Optical Coherence Tomography Angiography Parameters Research Articles

Retinal vasculature changes as indicators of imaging signs of cerebral small vessel disease: A community-based, cross-sectional study of older adults.

This study investigated the correlation between retinal vasculature and cerebral small vessel disease (CSVD) imaging markers, providing new evidence for the retina-brain association. Two hundred and thirty-nine participants aged 55-85 were enrolled in the study. CSVD indicators, encompassing white matter hyperintensities (WMHs), lacunes (LAs), cerebral microbleeds (CMBs), and enlarged perivascular spaces (EPVSs), were assessed. The vascular density (VD) of the superficial vascular plexus (SVP) and deep vascular plexus (DCP) was evaluated using optical coherence tomography angiography (OCTA). Furthermore, the software automatically calculated SVP's small vessel density (sVD). Finally, the area, perimeter, circularity index (CI), and VD-300μm of the foveal avascular zone (FAZ) were assessed utilizing OCTA. The mean values of binocular OCTA parameters were used for data analysis. The association between OCTA parameters and CSVD imaging markers was evaluated using binary logistic regression analysis. The median age was 68 (64-71) years with 40.2% of the participants being male. In the binary logistic regression analysis, WMHs exhibited a negative association with the SVP-VD, DCP-VD, and FAZ VD-300μm (P<0.05); LAs displayed a negative correlation with the SVP-sVD and SVP-VD (P<0.05); and EPVSs indicated a negative correlation with both the area and perimeter of the FAZ (P<0.05); however, CMBs did not demonstrate any significant correlation with OCTA indicators (P>0.05). The study demonstrated that different CSVD indicators are associated with distinct OCTA markers. OCTA may be a valuable tool for monitoring CSVD-related indicators.

Evaluation of Retinal and Choroidal Microvascularity in Patients with Benign Essential Blepharospasm

Purpose To assess the retinal and choroidal microvascular changes in patients with benign essential blepharospasm (BEB) and to investigate the factors that may be effective on microvascularity. Methods This study included patients with BEB and healthy controls. All participants underwent a comprehensive examination followed by optical coherence tomography angiography (OCTA). Macular vascular perfusion density (VPD), foveal avascular zone (FAZ), and subfoveal choroidal thickness (CT) were measured. The clinical findings of the BEB group and the administration of botulinum toxin A (BTx-A) prior to OCTA imaging were recorded retrospectively from the medical records. Results A total of 16 patients with BEB and 20 healthy controls were included in this study. VPD values in all quadrants of the superficial and deep macular capillary plexus were significantly different in the BEB group compared to the control group (each p-value <0.05). In the choriocapillaris layer, VPD was significantly higher in the superior, nasal, and temporal quadrants compared to the control group (each p-value <0.05). The BEB group exhibited significantly smaller superficial and deep FAZ values compared to the control group, consistent with the observed increase in vascular density (each p-value <0.05). CT was thinner in the BEB group, although not statistically significant (p = 0.138). No correlation was found between the total dose of BTx-A administered to the BEB group and OCTA parameters (each p-value >0.05) Conclusion Benign essential blepharospasm may be associated with increased retinal vascular density in the superficial and deep capillary plexus and decreased FAZ area.

The repeatability of macular and peripapillary vessel density in participants with different severities of glaucoma.

To investigate the repeatability of optical coherence tomography angiography (OCTA) parameters in participants with different severities of glaucoma. Subjects with open-angle glaucoma were enrolled prospectively and categorised into mild (mean deviation [MD] of 24-2 visual field test ≥ -6 dB), moderate to advanced (-6 > MD ≥ -20 dB) and severe glaucoma groups (MD < -20 dB). OCTA was performed three times within a single visit to obtain superficial and deep macular vessel density (VD) and peripapillary vessel and capillary density. The association between the coefficient of variation (CoV) and intraclass correlation coefficient (ICC) of these OCTA parameters and glaucoma severity (MD, the thickness of the retinal nerve fibre layer and the ganglion cell complex) was analysed, along with factors associated with the CoV of OCTA parameters. A total of 57 mild, 92 moderate to advanced and 39 severe glaucomatous eyes were included. CoV for superficial (p < 0.001) and deep macular VD (p < 0.001) and peripapillary VD (p = 0.004) increased with glaucoma severity. Greater CoV for superficial and deep macular VD and peripapillary VD was associated with worse MD and scan quality index in multivariable analysis. The association between a higher CoV of superficial and deep macular VD and worse MD was only noticeable in participants with a scan quality index <7. The relationship between the CoV of peripapillary VD and MD was consistent across varying image qualities. The intrasession variability of OCTA parameters was greater in glaucoma participants with advanced disease, especially in those with suboptimal scan quality.

