The vascular geometry of the choriocapillaris is associated with spatially heterogeneous molecular exchange with the outer retina.

Vision relies on the continuous exchange of material between the photoreceptors, retinal pigment epithelium and choriocapillaris, a dense microvascular bed located underneath the outer retina. The anatomy and physiology of the choriocapillaris and their association with retinal homeostasis have proven difficult to characterize, mainly because of the unusual geometry of this vascular bed. By analysing tissue dissected from 81 human eyes, we show that the thickness of the choriocapillaris does not vary significantly over large portions of the macula or with age. Assessments of spatial variations in the anatomy of the choriocapillaris in three additional human eyes indicate that the location of arteriolar and venular vessels connected to the plane of the choriocapillaris is non-random, and that venular insertions cluster around arteriolar ones. Mathematical models built upon these anatomical analyses reveal that the choriocapillaris contains regions where the transport of passive elements is dominated by diffusion, and that these diffusion-limited regions represent areas of reduced exchange with the outer retina. The width of diffusion-limited regions is determined by arterial flow rate and the relative arrangement of arteriolar and venular insertions. These analyses demonstrate that the apparent complexity of the choriocapillaris conceals a fine balance between several anatomical and functional parameters to effectively support homeostasis of the outer retina. KEY POINTS: The choriocapillaris is the capillary bed supporting the metabolism of photoreceptors and retinal pigment epithelium, two critical components of the visual system located in the outer part of the retina. The choriocapillaris has evolved a planar multipolar vascular geometry that differs markedly from the branched topology of most vasculatures in the human body. Here, we report that this planar multipolar vascular geometry is associated with spatially heterogenous molecular exchange between choriocapillaris and outer retina. Our data and analyses highlight a necessary balance between choriocapillaris anatomical and functional parameters to effectively support homeostasis of the outer retina.

Changes in choroidal hemodynamics of form-deprivation myopia in Guinea pigs.

PURPOSE: We studied changes in the choroid, particularly variation in blood flow, during the development of myopia. The hemodynamic mechanism in play remains unclear. We evaluated blood flow by quantitating indocyanine green (ICG) fluorescence in a guinea pig model of form-deprivation myopia. METHODS: Guinea pigs were divided into form-deprivation myopia (FDM) and normal control (NC) groups. Ocular biometric and choroidal hemodynamics parameters were quantitatively derived via ICG imaging, and included the maximal ICG fluorescence intensity (Imax), rising time (Trising), blood flow index (BFI), and mean transit time (MTT). RESULTS: Form deprivation was associated with significant interocular differences in terms of both refractive error and axial length. ICG fluorescence hemodynamic maps of fundal blood flow and vasculature density were evident. In deprived eyes, the fluorescence signals exhibited significantly longer Trising and MTT but lower Imax and BFI than fellow eyes and NC group. The interocular differences in terms of the ocular biometric and hemodynamic parameters were significantly correlated. Hemodynamic analysis of choriocapillaris lobules revealed weakened fluorescence intensity and prolonged arrival and filling times in deprived eyes. Form deprivation reduced the number of lobulated choriocapillaris structures. CONCLUSION: Form-deprivation myopia triggered changes in the hemodynamic and vascular network structures of the choroid and choriocapillaris. The ICG fluorescence imaging/analysis method provides a unique tool for further myopia research.

Chorioretinal biomarkers in hypothalamic amenorrhea.

