) and superficial retinal vessel density (ß = 0.56, p = 0.02). In women, only higher systolic blood pressure was independently associated with a lower deep retinal vessel density (ß = -0.50, p = 0.003). CONCLUSIONS: This large cross-sectional study shows that older age and type 2 diabetes mellitus are associated with lower superficial and deep retinal capillary vessel density in men. This may help clinicians better understand how systemic factors influence retinal vessel density in different genders and future studies can ascertain more potential sex differences.

Linking Vascular Structure and Function: Image-Based Virtual Populations of the Retina.

Purpose: This study explored the relationship among microvascular parameters as delineated by optical coherence tomography angiography (OCTA) and retinal perfusion. Here, we introduce a versatile framework to examine the interplay between the retinal vascular structure and function by generating virtual vasculatures from central retinal vessels to macular capillaries. Also, we have developed a hemodynamics model that evaluates the associations between vascular morphology and retinal perfusion. Methods: The generation of the vasculature is based on the distribution of four clinical parameters pertaining to the dimension and blood pressure of the central retinal vessels, constructive constrained optimization, and Voronoi diagrams. Arterial and venous trees are generated in the temporal retina and connected through three layers of capillaries at different depths in the macula. The correlations between total retinal blood flow and macular flow fraction and vascular morphology are derived as Spearman rank coefficients, and uncertainty from input parameters is quantified. Results: A virtual cohort of 200 healthy vasculatures was generated. Means and standard deviations for retinal blood flow and macular flow fraction were 20.80 ± 7.86 µL/min and 15.04% ± 5.42%, respectively. Retinal blood flow was correlated with vessel area density, vessel diameter index, fractal dimension, and vessel caliber index. The macular flow fraction was not correlated with any morphological metrics. Conclusions: The proposed framework is able to reproduce vascular networks in the macula that are morphologically and functionally similar to real vasculature. The framework provides quantitative insights into how macular perfusion can be affected by changes in vascular morphology delineated on OCTA.

The long-term influence of perinatal factors on macular morphology and vessel density in preterm children.

BACKGROUND: Increased survival rate of extremely preterm children is associated with a higher risk of retinopathy of prematurity (ROP) and long-term sequelae, which implicate retinal changes. PURPOSE: To assess an influence of perinatal characteristics on morphology and retinal vascularity of the macula in preterm children. METHODS: A cohort of 123 preterm children at the age of 10.5 years (IQR: 8.12-12.77) was prospectively assessed. Optical coherence tomography angiography (OCTA) was performed using RTVueXR Avanti. Foveal thickness, parafoveal thickness, size of foveal avascular zone (FAZ), superficial and deep vessel density, central choroidal thickness (CCT) were analyzed. The associations between OCTA results and perinatal factors, including the presence of ROP and therapy requirements were assessed in preterm children. RESULTS: Significantly smaller FAZ, higher foveal thickness and vessel density were noted in children with ROP, Respiratory Distress Syndrome, Bronchopulmonary Dysplasia, required erythropoietin, transfusion or steroids. Foveal thickness was increased in children with ROP (p < 0.001) and following laser treatment (p < 0.05). Thinner CCT was noted in children with a history of sepsis (p < 0.05) and ROP required treatment (p < 0.05). Pregnancy bleeding was associated with higher superficial foveal vessel density (p < 0.05) and smaller FAZ (p < 0.05). CONCLUSION: Neonatal factors have a huge impact on retinal development, but the role of prenatal factors should not be neglected in preterm children.

The use of optical coherence tomography (OCT) and OCT angiography in borderline personality disorder compared to health control subjects.

