CHANGES IN OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY AND DISEASE ACTIVITY IN TYPE 3 NEOVASCULARIZATION AFTER ANTI–VASCULAR ENDOTHELIAL GROWTH FACTOR TREATMENT

Review of type 3 macular neovascularization in age-related macular degeneration: no DRAMA (Deep Retinal Age-related Microvascular Anomalies)

Type 3 macular neovascularization (MNV) is a unique form of neovascular age-related macular degeneration (AMD) that presents distinct pathogenetic features, clinical manifestations, and prognostic considerations when compared to types 1 and 2 MNV. Insights gained from clinicopathological correlations, bridging in vivo examination techniques with ex vivo histological analysis, have significantly enhanced our comprehension of this MNV phenotype, shaped current management strategies and influenced future directions for therapeutics. The particularities of type 3 MNV, which may largely stem from its origin from the retinal vasculature, are critically important for predicting the disease course. Our current understanding suggests that type 3 MNV occurs in response to retinal pigment epithelium (RPE) disruption and photoreceptor loss when neovessels originating from the deep capillary plexus are accompanied by activated Müller glia as they infiltrate sub-retinal pigment epithelium basal laminar deposits. Dysregulation of angiogenic and angiostatic factors are thought to play a key role in its pathogenesis. The prognosis for type 3 MNV is likely bilateral involvement and progression towards macular atrophy. It may be imperative for practitioners to distinguish type 3 MNV from other mimicking pathologies such as intraretinal microvascular anomalies, which are also part of the type 3 disease spectrum. For instance, deep retinal age-related microvascular anomalies (DRAMA) may present with similar features on multimodal imaging yet may necessitate distinct management protocols. Distinguishing between these conditions may be vital for implementing tailored treatment regimens and improving patient outcomes in the diverse landscape of AMD phenotypes in the future.

Current Perspectives on Type 3 Macular Neovascularization due to Age-Related Macular Degeneration

BACKGROUND

The aim of this review was to systematically summarize the current knowledge on type 3 macular neovascularization (MNV3) in age-related macular degeneration (AMD).

SUMMARY

Recent histopathologic and multimodal imaging findings led to the consensus definition of the new term "type 3 macular neovascularization" in AMD. MNV3 originates in the deep vascular plexus as a neovascular process without connection with the retinal pigment epithelium in the initial stages. This type has numerous clinical and pathomorphologic features that separate it from the other two types of MNV in AMD. Besides, its frequency appears to be higher than previously thought. In optical coherence tomography (OCT), MNV3 can be classified into stages 1-3. Hyperreflective foci in the outer retina possibly represent a precursor lesion. In addition, MNV3 is characterized by a strong association with reticular pseudodrusen, a high rate of bilaterality, close associations with advanced age and arterial hypertension, decreased choroidal thickness, and decreased choriocapillaris flow signals. Data from latest anti-vascular endothelial growth factor studies in MNV3 suggest that the OCT biomarkers in intraretinal and subretinal fluids should be interpreted differently than in the other types. Additionally, data from MNV3 eyes should be analyzed separately, allowing optimal type-specific treatment strategies in the future.

KEY MESSAGES

This review highlights the need for accurate characterization of neovascular AMD lesions and an MNV type-specific approach, particularly for MNV3.

Histology of type 3 macular neovascularization and microvascular anomalies in treated age-related macular degeneration: a case study

Purpose

To investigate intraretinal neovascularization and microvascular anomalies by correlating in vivo multimodal imaging with corresponding ex vivo histology in a single patient.

Design

A case study comprising clinical imaging from a community-based practice, and histologic analysis at a university-based research laboratory (clinicopathologic correlation).

Participants

A White woman in her 90s treated with numerous intravitreal anti-VEGF injections for bilateral type 3 macular neovascularization (MNV) secondary to age-related macular degeneration (AMD).

Methods

Clinical imaging comprised serial infrared reflectance, eye-tracked spectral-domain OCT, OCT angiography, and fluorescein angiography. Eye tracking, applied to the 2 preserved donor eyes, enabled the correlation of clinical imaging signatures with high-resolution histology and transmission electron microscopy.

