Chronic choriocapillaris ischemia in dilated vortex vein region in pachychoroid neovasculopathy

Inversion of Asymmetric Vortex Vein Dilatation in Pachychoroid Spectrum Diseases

Purpose

Intervortex venous anastomosis is widely recognized as compensating for vortex vein congestion in pachychoroid spectrum diseases. However, determining the blood flow direction within the compensated drainage route is often challenging. Herein, we investigated the morphological patterns of vortex veins in eyes showing retrograde pulsatile vortex venous flow.

Design

Retrospective observational case series.

Subjects

Six hundred eighty-nine consecutive eyes with treatment-naive central serous chorioretinopathy, pachychoroid neovasculopathy, or polypoidal choroidal vasculopathy.

Methods

We reviewed the clinical records of patients with these pachychoroid spectrum diseases. Multimodal images including indocyanine green angiography (ICGA) and en face OCT were analyzed.

Main Outcome Measures

Intervortex venous anastomosis between superotemporal and inferotemporal vortex veins and the dominant site of dilated temporal vortex veins were determined in the eyes with retrograde pulsatile vortex venous flow in the temporal vortex veins.

Results

Twenty-two eyes with retrograde pulsatile vortex venous flow in the temporal vortex veins were identified utilizing early phase ICGA videos. In 9 eyes, retrograde pulsatile flow was detected in the superotemporal vortex veins, which were connected to the inferotemporal vortex veins via intervortex venous anastomoses. Among these cases, contralateral inferotemporal vortex vein dilatation was dominant in 7 eyes (77.8%), while superotemporal and inferotemporal vortex veins were symmetrically dilated in the other 2 eyes (22.2%). On the other hand, in 13 eyes, the retrograde pulsatile flow was detected in the inferotemporal vortex veins, which were linked to the superotemporal vortex veins via intervortex venous anastomoses. In these eyes, contralateral superotemporal vortex vein dilatation was dominant in 10 eyes (76.9%). Superotemporal and inferotemporal vortex veins were symmetrically dilated in 2 eyes (15.4%), while mainly inferotemporal vortex veins were dilated in 1 eye (7.7%).

Conclusions

In pachychoroid spectrum diseases, there are cases wherein congested venous blood might drain into the contralateral vortex veins via intervortex anastomoses. Overloaded contralateral vortex veins may, as a consequence, become more dilated than the primary congested vortex veins. Inversion of asymmetric vortex vein dilatation might thereby develop in pachychoroid spectrum diseases.

Financial Disclosures

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Pachychoroid disease: review and update

The pachychoroid disease spectrum is a phenotype characterized by alterations in choroidal vasculature which result in outer retinal and choriocapillaris damage and visual loss. The presence of pachyvessels is one of the key features of the pachychoroid phenotype. Recent imaging studies suggest that pachyvessels may form because of choroidal venous congestion in one or more quadrants. The formation of intervortex anastomosis may function as a compensatory mechanism to dissipate the increased venous pressure, while outflow obstruction has been hypothesized to occur at the site of the vortex vein exiting the sclera. This review aims to summarize recent imaging findings and discuss evolution in the understanding of pathogenesis of the pachychoroid disease spectrum. We have summarized notable treatment trials in central serous chorioretinopathy and polypoidal choroidal vasculopathy and included an update of the current diagnostic and management strategies of the entities that are part of the pachychoroid disease spectrum.

Understanding the relationship between pachychoroid spectrum disorders and retinitis pigmentosa: A review of the evidence

This study aims to investigate the relationship between pachychoroid spectrum disorders and retinitis pigmentosa (RP) or rod-cone dystrophy through a comprehensive literature review. The purpose is to explore the association between these disorders, understand their underlying mechanisms, and summarize the existing hypotheses and opinions. A thorough review of the literature was conducted using PubMed, focusing on articles related to central serous chorioretinopathy (CSC), RP, pachychoroid pigment epitheliopathy, pachychoroid neovasculopathy, polypoidal choroidal vasculopathy, focal choroidal excavation, peripapillary pachychoroid neovasculopathy, and peripheral exudative hemorrhagic chorioretinopathy. Relevant studies were selected for a detailed narrative review and analysis. Several studies have reported the coexistence of CSC and RP, indicating a potential association between the two conditions. The dysfunction of the retinal pigment epithelium is proposed as a common factor. Choroidal thinning is observed in RP, but conflicting results exist regarding choroidal thickness (CT). While some studies support choroidal thinning in RP, others suggest preserved or increased thickness. Additionally, cases of pachychoroid neovasculopathy and polypoidal choroidal vasculopathy in RP have been reported, suggesting an overlap between these conditions. The literature suggests conflicting reports on CT changes in RP. Future research should focus on large-scale studies using comprehensive imaging techniques, genetic analysis, and long-term follow-up to uncover the underlying mechanisms and determine the prevalence of pachychoroid spectrum disorders in RP patients.

