Choroidal Blood Flow Research Articles

Changes in choroidal thickness and blood flow in response to form deprivation-induced myopia and repeated low-level red-light therapy in Guinea pigs.

To evaluate ocular refractive development, choroidal thickness (ChT) and changes in choroidal blood flow in form-deprived myopia (FDM) Guinea pigs treated with repeated low-level red-light (RLRL) therapy. Twenty-eight 3-week-old male tricolour Guinea pigs were randomised into three groups: normal controls (NC, n = 10), form-deprived (FD, n = 10) and red light treated with form-deprivation (RLFD, n = 8). Interocular refraction and axial length (AL) changes were monitored. Optical coherence tomography angiography (OCTA) measured choroidal thickness, vessel area density, vessel skeleton density and blood flow signal intensity (flux) in the choriocapillaris and medium-large vessel layers. The experimental intervention lasted 3 weeks. At week 3, the FD group had higher myopia and longer axial length than the NC group (all p < 0.001). The RLFD group had higher hyperopia and shorter axial length than the FD group (all p < 0.001). At week 1, the NC group had a thicker choroidal thickness than the FD group (p < 0.05). At weeks 2 and 3, the RLFD group had a thicker choroidal thickness than the FD group (p = 0.002, p < 0.001, respectively). Additionally, the NC group had higher vessel area density, vessel skeleton density and flux in the choriocapillaris layer than the FD group at the three follow-up time points (all p < 0.05). At week 3, the vessel skeleton density and flux were higher in the RLFD group than in the FD group (all p < 0.05). Correlation analysis results showed that weekly changes in refraction and choroidal thickness were negatively correlated with changes in axial length (all p < 0.05). Choroidal thickness changes were positively correlated with alterations in the vessel area density, vessel skeleton density and flux in the choriocapillaris layer, as well as vessel skeleton density and flux changes in the medium-large vessel layers (all p < 0.05). Repeated low-level red-light (RLRL) therapy retards FDM progression in Guinea pigs, potentially through increased choroidal blood flow in the choriocapillaris layer.

Anatomic changes in asymptomatic pachychoroid spectrum diseases after cataract surgery

Pachychoroid spectrum disease (PSD) involves various chorioretinal pathologies associated with increased choroidal blood flow. Theoretically, PSD could worsen after cataract surgery since the choroidal thickness tends to increase after surgery. Therefore, we evaluated the prevalence of asymptomatic PSD in patients who underwent cataract surgery and compared the clinical characteristics according to the presence of PSD. The subretinal fluid (SRF) development risk was evaluated using the Cox proportional hazard model. Of 924 eyes, 184 (19.9%) showed asymptomatic PSD. Patients with asymptomatic PSD were older, predominantly male, hyperopic, and showed thicker choroid (P < 0.001, 0.001, < 0.001, and < 0.001). Seven (3.8%) of 184 eyes with asymptomatic PSD developed SRF. The Cox proportional hazard model showed that the flat, irregular pigment epithelial detect (FI-PED; HR 37.337, 95% CI 3.880–359.9300, P = 0.002) was the sole indicator for the SRF development after adjustment of age, sex, and axial length. The SRF-developed PSD group experienced a profound and prolonged increase in the choroidal thickness (P = 0.001, 0.002, and 0.002 at 1, 3, and 12 months). Meticulous preoperative evaluation for FI-PED and postoperative monitoring for choroidal thickness would predict SRF development after cataract surgery in eyes with asymptomatic PSD.

VEGFA may be a potential marker of myopic choroidal thickness and vascular density changes

To evaluate the changes of choroidal thickness (CT) and blood flow related to myopia, and its effects of vascular endothelial growth factor (VEGFA) on choroidal vessels in myopia. Subjects were included and divided into emmetropia (EM), non-high myopia (Non-HM) and high myopia (HM) groups. we measured choroidal thickness (CT), choriocapillaris vessel density (VD), and VEGFA content in tears in humans (137 subjects for CT, VD and 84 for tear) and detected the role of VEGFA in the choroid in form-deprivation myopia (FDM) in guinea pigs. Twenty-four guinea pigs were divided into control and FDM groups, and the expression changes of choroidal vessels and VEGFA were observed and compared using immunohistochemistry and Western blotting. Twenty-one guinea pigs were divided into control, FDM + Vehicle and FDM + Conbercept groups. The changes of diopter, axis length and choroidal vessels after intravitreal injection of Conbercept were observed. There were significant differences in CT and VD among the three groups (p < 0.05). VEGFA levels in tears were significantly lower in the myopic groups, with a decreasing trend from EM to Non-HM to HM. The choroidal vascular area fraction of FDM decreased compared to the control group. FDM guinea pigs exhibited reduced choroidal vasculature and significant downregulation of VEGFA expression. Following intravitreal injection of conbercept, the FDM + Conbercept group showed greater myopia, longer axial length, and lower choroidal vascular area fraction compared to the control group. VEGFA may participate in the regulation of choroidal blood vessels and blood flow in the progression of myopia. The reduction in VEGFA may accelerates the progression of myopia.