Main Outcome Measures

Histologic/ultrastructural descriptions and diameters of vessels seen in clinical imaging.

Results

Six vascular lesions were histologically confirmed (type 3 MNV, n = 3; deep retinal age-related microvascular anomalies [DRAMAs], n = 3). Pyramidal (n = 2) or tangled (n = 1) morphologies of type 3 MNV originated at the deep capillary plexus (DCP) and extended posteriorly to approach without penetrating persistent basal laminar deposit. They did not enter the subretinal pigment epithelium (RPE)-basal laminar space or cross the Bruch membrane. Choroidal contributions were not found. The neovascular complexes included pericytes and nonfenestrated endothelial cells, within a collagenous sheath covered by dysmorphic RPE cells. Deep retinal age-related microvascular anomaly lesions extended posteriorly from the DCP into the Henle fiber and the outer nuclear layers without evidence of atrophy, exudation, or anti-VEGF responsiveness. Two DRAMAs lacked collagenous sheaths. External and internal diameters of type 3 MNV and DRAMA vessels were larger than comparison vessels in the index eyes and in aged normal and intermediate AMD eyes.

Conclusions

Type 3 MNV vessels reflect specializations of source capillaries and persist during anti-VEGF therapy. The collagenous sheath of type 3 MNV lesions may provide structural stabilization. If so, vascular characteristics may be useful in disease monitoring in addition to fluid and flow signal detection. Further investigation with longitudinal imaging before exudation onset will help determine if DRAMAs are part of the type 3 MNV progression sequence.

Financial Disclosures

Proprietary or commercial disclosure may be found after the references.

Impact of macular fluid features on outcomes of anti-vascular endothelial growth factor treatment for type 3 macular neovascularization

We evaluated the impact of macular fluid features on visual and anatomical outcomes in type 3 macular neovascularization (MNV) patients treated with anti-vascular endothelial growth factor (VEGF). We retrospectively enrolled 89 eyes with type 3 MNV with at least 12 months of follow-up. All patients were treatment-naïve and received a monthly loading injection of anti-VEGF for three months, followed by further injections as required. The association of baseline macular morphology, including intraretinal fluid (IRF) and subretinal fluid (SRF), with visual and anatomical outcomes was analyzed. At baseline, IRF was present in all enrolled patients (100%), and SRF was present in 43.8% (39/89) of them. After 12 months of treatment, no significant difference was found in terms of best-corrected visual acuity (BCVA) and changes in central foveal thickness between the eyes with (39) and without (50) SRF at baseline. In addition, the proportion of improved or worsened (gain or loss of more than three lines in the BCVA) visual acuity at 12 months was not significantly different among the groups. Incidence of macular atrophy during the treatment showed no difference between the groups, regardless of the presence of SRF. In conclusion, the macular fluid morphology, specifically SRF, in type 3 MNV showed no significant correlation with visual and anatomical outcomes during anti-VEGF treatment.

Clinical Pathological Features and Current Animal Models of Type 3 Macular Neovascularization

Type 3 macular neovascularization (MNV3), or retinal angiomatous proliferation (RAP), is a distinct type of neovascular age-related macular degeneration (AMD), which is a leading cause of vision loss in older persons. During the past decade, systematic investigation into the clinical, multimodal imaging, and histopathological features and therapeutic outcomes has provided important new insight into this disease. These studies favor the retinal origin of MNV3 and suggest the involvement of retinal hypoxia, inflammation, von Hippel–Lindau (VHL)–hypoxia-inducible factor (HIF)–vascular endothelial growth factor (VEGF) pathway, and multiple cell types in the development and progression of MNV3. Several mouse models, including the recently built Rb/p107/Vhl triple knockout mouse model by our group, have induced many of the histological features of MNV3 and provided much insight into the underlying pathological mechanisms. These models have revealed the roles of retinal hypoxia, inflammation, lipid metabolism, VHL/HIF pathway, and retinoblastoma tumor suppressor (Rb)–E2F cell cycle pathway in the development of MNV3. This article will summarize the clinical, multimodal imaging, and pathological features of MNV3 and the diversity of animal models that exist for MNV3, as well as their strengths and limitations.