Association between macular vessel density and microvascular biomarkers in pediatric chronic kidney disease

Purpose This study evaluated retinal microvasculature changes in children with chronic kidney disease (CKD) using optical coherence tomography angiography (OCTA). It aimed to identify associations between OCTA parameters and serum levels of vitamin D, asymmetric dimethyl arginine (ADMA), vascular endothelial growth factor-A (VEGF-A), and angiopoietin-2 (Ang-2), and to examine their relationship with CKD progression as measured by estimated glomerular filtration rate (eGFR). Patients and methods A single-center, cross–sectional, prospective correlation study used OCTA to compare retinal vessel density (VD) and foveal avascular zone area in 105 children: 35 on dialysis, 35 with nondialysis CKD, and 35 controls. Blood tests assessed kidney function and microvascular markers including ADMA, VEGF-A, and Ang-2. Results Compared with controls, both CKD groups showed significantly lower VD in the macula. Additionally, both CKD groups had a larger foveal avascular zone area. In the dialysis group, vitamin D levels positively correlated with VD, while ADMA and Ang-2 levels negatively correlated. In the nondialysis group, albumin and vitamin D levels positively correlated with VD, while ADMA, VEGF, and Ang-2 levels were negatively correlated. Conclusion Our findings suggest that OCTA is a valuable tool for monitoring microvascular health in children with CKD and highlights the potential roles of vitamin D, ADMA, Ang-2, and VEGF in CKD progression and microvascular damage.

Difference in Optical Coherence Tomography Angiography Parameters After SARS-CoV-2 Infection During the Alpha and Delta Variant Dominance Periods.

The SARS-CoV-2 infection manifests with diverse clinical manifestations, with severity potentially influenced by the viral variant. COVID-19 has also been shown to impact ocular microcirculation in some patients, but whether this effect varies by viral lineage remains unclear. This prospective study compared clinical features and ocular parameters assessed via optical coherence tomography angiography (OCTA) in patients recovering from SARS-CoV-2 infections during the dominance of two distinctive viral lineages, Alpha (B.1.1.7) and Delta (B.1.617.2), and compared them to a control group. The following parameters were measured: vessel density (VD) in the superficial capillary plexus (SCP), deep capillary plexus (DCP), and choriocapillaris (CCP) using OCTA, with a manual assessment of the foveal avascular zones in the SCP (FAZs) and DCP (FAZd). A control group was also included. Among 63 patients in the Alpha group and 41 in the Delta group, no eye-related symptoms were reported during the examination. However, the Delta group showed significantly lower VD in the SCP and DCP across all quadrants (p < 0.001-0.039), while the Alpha group showed reduced VD in the foveal CCP (p = 0.005) and significantly wider FAZs and FAZd (p = 0.002 for both). In conclusion, ocular microcirculatory changes differed between the two variants, with Alpha associated with foveal choroidal VD reduction and larger FAZs and Delta linked to lower SCP and DCP VD across multiple regions. These findings highlight the potential for SARS-CoV-2 variants to differentially impact ocular vasculature, underscoring the need for variant-specific follow-up in COVID-19 patients.