NAD+ and Niacin Supplementation as Possible Treatments for Glaucoma and Age-Related Macular Degeneration: A Narrative Review.

Glaucoma and age-related macular degeneration (AMD) are progressive retinal diseases characterized by increased oxidative stress, inflammation, and mitochondrial dysfunction. This review investigates the potential therapeutic benefits of NAD+ and niacin supplementation in managing glaucoma and AMD. A literature search was conducted encompassing keywords such as "niacin", "NAD", "glaucoma", "AMD", and "therapeutics". NAD+ depletion is associated with increased oxidative stress and mitochondrial dysfunction in glaucoma and AMD. Niacin, a precursor to NAD+, has shown promise in replenishing NAD+ levels, improving choroidal blood flow, and reducing oxidative damage. Animal studies in glaucoma models indicate that nicotinamide (NAM) supplementation preserves RGC density and function. Large-scale population-based studies indicate an inverse correlation between niacin intake and glaucoma prevalence, suggesting a preventative role. Randomized controlled trials assessing niacin supplementation showed significant improvements in visual field sensitivity and inner retinal function, with a dose-dependent relationship. In AMD, nicotinamide supplementation may improve rod cell function and protect against oxidative stress-induced damage. Cross-sectional studies reveal that individuals with AMD have a lower dietary intake of niacin. Further studies suggest niacin's role in improving choroidal blood flow and dilating retinal arterioles, potentially mitigating ischemic damage and oxidative stress in AMD. Beyond current management strategies, NAD+ and niacin supplementation may offer novel therapeutic avenues for glaucoma and AMD. Further research is warranted to elucidate their efficacy and safety in clinical settings.

Pathogenesis of Pachyvein Formation in Central Serous Chorioretinopathy: A Hydrodynamic Analysis.

Objectives: To attain an understanding of pachyvein formation seen with central serous chorioretinopathy (CSC) by measuring the choroidal blood flow (CBF) velocity and to apply the findings to existing hydrodynamic theorems. Methods: Nineteen subjects with monocular CSC (mean age 51.8 ± 12.7 years) were included. Laser speckle flowgraphy measured the mean blur rate (MBR) in the foveal and perifoveal regions, and the findings were applied to the Equation of Continuity (Q = AV) and Bernoulli's theorem (1/2V2 + P/ρ = constant). Results: The mean foveal/perifoveal MBRs in the CSC eyes were 6.4 ± 3.2/9.6 ± 3.2 (p < 0.001). The mean MBRs in the non-CSC eyes were 8.3 ± 3.2/7.9 ± 2.4 (p = 0.37). The significant foveal CBF velocity decrease in CSC eyes occurs because of exudation from the hyperpermeable choriocapillaris. The subsequent decrease in blood volume due to the exudation elicits a decrease in the blood flow velocity in the inferior venules in accordance with the Equation of Continuity. The decrease in the blood flow velocity may result in an elevated blood flow pressure in the inferior venules and veins at the exudation site, in accordance with Bernoulli's theorem. Conclusion: A significant decrease in the foveal MBR may result from exudation from the hyperpermeable macular choriocapillaris. This decreased velocity may elicit a blood pressure elevation that can expand the inferior venules and veins at the exudation site, so-called pachyvein and pachychoroid formation. The application of hydrodynamic theorems to the measurement of ocular blood flow can provide new insights into the understanding of the pathogenesis of chorioretinal disease.