BACKGROUND: Optical coherence tomography (OCT) or OCT angiography (OCTA) has been investigated in few research studies of psychiatric disorders. No research has been done using OCT or OCTA in patients with borderline personality disorder (BPD). METHODS: OCTA measured foveal avascular zone (FAZ), macular vessel density (MVD), and peripapillary vessel density (PVD). OCT measured the peripapillary retinal fiber layer (RNFL) and central retinal thickness (CRT). The study utilized the Ottawa Self-Injury Inventory, Hamilton Anxiety Rating Scale (HAMA), and Global Assessment of Functioning (GAF) to assess the symptom characteristics of individuals with BPD. RESULTS: Fifty-nine eyes of BPD patients and 58 eyes of normal subjects were analyzed, MVD of the superficial retinal capillary plexus declined noticeably in most subfields (p < 0.05). Significant differences were observed in the whole inner ring and outer ring index between BPD and HC groups (p < 0.05). The patients with BPD exhibited lower RNFL and CRT, the difference was significant (p < 0.05). CRT indicated a significant negative correlation with the Ottawa Self-Injury Inventory (p < 0.05). In addition, we observed that there was a negative correlation identified between the MVD of the inner ring and HAMA (p < 0.05). Meanwhile, the MVD of the outer ring was positively correlated with GAF (p < 0.05). The areas under the receiver operating characteristic curves (AUROCs) for distinguishing BPD and HC eyes in OCTA were the highest for fovea MVD (0.679), followed by outer ring MVD (0.669), inner ring MVD (0.641), FAZ (0.579). In OCT, CRT was highest for BPD (0.711), followed by RNFL (0.625). CONCLUSION: The OCT and OCTA can non-invasively detect microvascular and morphology changes of the retina in BPD patients compared to healthy control subjects.

Baseline imaging characteristics and early structural changes in macula on rhegmatogenous retinal detachment.

Animal models have demonstrated that structural changes affect the macula during peripheral rhegmatogenous retinal detachment. This study aimed to assess photoreceptors, retinal and choriocapillaris perfusion in non-macula involving rhegmatogenous retinal detachment by analyzing en-face images from structural OCTA segmented at the ellipsoid zone (EZ) level, calculating (1) "normalized" reflectivity as a surrogate biomarker of photoreceptor damage (2) perfusion density (PD), vessel length density (VLD) and vessel diameter index (VDI) of superficial capillary plexus (SCP) and deep capillary plexus (DCP) (3) perfusion density of choriocapillaris (PDCC). Twenty-one eyes affected by macula-on rhegmatogenous retinal detachment (RRD) were enrolled at the University "G. d'Annunzio", Chieti-Pescara. The fellow unaffected eye was used as control. The mean age at the onset of RRD was 60.09 ± 10.22 (range 34-83). Compared with fellow eyes, we found lower EZ "normalized" reflectivity in macula-on (0.42 ± 0.15 in fellow eyes and 0.31 ± 0.09 in macula on p = 0.004). The affected eye was also characterized by impaired perfusion in SCP (17.26 ± 3.34% in macula on and 20.56 ± 3.62% in the fellow eye p = 0.004) and CC (50.21 ± 6.20% in macula on the eye and 57.43 ± 6.20% in the fellow eye p = 0.004). Macula-on rhegmatogenous retinal detachment has subclinical changes in photoreceptors, SCP, and CC. Future longitudinal studies should evaluate if early changes could impact post-operative macular function.

The Influence of Topical Perioperative Nepafenac on Retinal Vasculature Following Phacoemulsification Using Optical Coherence Tomography Angiography: A Randomized Clinical Trial.

PURPOSE: To investigate topical nepafenac drops (TND) effect on retinal vasculature following uneventful phacoemulsification. METHODS: 54 eyes were randomly assigned to G1: TND 3 days preoperatively and 1 month postoperatively; G2: TND for 1 month postoperatively; and G3 no TND (control). BCVA, macular OCTA were compared baseline, 1 week and 1 month. RESULTS: No statistically significant differences found between 3 groups in OCTA parameters during study visits. However, at 1 month (compared to baseline) there were a statistically significant increase in superficial capillary plexus (SCP) capillary vessel density (CVD) in G2 (p=0.036); increase in central foveal thickness (CFT) in G2 (p=0.011) and G3 (control) (p=0.001); and reduced number of patients with SCP disorganization in G2 (p=0.04). There were no significant correlation/association between most of OCTA parameters and final BCVA. CONCLUSION: TND use perioperative did not show any effect on retinal OCTA microvasculature and might affect macular edema by other mechanisms.

Reduction in retinal microvascular perfusion during migraine attacks.

