20

Choroidal Neovascularization of Other Causes

Brian K. Do, MD; Richard I. Kaplan, MD; Patricia Garcia, MD; Andre Romano, MD; and Richard Rosen, MD

BACKGROUND

While dye-based angiography has historically served as the gold standard of imaging modalities in the diagnosis of choroidal neovascularization (CNV), the introduction of optical coherence tomography angiography (OCTA) has clearly demonstrated the ability to delineate neovascular membranes in exudative maculopathies of various nonage-related macular degeneration (AMD) etiologies, without introducing patients to the potential morbidities associated with dye-based testing. The cases presented here further corroborate that which has been suggested in recently published studies: OCTA has the ability to diagnose CNV even when fluorescein angiography (FA) may fail to do so definitively, and can help guide treatment as well.

CNV can complicate myriad disorders of the posterior segment. In CNV, abnormal vascular proliferations from the choroid extend through Bruch’s membrane into the sub-retinal pigment epithelium (RPE), subretinal, or intraretinal space, often resulting in significant visual loss. Prompt diagnosis and treatment is essential to minimize such vision loss. Current imaging modalities commonly used to detect CNV include spectral domain optical coherence tomography (SD-OCT), FA, and indocyanine green angiography (ICGA).

SD-OCT is a noninvasive and noncontact modality for imaging ocular tissues with micrometer-level resolution. Based on the principle of low-coherence interferometry, OCT produces 2-dimensional images by measuring backscattered light from different tissue layers. Tissues with higher reflectivity, such as the retinal nerve fiber layer, appear brighter than structures that reflect less light, such as fluid. The advent of SD-OCT has increased both the resolution and the speed of this imaging.¹ While structural OCT does not specifically detect blood flow, it has become a clinical standard for detecting and managing intraretinal and subretinal changes associated with CNV. In fact, SD-OCT has been advocated as a capable alternative to fluorescein angiogram with sensitivity and specificities of greater than 85% and 84%, respectively.²

FA remains the gold standard of imaging modalities for detection of CNV. The retinal and choroidal circulations are revealed by capturing the filtered fluorescence of sodium fluorescein, which is administered intravenously or orally. In cases of CNV, FA shows leakage of dye in the latter frames of the angiogram. While FA is excellent in identifying vascular leakage, it is time sensitive and not depth resolved. Additionally, structural details are often obscured by variable diffusion of the hyper-fluorescence. Moreover, FA is both invasive and resource intensive and has been associated with multiple adverse effects. Nausea and vomiting are associated with 10% of injections; more serious adverse effects such as anaphylaxis and syncope are much rarer.³ ICGA is often combined with FA in the evaluation of CNV. Because a greater percentage of ICG is bound to plasma protein, it is not subject to diffuse leakage, which makes it useful for differentiating active leakage from diffuse staining that often complicates FA imaging. The longer wavelength of stimulation and fluorescence of ICG makes it useful for visualizing choroidal pathology but it is still limited in its ability to resolve the choriocapillaris (CC). While associated with fewer adverse effects than FA, rare events with ICGA may be life threatening. It is also plagued with lack of depth resolution.4

OCTA is a new development in the evolution of OCT that allows noninvasive, 3-dimensional visualization of the retinal and choroidal vasculature by using motion-contrast analysis in conjunction with en face OCT reconstruction.^5,6 Currently, studies on the potential clinical utility of OCTA have largely focused on exudative AMD, which is the object of growing therapeutic interventions.^5–10 In patients with exudative AMD, OCTA has proven an effective method of visualizing CNV;^11–13 another study reports 50% sensitivity and 91% specificity in this regard.⁵

Despite being in a germinal stage, OCTA has also shown promise in imaging and delineating in detail CNV in other forms of exudative maculopathy:

• Hong et al¹⁴ described abnormal choroidal vasculature in 2 eyes with myopic CNV, and 5 eyes with polypoidal choroidal vasculopathy imaged with a proprietary high-penetration OCTA prototype based on swept source OCT technology.
  