Clinical Characteristics of Unilateral Macular Neovascularization Patients with Pachydrusen in the Fellow Eye

Background/Objectives: To approach the clinical properties of pachydrusen that differ from conventional drusen, we investigated the incidence of macular neovascularization (MNV) in fellow eyes and the treatment outcomes of intravitreal aflibercept (IVA) in MNV eyes of unilateral MNV patients with pachydrusen in the fellow eye. Methods: We retrospectively studied 261 consecutive patients with treatment-naïve unilateral MNV. Patients were classified into four groups according to the type of drusen in the fellow eye: the pachydrusen group (n = 49), the soft drusen group (n = 63), the subretinal drusenoid deposit (SDD) group (n = 24), and the no drusen group (n = 125). The development of the MNV in the fellow eye was evaluated for five years, and the retreatment proportion after three monthly aflibercept injections was evaluated for one year. Results: The choroidal thickness in the fellow eyes and MNV eyes was the greatest in the pachydrusen group (all p < 0.001). The 5-year incidence of MNV in the pachydrusen group was similar to that in the soft drusen group and no drusen group. The pachydrusen group had a lower retreatment rate than the other groups did (pachydrusen group: 46.4%; soft drusen group: 78.1%; SDDs: 87.5%; no drusen group: 83.3%). Conclusions: Unilateral MNV patients with pachydrusen in the fellow eye had a lower retreatment rate (46.4%/1 year); therefore, aflibercept monotherapy using the PRN regimen is one of the preferred treatment methods for MNV patients with pachydrusen in the fellow eye.

Qualitative and quantitative comparisons of type 1 macular neovascularizations between pachychoroid neovasculopathy and neovascular age-related macular degeneration using optical coherence tomography angiography

OBJECTIVES

To compare qualitative and quantitative features of type 1 macular neovascularizations (MNV) in pachychoroid neovasculopathy (PNV) and neovascular age-related macular degeneration (nAMD).

METHODS

Forty-three treatment-naive eyes of 41 PNV patients and 40 treatment-naive eyes of 38 patients with nAMD were included. The patients were classified as PNV or nAMD according to the presence of pachychoroid features and soft/reticular drusen. Presence of central trunk and maturity of the MNV were evaluated on optical coherence tomography angiography (OCTA) images. MNV area, vessel density (VD), total vessel length (VL), number of intersection points (IPs), fractal dimension (FD), and lacunarity (LAC) were calculated using ImageJ software and FracLac plugin.

RESULTS

The mean age was 56.8 ± 8.7 years in PNV and 70.4 ± 8.8 years in neovascular AMD groups (p < 0.001). Compared to nAMD, the presence of central trunk was less frequent in PNV (48.8% vs 77.5%, p = 0.007). Immature MNV pattern was observed more frequently in PNV eyes than nAMD (41.9% vs 20.0%, p = 0.009). PNV cases had significantly lower median MNV area [0.913(1.115) vs 2.542(3.273) mm²], total VL [14.84 (20.46) vs 36.34 (44.68) mm], number of IPs [104(140) vs 335(417.3)], and FD [1.56(0.10) vs 1.59(0.11)] comparing to nAMD cases (p < 0.001, p = 0.001, p < 0.001, p = 0.043 respectively). However, the mean VD (42.4 ± 6.8 vs 42.9 ± 9.0%) and the median LAC values [0.42 (0.09) vs 0.42 (0.09)] did not differ significantly between groups (p = 0.776, p = 0.526, respectively).

CONCLUSION

Morphological and quantitative differences exist in type 1 neovascular lesions. Type 1 MNVs in the PNV group are characterized by a smaller and less complex structure.

Pro re nata anti-VEGF treatment in pachychoroid neovasculopathy compared with age-related macular degeneration based on optical coherence tomography

PURPOSE

To compare anti-vascular endothelial growth factor (anti-VEGF) treatment in pachychoroid neovasculopathy (PNV) and age related macular degeneration (AMD).