OBJECTIVE: To determine if there are changes in structure and function of the retinal vasculature during and between migraine attacks using optical coherence tomography angiography (OCTA). BACKGROUND: Migraine attacks commonly include visual symptoms, but the potential role of the retina in these symptoms is not well understood. OCTA is a rapid, non-invasive imaging technique that is used to visualize the retinal microvasculature with high spatial resolution in a clinical setting. In this study we used OCTA to quantify different features of the retinal vasculature in patients with migraine during and between attacks, as well as in healthy controls (HCs). METHODS: We performed a prospective cohort study of 37 patients with migraine with aura (MA) (median [interquartile range, IQR] age of 37 [14] years, 86% female) and 30 with migraine without aura (MO) (median [IQR] age of 37 [17] years, 77% female) and 20 HCs (median [IQR] age of 35 [7] years, 50% female). Macular OCTA scans were obtained for all participants for the interictal analysis. In 12 MA and eight MO, scans were captured both during and outside of migraine attacks and five HCs had initial and repeat scans. In addition to analyzing the morphology of the foveal avascular zone, we calculated the vessel flux index (VFI), which is an indicator of retinal perfusion and conventional metrics (such as vessel area density) in the foveal and parafoveal regions. RESULTS: There was a significant difference in the parafoveal VFI in the ictal state between the groups (p = 0.009). During migraine attacks there was a significant reduction in the parafoveal region VFI in MA (-7%, 95% confidence interval [CI] -10% to -4%; p = 0.006) and MO (-7%, 95% CI -10% to -3%; p = 0.016) from their interictal baseline as compared to the change between repeat scans in HCs (2%, 95% CI -3% to 7%). Interictally, there was a mean (standard deviation [SD]) 13% (10%) (p = 0.003) lower blood perfusion in the MA group as compared to the MO group in the foveal region (mean [SD] 0.093 [0.023] vs. 0.107 [0.021], p = 0.003). Interictal analysis also revealed higher circularity in the superficial foveal avascular zone in the MA group compared with the MO group (mean [SD] 0.686 [0.088] vs. 0.629 [0.120], p = 0.004). In addition, interictal analysis of the patients with MA or MO and unilateral headache showed increased retinal vascular parameters consistent with greater perfusion in the eye ipsilateral to the side of the pain as compared with the contralateral eye. CONCLUSIONS: These results indicate that perfusion is reduced in MA and MO in the parafoveal retina during the ictal period. Interictally, the foveal retina in MA has reduced perfusion when compared to the foveal retina in MO. Patients with unilateral headache showed interictal asymmetry of retinal perfusion between eyes. These results indicate that changes in retinal perfusion could be a part of migraine pathophysiology, and that distinct retinal vascular signatures identified with OCTA could represent biomarkers for migraine.

CHANGES IN OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY MEASURES THROUGHOUT THE DAY: Diurnal Variation or Test-Retest Variability?

PURPOSE: To evaluate the repeatability and diurnal variation of the retinal vessel density and foveal avascular zone parameters using optical coherence tomography angiography. METHODS: Forty-one healthy individuals were measured twice in the morning and once in the evening. Foveal avascular zone area, perimetry, foveal density; superficial and deep capillary plexus (superficial capillary plexus, deep capillary plexus) vessel density, and central macular thickness were evaluated with the intraclass correlation coefficient, coefficient of repeatability, and Bland-Altman plots. RESULTS: Repeatability was evaluated with two consecutive scans taken in the morning. The coefficient of repeatabilities (%) was 5.4; 4.3, and 8.8 for the foveal avascular zone area, perimetry, and foveal density, respectively, with excellent intraclass correlation coefficients. Intraclass correlation coefficient was poor for parafovea (0.33), whereas excellent for fovea (0.97) in superficial capillary plexus-vessel density. Coefficient of repeatability for fovea and parafovea was 19.19% and 10.43%, respectively. Intraclass correlation coefficient values were poor (0.3-0.4) with 10% to 16% measurement differences in deep capillary plexus-vessel density parameters. Coefficient of repeatabilities for central macular thickness was between 1% and 2% with excellent intraclass correlation coefficient. The analysis on diurnal variation yielded comparable results. CONCLUSION: Except for the parafoveal vessel density, optical coherence tomography angiography is a highly reproducible device for measuring foveal avascular zone and vessel density using 6 × 6 scans with undilated pupils. However, variation in optical coherence tomography angiography parameters observed throughout the day could be attributed to test-retest variation rather than diurnal rhythm.