Association of choroidal thickness and blood flow features with asymmetric axial lengths in children with unilateral myopic anisometropia

BackgroundConsidering that changes in the choroidal thickness are closely related to ocular growth, we studied the choroidal thickness (CT) and the blood flow features in children with unilateral myopic anisometropia (UMA) as well as investigating the relationship between choroidal changes and myopia.MethodsSubjective refractive, axial length (AL), and biometric parameters were measured in 98 UMA children (age: 8–15 years). CT and choroidal blood-flow features, including the choroidal vessel volume (CVV), choroidal vascularity index (CVI), and choriocapillaris perfusion area (CCPA), were measured through swept-source optical coherence tomography angiography. The macular region was categorized into four concentric circles of diameters 0–1 mm (central fovea), 1–3 mm (parafovea), 3–6 mm (perifovea), and 6–9 mm (extended), and further categorized into superior (S), inferior (I), temporal (T), and nasal (N) quadrants.ResultsThe aforementioned four regions of myopic eyes displayed significantly lower CT, CVV, and CVI than those of non-myopic eyes. CCPA changes differed across different regions of both the eyes (parts of N and T quadrants). There was an inverse association between CT and the interocular AL difference (central and other regions S, T quadrant). No correlation was noted between CVV and CVI with interocular AL difference. CT and CVV were positively correlated in the 0–6-mm macular region of myopic eyes (Spearman correlation coefficient = 0.763, P < 0.001).ConclusionsIn UMA children, CCT and blood flow may be related to myopia progression. A robust correlation between CT and CVV in the 0–6-mm macular region and reduced CT and diminished blood flow indicated an association with myopia.

The effect of heart rate variability on the choroidal vascularity of the optical coherence tomography and angiography in central serous chorioretinopathy.

To investigate the correlation between the autonomic nervous system and choroidal vascularity in patients with central serous chorioretinopathy (CSC), using heart rate variability (HRV) analysis, optical coherence tomography (OCT) and OCT angiography (OCTA). We retrospectively analyzed data of 25 patients with unilateral CSC (50 eyes, including the unaffected fellow eyes) and 25 healthy controls. The assessment involved a 5-minute HRV analysis encompassing both frequency and time domains, especially low frequency (LF), high frequency (HF), and LF/HF ratio. In OCT (12 × 9mm) and en-face OCTA (3 × 3mm) scans, we measured parameters including choroidal vascularity index (CVI), choroidal vessel density in the middle and deep layers, and choriocapillaris flow void. Regression analysis was conducted to elucidate the associations between HRV parameters and OCT/OCTA measurements. Normalized LF(LFnorm) and LF/HF ratios were higher in patients with CSC than in healthy controls. LFnorm and the log-transformed ratio of LF to HF [log(LF/HF)] demonstrated a significant and borderline correlation with CVI in the linear regression analysis (P = 0.040, R2 = 0.171, and P = 0.059, R2 = 0.147, respectively). Both CVI and deep choroid vessel density showed a more significant association with LFnorm and log (LF/HF) in the non-linear quadratic regression analysis than in the linear analysis (all, P < 0.04, R2 > 0.25). The frequency-domain parameters of HRV, including LFnorm and log (LF/HF), demonstrated a significant association with indicators reflective of large choroidal vessel luminal area on macular OCT/OCTA scans. This observation implies complicated modulation of choroidal blood flow by the autonomic nervous system in CSC.

Response of the human choroid to short-term changes in eyelid and periocular temperature

ABSTRACT Clinical relevance Choroidal thickness measurement is gaining popularity in clinical practice and research as an early indicator of myopia progression. Understanding the influence of temperature on choroidal thickness changes will improve the reliability of the measures. Background It has been suggested that environmental temperature may affect choroidal thickness and blood flow, with potential implications for ocular disease and refractive development. This study investigates the effect of changes in eyelid/ocular adnexa temperature on choroidal thickness. Methods In a paired-eye study, 20 young, healthy subjects received a warm stimulus (heat pack) over one closed eye and simultaneously a cold stimulus (ice pack) over the other for 10 min. Eyelid temperatures were monitored with thermal probes, and optical coherence tomography scans of the retina and choroid were taken before and after heating and cooling, and then every 5 min during a 15-min recovery period. Retinal and choroidal thicknesses were measured across the macular region (6 mm), including the subfoveal (1 mm), parafoveal (1–3 mm), and perifoveal (3–5 mm) regions, and compared between the cooled and warmed eyes. Results When the thermal stimuli were applied, eyelid surface temperatures changed predictably and remained significantly different (by approximately 10–15°C) between the eyes after 2 min (p < .001). Relative to the warmed eye, macular choroidal thickness in the cooled eye increased significantly after 10 min of treatment (p = .004). This choroidal thickening response occurred in the subfoveal, parafoveal, and perifoveal regions (all p < .05). Upon removal of the thermal stimuli, choroidal thickness rapidly returned to the baseline and was no longer different between the cooled and warmed eye (p = .641). Conclusion Cooling the anterior eye by application of a cold stimulus directly onto the closed eyelid caused a small but significant increase in choroidal thickness relative to warming the anterior eye, demonstrating that the choroid can modulate its thickness rapidly and transiently in response to local temperature changes.

