Haller's Vessel Research Articles

Quantitative assessment of intervortex anastomosis in central serous chorioretinopathy and fellow eyes: Does the size of anastomotic vessels matter for the diagnosis?

PurposeTo evaluate the frequency and size of intervortex anastomosis at the posterior pole on en-face spectral domain optical coherence tomography (SD-OCT) images in central serous chorioretinopathy (CSC) cases and their fellow eyes and its associations with choroidal morphology.MethodsSixty-five treatment-naive eyes of 65 patients with CSC, 65 fellow eyes, and 55 eyes of healthy age-matched participants were included. The presence of intervortex anastomosis at the watershed zone and asymmetry of the choroidal vessels between the superior and inferior macula were evaluated using 6 × 6 mm en-face SD-OCT. The diameter of the widest Haller vessel and the diameter of the widest anastomotic Haller vessel passing through the watershed zone were measured on en-face SD-OCT images. The choroidal vascularity index (CVI) was assessed using ImageJ software.ResultsIntervortex vein anastomosis on the horizontal watershed zone was detected in 75.4% diseased eyes, 61.5% in fellow eyes, and 36.4% in healthy age-matched controls (p < 0.001). The mean CVI was significantly higher in both diseased (74.3 ± 2.3%) and fellow (73.8 ± 2.2%) eyes of CSC cases than in healthy controls (72.5 ± 2.3%) (p = 0.002, p = 0.013, respectively). In the cases with intervortex vein anastomosis, the diameter of the widest anastomotic Haller vessel passing through the watershed zone was 0.40 ± 0.10 mm in diseased eyes, 0.35 ± 0.11 mm in fellow eyes, and 0.30 ± 0.09 mm in healthy age-matched controls (p = 0.001).ConclusionsIntervortex anastomosis might be seen as a variation in normal eyes, however, its frequency and the size of anastomotic vessels are significant higher in not only CSC but also in fellow eyes.

Vortex Veins in Eyes With Pachychoroid Spectrum Disorders Evaluated by the Adjusted Reverse 3-Dimensional Projection Model

To compare the distribution of vortex vein ampulla (VVA) between pachychoroid spectrum disorder (PSD) and controls. A single-center, case-control study. This study included 75 PSD, 35 fellow, and 65 control eyes. We quantified VVA distribution using a 3-dimensional reverse projection model corrected for image distortion. We investigated the distribution of major drainage veins (MDV), in which macular Haller's vessels directly influx. The mean distances from the optic disc to VVAs and the mean angles between VVAs and the fovea-disc line. The PSD group had significantly fewer VVA in infranasal sector (PSD, fellow, control; 1.6±0.6, 1.8±0.6, 1.9±0.6, respectively, P= 0.026). In supralateral sector, for PSD, fellows, and controls, the mean distances from the optic disc to VVAs were 14.1±1.0 mm, 14.1±1.1 mm, and 13.6±1.4 mm, respectively, and were significantly farther in PSD than in controls (P= 0.023). The mean angles between VVAs and the fovea-disc line were 64.8±5.9°, 66.4±6.4°, and 61.7±6.4°, respectively, and were significantly higher in PSD and fellows than in controls (P=0.008). The mean distances from the optic disc to MDV in supratemporal sector were 14.1±1.2 and 13.7±1.2 in eyes whose Haller's vessels extended beyond the fovea-disc line (asymmetry), and those that did not, respectively, with the asymmetric eyes significantly farther (P= 0.016). The VVA position in supralateral sector was farther and higher in PSD than in controls, suggesting that the distribution of VVA may be associated with the development of PSD. Proprietary or commercial disclosure may be found after the references.

Choroidal Morphology on Ultra-Widefield Indocyanine Green Angiography and Response to Aflibercept in Pachychoroid Neovasculopathy.