Subclinical macular vessel density alterations in patients with juvenile systemic lupus erythematosus.

OBJECTIVE: The aim is to evaluate subclinical alterations of macular microvasculature in patients with juvenile systemic lupus erythematosus (JSLE). METHODS: This is a cross-sectional study of 29 eyes of 29 patients diagnosed with JSLE and 29 eyes of 29 healthy controls. The vessel density (VD) of the superficial capillary plexus (SCP), intermediate capillary plexus (ICP), deep capillary plexus (DCP), choriocapillaris (CC), and area of foveal avascular zone (FAZ) was measured using optical coherence tomography angiography (OCTA). A multiple linear regression analysis was performed to evaluate the effects of disease duration and activity on OCTA parameters. RESULTS: The VD of total (p = .007) and the superior (p = .014) and inferior (p = .004) quadrants in SCP was significantly lower in children with JSLE. The VD of total and all quadrants in ICP decreased (p = .015, p = .0045, p = .015, p = .033), except that of the temporal quadrant (p = .366). The total (p = .011) and superior quadrant (p<.01) DCP-VD showed a significant decrease in children with JSLE. The decrease in VD in the total (p = .003) and nasal quadrant (p = .017) of CC was also remarkable. No significant difference in the FAZ area was found between the two groups (p = .774). Multiple linear regression analyses adjusted for age, spherical equivalent, and intraocular pressure were conducted. No contributing factor to OCTA parameters was found. CONCLUSIONS: We demonstrated decreased VD in all layers of the retina and CC in patients with JSLE without ocular involvement. Early screening and close follow-up were recommended.

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

PURPOSE: To evaluate the relationship between the nonperfusion area (NPA) from widefield optical coherence tomography angiography (OCTA) and macular vascular parameters in diabetic retinopathy (DR). METHODS: In 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. RESULTS: A 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). CONCLUSION: Diabetic 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.

Evaluating macular and optic nerve changes during Ramadan fasting by optical coherence tomography angiography-a prospective before-and-after study.

PURPOSE: During Ramadan, millions of Muslims fast from sunrise to sunset. Fasting influences the hormonal system, sympathetic activity, blood circulation, and metabolic pathways. Because of these changes, we employed optical coherence tomography angiography (OCTA) to investigate the effects of fasting on the macula and optic nerve. METHODS: In this prospective before-and-after study, both eyes of 45 participants were examined. Vascular characteristics of the macula and optic nerve head were evaluated in the morning and evening, once before Ramadan and once on the 20th day of Ramadan. RESULTS: Compared to the non-fasting condition, fasting significantly reduced inner parafoveal retinal thickness in both eyes and total foveal retinal thickness in the left eye in the morning and evening. Fasting in the morning also considerably reduced inner foveal retinal thickness in both eyes and total parafoveal retinal thickness in the right eye. Fasting significantly reduced central choroidal flow (1 mm) in both eyes in the evening (all p-values are < 0.05). In the morning, there were significant increases in the foveal avascular zone (FAZ) area (p-value = 0.006) and deep parafoveal vascular density in the left eye (p-value = 0.001). CONCLUSION: Fasting alters both the macular characteristics and the optic nerve head, as seen in OCTA, although it did not affect participants' vision. However, further research is needed before reaching a broad conclusion.

Associations between macular retinal vasculature and severity of idiopathic epiretinal membrane.

BACKGROUND: To demonstrate the associations between the morphology of macular retinal vasculature and disease severity of idiopathic epiretinal membrane (ERM). METHODS: Macular structures were assessed using optical coherence tomography (OCT), and were classified as "with pseudohole" or "without pseudohole". The 3 × 3 mm macular OCT angiography images were analyzed using the Fiji software to obtain the vessel density, skeleton density, average vessel diameter, vessel tortuosity, fractal dimension, and foveal avascular zone (FAZ)-related parameters. The correlations between these parameters and ERM grading as well as visual acuity were analyzed. RESULTS: For ERM with or without a pseudohole, increased average vessel diameter, decreased skeleton density, and decreased vessel tortuosity were all associated with inner retinal folding and thickened inner nuclear layer, indicating more severe ERM. In 191 eyes without a pseudohole, the average vessel diameter increased, fractal dimension decreased and vessel tortuosity decreased with increasing ERM severity. The FAZ was not associated with ERM severity. Decreased skeleton density (r = -0.37), vessel tortuosity (r = -0.35), and increased average vessel diameter (r = 0.42) were correlated with worse visual acuity (All P < 0.001). In 58 eyes with pseudoholes, a larger FAZ was associated with a smaller average vessel diameter (r = -0.43, P = 0.015), higher skeleton density (r = 0.49, P < 0.001), and vessel tortuosity (r = 0.32, P = 0.015). However, none of the retinal vasculature parameters correlated with visual acuity and central foveal thickness. CONCLUSION: Increased average vessel diameter, decreased skeleton density, decreased fractal dimension and decreased vessel tortuosity were good indicators of ERM severity and associated visual impairment.