PURPOSE: The aim of our study was to evaluate changes in the retinal and choriocapillaris circulations in patients with hypothalamic amenorrhea. METHODS: Prospective, cross-sectional observational study on 25 patients (50 eyes) diagnosed with hypothalamic amenorrhea and 25 age-matched healthy women. Optical coherence tomography angiography (OCTA) was used to evaluate the vessel density (VD) of superficial capillary plexus (SCP), deep capillary plexus (DCP), and choriocapillaris VD layers in whole 6.4 × 6.4-mm image and in fovea grid-based image. In patients' group, systemic parameters were collected: body mass index (BMI), endometrial rhyme thickness, follicle stimulating hormone (FSH), luteinizing hormone (LH), prolactin, insulin, and cortisol. RESULTS: SCP and DCP did not show any statistical difference when comparing patients and controls (all p > 0.05). Differently, choriocapillaris VD in the whole region showed a non-significant tendency toward higher values in the patients group in both eyes (p = 0.038 for right eye [RE], p = 0.044 for left eye [LE]). Foveal choriocapillaris VD was higher in hypothalamic amenorrhea women vs. healthy controls (66.0 ± 2.4 vs. 63.7 ± 6.6%, p = 0.136 for RE; 65.0 ± 2.4 vs. 61.6 ± 7.0%, p = 0.005 for LE). Focusing on correlation with systemic parameters, SCP and DCP foveal density had a medium/high effect size with endometrial rhyme, along with DCP in the fovea area vs. cortisol and SCP in the whole area vs. FSH. CONCLUSION: When comparing hypothalamic amenorrhea patients to healthy subjects, OCTA detected changes in the choriocapillaris layer, showing increased VD in the early stage of the systemic pathology, suggesting that microvascular "compaction" could be a first phase of hypoestrogenism adaptation.

Subclinical choroidal involvement in Systemic Lupus Erythematosus.

PURPOSE: To assess the choroidal status of Systemic Lupus Erythematosus (SLE) patients using Optical Coherence Tomography (OCT) and OCT-Angiography. METHODS: SLE patients with disease duration < 10 years, no disease activity and no ocular involvement were recruited and cross-sectionally evaluated. A demographically similar cohort of healthy subjects was used for comparison. The main outcome is choroidal vascularity index (CVI). As secondary outcomes, choriocapillaris parameters and choroidal thickness (CT) were evaluated. RESULTS: Forty eyes of 40 subjects (20 SLE patients and 20 healthy subjects) were studied with a mean ± SD age of 36.7 ± 9.9 years. In the SLE group, the mean ± SD duration of disease was 7.35 ± 2.21 years. Increased CVI was found in the SLE group (p = 0.022). Considering the choriocapillaris, SLE patients presented a lower number (p = 0.037) and a smaller total area (p = 0.041) of signal voids. No differences between groups were found in CT. For SLE patients, CT at subfoveal, temporal and inferior locations presented a negative moderate correlation with disease duration. A strong correlation between choriocapillaris parameters and age was demonstrated for both groups. CONCLUSIONS: This study provides evidence of subclinical choroidal changes in adult SLE patients with inactive disease and no overt ocular manifestation. Increased CVI and fewer and smaller flow voids in choriocapillaris with normal CT suggest increased choroidal vascularity in SLE.

Impact of preocular and ocular circulatory dynamics on the vascular density of retinal capillary plexuses and choriocapillaris.

PURPOSE: To highlight the influence of preocular and ocular vascular circulatory dynamics on the vascular density (VD) of retinal capillary plexuses (RCPs) and choriocapillaris (CC) in patients with and without cardiovascular risk (CVR) factors. METHODS: A retrospective observational study in patients with and without CVR factors (type 1 and 2 diabetes, arterial hypertension, and hypercholesterolemia). Fluorescein (FA) and indocyanine (ICGA) angiography circulatory times were arterial time (FAAT), start (FAstartLF) and end (FAendLF) of laminar flow, and arterial time (ICGAAT), respectively. OCT angiography VDs were superficial (VDSCP) and deep (VDDCP) RCPs and CC (VDCC) VDs. Correlation and regression analysis were performed after adjusting for confounding factors. RESULTS: 177 eyes of 177 patients (mean age: 65.2 ± 15.9 years, n = 92 with and 85 without CVR) were included. VDSCP and VDDCP were significantly inversely correlated with FAAT, FAstartLF and FAendLF likewise VDCC with ICGAAT. Correlations were stronger in patients without CVR than with CVR. CVR, FAAT, FAstartLF and FAendLF were more strongly correlated with VDDCP than VDSCP. FAAT, FAstartLF and FAendLF significantly impacted VDSCP and VDDCP, likewise ICGAAT impacted VDDCP. VDDCP was most strongly impacted by FAAT and FAstartLF. CONCLUSION: Ocular and pre-ocular circulatory dynamics significantly impacted RCPs and CC VDs, especially deep RCP.