EVALUATION OF RETINAL MICROCIRCULATION CHARACTERISTICS FOLLOWING RHEGMATOGENOUS DETACHMENT

Introduction. Despite advancements in surgical techniques for treating retinal detachment, the risk of vision loss remains significant. Accurate assessment of changes in the macular microvascuature using optical coherence tomography-angiography (OCT-A) can improve predictions for recovery of vision in patients, making this a critical area of focus in modern ophthalmology. Purpose: to analyze changes in the retinal microvasculature following successful vitrectomy for rhegmatogenous retinal detachment (RRD), both with and without macular detachment, and to evaluate their impact on postoperative visual function. Materials and methods. A total of 89 patients were studied. Group I consisted of 47 patients with RRD without macular detachment, while Group II included 42 patients with RRD with macular detachment. Retinal microvasculature parameters were assessed in the late postoperative period (18 months) using OCT-A. All patients underwent closed subtotal vitrectomy, retinal endolaser coagulation, and vitreous tamponade with an octafluoropropane (C3F8) gas-air mixture. Results. In Group II, correlation analysis at 18 months revealed a significant relationship between the density of the deep capillary plexus and best-corrected visual acuity (BCVA) (r = 0.69, p = 0.023). Additionally, a correlation was observed between BCVA and the area of the foveal avascular zone (FAZ) (r = 0.24, p = 0.013). Conclusions. Restoration of the retinal microvasculature continues into the late postoperative period in patients with RRD involving macular detachment. OCT-A parameters, specifically deep capillary plexus density and FAZ area, are significant factors influencing visual function following surgery for RRD.

Optical Coherence Tomography in the Diagnosis of Open-angle Glaucoma

This literature review provides information on the capabilities and role of OCT-A in the diagnosis of open-angle glaucoma. The need for non-invasive methods of assessing the ocular vasculature has led to the development of OCT-angiography (OCT-A), which provides information on the state of both the retinal structure and its vascular bed through blood flow analysis, further increasing the value of this imaging method compared to conventional OCT. Blood flow assessment with OCT-A can be used to detect many retinal vascular abnormalities, such as the definition of areas of non-perfusion, non-functioning vessels, the appearance of new vessels in areas that are avascular, increased vascularity, the presence of micro- and macroaneurysms, capillary remodeling, macular telangiectasia, and venous malformations. OCT-A is a non-invasive imaging tool for the retinal and choroidal vasculature, providing a unique view of the vascular system that can be combined with information from other imaging modalities to complement and eventually provide unique information to assist the eye care practitioner in diagnosing or evaluating the effectiveness of interventions. OCT-A parameters are measured in the peripapillary region, and monitoring peripapillary and macular vessel density can provide important information to assess glaucoma progression and predict the rate of disease worsening. Studies show a strong correlation between OCT parameters, OCT parameters, and visual function as measured by visual field analysis in glaucomatous eyes. Future prospects for OCT-A in glaucoma diagnostics using artificial intelligence to predict structural and functional features based on early vascular changes will provide opportunities for early identification of patients at high risk for developing and rapidly progressing glaucoma. OCT-A has the potential to become part of glaucoma diagnostics and treatment.

Impact of Rhegmatogenous Retinal Detachment on Macular Vascular and Functional Integrity.

This study aimed to evaluate the correlations between optical coherence tomography angiography (OCTA), best corrected visual acuity (BCVA), and macular integrity assessment (MAIA) microperimetry (MP) in both a control group and patients with rhegmatogenous retinal detachment (RRD). Additionally, it assessed differences between the groups and examined whether the time from symptom onset to surgery influenced microvascular or functional changes in the RRD group. A cross-sectional study was conducted involving 47 patients who had undergone successful RRD surgery with pars plana vitrectomy (PPV) and sulfur-hexafluoride (SF6) gas injection, with or without scleral buckling (SB), and a control group of 136 healthy eyes. All participants underwent comprehensive ophthalmologic examinations, including BCVA, OCTA, and MAIA. In the RRD group, additional data on symptom duration, time from symptom onset to surgery, and time from surgery to testing were collected. The RRD group exhibited significantly worse BCVA (p < 0.001) compared to the control group. Significant differences were found in all MAIA sectors, with controls showing superior macular integrity and average threshold values (p < 0.001). OCTA analysis revealed differences in the superficial capillary plexus (SCP) and deep capillary plexus (DCP) across various sectors, particularly in the foveal avascular zone (FAZ). In the control group, the vertical diameter of the FAZ in the SCP was positively correlated with most MAIA sectors, while in the DCP, correlations were seen in nearly all sectors. The RRD group showed fewer correlations between OCTA and MAIA, and no significant correlations were found between OCTA parameters and BCVA. However, there were correlations between the time from surgery to testing and MAIA outcomes, indicating improved results with longer intervals. Earlier surgical intervention after symptom onset was associated with better microvascular outcomes. RRD group exhibited significant impairments in BCVA, retinal sensitivity, and microvascular parameters compared to healthy controls. Correlations between OCTA findings and microperimetry were stronger in the control group, whereas the RRD group showed fewer and weaker associations.