Influence of implantable Collamer lens implantation on choroidal thickness and blood flow density

Objective: To observe the impact of implantable Collamer lens (ICL) implantation surgery on choroidal thickness and blood flow density in myopic patients. Methods: This was a prospective cohort study. Patients undergoing ICL surgery at Qingdao University Affiliated Hospital between June 2021 and May 2023 were consecutively enrolled. Patients were categorized into high myopia (HM) and super high myopia (SHM) groups based on whether their spherical equivalence power exceeded 10.00 D. Comprehensive ophthalmic examinations, including optical coherence tomography, optical coherence tomography angiography, visual acuity assessment, intraocular pressure measurement, and optometry, were performed preoperatively and at 1 week, 1 month, and 3 months postoperatively. Results: A total of 42 patients (84 eyes), with an average age of (25.27±3.18) years, comprising 11 males and 31 females, were enrolled in the study. Among them, 20 patients belonged to the HM group, while 22 patients were in the SHM group. Both choroidal thickness and blood flow density exhibited significant increases at postoperative 1 week and 1 month compared to preoperative levels (P<0.05), but returned to baseline levels by postoperative 3 months. Specifically, the subfoveal choroidal thickness increased from (169.49±61.57) μm preoperatively to (180.16±66.61) μm at 1 week, (186.69±63.32) μm at 1 month, and then reverted to (169.58±60.82) μm at 3 months. The central choroidal blood flow density showed changes from 60.03%±1.60% preoperatively to 61.04%±1.17% at 1 week, 60.42%±1.81% at 1 month, and 60.22%±1.57% at 3 months. Furthermore, the HM group exhibited more pronounced changes in both choroidal thickness and blood flow density across all time points compared to the SHM group. Significant differences were observed in choroidal thickness changes at various areas at 1 month, while changes in blood flow density in specific areas were significant. However, no significant differences were noted at 3 months postoperatively. Correlation analysis revealed a negative correlation of changes in subfoveal choroidal thickness and central choroidal blood flow density postoperatively at 1 week and 3 months with preoperative choroidal blood flow density. Notably, no correlation was found between preoperative choroidal thickness and postoperative changes. Conclusions: In the early period following ICL implantation, the increase in choroidal thickness and blood flow density may be more pronounced in HM compared to SHM, but the two parameters can return to baseline levels by 3 months. ICL implantation transiently affects the fundus microenvironment in myopic patients, with implications of preoperative choroidal blood flow.

A preliminary study on the characteristics of refractive parameters and retinal blood flow in dominant eyes