This study assessed the relationship between the choroidal morphology and short-term response to aflibercept treatment in pachychoroid neovasculopathy (PNV). This was a retrospective case-control study. Ultra-widefield indocyanine green angiography (UWICGA) and optical coherence tomography (OCT) images of 90 PNV eyes of 90 patients treated with aflibercept were enrolled. Responsiveness to aflibercept was defined as a complete resolution of sub- or intra-retinal fluid after three loading doses (50 dry and 40 non-dry eyes). Subfoveal choroidal thickness (SFCT) was measured on OCT images, and choroidal vessel density (CVD), CVD asymmetry, intervortex anastomosis, and choroidal vascular hyperpermeability (CVH) were assessed on UWICGA images. CVD on UWICGA differed between groups in terms of the total area (0.323 ± 0.034 in dry vs. 0.286 ± 0.038 in non-dry, p &lt; 0.001) and area of each quadrant (superotemporal: 0.317 ± 0.040 vs. 0.283 ± 0.040, superonasal: 0.334 ± 0.040 vs. 0.293 ± 0.045, inferonasal: 0.306 ± 0.051 vs. 0.278 ± 0.052, inferotemporal: 0.334 ± 0.047 vs. 0.290 ± 0.046; all p ≤ 0.010). The CVH grade differed between groups (mean 1.480 ± 0.735 vs. 1.875 ± 0.822, p = 0.013). ST and IT intervortex anastomoses were common in the dry group, while SN, ST, and IT were most common in the non-dry group (p = 0.001). A poor short-term response to aflibercept treatment in PNV eyes was associated with a lower Haller vessel density, higher CVH grade, and intervortex anastomosis involving more quadrants on UWICGA.

NORMAL PERIPHERAL CHOROIDAL THICKNESS MEASURED BY WIDEFIELD OPTICAL COHERENCE TOMOGRAPHY.

Choroidal stasis plays an important role in the pathogenesis of many conditions and leads to choroidal thickening. However, the normal peripheral choroidal thickness (PCT) pattern remains unknown. This study investigated PCT and associated factors using ultrawidefield optical coherence tomography in healthy eyes. This cross-sectional study included 120 healthy eyes (57 males; age, 52.0 ± 20.5 years). We used choroidal thickness maps created by ultrawidefield optical coherence tomography (viewing angle, 200°) with real-shape correction. The peripheral area was defined from 60° to 100° and further separated vertically and horizontally. The PCT and the correlations between PCT and subjects' characteristics were examined. The PCT were 227.1 ± 57.0 µ m, 199.6 ± 53.9 µ m, 196.6 ± 57.1 µ m, and 148.0 ± 38.2 µ m in supratemporal, infratemporal, supranasal, and infranasal areas, respectively. The thickest peripheral sector was most frequently observed in supratemporal (69.2%). The PCT negatively correlated with age in all regions ( P -values < 0.001) and axial length in supratemporal, supranasal, and infranasal areas ( P -values ≤ 0.003). The temporal PCT was thicker on the side contiguous with the posterior pole Haller's vessels ( P -values ≤ 0.020). The PCT is associated with age, axial length, and the running pattern of Haller's vessels.

A Comparative Study of Choroidal Vascular and Structural Characteristics of Typical Polypoidal Choroidal Vasculopathy and Polypoidal Choroidal Neovascularization: OCTA-Based Evaluation of Intervortex Venous Anastomosis

The aim of this study was to compare the choroidal characteristics of typical polypoidal choroidal vasculopathy (T-PCV) and polypoidal choroidal neovascularization (P-CNV) cases, and to investigate the presence of intervortex venous anastomoses in these PCV subtypes by using en face optical coherence tomography angiography (OCTA). A total of 35 eyes of 33 PCV cases were included. The PCV cases were divided into T-PCV and P-CNV groups. The choroidal vascularity index (CVI) was calculated. En face OCTA images were evaluated for the presence of intervortex venous anastomoses. The diameter of the largest anastomotic Haller vessel was measured. T-PCV cases had significantly higher mean CVI values (73.9 ± 3.7 vs. 70.8 ± 4.5%) than P-CNV cases (p = 0.039). Intervortex venous anastomoses were observed in 85.7% of T-PCV eyes and in 91.7% of P-CNV eyes on en face OCTA (p = 1.000). In the cases with intervortex venous anastomosis, the mean diameter of the largest anastomotic vessel on en face OCTA was 341.2 ± 109.1 µm in the T-PCV and 280.4 ± 68.4 µm in the P-CNV group (p = 0.048). The higher CVI value in T-PCV may be an important feature concerning the pathogenesis and classification of PCV. Although there was no difference between the two subtypes in terms of intervortex anastomosis, more dilated anastomotic vessels were observed in the T-PCV.