Monitoring Progression in Hypertensive Patients with Dyslipidemia Using Optical Coherence Tomography Angiography: Can A.I. Be Improved?

Background: With the development of artificial intelligence (A.I.), the optical coherence tomography angiography (OCTA) analysis of progression in hypertensive retinopathy could be improved. Our purpose was to use the OCTA to study the effect of uncontrolled dyslipidemia and hypertensive retinopathy on the retinal microvasculature and to identify a potential software update of the A.I. secondary to the OCTA analysis. By using our most relevant data, the A.I. software can be upgraded by introducing new mathematic formulas between the OCTA parameters and the lipid level. Methods: We performed a prospective cohort study on 154 eyes of participants from Eastern Europe. We used a standardized protocol to collect data on past medical history of dyslipidemia and hypertension and OCTA to measure retinal vascular parameters. Results: The average age of the participants was 56.9 ± 9.1, with a minimum of 34 and a maximum of 82 and with a higher percentage of males: 55.8%. Statistically significant correlations were found for total cholesterol and skeleton total (r = -0.249; p = 0.029), foveal avascular zone (FAZ), circularity and low-density lipoprotein (LDL) (r = 0.313; p = 0.006), non-flow area (NFA) and LDL (r = 0.233; p = 0.042), and vascular flow area (VFA) and LDL (r = -0.354; p = 0.002). Conclusions: Subjects with dyslipidemia and progressive hypertensive retinopathy had a reduction in microvascular density and vascular flow, a focal capillary non-perfusion, and an increased FAZ. Thus, by improving the A.I. system, our research aims to provide better OCTA monitoring, which could help in the early-stage detection of progression and development of A.I. screening programs, leading to increased efficiency in diagnosing patients.

Diminished retinal microcirculation in mild preeclampsia without obvious retinopathy in high-altitude native Tibetans by OCTA

BackgroundTo investigate the retinal microcirculation in mild preeclampsia (PE) without obvious retinopathy in high-altitude native Tibetans by optical coherence tomography angiography (OCTA). MethodsThis study enrolled 64 mild preeclamptic pregnant women without retinopathy (group PPW), 63 healthy pregnant women (group HPW), and 61 healthy non-pregnant women (group HNPW). All participants were high-altitude native Tibetans who underwent OCTA, retinal thickness (RT), vascular density (VD), perfusion density (PD) and foveal avascular zone (FAZ) parameters were measured in the macula. Differences in these parameters among the groups were compared, and the correlations of these parameters with blood pressure were evaluated. ResultsIn the entire macula, VD and PD were significantly lower in group PPW than in group HPW and HNPW (p < 0.05). In the subregions, VD was significantly different in fovea, parafovea and perifovea, PD was significantly different in parafovea and perifovea among the three groups (p < 0.05), the further pairwise comparisons showed VD and PD in parafovea and perifovea were lower in group PPW than in group HPW, and VD and PD in perifovea were lower in group PPW than in group HNPW (p < 0.05). RT and FAZ parameters did not differ among the groups (P > 0.05). VD and PD exhibited negative correlations with SBP and DBP (p < 0.05). ConclusionOCTA can objectively evaluate diminished microcirculation in mild PE without obvious retinopathy among high-altitude native Tibetans, and provide a crucial time window for early screening of PE-induced retinopathy.

Clinical and Structural Parameters in Autosomal Dominant Optic Atrophy Patients: A Cross-Sectional Study Using Optical Coherence Tomography.