METHODS

Cases having pro re nata (PRN) anti-VEGF treatment for choroidal neovascularization were reviewed and grouped as PNV and AMD. Groups were compared according to central foveal thickness (CFT), best corrected visual acuity (BCVA), and total injection over 12 months. The correlation of beginning choroidal thickness, CFT, and BCVA with final BCVA was analyzed.

RESULTS

Forty-seven PNV and 65 AMD cases were reviewed. Both the PNV group (p = 0.0001) and the AMD group (p = 0.003) had a significant improvement in BCVA and a significant decrease in CFT (p = 0.0001). However, BCVA was better at the 3-, 6-, and 12-month follow-up in PNV (p = 0.003, 0.002, 0.02). No significant CFT difference was observed between groups. The total number of injections was 5.7 ± 1.7 for PNV and 5.2 ± 1.5 for AMD (p = 0.09). Beginning BCVA was positively correlated with final BCVA in both groups.

CONCLUSION

The PRN treatment regimen was effective for PNV and AMD in terms of visual and anatomical outcomes. Visual response was better in PNV with PRN treatment with the same number of injections.

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.

Attenuation of irradiated choroid and its regional vortex veins in central serous chorioretinopathy after photodynamic therapy

We retrospectively studied 12 eyes of 12 patients with central serous chorioretinopathy (CSC) to investigate choroidal thickness changes following half-fluence photodynamic therapy (PDT) using widefield choroidal thickness maps obtained by optical coherence tomography (OCT). Additionally, we assessed the relationship between choroidal thickness changes and the regional vortex veins as visualized on widefield en face OCT of the choroid. Pre-treatment en face images of the choroidal vasculature were superimposed on subtracted choroidal thickness maps before and 3 months after half-fluence PDT. The choroidal thickness decreased mainly in the irradiated macular area and in the region of vortex veins which function as drainage for the macula in all eyes. Eleven eyes (91.7%) showed choroidal thinning in the nasal area which overlapped with the nasal vortex vein distribution. Moreover, in 10 (90.9%) of those eyes, we observed intervortex venous anastomosis across the vertical watershed zone. Quantitative analysis revealed that the reduction in choroidal thickness was most pronounced in the macular area. Furthermore, the choroidal thickness reduction in the area with macular drainage vortex veins was significantly greater than that in the area without such vortex veins. These results suggest that half-fluence PDT might decrease choroidal thickness due to choriocapillaris occlusion in the irradiated macula, possibly leading to diminished venous drainage from the macula to regional vortex veins. Moreover, venous blood flow through the anastomotic vessels from the macular drainage vortex veins into the nasal vortex veins might be reduced post-treatment.

Pachychoroid neovasculopathy has clinical properties that differ from conventional neovascular age-related macular degeneration

To determine the clinical properties of pachychoroid neovasculopathy (PNV) that differ from conventional neovascular age-related macular degeneration (nAMD) and suggest that they are different clinical entities. To accomplish this, we reviewed the medical records of 100 consecutive patients diagnosed with nAMD. All of the patients were Japanese, and their mean age was 75.5 years. There were 72 men and 28 women. For the bilateral cases, only the right eye was analyzed. An eye was diagnosed with PNV when a macular neovascularization (MNV) was detected just above the dilated choroidal vessels. The Indocyanine green angiographic (ICGA) and en face optical coherence tomographic (OCT) images were used to assess the vertical symmetry of the medium and large choroidal vessels. The subfoveal choroidal thickness (SCT) was also measured manually in the OCT images. After reclassification, there were 29 (29%) patients with typical nAMD (25 with type 1 MNV, 4 with type 2 MNV), 43 (43%) with PNV, 21 (21%) with polypoidal choroidal vasculopathy, and 7 (7%) with retinal angiomatous proliferation. Of the 43 PNV, 17 (39.5%) had polypoidal lesions and 26 (60.5%) had no polypoidal lesions. The percentage of eyes with vertical asymmetry of the medium and large choroidal vessels was significantly greater in the 35 PNV (81.4%) than in the 16 non-PNV (28.1%; P < 0.01) cases. The mean SCT was significantly thicker in the PNV eyes than in the non-PNV eyes (298 ± 96 μm vs. 228 ± 82 μm; P < 0.01). The response of PNV to anti-vascular endothelial growth factor treatments was better than that of non-PNV eyes [higher dry macula rate after the loading period (90.9% vs. 59.1%), fewer total number of injections (11.0 ± 2.9 vs. 13.4 ± 3.2), and longer treatment intervals for the anti-VEGF therapy (8.4 ± 3.1 vs. 13.4 ± 3.2 weeks) at 2 years (all P < 0.01)]. These differences in the morphology and response to anti-VEGF treatments suggest that PNV is a separate clinical entity to conventional nAMD.