Morphology of en face Haller vessel and macular neovascularization at baseline and 3 months as predictive factors in age-related macular degeneration

The clinical implication of en face imaging of Haller vessels and macular neovascularization (MNV) in neovascular age-related macular degeneration (nAMD) is not well established. The purpose of this study is to investigate whether the early-phase morphology of en face Haller vessel and MNV is related to the injection frequency and visual outcome in treatment-naïve nAMD. En face images of Haller vessel and MNV were acquired from 52 eyes at baseline, after three loading doses and at 12 months later using optical coherence tomography (OCT) and OCT angiography. Vessel area, diameter, length, intersection number, fractal dimension, and lacunarity were calculated. Patients were classified according to the injection frequency (< 5 as the infrequent group) and visual gain (≥ 0.3 logMAR) over 12 months. The infrequent group was associated with a longer Haller vessel length after loading doses (OR 3.05, P = 0.01), while visual gain was associated with a smaller maximal MNV diameter after loading doses (OR 0.22, P = 0.03). A predictive model for frequent injection based on the Haller vessel length demonstrated an AUC of 0.71. In conclusion, the en face Haller vessel and MNV morphology after loading doses can be used as biomarkers for the injection frequency and visual gain during the first year in treatment-naïve nAMD patients.

Choroidal Neovascularization and Haller Vessel Morphology Associated with Vision and Treatment Number after 1 Year in Age-related Macular Degeneration.

PurposeThe present study aimed to quantify various factors of vessel morphology, including vessel diameter, length, and complexity (fractal dimension and lacunarity) of both choroidal neovascularization (CNV) and en face Haller vessels using optical coherence tomography angiography (OCTA) and en face structural optical coherence tomography in typical neovascular age-related macular degeneration (nAMD) and polypoidal choroidal vasculopathy (PCV) and to identify factors associated with visual acuity (VA) loss and number of injections within a year after the day of OCTA.MethodsWe retrospectively analyzed 43 eyes of nAMD patients and 33 eyes of PCV patients whose OCTA was performed at least 12 months after an initial anti-vascular endothelial growth factor treatment. Quantitative parameters, including vessel area, vessel diameter, vessel length, fractal dimension, and lacunarity were analyzed from en face images of CNV and Haller vessels. Clinical information, including logarithm of the minimum angle of resolution visual acuity and injection number of anti-vascular endothelial growth factor were acquired after 12 months from OCTA date. Using logistic regression analyses, parameters associated with logarithm of the minimum angle of resolution VA loss of 0.2 or more (VA loss group) and a number of injections of four or more (unstable group) after 12 months were analyzed.ResultsIn typical nAMD, the VA loss group was associated with a smaller number of intersections of Haller vessels. The unstable group was associated with an increased lacunarity of CNV in typical nAMD. In PCV, both VA loss and unstable groups were associated with a higher maximal diameter of Haller vessels.ConclusionsVA loss and injection number of nAMD and PCV 12 months after OCTA imaging were associated with different morphological parameters of CNV and Haller vessels. Therefore, quantitative analyses of both CNV and Haller vessels from OCTA and en face optical coherence tomography might provide prognostic information about visual outcome and injection frequency within 12 months after OCTA imaging.

Integrative analysis of the choroid by quantifying Haller vessel and choriocapillaris parameters in different drusen subtypes

This study aimed to quantify the Haller vessel and choriocapillaris (CC) parameters in drusen subtypes in nonexudative age-related macular degeneration (AMD) and pachydrusen. Ninety-five eyes of 80 patients and 28 control eyes were categorized into soft drusen, subretinal drusenoid deposit (SDD), soft drusen plus SDD, pachydrusen, and control groups. The diameter, length and intersections of Haller vessels and the total area, size and number of CC flow voids were quantified using en face optical coherence tomography (OCT) or OCT angiography. The pachydrusen group showed the largest Haller vessel area and diameter and shortest total length but similar CC parameters to those in the control group. The soft drusen plus SDD group showed the largest CC flow void area and size, while the Haller parameters were similar to those in the control group. The area and size of the flow voids in the SDD group were smaller than those in the soft drusen plus SDD group. Based on unsupervised machine learning, the eyes were classified into 4 clusters—the control, pachydrusen, soft drusen plus SDD and soft drusen plus SDD groups. Cluster 3 showed a larger diameter and shorter total length of the Haller vessels than cluster 4.