Objective: To explore the characteristics of refractive parameters and retinal and choroidal blood flow in dominant and non-dominant eyes. Methods: A cross-sectional study. Students who were 18 to 32 years old and had emmetropia or myopia but no systemic diseases were recruited from universities in Wuhu, Anhui Province from April 2019 to August 2023. They were divided into 4 groups based on the difference in spherical equivalent between two eyes:<0.50 D (group A), 0.50 to 1.74 D (group B), 1.75 to 2.49 D (group C), and≥2.50 D (group D). The card hole method was used to determine the dominant eye. The refractive parameters of both eyes were recorded, including spherical equivalent, myopia degree, astigmatism degree, axial length, and corneal curvature difference (K2-K1). Optical coherence tomography angiography was performed to measure the blood flow density of the superficial retinal capillaries, deep retinal capillaries (DVC), avascular layer (AC), entire retina, choroidal capillaries, and choroidal vessels, as well as the retina and choroid as a whole. Statistical analysis was conducted using the paired sample t-test, chi square test, and variance analysis. Results: A total of 78 eligible subjects, aged (24.50±2.36) years old, 28 males and 50 females, were included. Fifty subjects had the right eye and 28 had the left eye as the dominant eye. Forty-two subjects had high myopia in the dominant eye, and 30 had high myopia in the non-dominant eye. There were statistically significant differences (all P<0.05) in the spherical equivalent [(-4.588±2.534) D vs. (-4.058±2.453) D], myopic spherical power [(-4.253±2.504) D vs. (-3.779±2.425) D], and axial length [(25.531±1.212) mm vs. (25.256±1.238) mm] between dominant and non-dominant eyes among all subjects, as well as in the astigmatism degree of groups A and C, spherical power of groups B to D, and spherical power and axial length of groups C and D. There were also statistically significant differences (all P<0.05) in the blood flow density of the DVC [(0.291±0.130) vs. (0.257±0.148)], AC [(0.347±0.118) vs. (0.326±0.126)], and overall retina and choroid [(0.385±0.102) vs. (0.349±0.084)] between dominant and non-dominant eyes among all subjects, as well as in the blood flow density of the superficial retinal capillaries, DVC, AC, choroidal capillaries, and overall retina and choroid of groups C and D, density of the choroidal vessels of group C, and density of the entire retina of group D. Conclusions: In young individuals with emmetropia or near vision, the degree of myopia in dominant eyes is higher than that in non-dominant eyes. When the difference in the spherical equivalent between two eyes is ≥1.75 D, the blood flow density of the retina and choroid in the dominant eye is greater than that in the non-dominant eye.

COMPARISON OF CHOROIDAL VASCULATURE BETWEEN CENTRAL SEROUS CHORIORETINOPATHY WITH AND WITHOUT THICK CHOROID USING SWEPT-SOURCE OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY.

To distinguish between central serous chorioretinopathy (CSC) with and without thick choroid and to elucidate their characteristics of choroidal vasculature. This prospective observational study enrolled 76 eyes with treatment-naive CSC and 76 normal eyes. Mean + 2 times SD of subfoveal choroidal thickness of healthy individuals was set as the upper limit of normal choroidal thickness to divide patients with CSC into two groups: the thick-choroid and non-thick-choroid groups. Their choroid blood flow was compared using widefield swept-source optical coherence tomography angiography. According to the discrimination value of subfoveal choroidal thickness as 326.8 µm, 76 eyes with CSC were divided into the thick-choroid (55, 72.4%) and non-thick-choroid (21, 27.6%) groups. Higher proportions of vortex vein anastomosis were found in the thick-choroid group (81.8% vs. 33.3%, P < 0.001). Choroid thickness, three-dimensional choroidal vascularity index, and mean choroidal stroma volume per 1 mm2 were higher in the thick-choroid group. In multivariate analysis, younger age, higher percentages of vortex vein anastomosis, and double layer sign were the independent predictors of choroid thickening in CSC. There are discrepancies in the degree of choroidal congestion and distribution of vortex veins in the CSC with different choroidal thicknesses.

Improved MRI methods to quantify retinal and choroidal blood flow applied to a model of glaucoma.

Blood flow (BF) of the retinal and choroidal vasculatures can be quantitatively imaged using MRI. This study sought to improve methods of data acquisition and analysis for MRI of layer-specific retinal and choroidal BF and then applied this approach to detect reduced ocular BF in a well-established mouse model of glaucoma from both eyes. Quantitative BF magnetic resonance imaging (MRI) was performed on glaucomatous DBA/2J and normal C57BL/6J mice. Arterial spin labeling MRI was applied to image retinal and choroidal BF using custom-made dual eye coils that could image both eyes during the same scan. Statistics using data from a single eye or two eyes were compared. BF values were calculated using two approaches. The BF rate per quantity of tissue was calculated as commonly done, and the peak BF values of the retinal and choroidal vasculatures were taken. Additionally, the BF rate per retinal surface area was calculated using a new analysis approach to attempt to reduce partial volume and variability by integrating BF over the retinal and choroidal depths. Ocular BF of both eyes could be imaged using the dual coil setup without effecting scan time. Intraocular pressure was significantly elevated in DBA/2J mice compared to C57BL/6J mice (P<0.01). Both retinal and choroidal BF were significantly decreased in DBA/2J mice in comparison to the age-matched normal C57BL/6J mice across all measurements (P < 0.01). From simulations, the values from the integrated BF analysis method had less partial volume effect, and from in vivo scans, this analysis approach also improved power. The dual eye coil setup allows bilateral eye data acquisition, increasing the amount of data acquired without increasing acquisition times in vivo. The reduced ocular BF found using the improved acquisition and analysis approaches replicated the results of previous studies on DBA/2J mice. The ocular hypertensive stress-induced BF reduction found within these mice may represent changes associated with glaucomatous progression.