Normative data and correlation parameters for vessel density measured by 6 × 6-mm optical coherence tomography angiography in a large chinese urban healthy elderly population: date from the Beichen eye study.

BACKGROUND: To establish a normative database for macular vessel density (VD) measured by optical coherence tomography angiography (OCTA) and explore the parameters related to the VD. METHODS: An observational study in epidemiology. 5840 healthy elderly participants in Beichen district, Tianjin, China underwent detailed ophthalmic and systemic examinations. OCTA was performed in all subjects using a 6 × 6-mm line scan mode centered on the macula and the built-in software was used to quantify VD and stratify the retina. RESULTS: One thousand four hundred sixty-one healthy elderly citizens (30.4% men) were included, with a median age of 60.0 years (8.0 years) and an age range of 50 to 87 years.VDs in the different plexuses: superficial capillary plexus (SCP) 43.9% (3.2%), deep capillary plexus (DCP) 44.3% (2.8%), outer capillary plexus (OCP) 21.9% (5.9%), choriocapillaris (CC) 52.1% (1.4%). 90% medical reference range of the VDs at different plexuses was reported. Age was correlated with the VDs of each capillary plexus. Sex was correlated with the VDs of DCP and OCP, and the VDs of DCP (p < 0.001) and OCP (p = 0.015) in women were higher than that in men. After age and sex adjustment, choroid average thickness was positively correlated with VDs of SCP (R = 0.067, p = 0.010) and DCP (R = 0.108, p < 0.001), ganglion cell layer (GCL) average thickness (R = 0.072, p = 0.006) was positively correlated with the VD of OCP, best-corrected visual acuity (BCVA) (R = 0.082, p = 0.002) was positively correlated with the VD of CC. CONCLUSIONS: In this study, the normative VD database of the Chinese urban healthy elderly population measured by the OCTA was established, and parameters related to the VD of each capillary plexus were analyzed, providing new ideas for the future study of the relationship between macular VD and disease. TRIAL REGISTRATION: The Beichen Eye Study had been registered on the Chinese Clinical Trial Registry website (registry number: ChiCTR2000032280) on April 25, 2020.

Assessment of the effects of myopic and hyperopic anisometropia on choroidal vascular structure in children using SS-OCTA.

OBJECTIVE: To compare large- and medium-sized choroidal vascularity and the choriocapillaris (CC) flow area in children with different refractive errors using swept-source optical coherence tomography angiography (SS-OCTA). METHODS: Forty-two anisometropic children were enrolled and divided into hyperopic anisometropia (HA) and myopic anisometropia (MA) groups. SS-OCTA was performed to analyse choroidal vascularity. Mean choroidal thickness (CT), choroidal vascularity volume (CVV), choroidal vascularity index (CVI) and CC flow area were compared between the two eyes. The inter-ocular differences between the two groups were also determined. RESULTS: Mean CT and CVV were highest in eyes with shorter axial lengths in both refractive groups, and the difference between the two eyes was positively correlated with the difference in axial length at the foveal region. Significant differences in the CVI in the MA group were only found in the parafoveal region. Inter-ocular differences in the CC were significantly reduced in eyes with longer axial lengths in the foveal and parafoveal regions of the HA and MA groups, respectively. Comparing inter-ocular differences, CC was significantly greater in the parafoveal region of the MA group than the HA group. CONCLUSIONS: All layers of choroidal vasculature were thinner in eyes with longer axial lengths in all groups. The inter-ocular CC difference was greater in the MA than in the HA group, with similar differences in axial length. This suggests that both medium-to-large choroidal vascular and choroidal capillaries may play a role in myopia development.

Choriocapillaris reduction accurately discriminates against early-onset Alzheimer's disease.