Пахихориоидальная неоваскулопатия при нормальной субфовеолярной толщине хориоидеи

Pachychoriod neovasculopathy and typical neovascular age-related macular degeneration often look similar, but some differences have been described both genotypically and in the level of cytokine profile, which explains the difference in response to antiangiogenic therapy. It is known that pachychoriod diseases are characterized by choroidal subfoveolar thickening. However, there is currently no data on the structural features of the choroid in the presence of pachychoriod neovasculopathy outside the fovea. Purpose. To perform a detailed analysis of choroial structure on OCT scans of patients with neovascular AMD with normal choroidal subfoveolar thickness and to reveal the frequency of pachychoriodal neovasculopathy identification. Material and methods. In retrospective study, the data of 30 treatment-naive patients (30 eyes) aged 71.5±7.6 years with CNV type 1 were analyzed, including 18 women and 12 men, with a subfeolar thickness of the choroidal membrane not exceeding 250 µm. The patients underwent OCT and OCT-angiography using a Spectralis device (Heidelberg Engineering, Germany). In the foveolar zone and under the neovascular complex, if it is located outside the fovea, the structure of the choroid was analyzed: the choroidal thickness, Haller layer and choriocapillaries / layer of Sattler vessels were measured. Results. The average thickness of the choroid in the fovea in all patients was 170.1±40 µm. The thickness of Haller vessels layer was on average 112.3±20 μm, and the layer of choriocapillaries / Sattler vessels was 57.8±12 μm. In 22 eyes, the structure of the choroid and the ratio of all layers were similar in all analyzed OCT scans. However, in 8 eyes, under the CNV located extrafoveally, a thickening of the choroid was revealed up to 210.5±51 µm, the main volume of the choroid was presented by pachyvessels – dilated and enlarged vessels of the Haller layer which thickness was 189.4 ± 48 µm, and thinning of the choriocapillary / Sattler layer to 21.1±16 µm. Conclusion. Among 30 patients with normal subfoveolar thickness of the choroid, the frequency of PNV was 26.6%. Taking into account the literature data on different responses to antiangiogenic therapy in patients with PNV and typical AMD, we can once again emphasize the importance of a detailed assessment of changes in the choroid not only in the foveolar zone, but also specifically in the area of the neovascular complex. Key words: pachychoriod neovasculopathy, choroid, OCT.

Classification of pachychoroid on optical coherence tomography using deep learning.

Pachychoroid is characterized by dilated Haller vessels and choriocapillaris attenuation that are seen on optical coherence tomography (OCT) B-scans. This study investigated the feasibility of using deep learning (DL) models to classify pachychoroid and non-pachychoroid eyes from OCT B-scan images. In total, 1898 OCT B-scan images were collected from eyes with macular diseases. Images were labeled as pachychoroid or non-pachychoroid based on strict quantitative and qualitative criteria for multimodal imaging analysis by two retina specialists. DL models were trained (80%) and validated (20%) using pretrained convolutional neural networks (CNNs). Model performance was assessed using an independent test set of 50 non-pachychoroid and 50 pachychoroid images. The final accuracy of AlexNet and VGG-16 was 57.52% for both models. ResNet50, Inception-v3, Inception-ResNet-v2, and Xception showed a final accuracy of 96.31%, 95.25%, 93.40%, and 92.61%, respectively, for the validation set. These models demonstrated accuracy on an independent test set of 78.00%, 86.00%, 90.00%, and 92.00%, and an F1 score of 0.718, 0.841, 0.894, and 0.920, respectively. DL models classified pachychoroid and non-pachychoroid images with good performance. Accurate classification can be achieved using CNN models with deep rather than shallow neural networks.

Haller's vessels patterns in non-neovascular age-related macular degeneration.

To investigate the optical coherence tomography (OCT) en face reconstruction of the choroid in different phenotypes of non-neovascular age-related macular degeneration (AMD), to identify the relative distribution of the vascular patterns of the Haller's layer in each AMD category. Retrospective study enrolling consecutive patients with non-neovascular AMD. Patients were divided into the following: (1) those with reticular pseudodrusen (RPD); (2) those with small (< 63μm) or medium-large drusen (63-124μm); (3) those with geographic atrophy (GA). Qualitative analysis of the en face images provided by CIRRUS HD-OCT 5000 (Carl Zeiss Meditech, Inc., Dublin, USA) was performed, identifying five arrangements of Haller's vessels: temporal herringbone, branched from below, laterally diagonal, double arcuate, and reticular. Choroidal thickness (CT) was measured from structural OCT. Healthy age-matched subjects were included as a control group. Fifty-eight eyes of 58 patients (20 eyes with RPD; 22 eyes with drusen; 16 eyes with GA) and 18 control eyes were enrolled. The laterally diagonal configuration was the most prevalent (40.0%) in the RPD group; the reticular pattern was the most frequent in the drusen group (50.0%); the double arcuate (62.5%) was the most recurrent pattern in patients with GA. In the control group, the temporal herringbone (38.9%) arrangement was the most represented. The CT associated with the temporal herringbone and reticular arrangement was significantly higher compared to the branched from below (p < 0.001), the laterally diagonal (p = 0.014), and the double arcuate pattern (p = 0.009). Different phenotypes of non-neovascular AMD present a specific distribution of vascular arrangement on en face OCT. The temporal herringbone and the reticular pattern (the ones more associated in a physiological setting) disclosed a thicker choroid compared to the arrangements more represented in non-neovascular AMD-correlated phenotypes.