Myopia Is an Ischemic Eye Condition: A Review from the Perspective of Choroidal Blood Flow.

Myopia is a common refractive error that affects a large proportion of the population. Recent studies have revealed that alterations in choroidal thickness (ChT) and choroidal blood flow (ChBF) play important roles in the progression of myopia. Reduced ChBF could affect scleral cellular matrix remodeling, which leads to axial elongation and further myopia progression. As ChT and ChBF could be used as potential biomarkers for the progression of myopia, several recent myopia treatments have targeted alterations in ChT and ChBF. Our review provides a comprehensive overview of the recent literature review on the relationship between ChBF and myopia. We also highlight the importance of ChT and ChBF in the progression of myopia and the potential of ChT as an important biomarker for myopia progression. This summary has significant implications for the development of novel strategies for preventing and treating myopia.

Changes in Outcomes of Macular Optical Coherence Tomography Angiography Following Surgery for Optic Disc Pit Maculopathy.

we aimed to report on the optical coherence tomography angiography (OCTA) outcomes of eight patients with optic disc pit maculopathy (ODP-M) who were treated with 23-gauge pars plana vitrectomy (PPV). We examined sixteen eyes of eight patients-eight eyes with ODP-M and eight healthy fellow eyes. Fundus color photography, fundus autofluorescence, fundus fluorescein angiography, optical coherence tomography (OCT), and OCTA were performed. The vascular density, choriocapillaris blood flow (CCBF), and foveal avascular zone (FAZ) were analyzed using OCTA. Moreover, the correlation between the best-corrected visual acuity (BCVA) and macular OCTA parameters was assessed. Compared with the healthy fellow eyes, the eyes with ODP-M preoperatively were found to have decreased BCVA, superficial capillary plexus (SCP) vascular density (i.e., total, foveal, parafoveal, and perifoveal), deep capillary plexus (DCP) vascular density (i.e., total, parafoveal, and perifoveal), and CCBF but a significantly increased FAZ (p < 0.05). When the eyes with ODP-M were analyzed pre- and postoperatively at month 12 after surgery, the BCVA, SCP vascular density (i.e., perifoveal), and CCBF had significantly increased, and the FAZ had significantly decreased (p < 0.05). When the eyes with ODP-M were compared with the healthy fellow eyes postoperatively at month 12, the BCVA, SCP, and DCP vascular density parameters had increased, along with CCBF, and the FAZ had decreased in eyes with ODP-M, though not to the levels of the healthy fellow eyes (p < 0.05). Moreover, a positive correlation was found between the postoperative BCVA and SCP total vascular density (p < 0.05). The BCVA and macular OCTA parameters improved in eyes with ODP-M at month 12 following surgery. However, the BCVA and OCTA of the eyes operated on did not reach the levels of the healthy fellow eyes, possibly due to impaired choroidal blood flow (CBF) recovery and the presence of a larger FAZ. In summary, OCTA seems to be useful for assessing qualitative and quantitative perioperative microvascular changes.

Evaluation of the effect of phacoemulsification surgery on retinal and choroidal microvasculature in diabetic patients using optical coherence tomography angiography