Nonexudative morphologic changes of neovascularization on optical coherence tomography angiography as predictive factors for exudative recurrence in age-related macular degeneration

PURPOSE

To evaluate morphologic changes of choroidal neovascularization (CNV) on optical coherence tomography angiography (OCTA) during the nonexudative period and to correlate the features and timing of recurrence in neovascular age-related macular degeneration. (AMD).

METHODS

Two hundred thirty-eight eyes with type 1 CNV were retrospectively reviewed. For cases with exudative recurrence, OCTA images were tracked for analysis between the recurrences. Qualitative parameters of morphologic changes of CNV on OCTA, including tiny branching vessels, anastomotic loops, peripheral vascular arcade, and perilesional halo, were correlated with the features of exudative recurrence.

RESULTS

Exudative recurrence was identified in 163 cases, and among them, nonexudative morphological changes in CNV were identified using OCTA in 45 cases. For the cases with nonexudative changes on OCTA, exudative recurrence eventually developed within 0.5-3.5 months (mean, 2.3 ± 2.0 months) after identifying morphologic changes OCTA. The following changes in CNV were revealed on OCTA: tiny branching vessels in 53.3% (24/45) of cases, anastomotic loops in 40.0% (18/45), peripheral vascular arcades in 44.4% (20/45), and perilesional halo in 35.6% (16/45). Among the morphologic parameters, development of tiny branching vessels was significantly associated with early exudative recurrence (1.5 ± 1.2 months, p = 0.019), higher incidence of intraretinal fluid (IRF) (p = 0.016), and subretinal or subretinal pigment epithelial hemorrhage (p = 0.023) at recurrence, compared with other morphologic changes.

CONCLUSION

Development of tiny branching vessels of CNV on OCTA during the nonexudative period was associated with early exudative recurrence, including IRF or hemorrhage. Identifying the nonexudative changes of CNV on OCTA might predict exudative recurrence and provide additional parameters for monitoring neovascular AMD.

Longitudinal assessment of type 3 macular neovascularization using three-dimensional volume-rendering OCTA

OBJECTIVE

To investigate the evolution of treatment-naive type 3 macular neovascularization (MNV) undergoing anti-vascular endothelial growth factor (VEGF) treatment through volume rendered three-dimensional (3D) optical coherence tomography angiography (OCTA).

DESIGN

Retrospective observational study.

PARTICIPANTS

Patients with type 3 MNV and age-related macular degeneration (AMD).

METHODS

Included subjects had three loading injections of an anti-VEGF agent. The OCTA volume data at baseline and follow-up were processed with a previously published algorithm in order to obtain a volume-rendered representation of type 3 MNV. Progressive changes in type 3 lesions were analyzed via 3D OCTA volume rendering.

RESULTS

A total of 14 treatment-naive eyes with type 3 MNV from 11 AMD patients (7 females) were included. At both baseline and follow-up visits, a type 3 MNV complex was identifiable. Each complex was composed of a mean number of 2.5 ± 0.7 vascular branches at baseline and 1.4 ± 0.6 at the follow-up visit (p < 0.0001). The mean changes in central macular thickness and visual acuity were significantly correlated with modifications in the number of type 3 MNV branches (ρ = -0.533, p = 0.049, and ρ = -0.581, and p = 0.040, respectively).

CONCLUSIONS

This study demonstrated that type 3 lesions do not disappear completely after loading treatment, as indicated previously by histopathologic studies. Importantly, quantitative volume changes in type 3 lesions are directly associated with treatment response.

Assessing the long-term evolution of type 3 neovascularization in age-related macular degeneration using optical coherence tomography angiography

PURPOSE

To analyze the evolution of type 3 neovascularization in eyes with age-related macular degeneration during anti-vascular endothelial growth factor (VEGF) treatment using optical coherence tomography angiography (OCTA) analysis.

METHODS

Forty-one treatment-naïve eyes (37 patients) with type 3 neovascularization were retrospectively included in the study. The growth and morphological changes in the type 3 lesions, which were recorded using OCTA, were compared across time.