CHOROIDAL MORPHOLOGY IN EYES WITH PERIPAPILLARY POLYPOIDAL CHOROIDAL VASCULOPATHY.

This study analyzes a subset of patients with peripapillary polypoidal choroidal vasculopathy (PCV) to determine whether quantifiable pachychoroid features colocalize with disease foci. Patients with PCV diagnosed by indocyanine green angiography were identified for the analysis of medical records and multimodal imaging and classified as having peripapillary or macular PCV. The ratio of Haller layer thickness to total choroidal thickness was calculated at the fovea and at the site of dilated Haller vessels that showed spatial correlation with the origin of neovascularization. Choroidal thickness was measured horizontally across the fovea and circumferentially around the temporal side of the disk to study its relationship to neovascularization. Three hundred and fourteen eyes of 299 patients with PCV were identified, of which 17 eyes (5%) had peripapillary disease. Although eyes with peripapillary PCV exhibited thinner subfoveal choroids than those with macular PCV, at the extrafoveal disease foci, choroidal thickness, Haller's layer thickness, and its ratio to total choroidal thickness were relatively high. Quantitative indices of choroidal structure previously identified in macular PCV performed consistently when applied to a peripapillary PCV cohort, thus supporting the hypothesis that inner choroidal thinning and Haller vessel enlargement are mechanistically relevant to these related entities.

Polypoidal Choroidal Vasculopathy: Outer Retinal and Choroidal Changes and Neovascularization Development in the Fellow Eye.

We investigated the outer retinal, RPE, and choroidal changes and the development of choroidal neovascularization (CNV) in fellow eyes of patients with unilateral polypoidal choroidal vasculopathy or aneurysmal type 1 neovascularization (PCV/AT1). In this retrospective observational cohort study, 263 patients with unilateral PCV/AT1 were enrolled. Fundus photography, enhanced depth imaging optical coherence tomography, and indocyanine green angiography at baseline and follow-up were analyzed. Incidence and risk factors for the development of CNV were analyzed. In fellow eyes of unilateral PCV/AT1 cases, RPE and outer retinal abnormalities were observed in 222 (84%) eyes, and dilated Haller vessels (pachyvessel) were identified in the corresponding abnormality area in 157 (71%) eyes. Follow-up data were available for 233 patients. During a 27.6-month mean follow-up period, 20/233 (9%) eyes had CNV (12 PCV/AT1 and eight type 1 CNV). In 18 eyes (90%), CNV developed at the RPE or outer retinal abnormality areas accompanied by pachyvessel. A significantly higher risk for CNV was observed if RPE and outer retinal abnormalities were accompanied by pachyvessel (hazard ratio, 9.3; 95% confidence interval, 1.1-75.9, P = 0.037). RPE and outer retinal abnormalities were common in fellow eyes of patients presenting with unilateral PCV/AT1. CNV developed in fellow eyes of 9% of patients, frequently in the areas with RPE and outer retinal abnormality accompanied by pachyvessel.

Choroidal morphology under pachydrusen.