INTRODUCTION: This study addresses the urgent need for non-invasive early-onset Alzheimer's disease (EOAD) prediction. Using optical coherence tomography angiography (OCTA), we present a choriocapillaris model sensitive to EOAD, correlating with serum biomarkers. METHODS: Eighty-four EOAD patients and 73 controls were assigned to swept-source OCTA (SS-OCTA) or the spectral domain OCTA (SD-OCTA) cohorts. Our hypothesis on choriocapillaris predictive potential in EOAD was tested and validated in these two cohorts. RESULTS: Both cohorts revealed diminished choriocapillaris signals, demonstrating the highest discriminatory capability (area under the receiver operating characteristic curve: SS-OCTA 0.913, SD-OCTA 0.991; P < 0.001). A sparser SS-OCTA choriocapillaris correlated with increased serum amyloid beta (Aß)42, Aß42/40, and phosphorylated tau (p-tau)181 levels (all P < 0.05). Apolipoprotein E status did not affect choriocapillaris measurement. DISCUSSION: The choriocapillaris, observed in both cohorts, proves sensitive to EOAD diagnosis, and correlates with serum Aß and p-tau181 levels, suggesting its potential as a diagnostic tool for identifying and tracking microvascular changes in EOAD. HIGHLIGHTS: Optical coherence tomography angiography may be applied for non-invasive screening of Alzheimer's disease (AD). Choriocapillaris demonstrates high sensitivity and specificity for early-onset AD diagnosis. Microvascular dynamics abnormalities are associated with AD.

Angiopoietin-1 Is Required for Vortex Vein and Choriocapillaris Development in Mice.

BACKGROUND: The choroidal vasculature, including the choriocapillaris and vortex veins, is essential for providing nutrients to the metabolically demanding photoreceptors and retinal pigment epithelium. Choroidal vascular dysfunction leads to vision loss and is associated with age-related macular degeneration and the poorly understood pachychoroid diseases including central serous chorioretinopathy and polypoidal choroidal vasculopathy that are characterized by formation of dilated pachyvessels throughout the choroid. METHODS: Using neural crest-specific Angpt1 knockout mice, we show that Angiopoietin 1, a ligand of the endothelial receptor TEK (also known as Tie2) is essential for choriocapillaris development and vortex vein patterning. RESULTS: Lacking choroidal ANGPT1, neural crest-specific Angpt1 knockout eyes exhibited marked choriocapillaris attenuation and 50% reduction in number of vortex veins, with only 2 vortex veins present in the majority of eyes. Shortly after birth, dilated choroidal vessels resembling human pachyvessels were observed extending from the remaining vortex veins and displacing the choriocapillaris, leading to retinal pigment epithelium dysfunction and subretinal neovascularization similar to that seen in pachychoroid disease. CONCLUSIONS: Together, these findings identify a new role for ANGPT1 in ocular vascular development and demonstrate a clear link between vortex vein dysfunction, pachyvessel formation, and disease.

Acute and continuous exposure of airborne fine particulate matter (PM2.5): diverse outer blood-retinal barrier damages and disease susceptibilities.

BACKGROUND: The association between air pollution and retinal diseases such as age-related macular degeneration (AMD) has been demonstrated, but the pathogenic correlation is unknown. Damage to the outer blood-retinal barrier (oBRB), which consists of the retinal pigment epithelium (RPE) and choriocapillaris, is crucial in the development of fundus diseases. OBJECTIVES: To describe the effects of airborne fine particulate matter (PM2.5) on the oBRB and disease susceptibilities. METHODS: A PM2.5-exposed mice model was established through the administration of eye drops containing PM2.5. Optical coherence tomography angiography, transmission electron microscope, RPE immunofluorescence staining and Western blotting were applied to study the oBRB changes. A co-culture model of ARPE-19 cells with stretching vascular endothelial cells was established to identify the role of choroidal vasodilatation in PM2.5-associated RPE damage. RESULTS: Acute exposure to PM2.5 resulted in choroidal vasodilatation, RPE tight junctions impairment, and ultimately an increased risk of retinal edema in mice. These manifestations are very similar to the pachychoroid disease represented by central serous chorioretinopathy (CSC). After continuous PM2.5 exposure, the damage to the RPE was gradually repaired, but AMD-related early retinal degenerative changes appeared under continuous choroidal inflammation. CONCLUSION: This study reveals oBRB pathological changes under different exposure durations, providing a valuable reference for the prevention of PM2.5-related fundus diseases and public health policy formulation.