Autosomal Dominant Optic Atrophy (ADOA) is a hereditary optic neuropathy characterized by retinal ganglion cell degeneration and optic nerve fiber loss. This study examined the correlation between clinical and structural parameters in patients with ADOA using optical coherence tomography (OCT) and explored potential clinical biomarkers. A cross-sectional, case-control observational study included 27 patients with ADOA and 27 age- and sex-matched healthy controls. Clinical examinations, OCT imaging, and OCT angiography (OCTA) were performed. Statistical analyses were conducted to establish correlations between clinical and OCT parameters. Patients with ADOA exhibited gradual bilateral vision loss, central scotomas, and optic disc pallor. Structural OCT analysis revealed significant reductions in central macular thickness, macular volume, ganglion cell complex (GCC), and peripapillary retinal nerve fiber layer compared with controls. Correlation analysis demonstrated associations between worsening clinical parameters (best corrected visual acuity, Sloan Letters Low Contrast Chart 25%, Pseudoisochromatic Test) and increased OCT damage (structural and OCTA). GCC emerged, at least at exploratory terms, as the most important clinical biomarker in patients with ADOA given its multiple positive functional associations, while OCTA parameters correlated with visual field defects. Our study revealed significant correlations between clinical and structural parameters in patients with ADOA, highlighting the importance of OCT in assessing disease severity. GCC measurement shows promise as a clinical biomarker, aiding in disease monitoring. OCTA parameters offer potential early biomarkers for vascular changes. These findings contribute to understanding ADOA pathophysiology and may improve patient diagnosis and management. Further research is warranted to validate these findings and explore potential therapeutic interventions.

Angioarchitectural alterations in the retina and choroid in frontotemporal dementia.

Frontotemporal dementia (FTD) is a progressive neurodegenerative disorder that affects the frontal and temporal lobes of the brain, leading to cognitive decline and personality changes. The objective of this cross-sectional study was to characterize angioarchitectural changes in the retina and choroid of individuals with FTD compared to cognitively normal controls using optical coherence tomography (OCT) and OCT angiography (OCTA). Cross-sectional comparison of patients with FTD and controls with normal cognition. All participants underwent Mini-Mental State Examination (MMSE) at the time of imaging. Outcome measures included OCT parameters: retinal nerve fiber layer (RNFL) thickness, ganglion cell layer-inner plexiform layer (GC-IPL) thickness, central subfield thickness (CST), subfoveal choroidal thickness (SFCT), choroidal vascularity index (CVI); and OCTA superficial capillary plexus parameters: foveal avascular zone (FAZ) area, 3x3mm and 6x6mm macular perfusion density (PD) and vessel density (VD), 4.5x4.5mm peripapillary capillary perfusion density (CPD) and capillary flux index (CFI). Generalized estimating equation analysis was used to account for the inclusion of 2 eyes from the same participant. 29 eyes of 19 patients with FTD and 85 eyes of 48 controls were analyzed. In FTD, 3x3mm macular PD (p = 0.02) and VD (p = 0.02) and CFI (p = 0.01) were reduced compared to controls. There was no difference in average 4.5x4.5mm CPD, RNFL thickness, GC-IPL thickness, CST, SFCT, CVI, FAZ, or 6x6mm VD or PD between FTD and controls (all p > 0.05); however, there was a trend toward lower macular 6x6mm PD and VD in patients with FTD. Decline of peripapillary and macular OCT and OCTA parameters merit further investigation as potential biomarkers for FTD detection. Noninvasive retinal and choroidal imaging may hold promise for earlier detection, and future longitudinal studies will clarify their role in monitoring of FTD.

Exploring retinal vessel density alterations in prolactinoma patients: Insights from OCTA imaging.