Scleral Thickness as a Risk Factor for Central Serous Chorioretinopathy and Pachychoroid Neovasculopathy

In the pathophysiology of central serous chorioretinopathy (CSC), scleral changes inducing increased venous outflow resistance are hypothesized to be involved. This work aims to investigate anterior scleral thickness (AST) as a risk factor for pachychoroid disorders. A randomized prospective case-control study was performed at the Ludwig Maximilians University, Department of Ophthalmology. In patients with CSC or pachychoroid neovasculopathy (PNV) and in an age- and refraction-matched control group, swept source optical coherence tomography (SS-OCT) was used to measure anterior scleral thickness (AST). Subfoveal choroidal thickness (SFCT) was assessed using enhanced depth imaging OCT (EDI-OCT). In total, 46 eyes of 46 patients were included in this study, with 23 eyes in the CSC/PNV and 23 eyes in the control group. A significantly higher AST was found in the CSC/PNV compared with the control group (403.5 ± 68.6 (278 to 619) vs. 362.5 ± 62.6 (218 to 498) µm; p = 0.028). Moreover, the CSC/PNV group showed a higher SFCT (392.8 ± 92.8 (191-523) vs. 330.95 ± 116.5 (167-609) µm, p = 0.004). Compared with the age- and refraction-matched controls, patients with CSC and PNV showed a significantly thicker anterior sclera. Scleral thickness might contribute to the venous overload hypothesized to induce pachychoroid phenotypes.

Quadrant laser photocoagulation trial to ameliorate choroidal congestion in central serous chorioretinopathy

PURPOSE

To investigate the efficacy and safety of quadrant laser photocoagulation to ameliorate the choroidal congestion in central serous choroidopathy (CSC).

STUDY DESIGN

Historically controlled study.

METHODS

We prospectively studied 20 eyes with acute CSC in the quadrant laser group, in which laser photocoagulation was applied to the macular leakage point(s) as well as the quadrant of the fundus showing vortex vein dilatation. Central choroidal thickness (CCT), vertical diameter of dilated vortex vein, resolution rate of serous retinal detachment (SRD), and visual field were evaluated post-treatment. We also compared the results with those of 18 retrospectively analyzed eyes with acute CSC in an external control group, in which laser photocoagulation had been applied only to the macular leakage point(s).

RESULTS

In the quadrant laser group, 2 eyes were excluded from data analysis due to choroidal neovascularization (CNV). CCT was significantly reduced in both groups, but more significantly in the quadrant laser group. The vertical diameter of the dilated vortex vein was significantly decreased only in the quadrant laser group. The resolution rate of SRD was similar in the two groups. In the quadrant laser group, 8 eyes (44.4%) showed mild deterioration of the visual field, consistent with the area subjected to quadrant laser photocoagulation.

CONCLUSION

Quadrant laser photocoagulation can have limited efficacy for ameliorating vortex vein congestion in CSC. When laser photocoagulation to the macular area is combined with quadrant laser photocoagulation, attention must be paid to the possible development of CNV and visual field deterioration.

Dilated choroidal vascular channels in pachychoroid neovasculopathy

BACKGROUND

To elucidate the pattern of the choroidal vasculature in exudative pachychoroid neovasculopathy (PNV) and its correlation with the clinical course and treatment outcomes.

METHODS

The retrospective study included consecutive patients in National Taiwan University Hospital between 2014 and 2020 who fulfilled the criteria for exudative PNV defined as active type 1 macular neovascularization (MNV) on optical coherence tomography angiography (OCTA) and with leakage on fluorescein angiography (FA) or indocyanine green angiography (ICGA) associated with pachychoroid features. The corrected distance visual acuity (CDVA), FA, ICGA, and OCT images obtained by Optovue (Optovue Inc, Freemont CA, USA) spectral domain OCT were evaluated at baseline and various time points during the 12-month treatment period. The correlations between the choroidal vascular patterns, specifically those with or without dilated choroidal vascular channels (DCVC) revealed by ICGA, and baseline characteristics and treatment outcomes were evaluated using multiple regression models.