To reveal choroidal morphological profiles under pachydrusen. Drusen in pachychoroid disorders show certain differences from conventional drusen and are recently named as "pachydrusen." This study analysed the specific choroidal morphology under pachydrusen. This study is a cross-sectional case series. Enrolled were 136 eyes with pachydrusen from 134 patients. The presence of pachydrusen in fundus area covered by a 12 × 9 mm2 optical coherence tomography (OCT) image was accessed in eyes with pachychoroid-related diseases or their fellow eyes using colour fundus photography and swept source OCT. Choroidal morphology under the pachydrusen was analysed using OCT B-scans and en face images. Choroidal thicknesses and topographical correlation between pachydrusen and pachyvessels. A total of 225 pachydrusen in 136 eyes were analysed. The mean number of pachydrusen was 1.65 ± 1.07 per eye. Most pachydrusen were located para- or perifoveally (37 subfoveal, 86 parafoveal and 102 perifoveal). The proportion of Haller's layer to total choroidal thickness was higher at the area of the pachydrusen compared to the subfovea (0.881 ± 0.081 vs 0.765 ± 0.111, P < 0.001). In multimodal image analysis, 90.1% of pachydrusen identified using fundus photography and OCT B-scan were located at the area of a dilated Haller vessel (pachyvessel) seen on en face images. Choroidal morphology under the pachydrusen showed increased Haller's layer thickness with an attenuated choriocapillaris layer, which is the hallmark of pachychoroid definition. Topographically, their locations correlated with the underlying pachyvessel.

CLASSIFICATION OF HALLER VESSEL ARRANGEMENTS IN ACUTE AND CHRONIC CENTRAL SEROUS CHORIORETINOPATHY IMAGED WITH EN FACE OPTICAL COHERENCE TOMOGRAPHY

To compare the prevailing patterns of Haller vessel arrangements at the posterior pole between healthy eyes and those with central serous chorioretinopathy (CSC) using en face optical coherence tomography. Eyes of normal subjects and patients with acute or chronic CSC underwent optical coherence tomography imaging (RTVue 100; Optovue Inc, Fremont, CA). En face sections at the level of the Haller layer were classified by two masked graders into five mutually exclusive morphologic categories (temporal herringbone, branched from below, laterally diagonal, double arcuate, and reticular). The relative prevalence of each Haller vessel arrangement pattern was determined for each phenotype. Numbers of eyes examined were as follows: 154 eyes of 77 normal subjects; 41 eyes of 31 patients with acute CSC; and 39 eyes of 33 patients with chronic CSC. The mean age of participants was 44.4 ± 14.6 years for healthy subjects (M:F = 37:40), 48.5 ± 8.2 years (M:F = 24:7) for acute CSC, and 65.3 ± 13.1 years (M:F = 28:5) for chronic CSC. The relative prevalence of each Haller vessel arrangement pattern differed by phenotype. The temporal herringbone pattern was most prevalent in healthy eyes (49.2%), whereas a reticular pattern was most prevalent in eyes with acute and/or chronic CSC (combined, 48.8%). A significant difference was observed in the prevalence of respective Haller vessel arrangement patterns between eyes of normal subjects and those of patients with either acute or chronic CSC. Although further study is needed to determine the mechanistic factors underlying these differences, and the hemodynamic implications, our data suggest that en face optical coherence tomography may find a formal role in choroidal disease classification.

CHOROIDAL MORPHOLOGY IN EYES WITH POLYPOIDAL CHOROIDAL VASCULOPATHY AND NORMAL OR SUBNORMAL SUBFOVEAL CHOROIDAL THICKNESS.

To subsegment the choroid in patients with polypoidal choroidal vasculopathy and to determine whether the ratio of choriocapillaris/Sattler layer thickness to total choroidal thickness is decreased at sites of polypoidal pathology. Retrospective, observational, cross-sectional study. A total of 320 eyes of 305 patients with polypoidal choroidal vasculopathy were studied with optical coherence tomography and dye angiography. The ratio of choriocapillaris/Sattler layer thickness to total choroidal thickness was calculated at polypoidal lesion sites in eyes with subfoveal choroidal thickness (SFCT) ≤200 μm. Mean SFCT was 267.7 ± 118.5 μm for the entire cohort. Mean SFCT was 151.2 ± 35.0 μm in eyes with SFCT ≤200 μm (n = 124, 39%). In this subgroup, dilated Haller vessels (pachyvessels) were identified under the site of neovascular ingrowth in 117 eyes (94%). Choroidal thickness in the pachyvessel zone was greater (213.3 ± 52.2 μm) than SFCT (P < 0.001) with a significantly lower choriocapillaris/Sattler layer to total thickness ratio (P < 0.001). Qualitative alterations of the retinal pigment epithelium were observed in 60 eyes (51%). Eyes with normal or subnormal SFCT exhibited extrafoveal choroidal thickening at sites of polypoidal disease. The choriocapillaris and Sattler layers were attenuated at these locations, but Haller vessels were markedly dilated. These changes were topographically associated with sites of neovascular ingrowth and support the classification of polypoidal choroidal vasculopathy as a pachychoroid disorder.