To investigate microvascular changes in the macular and peripapillary area in prolactinoma patients by using optical coherence tomography angiography (OCTA). A retrospective study. This study included 40 patients with treatment-naive prolactinoma and 42 healthy controls. Participants underwent comprehensive ophthalmic examinations, visual field testing, and optical coherence tomography (OCT) assessments, including retinal nerve fiber layer (RNFL) thickness, macular, and peripapillary region OCTA by using the Topcon DRI OCT Triton Swept Source-OCT system. The OCTA results were evaluated between groups and then correlated with PRL levels. The differences in best-corrected visual acuities were statistically significant among the groups. The RNFL thickness in the superior and nasal quadrants was significantly lower in the prolactinoma group. The prolactinoma group showed significant reductions in macular vessel density (VD) across all layers than the control group, except in the deep retinal capillary plexus temporal quadrants. The radial peripapillary capillary (RPC) temporal VD in the prolactinoma group was significantly lower. In patients with optic neuropathy, correlations were observed between the RPC temporal and RNFL temporal sectors (r = 0.650, P = 0.03), and between the RPC inferior and RNFL inferior sectors (r = -0.612, P = 0.045). Between PRL levels and OCTA parameters, negative correlations were observed (RPC inferior: r = -0.452, P = 0.003; DCP superior: r = -0.379, P = 0.016). Our study revealed reduced VD in the macula and RPC temporal regions in patients with treatment-naive prolactinoma. OCTA holds significant importance in detecting potential retinopathies and vasculopathies. Future research should focus on examining pre- and post-treatment changes in treatment-naive patients without ON to better understand the impact of prolactinoma.

Combined evaluation of visual field and optical coherence tomography angiography data in multiple sclerosis patients

Aims: To evaluate Humphrey visual field analyzer (HVFA) data and optical coherence tomography angiography (OCT-A) parameters in multiple sclerosis (MS) patients with optic neuritis (ON) attacks. Methods: 34 eyes of 34 patients with MS diagnosis who had ON attacks were included in the study. After detailed ophthalmoscopic examination, OCT-A and HVFA images were taken. Spearman correlation analysis was used in statistical analysis. Results: The mean age of the participants was 31.52±10.09 years. In the correlation analysis, a moderate correlation was found between mean deviation (MD) and foveal deep blood flow (DF) (rho=0.52), and a weak correlation was found between MD and foveal superficial blood flow (SF) (rho=0.40) and optic disc head blood flow (ODF) (rho=0.38). A weak negative correlation was found between pattern standard deviation (PSD) and DF (rho=-0.37) and ODF (rho=-0.40). Conclusion: This study showed that OCTA data were affected in a manner consistent with HVFA data. More practical and quickly applicable OCTA scans may facilitate the estimation of visual field findings in MS patients.

Intracranial pressure affects retinal venular complexity in idiopathic intracranial hypertension: a retrospective observational study

BackgroundIncreased intracranial pressure (ICP) in patients with idiopathic intracranial hypertension (IIH) affects the retinal microvasculature, which can be imaged and quantified by optical coherence tomography angiography (OCTA). We aimed to identify the mediating factor between ICP and OCTA parameters association in IIH patients.MethodsIIH patients with active intracranial hypertension were enrolled. OCTA imaging was performed after ICP measurement. We quantified the branching complexity of the retinal arterioles and venules from the superficial vascular complex of the OCTA image. Eyes of IIH patients were stratified into eyes with papilledema (IIH-P) and eyes without papilledema (IIH-WP). All participants underwent visual acuity (VA) examination.ResultsOne hundred and thirty-eight eyes from 70 IIH patients and 146 eyes from 73 controls were included. Compared to the control group, IIH patients and IIH-P had reduced arteriole complexity and increased venule complexity (p < 0.05). For IIH patients and IIH-P, increased retinal venule complexity correlated with increased ICP and reduced VA (p < 0.05); while decreased arteriole complexity only correlated with Frisen scores (p = 0.026). Papilledema mediated the effect (p < 0.001) between ICP and arteriole complexity while ICP had a direct effect (p < 0.001) on venule complexity.ConclusionRetinal venules imaged via OCTA may reflect ICP levels and may underpin the direct effect of increased ICP in IIH patients.