The role of choriocapillaris vessel density in the pathogenesis of macular neovascularization associated with choroidal osteoma.

PURPOSE: To detect the vessel density of choriocapillaris (CC) vascular network in eyes affected by choroidal osteoma and in eyes complicated by macular neovascularization (MNV), using optical coherence tomography angiography (OCTA). METHODS: In this retrospective study, twenty-eight eyes of 28 patients were divided into three groups: group 1 including patients with calcified choroidal osteoma, group 2 including patients with decalcified choroidal osteoma, and group 3 including patients with decalcified choroidal osteoma complicated by MNV. OCTA analyzed the vessel density of CC in these lesions localized in the peripapillary region. RESULTS: We enrolled 12 eyes with calcified choroidal osteoma, 11 eyes with decalcified choroidal osteoma, and 5 eyes with decalcified choroidal osteoma complicated by MNV. The eyes with decalcified choroidal osteoma and MNV revealed a statistically significant reduction in vessel density of the CC respect to the other groups (p < 0.001). Moreover, the vessel density of CC in decalcified choroidal osteoma was significantly reduced compared to calcified choroidal osteoma (p < 0.001). CONCLUSIONS: OCTA allowed a quantitative evaluation of choriocapillaris vessel density in choroidal osteoma, in order to detect the changes of this vascular network, which could lead to the development of MNV. Therefore, OCTA could be a new diagnostic tool in the clinical management of the choroidal osteoma. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT05342324.

Hyper- and hypo-perfusion of choriocapillaris in the eyes with pachychoroid pigment epitheliopathy.

PURPOSE: To evaluate the changes in choriocapillaris vessel density (VD) in eyes with pachychoroid pigment epitheliopathy (PPE) using swept-source optical coherence tomography (OCT) angiography (OCTA). METHODS: This study included 83 eyes with PPE and 42 control eyes. We collected OCT and OCTA parameters, including central point thickness, subfoveal choroidal thickness (SFChT), and choriocapillaris VD of the fovea (CC fovea) and parafovea. The parafoveal area was divided into superior, nasal, inferior, and temporal choriocapillaris areas. Maximum (CC max) and minimum (CC min) choriocapillaris VD were defined as the highest and lowest values among the four parafoveal subfield VDs, respectively. We analyzed the average choriocapillaris VD, CC max, CC min, CC fovea, and the difference between CC max and CC min (CC delta) individually and compared all the parameters between PPE and control eyes. RESULTS: CC max (56.0% ± 1.7%) was significantly higher and CC min (50.9% ± 2.0%) significantly lower in eyes with PPE than in control eyes (CC max, 55.3% ± 1.0%, P = 0.006; CC min, 51.5% ± 1.3%, P = 0.046). The CC delta value (5.0% ± 2.1%) and SFChT (389.9 ± 129.9 µm) were also significantly higher in eyes with PPE than in the control group (3.7% ± 1.5%, P < 0.001; 268.2 ± 102.2 µm, P < 0.001; respectively). CONCLUSIONS: Choriocapillaris VD showed higher variability (hyperperfusion and hypoperfusion) in eyes with PPE than in control eyes. Choriocapillaris hypoperfusion may precede the development of PPE; however, choriocapillaris hyperperfusion is associated with projection artifacts.

Changes in choriocapillaris structure occurring in idiopathic macular hole before and after vitrectomy.