RESULTS

The study enrolled 34 eyes of 31 patients. The average age was 59.0 ± 9.3 years, and 20 participants were men. ICGA revealed DCVCs in 21 eyes, while the remaining 13 eyes did not have DCVCs. At baseline, DCVC group was older (p = 0.03) and had a longer duration of visual symptoms (p = 0.02), with a higher vessel density (defined as the percentage of the measured area occupied by flow area) of MNV (p = 0.04), higher proportion of ellipsoid zone disruption (p = 0.01), and poorer CDVA (p = 0.03). After the 12-month treatment period, the frequency of requirement of anti-VEGF injections (p < 0.01) was higher, and the risk for CDVA <20/40 was higher (adjusted OR: 5.29, 95% CI: 1.24-22.48, p = 0.02) in eyes with DCVCs.

CONCLUSIONS

For PNV, eyes with DCVCs were associated with higher vessel density of macular neovascularization and poorer CDVA at baseline, and had poorer visual and anatomical outcomes although more anti-VEGF injections were given.

Vortex vein congestion in the monkey eye: A possible animal model of pachychoroid

Purpose

To create vortex vein congestion in the monkey eye as a possible pachychoroid model.

Methods

We ligated superotemporal and inferotemporal vortex veins at the surface of the sclera in monkey eyes. Optical coherence tomography (OCT) and indocyanine green angiography (ICGA) were performed before and 2, 7, and 28 days after the vortex vein ligations to investigate changes in vortex vein morphology and alterations in choroidal blood flow.

Results

Before the vortex vein ligations, en face OCT and ICGA images showed well organized vortex veins as well as horizontal and vertical watershed zones. Two days after the vortex vein ligations, dilatation of the superotemporal and inferotemporal vortex veins as well as intervortex venous anastomoses were seen on en face OCT and ICGA images. B-mode OCT images showed choroidal thickening associated with dilatation of the outer choroidal vessels. Moreover, video ICGA revealed choriocapillaris filling delay and pulsatile flow in the dilated vortex veins. At 7 and 28 days after we ligated the vortex veins, these findings were reduced, except for the intervortex venous anastomoses.

Conclusions

We created a monkey model of vortex vein congestion by ligating two vortex veins. This animal model demonstrated pachychoroid-related findings, indicating that vortex vein congestion is involved in the pathogenesis of pachychoroid. However, remodeling of the choroidal drainage route via intervortex venous anastomosis appeared to compensate for the vortex vein congestion created in this model.

Relationship between Pachychoroid and Polypoidal Choroidal Vasculopathy

Previous clinical studies have suggested that pachychoroid can induce macular neovascularization (MNV) to develop pachychoroid neovasculopathy (PNV) and that PNV can progress to polypoidal choroidal vasculopathy (PCV). Recent studies based on the pachychoroid concept are now gradually revealing the true nature of, at least some part of, PCV. However, previous studies on PNV and/or PCV have used different frameworks for the classification of PNV, PCV, and neovascular age-related macular degeneration (nAMD). These have hampered the rapid overhaul of the understanding of PCV. Some investigators have assumed that all PCV is pachychoroid-driven whereas other investigators have classified PCV into “pachychoroid PCV” and “non-pachychoroid PCV”. Furthermore, since there is no consensus as to whether PNV includes PCV, some studies have included PCV with PNV, while other studies have excluded PCV from PNV. To address these gaps, we summarize previous studies on PCV and pachychoroid. Even before the proposal of the pachychoroid concept, previous studies had suggested that PCV could be divided into two subtypes, of which one was characterized by pachychoroid features. Previous studies had also provided keys to understand relationship between PCV and PNV. We here recommend a refined conceptual framework for future studies on PNV, PCV, and nAMD. Considering the current inconsistent understanding of PCV, we should be cautious about using the term PCV until we understand the true nature of PCV.

Choriocapillaris Flow Imbalance in Fellow Eyes in Age-Related Macular Degeneration

Purpose

The purpose of this study was to identify early changes in choriocapillaris flow in patients with age-related macular degeneration (AMD) with no history of macular neovascularization (MNV).

Methods

Clinical records of fellow eyes of patients with unilateral neovascular AMD without fundus findings and control eyes of otherwise healthy individuals, except for mild cataract, diagnosed at St. Luke's International Hospital from April 2020 to March 2021, were retrospectively analyzed. Optical coherence tomography (OCT) angiography images of the choriocapillaris slab were binarized using the Phansalkar local thresholding methods to evaluate the choriocapillaris flow area (CCFA) and its coefficient of variation (CV).