• In 8 of 33 eyes with central serous chorioretinopathy imaged by Costanzo et al,¹⁵ OCTA showed abnormal choroidal vessel patterns and abnormal outer retinal blood flow associated with CNV in affected eyes.
  
• Inoue et al¹⁶ report that en face OCTA and cross-sectional OCTA images provided anatomical and pathophysiological information regarding neovascular phenomena in polypoidal choroidal vasculopathy. This suggestion is corroborated by another study on the use of OCTA in polypoidal choroidal vasculopathy by Miura et al.¹⁷
  
• Levison et al¹⁸ reported a single case of choroidal neovascularization in acute zonal occult retinopathy, in which OCTA confirmed the presence of CNV.

One of the more important developments in OCTA technology has been the implementation of the split-spectrum amplitude-decorrelation angiography algorithm (SSADA), a patented primary technology initially described by Jia et al¹⁹. SSADA improves both signal-to-noise ratio for flow detection and connectivity of microvascular networks, and has greatly improved the imaging of choroidal vasculature. Mastropasqua et al²⁰ assert that the differentiation of CNV from surrounding outer retinal tissue, RPE, and hemorrhage would have been exceedingly difficult without SSADA.

In the cases that follow, we present a variety of CNV examples associated with non-AMD etiologies. All eyes were imaged using the RTVue XR Avanti SD-OCT (Optovue Inc), equipped with the most current of the SSADA, and in some cases, with the AngioAnalytics.

CASE 1: CHOROIDAL NEOVASCULARIZATION SECONDARY TO ANGIOID STREAKS

This is a case of a young woman with a history of angioid streaks, who presented with several weeks of metamorphopsia of the right eye.

As seen in the included color photograph of the right macula (Figure 20-1A), examination revealed pigmentary changes consistent with angioid streaks, as well as a grayish, partially pigmented lesion immediately superonasal to the fovea. FA (Figure 20-1B) demonstrated late hyper-fluorescence in the area of the lesion visualized on clinical examination.

En face OCTA of the right eye revealed a neovascular network superonasal to the fovea within the avascular outer retina (Figure 20-1C), and displayed abnormal flow signals at the level of the CC as well (Figure 20-1D).

Review of SD-OCT of the right macula performed concurrently confirmed the presence of a defect in Bruch’s membrane (Figure 20-1E; yellow arrows) corresponding with an overlying elevation of the RPE, and associated hyper-reflective material, likely representing the choroidal neovascular membrane (CNVM) seen on OCTA.

CASE 2: CHOROIDAL NEOVASCULARIZATION COMPLICATING CHRONIC CENTRAL SEROUS CHORIORETINOPATHY

A 36-year-old man with no significant past medical or ocular history presented with worsening serous retinal detachments following treatment for bilateral inflammatory chorioretinitis. The diagnosis of central serous chorioretinopathy was made based on the patient’s fundus imaging in response to oral prednisone.

On initial examination, best-corrected visual acuity was 20/25 in the right eye, and 20/40 in the left eye, despite large serous retinal detachments in both eyes.

Clinical examination of the left eye showed a gray-yellow, irregularly shaped lesion in the fovea, as seen in the color fundus photograph (Figure 20-2A). FA (Figure 20-3) and ICGA performed at the time of initial evaluation revealed areas of foveal and juxtafoveal late hyper-fluorescence (Figure 20-2B) in the area of the lesion.

A hyper-reflective lesion in the fovea surrounded by serous subretinal fluid was visualized on structural SD-OCT of the left macula, as well as on OCTA of the left macula (Figures 20-3E and 20-3F) This confirmed the presence of a neovascular complex in the fovea of the left eye.

En face OCTA showed a hyper-reflective vascular lesion in the avascular region of the outer retina (Figure 20-3C). A surrounding area devoid of flow signals corresponded to serous subretinal fluid seen on cross-sectional OCT.

En face OCTA at the CC level (Figure 20-3D) showed a relative flow void beneath the neovascular complex in the outer retina, which may have been due to shadowing artifacts.

Stay updated, free articles. Join our Telegram channel

Join