PURPOSE: The aim of this study was to analyze the anatomical choroidal vascular layers and the changes in idiopathic macular hole (IMH) eyes over time after vitrectomy. METHODS: This is a retrospective observational case-control study. Fifteen eyes from 15 patients who received vitrectomy for IMH and age-matched 15 eyes from 15 healthy controls were enrolled in this study. Retinal and choroidal structures were quantitatively analyzed before vitrectomy and 1 and 2 months after surgery using spectral domain-optical coherence tomography. Each choroidal vascular layer was divided into the choriocapillaris, Sattler's layer, and Haller's layer, and then, the choroidal area (CA), luminal area (LA), stromal area (SA), and central choroidal thickness (CCT) were calculated using binarization techniques. The ratio of LA to CA was defined as the L/C ratio. RESULTS: The CA, LA, and L/C ratios were 36.9 ± 6.2, 23.4 ± 5.0, and 63.1 ± 7.2 in the choriocapillaris of IMH and were 47.3 ± 6.6, 38.3 ± 5.6, and 80.9 ± 4.1 in that of control eyes, respectively. Those values were significantly lower in IMH eyes than in control eyes (each P < 0.01), whereas there was no significant difference in total choroid, Sattler's layer, and Haller's layer or CCT. The ellipsoid zone defect length showed a significant negative correlation with the L/C ratio in total choroid and with CA and LA in the choriocapillaris of IMH (R = - 0.61, P < 0.05, R = - 0.77, P < 0.01, and R = - 0.71, P < 0.01, respectively). In the choriocapillaris, the LA were 23.4 ± 5.0, 27.7 ± 3.8, and 30.9 ± 4.4, and the L/C ratios were 63.1 ± 7.2, 74.3 ± 6.4, and 76.6 ± 5.4 at baseline, 1 month, and 2 months after vitrectomy, respectively. Those values showed a significant increase over time after surgery (each P < 0.05), whereas the other choroidal layers did not alter consistently with respect to changes in choroidal structure. CONCLUSIONS: The current OCT-based study demonstrated that the choriocapillaris was exclusively disrupted between choroidal vascular structures in IMH, which may correlate with the ellipsoid zone defect. Furthermore, the L/C ratio of choriocapillaris recovered after IMH repair, suggesting an improved balance between supply and demand of oxygen that has collapsed due to temporary loss of central retinal function by IMH.

Unilateral hypertensive choroidopathy as a sole manifestation in malignant hypertension: optical coherence tomography angiography findings-case report.

BACKGROUND: We present a case of hypertensive choroidopathy due to malignant hypertension with exudative retinal detachment as a sole finding. We use OCT- angiography for initial diagnosis and report findings from extensive follow up. CASE PRESENTATION: A 51-year-old female with no past medical history, presented to our clinic with painless loss of vision in her left eye. Fundus examination revealed only exudative retinal detachment in her left eye that was confirmed with Optical Coherence Tomography. Fluorescein angiography showed hyperfluorescent spots with leakage in late phases. OCTA manifested a focal dark area in the choriocapillaris slab corresponding to flow signal voids, signifying regions of non-perfusion. Her blood pressure was 220/120 mmHG. Complete blood work -up failed to reveal any other possible etiology. During follow-up period of 9 months blood pressure normalized, patient regained visual function and choriocapillaris perfusion was completely restored. DISCUSSIONS AND CONCLUSIONS: Hypertensive choroidopathy with exudative retinal detachment can be the only sign of malignant hypertension and no pre-existing history of a systemic disease is required in order to become apparent. OCTA reveals areas of non-perfusion at choriocapillaris level, proving that it is an essential tool in the diagnosis and follow up of patients with hypertensive choroidopathy. Finally, we propose that early diagnosis prevents permanent damage of the RPE and leads to complete choroidal remodeling and better visual outcomes.

Longitudinal quantification of choriocapillaris flow deficits in persistent placoid maculopathy: a case report.