Results

The data of 24 AMD fellow eyes (17 for men, 71.7 ± 1.9 years old) and 21 control eyes (11 for men, 69.1 ± 2.0 years old) were analyzed. The mean CCFA ratio was lower in the AMD fellow eyes (58.6 ± 1.2%) than in the control eyes (62.4 ± 1.3%, P = 0.032), and the mean CV of CCFA ratio was greater in the AMD fellow eyes (0.174 ± 0.007) than in the control eyes (0.154 ± 0.007, P = 0.032). Eyes with CCFA ratio <60% and CV of CCFA ratio ≥0.154 had a 4.371-fold higher risk of being AMD fellow eyes (95% confidence interval = 1.029–18.56, P = 0.046). Differences in CV of CCFA ratio between AMD fellow eyes and control eyes were particularly clear in eyes with thick choroids (mean CV of CCFA in control versus AMD fellow eyes with central choroidal thickness ≥220 µm: 0.144 ± 0.005 vs. 0.173 ± 0.007, P = 0.009**).

Conclusions

Neovascular AMD fellow eyes without MNV had reduced, heterogeneous, and imbalanced choriocapillaris flow, which may constitute early changes in neovascular AMD, although further studies are required.

A new insight into pachychoroid diseases: Remodeling of choroidal vasculature

Purpose

Pachychoroid spectrum diseases are regarded as being different manifestations of a common pathogenic process. We suggest that pachychoroid diseases are consequences of chronic vortex vein stasis.

Methods

We describe how we came to this conclusion based on our own recent reports as well as a search of the related literature.

Results

Central serous chorioretinopathy (CSC) is the first stage of pachychoroid spectrum diseases. CSC is caused by congestion of choroidal veins, which are branches of the vortex veins. The venous outflow tract of the choroid is divided into four quadrants, based on horizontal and vertical watershed zones, with one or two vortex veins in each quadrant being independently responsible for venous outflow. In acute CSC, vortex vein stasis frequently causes asymmetric dilatation of the vortex veins in the horizontal watershed. The area of geographic filling delay in the choriocapillaris coincides with the area of this asymmetrically dilated vortex veins. With chronic stasis of the vortex veins, venous anastomosis occurs in the watershed zone as a means of compensating for the stasis, and the choriocapillaris becomes occluded in the area of filling delay. The anastomotic vessels dilate, becoming often hyperpermeable, and are then recognizable as pachyvessels. With the development of choriocapillaris ischemia, choroidal neovascularization (CNV) occurs at the site of pachyvessels. This is termed pachychoroid neovasculopathy (PNV). Polypoidal choroidal vasculopathy is regarded as a variant of PNV.

Conclusions

Intervortex venous anastomosis is among the key factors underlying the development of pachychoroid diseases. Remodeling of the venous drainage route though the anastomosis across the watershed zones is apparently a common response to chronic vortex vein stasis.

Clinical characteristics and pachychoroid incidence in Japanese patients with neovascular age-related macular degeneration

The phenotypes of neovascular age-related macular degeneration (nAMD) are recognized as differing between Caucasian and Asian patients. Pachychoroid is thought to be more prevalent in Asians than in Caucasians, and may be involved in the development of nAMD in Asian patients. Therefore, we investigated the clinical characteristics and pachychoroid incidence in Japanese patients with nAMD. We retrospectively analyzed 385 eyes of 370 consecutive Japanese patients with treatment naïve nAMD. According to the nAMD nomenclature, type 1 macular neovascularization (MNV) was observed in 132 eyes (34.3%), polypoidal choroidal vasculopathy (PCV) in 137 (35.6%), mixed type 1 and type 2 MNV in 32 (8.3%), type 2 MNV in 43 (11.2%), and type 3 MNV in 41 (10.6%). Pachychoroid was seen in 58.3% of type 1 MNV, 75.2% of PCV, 34.4% of mixed type 1 and type 2 MNV, 14.0% of type 2 MNV, and 0% of type 3 MNV. Compared to nAMD patients without pachychoroid (188 eyes), those who had nAMD with pachychoroid (197 eyes) were significantly younger, had a higher proportion of males, greater central choroidal thickness, and a higher frequency of macular vortex vein anastomoses (all P < 0.001). Furthermore, drusen subtypes differed significantly between the two groups (P < 0.001). These results suggest that most Japanese nAMD patients might have type 1 MNV or PCV. Moreover, in approximately half of patients, nAMD might be associated with pachychoroid, and choroidal congestion may be involved in the development of MNV in these cases.