Alterations in optical coherence tomography angiography parameters after cataract surgery in patients with diabetes

This prospective study aimed to investigate microvascular changes in diabetic patients undergoing cataract surgery. Foveal avascular zone (FAZ) area, as well as vessel density (VD) in the macula and radial peripapillary capillary plexus (RPC), were compared before and after surgery. Sixty eyes (72.3%) had no diabetic retinopathy (no DR group) and 23 eyes (27.7%) had non-proliferative diabetic retinopathy (DR group). In the no DR group, the FAZ area in the superficial capillary plexus (SCP) decreased from 0.41 ± 0.13 to 0.38 ± 0.11 mm2 (P = 0.036), while no significant change was observed in the DR group (0.33 ± 0.12 to 0.30 ± 0.12 mm2, P = 0.091) at 6 months postoperatively. VD in the RPC increased from 34.4 ± 2.3% to 35.6 ± 2.3% in the no DR group (P = 0.009), but there was no significant change in the DR group (33.0 ± 3.5% vs. 34.0 ± 2.3%, P = 0.051) after 6 months. VD in the macula did not change in either group. Phacoemulsification reduced the FAZ area in the SCP and increased the VD in the RPC in diabetic patients without diabetic retinopathy at six months postoperatively.

The effects of femtosecond laser-assisted small incision lenticule extraction and phakic intraocular lens implantation on macular perfusion

Aim The aim of this study was to assess the effect of femtosecond laser-assisted small incision lenticule extraction (Femto-SMILE) and phakic intraocular lens (PIOL) implantation on macular and optic nerve perfusion utilizing optical coherence tomography angiography (OCTA). Patients and methods This is a retrospective cohort study that included 60 eyes of 60 patients having moderate to high myopia (−7.0 to −15.0 D). The patients were categorized per intervention received into: group 1 that included 26 eyes (26 patients) for whom PIOL implantation was performed and group 2 that included 34 eyes (34 patients) for whom Femto-SMILE procedure was performed. All interventions took place at the Ophthalmology Department in Alexandria Main University Hospital, Alexandria, Egypt. The study parameters (including OCTA) were assessed preoperatively, on the first day, and 2 weeks postoperatively. The OCTA parameters included macular vessel density, foveal avascular zone size, optic disc flux index, optic disc perfusion, peripapillary and macular choroidal area, macular luminal area, and macular choroidal vascularity. Results There were no statistically significant differences in the baseline characteristics between the two groups (P&gt;0.05). The intraocular pressure (IOP) was markedly lower in the PIOL group than in the Femto-SMILE group on the first postoperative day (P=0.019). No other differences between the two groups were noted in terms of IOP, visual acuity, myopia, or astigmatism. There were no statistically significant differences between the two groups in macular and optic nerve perfusion, though both groups demonstrated a significant affection on the first postoperative day that was completely reversed by 2 weeks. The OCTA parameters were all comparable between the two groups both at day 1 and week 2. While certain OCTA parameters showed statistically significant differences at day 1 postoperatively, the 2-week OCTA measurements were comparable to the preoperative parameters. Conclusion Both Femto-SMILE and PIOL implantation refractive techniques demonstrated similar outcomes for macular and optic nerve perfusion. The PIOL group exhibited lower postoperative IOP on the first postoperative day.

Comparison of OCT Angiography Parameters after Administration of Intravitreal Brolucizumab versus Ranibizumab in Exudative Age-related Macular Degeneration

Abstract Purpose: To compare the OCT angiography (OCTA)–derived parametric changes before and after intravitreal administration of ranibizumab and brolucizumab in patients with neovascular age-related macular degeneration (ARMD) and to compare the changes between the two groups. Methods: This retrospective cohort study was done on 68 eyes with neovascular ARMD: 34 received injection ranibizumab and 34 received brolucizumab in a stratified manner. Central foveal thickness (CFT) and OCTA parameters like vessel density (VD), superficial capillary plexus (SCP), deep capillary plexus (DCP), foveal avascular zone, (FAZ), fractal dimension (FD) were assessed. The scans were repeated 1 month postinjection. Results: In total, 46% had type 1 CNVM and 54% had Type 2 CNVM. In both the ranibizumab and brolucizumab group, the corrected visual acuity showed comparable significant improvement 1 month postinjection. The CFT showed significant reduction in both, more significant in brolucizumab. OCTA showed a minimal nonsignificant reduction in the VD, SCP and DCP at 1 month, which were not significantly different. The FAZ and FD showed a significant increase and reduction, respectively, in the brolucizumab group, unlike the ranibizumab group. Conclusion: OCTA changes suggest that anti-VEGF drugs produce no change in the capillary density. A reduction in structural architecture of smaller capillary branches i.e. fractal dimension and increase in FAZ is noted with brolucizumab, suggesting that some structural alterations of retinal microvasculature do exist with the drug.