BACKGROUND: Persistent placoid maculopathy (PPM) is a rare idiopathic chorioretinopathy characterized by choriocapillaris (CC) hypoperfusion. In a case of PPM, we quantified CC flow deficits (FDs) over time and observed an increase in CC perfusion as the visual acuity and outer photoreceptor anatomy improved. CASE PRESENTATION: A 58-year-old man was diagnosed with PPM in both eyes based on the patient's clinical presentation and imaging. He presented with sudden-onset central scotomas in both eyes for about two months. On referral, the best corrected visual acuity (BCVA) was 20/20 in the right eye and 20/100 in the left eye. Plaque-like yellowish macular lesions were observed bilaterally and autofluorescence imaging showed bilateral hyperautofluorescent lesions. Fluorescein angiography (FA) revealed early-phase hyper-fluorescent staining that intensified in the late phases, while indocyanine green angiography (ICGA) displayed persistent hypofluorescence in both eyes. Foveal centered swept source optical coherence tomography (SS-OCT) B-scans showed bilateral focal deposits on the level of retinal pigment epithelium (RPE) and disruption of outer photoreceptor bands. The CC FDs were quantified on SS-OCT angiography (SS-OCTA) images using a previously published algorithm that was validated. The CC FD% was 12.52% in the right eye and 14.64% in the left eye within a 5 mm circle centered on the fovea. After 5 months of steroid treatment, BCVA remained 20/20 in the right eye and improved to 20/25 in the left eye. On OCT imaging, the outer photoreceptor bands fully recovered in both eyes, while some focal deposits remained along the RPE in the left eye. The CC perfusion in both eyes improved, with CC FD% decreasing from 12.52% to 9.16% in the right eye and from 14.64% to 9.34% in the left eye. CONCLUSIONS: Significant impairment of macular CC perfusion was detected after the onset of PPM. Improvement in central macular CC perfusion corresponded with improvements in BCVA and outer retinal anatomy. Our findings suggest that imaging and quantification of CC FDs could serve as a valuable imaging strategy for diagnosing PPM and for following disease progression.

Macular Choroidal Thickness and Choriocapillaris Vessel Density Alterations in Type 2 Diabetics with High Myopia.

INTRODUCTION: The purpose of this study was to investigate the change in macular choroidal thickness and choriocapillaris vessel density in type 2 diabetic (T2D) with high myopia. METHODS: This cross-sectional study recruited a total of 182 patients (182 eyes) in the Affiliated Hospital of Chengde Medical University between January 2018 and December 2021, including myopia + diabetes patients (40 eyes), T2D patients without myopia patients (47 eyes), myopia patients (45 eyes), and healthy volunteers (50 eyes). The choroidal thickness and choriocapillaris vessel density of macular were measured in all subjects by optical coherence tomography and optical coherence tomography angiography. RESULTS: The choroidal thicknesses in myopic, diabetes, myopia + diabetes groups were statistically significantly lower than those in control group (p < 0.001). Further pairwise comparisons showed that the choroidal thicknesses in myopia + diabetes group were statistically significantly lower than those in diabetes group (p < 0.001). The choriocapillaris vessel densities in diabetes, myopia + diabetes groups were statistically significantly lower than those in control group (p < 0.001). Interestingly, there were no significant differences in choriocapillaris vessel density between myopia group and control group (p > 0.05). Further pairwise comparisons showed that the choriocapillaris thicknesses in myopia + diabetes group were statistically significantly lower than those in myopia group (p < 0.001), while no statistically significant differences were found between diabetes group and myopia + diabetes group (p > 0.05). CONCLUSION: The choroidal thickness of the patients with high myopia and diabetes (without diabetic retinopathy [DR]) was significantly lower than that of normal people and diabetic patients, but the choriocapillaris vessel density was not significantly different from that of normal people, which may be one of the protective mechanisms of high myopia against DR.

Retinal microvasculature and choriocapillaris impairments according to the stage of dry age-related macular degeneration.

BACKGROUND: We aimed to analyse the retinal microvasculature and choriocapillaris according to the dry age-related macular degeneration (AMD) stage and to identify factors associated with their microvasculatures. METHODS: Patients were divided into four groups: normal controls, early, intermediate and advanced AMD groups. The vessel density (VD) of superficial capillary plexus (SCP), deep capillary plexus (DCP) and choriocapillaris was compared using optical coherence tomography angiography among the groups. Linear regression analysis was performed to identify factors associated with the VD. RESULTS: The VDs of the SCP were 22.1 ± 5.7, 19.1 ± 5.4, 18.0 ± 6.4 and 12.2 ± 6.4% (p < 0.001); the VDs of the DCP were 22.4 ± 4.5, 20.7 ± 4.3, 18.1 ± 5.3 and 14.6 ± 5.8% (p < 0.001); the VDs of the choriocapillaris were 29.4 ± 3.7, 26.4 ± 4.8, 24.5 ± 4.9 and 24.2 ± 3.7% (p < 0.001) in the control, early, intermediate, and advanced groups, respectively. AMD stage and age were significantly associated with the VDs of all layers, and the VDs of the SCP and DCP were associated with visual acuity (both p < 0.001). Additionally, hypertension was associated with the VDs of the DCP (p = 0.027) and choriocapillaris (p = 0.024). CONCLUSIONS: The retinal microvasculature and choriocapillaris tended to become more impaired as the AMD stage progressed. Age was significantly associated with the microvasculature impairments of all layers, and hypertension was significantly associated with impairments of the DCP microvasculature and choriocapillaris.