Optical Coherence Tomography Angiography of Volumetric Arteriovenous Relationships in the Healthy Macula and Their Derangement in Disease.

Purpose: To characterize relative arteriovenous connectivity of the healthy macula imaged by optical coherence tomography angiography (OCTA) using a new volumetric tool. Methods: OCTA volumes were obtained for 20 healthy controls (20 eyes). Two graders identified superficial arterioles and venules. We implemented a custom watershed algorithm to identify capillaries most closely connected to arterioles and venules by using the large vessels as seeds to flood the vascular network. We calculated ratios of arteriolar- to venular-connected capillaries (A/V ratios) and adjusted flow indices (AFIs) for superficial capillary plexuses (SCPs), middle capillary plexuses (MCPs), and deep capillary plexuses (DCPs). We also analyzed two eyes with proliferative diabetic retinopathy (PDR) and one eye with macular telangiectasia (MacTel) to evaluate the utility of this method in visualizing pathological vascular connectivity. Results: In healthy eyes, the MCP showed a greater proportion of arteriolar-connected vessels than the SCP and DCP (all P < 0.001). In the SCP, the arteriolar-connected AFI exceeded the venular-connected AFI, but this pattern reversed in the MCP and DCP, with higher venular-connected AFI (all P < 0.001). In PDR eyes, preretinal neovascularization originated from venules, whereas intraretinal microvascular abnormalities were heterogeneous, with some originating from venules and others representing dilated MCP capillary loops. In MacTel, diving SCP venules formed the epicenter of the outer retinal anomalous vascular network. Conclusions: Healthy eyes showed a higher MCP A/V ratio but relatively slower arteriolar vs. venular flow velocity in the MCP and DCP, which may explain deep retinal vulnerability to ischemia. In eyes with complex vascular pathology, our connectivity findings were consistent with histopathologic studies.

[Optical coherence tomography angiography in diagnosis of changes in macular capillary blood flow in chronic ischemic retinopathy]. / Opticheskaya kogerentnaya tomografiya-angiografiya v diagnostike izmenenii kapillyarnogo krovotoka makuly pri khronicheskoi ishemicheskoi retinopatii.

PURPOSE: Assessment of the indices of macular capillary blood flow and subfoveal choroidal thickness (SCT) using optical coherence tomography angiography in patients with retinal manifestations of ocular ischemic syndrome (RMOIS) associated with atherosclerotic internal carotid artery stenosis. MATERIAL AND METHODS: The study included 34 patients (68 eyes): 21 men, 13 women with RMOIS in one eye. All patients were divided into 2 groups depending on the severity of atherosclerotic internal carotid artery stenosis and ophthalmoscopic picture of the fundus. To obtain objective information we analyzed the degree of decrease in the main indices characterizing macular microcirculation and SCT depending on the severity of RMOIS. RESULTS AND DISCUSSION: Analysis of the results showed relationship between the severity of RMOIS and the deficit in macular microcirculation. The macula of the patients with mild RMOIS was characterized by a decrease in the density of superficial vascular plexus (SVP) and the density of deep capillary plexus (DCP) by 13.5% and 10.5% compared to the controls, respectively; in moderate RMOIS - by 19.7% and 14.6%; in severe RMOIS - by 35.9% and 28%, respectively. With an increase in the severity of RMOIS, the area of the foveal avascular zone increased too: in mild degree RMOIS - by 19%, in moderate - by 38.6%, in severe - by 51%. In proportion to the severity of RMOIS, SCT was reduced: in mild degree RMOIS - by only 8%, in moderate - by 22%, and in severe - by 29.8% of the control. CONCLUSION: The conducted research indicates that pathological changes in RMOIS extend to the entire capillary network of the macula and SCT. With increase in the degree of RMOIS, ischemic changes in all capillary layers of the central parts of the retina proportionally increase in comparison with the control group by 1.15 times in mild degree, by 1.24 times in moderate degree, and by 1.5 times in severe RMOIS.