Aim To evaluate the effect of phacoemulsification surgery on retinal and choroidal microvasculature in diabetic patients using optical coherence tomography angiography (OCTA). Settings and design A prospective comparative case-control study was performed at the Ophthalmology Department of Ain Shams University hospital, between November 2020 and November 2022. Patients and material A total 50 eyes of 35 cataractous patients were included in this prospective study and divided into two groups: the control group (25 eyes of 19 patients) and the diabetic group (25 eyes of 16 patients with mild nonproliferative diabetic retinopathy). All patients underwent routine ophthalmic examination, OCT and OCTA scans of the macula before phacoemulsification surgery and 1 week, 1, 3, and 6 months after the surgery. Results The best corrected visual acuity significantly improved in both groups by ∼ 0.26 logMAR units in control and diabetic groups (P &lt;0.001 for both). The mean change in central subfoveal thickness was 23.44±43.7 versus 13.6±22 um (P=0.3) in the control group and the diabetic group, respectively but statistically insignificant. There was insignificant change in each group in all vascular parameters during the follow-up period. In addition, there was insignificant difference between the two groups at each visit in most vascular parameters of superficial vessel density, deep vessel density (DVD), and choriocapillaris vessel density (CC VD). On the other hand, the diabetic groups have significantly lower superficial vessel density of whole image and perifovea at 1 week than controls (42.92±4.54% vs. 46.16±3.98%, P=0.01 in the whole image, respectively) (44.29±4.87% vs. 47.32±3.85%, P=0.018 in perifovea, respectively). The diabetic group also showed significantly higher parafoveal deep vessel density than the control group at 1 month postoperatively: 52.67±4.00 versus 47.24±9.85% (P=0.014) that leveled up on month 3 and 6 (P=0.397, 0.538, respectively). The diabetic group showed lower CC VD of the whole image than the control group at 1 week postoperatively: 70.60±2.87 versus 72.22±1.98%, respectively (P=0.025), and also significantly lower CC VD of perifovea than the control group at 1 week: 71.19±2.82 versus 72.72±2.20% (P=0.038), 1 month: 71.08±2.87 versus 72.78±2.61% (P=0.033) and 3 months: 71.35±2.63 versus 72.83±2.52% (P=0.048). Those values leveled up at the last postoperative visit at month 6 (P=0.152). Conclusion Phacoemulsification surgery may lead to the transient and mild reduction of choroidal blood flow in diabetic eyes rather than retinal blood flow. Most of choroidal and retinal vascular changes happened in the perifoveal area within 1 week to 1 month postoperatively and rarely extended to 3 months.

Choroidal Changes in Patients with Diabetic Retinopathy: A Retrospective Study.

This study aimed to investigate the characteristic choroidal changes in patients with diabetic retinopathy and identify factors affecting choroidal thickness (CTh), choroidal vascular index (CVI), and choriocapillaris flow. We retrospectively analyzed 79 eyes of 48 patients with diabetes between August 2021 and February 2022. We collected laboratory data, including HbA1c, serum creatinine, blood urea nitrogen, triglyceride, total cholesterol, high-density lipoprotein, and low-density lipoprotein (LDL) levels. Optical coherence tomography images of the foveal avascular zone, retinal vascular density, choroidal flow, retinal thickness, CTh, and CVI were analyzed. Possible determining factors affecting CTh, CVI, and choriocapillaris flow were analyzed using nonparametric multivariate analysis. LDL (p < 0.001) positively correlated with CTh, whereas CVI (p = 0.007) was negatively correlated with CTh in diabetic patients with diabetes. We also identified a negative correlation between choriocapillaris flow and deep parafoveal retinal vessel density in patients with low-grade diabetic retinopathy (DR), which diminished in those with more advanced DR. Our study provides further information on the changes in choroidal structure and blood flow in patients with diabetes.

LA-Net: layer attention network for 3D-to-2D retinal vessel segmentation in OCTA images

Objective. Retinal vessel segmentation from optical coherence tomography angiography (OCTA) volumes is significant in analyzing blood supply structures and the diagnosing ophthalmic diseases. However, accurate retinal vessel segmentation in 3D OCTA remains challenging due to the interference of choroidal blood flow signals and the variations in retinal vessel structure. Approach. This paper proposes a layer attention network (LA-Net) for 3D-to-2D retinal vessel segmentation. The network comprises a 3D projection path and a 2D segmentation path. The key component in the 3D path is the proposed multi-scale layer attention module, which effectively learns the layer features of OCT and OCTA to attend to the retinal vessel layer while suppressing the choroidal vessel layer. This module also efficiently captures 3D multi-scale information for improved semantic understanding during projection. In the 2D path, a reverse boundary attention module is introduced to explore and preserve boundary and shape features of retinal vessels by focusing on non-salient regions in deep features. Main results. Experimental results in two subsets of the OCTA-500 dataset showed that our method achieves advanced segmentation performance with Dice similarity coefficients of 93.04% and 89.74%, respectively. Significance. The proposed network provides reliable 3D-to-2D segmentation of retinal vessels, with potential for application in various segmentation tasks that involve projecting the input image. Implementation code: https://github.com/y8421036/LA-Net.