The Role of Diabetic Choroidopathy in the Pathogenesis and Progression of Diabetic Retinopathy.

Diabetic choroidopathy was first described on histopathological specimens of diabetic eyes. This alteration was characterized by the accumulation of PAS-positive material within the intracapillary stroma. Inflammation and polymorphonuclear neutrophils (PMNs) activation are crucial elements in choriocapillaris impairment. The evidence of diabetic choroidopathy in vivo was confirmed with multimodal imaging, which provides key quantitative and qualitative features to characterize the choroidal involvement. The choroid can be virtually affected in each vascular layer, from Haller's layer to the choriocapillaris. However, the damage on the outer retina and photoreceptor cells is essentially driven by a choriocapillaris deficiency, which can be assessed through optical coherence tomography angiography (OCTA). The identification of characteristic features of diabetic choroidopathy can be significant for understanding the potential pathogenic and prognostic implications in diabetic retinopathy.

The Essential Role of Light-Induced Autophagy in the Inner Choroid/Outer Retinal Neurovascular Unit in Baseline Conditions and Degeneration.

The present article discusses the role of light in altering autophagy, both within the outer retina (retinal pigment epithelium, RPE, and the outer segment of photoreceptors) and the inner choroid (Bruch's membrane, BM, endothelial cells and the pericytes of choriocapillaris, CC). Here autophagy is needed to maintain the high metabolic requirements and to provide the specific physiological activity sub-serving the process of vision. Activation or inhibition of autophagy within RPE strongly depends on light exposure and it is concomitant with activation or inhibition of the outer segment of the photoreceptors. This also recruits CC, which provides blood flow and metabolic substrates. Thus, the inner choroid and outer retina are mutually dependent and their activity is orchestrated by light exposure in order to cope with metabolic demand. This is tuned by the autophagy status, which works as a sort of pivot in the cross-talk within the inner choroid/outer retina neurovascular unit. In degenerative conditions, and mostly during age-related macular degeneration (AMD), autophagy dysfunction occurs in this area to induce cell loss and extracellular aggregates. Therefore, a detailed analysis of the autophagy status encompassing CC, RPE and interposed BM is key to understanding the fine anatomy and altered biochemistry which underlie the onset and progression of AMD.

Hyperreflective foci in the choroid of normal eyes.

PURPOSE: To investigate hyperreflective choroidal foci (HCF) using en face swept-source optical coherence tomography (SS-OCT) and determine the factors that contribute to the distribution of HCF in normal eyes. METHODS: In this retrospective study, we included healthy eyes with a normal fundus. HCF were defined as hyperreflective spots on en face SS-OCT images. The number, mean area, total area, and circularity of the HCF were compared with various choroid measurements obtained using SS-OCT, SS-OCT angiography, and fundus photography. RESULTS: We investigated 51 eyes from 51 patients. The mean patient age was 56.0 ± 14.7 years, and 32 (62.7%) were female. The number and total area of HCF did not differ between the female and male patients and the right and left eyes. The number of HCF was correlated with the stromal area of the choroid (r = 0.291, P = 0.040) and subfoveal choroidal vascularity index (r = - 0.364, P = 0.009). The total area of HCF was correlated with the stromal area of the choroid (r = 0.283, P = 0.045). However, the number and total area of HCF were not correlated with age, degree of macular tessellation, subfoveal choroidal thickness, and choriocapillaris vascular density and flow void area. CONCLUSION: HCF were observed in normal eyes, and their distribution was associated with the underlying stromal component of the choroid. The results of this study can be used as a reference for determining abnormal hyperreflective foci in the choroid of the eyes with various diseases.