MICROVASCULAR CHANGES IN TREATMENT-NAÏVE NONEXUDATIVE MACULAR NEOVASCULARIZATION COMPLICATED BY EXUDATION.

To assess differences in choriocapillaris (CC) and macular neovascularization (MNV) optical coherence tomography angiography quantitative parameters between long-term persistently nonexudative MNVs (NE-MNVs) and long-term activated NE-MNVs in age-related macular degeneration. Age-related macular degeneration patients with treatment-naïve NE-MNVs with >2 years of follow-up and no evidence of exudation within the first 6 months from diagnosis were retrospectively recruited. Two groups were considered according to the occurrence (EX group) or not (NE group) of exudation within the first 2 years of follow-up. Segmentation of the MNV and of the perilesional CC were obtained from enface optical coherence tomography angiography acquisitions at diagnosis and at 6-month follow-up. OCT B-scan images of the MNV were also collected. Fractal ratio was defined as the ratio between MNV fractal dimension (FrD) and CC FrD. Fifty (50) eyes were included (20 EX group and 30 NE group). EX group showed higher flow deficit density and flow deficit number at the 6-month follow-up. It also showed higher MNV FrD, lower CC FrD, and higher fractal ratio at the 6-month follow-up. The fractal ratio significantly increased at 6-month acquisitions in the EX group, showing an area under the ROC curves of 0.887 (95% CI 0.869-0.922). Fractal ratio at 6 months can predict exudation risk of MNV within 2 years from diagnosis. This suggests increased structural complexity of the NE-MNV accompanied by progressive capillary rarefaction of the perilesional CC as a key driving factor for the development of exudation in NE-MNV.

Retinal microcirculation changes in prediabetic patients with short-term increased blood glucose using optical coherence tomography angiography.

Retinal microcirculation alterations are early indicators of diabetic microvascular complications. Optical coherence tomography angiography (OCTA) is a noninvasive method to assess these changes. This study analyzes changes in retinal microcirculation in prediabetic patients during short-term increases in blood glucose using OCTA. To investigate the changes in retinal microcirculation in prediabetic patients experiencing short-term increases in blood glucose levels using OCTA. Fifty volunteers were divided into three groups: Group 1 [impaired fasting glucose (IFG) or impaired glucose tolerance (IGT)], Group 2 (both IFG and IGT), and a control group. Retinal microcirculation parameters, including vessel density (VD), perfusion density (PD), and foveal avascular zone (FAZ) metrics, were measured using OCTA. Correlations between these parameters and blood glucose levels were analyzed in both the fasting and postprandial states. One hour after glucose intake, the central VD (P = 0.023), central PD (P = 0.026), and parafoveal PD (P < 0.001) were significantly greater in the control group than in the fasting group. In Group 1, parafoveal PD (P < 0.001) and FAZ circularity (P = 0.023) also increased one hour after glucose intake. However, no significant changes were observed in the retinal microcirculation parameters of Group 2 before or after glucose intake (P > 0.05). Compared with the control group, Group 1 had a larger FAZ area (P = 0.032) and perimeter (P = 0.018), whereas Group 2 had no significant differences in retinal microcirculation parameters compared with the control group (P > 0.05). Compared with Group 1, Group 2 had greater central VD (P = 0.013) and PD (P = 0.008) and a smaller FAZ area (P = 0.012) and perimeter (P = 0.010). One hour after glucose intake, Group 1 had a larger FAZ area (P = 0.044) and perimeter (P = 0.038) than did the control group, whereas Group 2 showed no significant differences in retinal microcirculation parameters compared with the control group (P > 0.05). Group 2 had greater central VD (P = 0.042) and PD (P = 0.022) and a smaller FAZ area (P = 0.015) and perimeter (P = 0.016) than Group 1. At fasting, central PD was significantly positively correlated with blood glucose levels (P = 0.044), whereas no significant correlations were found between blood glucose levels and OCTA parameters one hour after glucose intake. A short-term increase in blood glucose has a more pronounced effect on retinal microcirculation in prediabetic patients with either IFG or IGT.