Insights into the pattern of choroidal vascularity index changes in idiopathic macular hole

This retrospective study aimed to investigate the changes in choroidal vascularity index (CVI) before and after surgery for idiopathic macular hole (MH). Enhanced depth imaging optical coherence tomography (EDI-OCT) images were analyzed at baseline and at 1-week, 1-month, and 3-month postoperative visits. A total of 97 patients (97 eyes) were included in the study. At baseline, overall CVI and macular CVI showed negative correlation with axial length (AL) and positive correlation with central corneal thickness (CCT). There were no significant differences in macular CVI or overall CVI between affected and healthy eyes, as well as in subgroup analysis of different stages of macular CVI. Following surgery, there was a significant decrease in CVI at 1 week postoperatively, followed by a gradual recovery to baseline levels over time. The observed changes in CVI may be attributed to factors such as air tamponade, pressure changes, and photoreceptor metabolism. This study provides insights into the pattern of CVI changes associated with MH surgery. The findings suggest that stage 4 MH is associated with decreased macular CVI in affected eyes. These results contribute to a better understanding of the effects of surgery on choroidal blood flow in MH patients.

The Effect of β-Blocker Eye Drops on Pulse Rate, Ocular Blood Flow, and Glaucoma Progression: A Retrospective Longitudinal Study.

Our study was conducted to determine factors associated with the effectiveness of a β-blocker eye drop add-on in altering pulse rate (PR) in glaucoma patients. This retrospective study examined 236 eyes of 138 patients who received a β-blocker eye drop add-on during follow-up. Patients were included if at least one PR measurement was available both before and after the add-on was started. We collected data on ophthalmic parameters: longitudinal PR; longitudinal choroidal blood flow, represented by laser speckle flowgraphy-measured mean blur rate (MBR); and diacron-reactive oxygen metabolites (d-ROMs). We used a multivariable linear mixed-effects model to investigate the effectiveness of the β-blocker eye drop add-on in altering PR and examined factors contributing to a larger PR alteration after the add-on was started by analyzing the effect on PR of the interaction term between the add-on and clinical factors. We used the k-means method to classify the patients. The β-blocker eye drop add-on reduced PR (- 7.61bpm, P < 0.001). Female gender, higher PR when the add-on was started, lower central corneal thickness, and a higher d-ROM level were associated with greater reduction in PR (P < 0.05). In a cluster of patients with these clinical features, choroidal MBR increased by + 3.42% when we adjusted for change over time; MD slope, which represents the speed of glaucoma progression, improved by + 0.64dB/year (P < 0.05). We identified a glaucoma subgroup in which PR decreased, choroidal blood flow increased, and glaucoma progression slowed after a β-blocker eye drop add-on was started.

Ridge‐shaped peripapila dry, fluid associated, and self‐resolved fluid associated presentations

Purpose: We aim to describe three different clinical presentations of ridge‐shaped peripapilla.Methods: A series of case reports. Fundus images, autofluorescence (AF), optical coherence tomography (OCT) Angio‐OCT, indocyanine (ICG) and fluorescein angiography (FA) was performed.Results: The first case is a 55‐year‐old woman, that was referred to the clinic due to central visual acuity loss in her left eye. RPE atrophy, and a scleral nasal protrusion (same configuration on both eyes) with a thinned overlying choroid, with subretinal fluid around the peripapillary area and the submacular area was observed on the OCT. FA and ICG with no hotspots, nor any dilated choroidal vascular pattern was observed, nor any signs of a neovascular membrane (NVM). On FA patched hypoAF was observed around the nasal retina. Posterior staphyloma was corroborated with ocular echography. Four months after initial presentation, fluid resolved spontaneously, visual acuity improved, but fundus pigmentary defects remained unchanged. The second case is a 60 year‐old woman (OS), peripapillary subretinal fluid was observed on the oct, choroidal thinning and scleral protrusion nasal to the optic disc. The third case, a 70‐year‐old male (OD), showed a temporal whitish lesion, engorged scleral protrusion was seen on oct, with overlying RPE atrophy, very thinned choroid and retina, without subretinal fluid.Conclusions: Pathologic myopia is defined as myopic refractive error greater than −6.00 diopters. Many chorioretinal findings have been described regarding this condition, one of these is a ridge shaped peripapilla, a form of scleral protrusion around the optic disc. These patients presented on the fluorescein angiography and OCT findings, signs of protrusion of the sclera that seemed to result in overlying choroidal thinning with choroidal blood flow disturbances, and consequent RPE atrophy, leading to the subretinal fluid accumulation.