RESULTS

The high-flow signal of the lesion on OCTA was significantly increased at the sub-retinal pigment epithelium (RPE) and the choriocapillaris during anti-VEGF treatment. The detection rate of the flow signal in the sub-RPE increased from 50.0% at baseline and 51.2% at 12 months to 65.9% at 24 months (P = 0.013). The flow signal extending into the choriocapillaris was detected in 0% of the eyes at baseline, 9.8% of the eyes at 12 months, and 17.1% of the eyes at 24 months (P = 0.018). The presence of subretinal drusenoid deposits (SDD) was significantly more frequent in the group with extension into the choriocapillaris (100%) than in the group without (61.8%, P = 0.036). For the four eyes with extension into the choroid, the morphological feature of the lesion on en face OCTA evolved into a tangled vascular network, similar to type 1 neovascularization.

CONCLUSION

OCTA analysis revealed that type 3 neovascularization gradually extended downward toward the sub-RPE and choroid during anti-VEGF treatment. The extension of the lesion into the choriocapillaris, suggesting retinal-choroidal anastomosis, was significantly more frequent in eyes with SDD.

The long-term effects of anti-vascular endothelial growth factor therapy on the optical coherence tomography angiographic appearance of neovascularization in age-related macular degeneration

Background

The short-term effects of anti-vascular endothelial growth factor (anti-VEGF) treatment on macular neovascularization (MNV) morphology is well described, but long-term studies on morphologic changes and correlation of such changes to the type of MNV have not been conducted. This study aims to determine if different types of MNVs in neovascular AMD (nAMD) behave differently with anti-VEGF treatment as visualized on optical coherence tomography angiography (OCTA).

Methods

Treatment-naïve nAMD patients were retrospectively screened for baseline and follow-up OCTA imaging 10 or more months after initial treatment. Images were graded for MNV type, area, activity, mature versus immature vessels, vessel density, presence of atrophy, atrophy location and area. Growth rate was calculated as the percent change in lesion area from baseline over the years of follow-up. In addition, the occurrence of complete regression and the percent of lesions that grew, remained stable, and shrunk per type was also evaluated.

Results

Forty-three eyes from 43 patients with a mean follow-up of 2 years were evaluated. On structural OCT, 26 lesions were classified as pure type 1 MNVs, 12 MNVs had a type 2 component, and 5 MNVs had a type 3 component. Of these cases, 2 mixed-type MNVs were considered to have completely regressed. There was no significant differences in MNV area and growth rate between type 1 and type 2 lesions, but all cases of type 3 lesions shrunk in the follow-up period. There was no correlation between the number of injections per year and growth rate, endpoint MNV area or endpoint activity status for any MNV type. There was no significant association between the development of atrophy and the number of injections, baseline MNV area, baseline vessel density, or lesion growth rate.

Conclusions

In nAMD, complete regression of an MNV network exposed to anti-VEGF is rare. This work emphasizes the role of anti-VEGF as anti-leakage rather than vascular regression agents in nAMD.

Optical Coherence Tomography Findings (SD-OCT and OCTA) in Early-Stage Type 3 Neovascularization

A 76-year-old male presented with a small hyperreflective density in the outer nuclear layer with subtle retinal pigment epithelium (RPE) elevation and few intraretinal cysts on spectral-domain optical coherence tomography (SD-OCT). Optical coherence tomography angiography (OCTA) confirmed the presence of a tuft-shaped intraretinal neovascular lesion. SD-OCT performed 2 months before showed a smaller RPE elevation at the same location without intraretinal fluid. A 79-year-old male presented with a small hyperreflective density in the outer retina surrounded by scant intraretinal fluid on SD-OCT and a bright vessel on OCTA, suggesting early-stage type 3 neovascularization. SD-OCT performed 2 months before showed a smaller hyperreflectivity at the same location, without intraretinal fluid. An 84-year-old female presented with hyperreflective foci in the outer retina overlying a serous pigment epithelium detachment (PED) with focal RPE disruption on SD-OCT. SD-OCT performed 2 months before showed the same hyperreflective lesion associated with a shallower PED. No neovascular lesions were found on OCTA after six injections of bevacizumab. To conclude, careful evaluation of SD-OCT allows for early detection of type 3 neovascularization at a pre-exudative stage. OCTA may be useful in confirming the presence of intraretinal neovascular lesion and monitoring response to anti-vascular endothelial growth factor agents.