Optical Coherence Tomography Angiography Assessment in Congenital Aniridia.

PURPOSE: This study aims to characterize foveal vasculature assessed by optical coherence tomography angiography (OCT-A) in congenital aniridia which is hallmarked by foveal hypoplasia (FH). DESIGN: Cross-sectional case-control analysis. METHODS: At the National Referral Center for congenital aniridia, patients with confirmed PAX6-related aniridia and FH diagnosed on spectral-domain OCT (SD-OCT) with available OCT-A and matched control subjects were included. OCT-A was performed in patients with aniridia and control subjects. Foveal avascular zone (FAZ) and vessel density (VD) were collected. VD in the foveal and parafoveal areas at the level of the superficial and deep capillary plexi (SCP and DCP, respectively) were compared between the 2 groups. In patients with congenital aniridia, correlation between VD and the grading of FH was assessed. RESULTS: Among 230 patients with confirmed PAX6-related aniridia, high-quality macular B-scans and OCT-A were available in 10 patients. On the foveal area, mean VD was higher in aniridia patients (41.10%, n = 10) than in control subjects (22.65%, n = 10) at the level of the SCP and the DCP (P = .0020 and P = .0273, respectively). On the parafoveal area, mean VD was lower in patients with aniridia (42.34%, n = 10) than in healthy subjects (49.24%, n = 10) at the level of both plexi (P = .0098 and P = .0371, respectively). In patients with congenital aniridia, a positive correlation was found between the grading of FH and the foveal VD at the SCP (r = 0.77, P = .0106). CONCLUSIONS: Vasculature is altered in PAX6-related congenital aniridia, higher in foveal and lower in parafoveal areas, especially when FH is severe, which is consistent with the concept that the absence of retinal blood vessels is essential for foveal pit development.

Reproducibility of peripapillary, optic nerve head and macular vessel density by OCT-A according to glaucoma severity staging.

OBJECTIVE: To assess the reproducibility of peripapillary, optic nerve head (PP-ONH) and macular vessel density (VD) by Spectral Domain optical coherence tomography angiography (SD OCT-A) in glaucoma patients and healthy subjects. METHODS: Cross-sectional study assessing 63 eyes of 63 subjects, including 33 glaucoma patients and 30 healthy subjects. Glaucoma was classified in mild, moderate, or advanced. Two consecutive scans were acquired by Spectralis Module OCT-A (Heidelberg, Germany), and provided images of the superficial vascular complex (SVC), nerve fiber layer vascular plexus (NFLVP), superficial vascular plexus (SVP); deep vascular complex (DVC), intermediate capillary plexus (ICP) and deep capillary plexus (DCP). VD (%) was calculated by AngioTool. Intraclass correlation coefficients (ICCs) and coefficients of variation (CV) were calculated. RESULTS: Among PP-ONH VD, better ICC presented advanced (ICC 0.86-0.96) and moderate glaucoma (ICC 0.83-0.97) compared with mild glaucoma (0.64-0.86). For the macular VD reproducibility, ICC results for superficial retinal layers were better for mild glaucoma (0.94-0.96) followed by moderated (0.88-0.93) and advanced glaucoma (0.85-0.91), and for deeper retinal layers ICC was better for moderate glaucoma (0.95-0.96) followed by advanced (0.80-0.86) and mild glaucoma (0.74-0.91). CVs ranged from 2.2% to 10.94%. Among healthy subjects, ICCs for the PP-ONH VD measurements (0.91-0.99) and for the macular VD measurements (0.93-0.97) were excellent in all layers, with CVs from 1.65% to 10.33%. CONCLUSIONS: SD OCT-A used to quantify macular and PP-ONH VD showed excellent and good reproducibility in most layers of the retina, both in healthy subjects and in glaucoma patients regardless of the severity of the disease.