LATE RECURRENCE OF CHOROIDAL NEOVASCULARIZATION IN PATIENTS WITH MULTIFOCAL CHOROIDITIS: CLINICAL SURVEILLANCE IN PERPETUITY.

PURPOSE: To report a very late recurrence of choroidal neovascularization (CNV) in elderly patients with noninfectious multifocal choroiditis (MFC). METHODS: Retrospective case series of patients with MFC with confirmed recurrence of CNV. Choroidal neovascularization was diagnosed with multimodal imaging, including optical coherence tomography angiography. Multifocal choroiditis-associated CNV eyes were treated with intravitreal injections of anti-vascular endothelial growth factor medication. RESULTS: Four eyes of three patients were included in our study, with a mean (range) age of 73 years (67-78). The period between the original CNV and the recurrence was 53 years, with a range of 48-60 years. The mean number (range) of injections given after the late recurrence per eye was 7 (5-11). The mean duration (range) of follow-up post-treatment initiation was 93 (40-122) weeks. All eyes improved to 20/30 visual acuity or better at 6 months after initial treatment. CONCLUSION: Patients with MFC are never exempt from recurrent CNV, warranting follow-up in perpetuity. Age-related factors are important to consider which may increase the susceptibility for activating MFC-associated CNV in elderly people. Macular neovascularization could respond to a standard approach to management, in these patients with MFC, by a judicious use of intravitreal injections of anti-vascular endothelial growth factor therapy.

Hyperreflective Foci, Optical Coherence Tomography Progression Indicators in Age-Related Macular Degeneration, Include Transdifferentiated Retinal Pigment Epithelium.

Purpose: By optical coherence tomography (OCT) imaging, hyperreflective foci (HRF) indicate progression risk for advanced age-related macular degeneration (AMD) and are in part attributable to ectopic retinal pigment epithelium (RPE). We hypothesized that ectopic RPE are molecularly distinct from in-layer cells and that their cross-retinal course follows Müller glia. Methods: In clinical OCT (61 eyes, 44 patients with AMD, 79.4 ± 7.7 years; 29 female; follow-up = 4.7 ± 0.9 years), one HRF type, RPE plume (n = 129 in 4 morphologies), was reviewed. Twenty eyes of 20 donors characterized by ex vivo OCT were analyzed by histology (normal, 4; early/intermediate AMD, 7; geographic atrophy, 6; neovascular AMD, 3). Cryosections were stained with antibodies to retinoid (RPE65, CRALPB) and immune (CD68, CD163) markers. In published RPE cellular phenotypes, red immunoreactivity was assessed semiquantitatively by one observer (none, some cells, all cells). Results: Plume morphology evolved over time and many resolved (40%). Trajectories of RPE plume and cellular debris paralleled Müller glia, including near atrophy borders. RPE corresponding to HRF lost immunoreactivity for retinoid markers and gained immunoreactivity for immune markers. Aberrant immunoreactivity appeared in individual in-layer RPE cells and extended to all abnormal phenotypes. Müller glia remained CRALBP positive. Plume cells approached and contacted retinal capillaries. Conclusions: HRF are indicators not predictors of overall disease activity. Gain and loss of function starts with individual in-layer RPE cells and extends to all abnormal phenotypes. Evidence for RPE transdifferentiation, possibly due to ischemia, supports a proposed process of epithelial-mesenchyme transition. Data can propel new biomarkers and therapeutic strategies for AMD.

DOCUMENTATION OF A NEW CHOROIDAL NEVUS.

PURPOSE: To describe the occurrence of an acquired choroidal nevus in a 73-year-old white man. METHODS: Case report. RESULTS: A 73-year-old white man was referred for an evaluation and treatment of macular changes in his left eye consistent with pachychoroid neovasculopathy. Baseline funduscopic examination and color fundus photographs showed two small peripheral choroidal nevi in the right eye and a single small choroidal nevus in the far temporal macula of the left eye. Treatment with intravitreal aflibercept was initiated in the left eye on a treat-and-extend dosing regimen. Approximately 1 year later, a new pigmented choroidal lesion was detected in the left macula in an area where previous high-resolution color fundus photographs had shown no abnormal pigmentation. Swept-source optical coherence tomography of the new pigmented lesion showed flat hyperreflectivity within the inner choroid consistent with a small choroidal nevus. The patient was referred to his internist who found no evidence of an occult malignancy. Over the course of more than 4 additional years of continuous follow-up, the new choroidal nevus remained stable, no new fundus abnormalities were detected in either eye, and the patient remained medically stable. CONCLUSION: To the best of our knowledge, this is the first documented case of a new choroidal nevus. Multimodal imaging performed before lesion detection and over the ensuing 4 years showed its stability, thus allowing for the conclusion that it was a benign choroidal nevus rather than a neoplastic or paraneoplastic process.

EVALUATION OF SEGMENTAL RETINAL ARTERITIS WITH OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY.

PURPOSE: To describe the vascular anatomy and intraluminal flow characteristics of segmental retinal arteritis (SRA) using structural and angiographic optical coherence tomography (OCT). METHODS: Retrospective case series of consecutive patients presenting with SRA. All patients were evaluated at presentation with fundus photography, spectral domain OCT, and OCT angiography. One patient was imaged with dense B-scan OCT angiography. RESULTS: Three eyes of three male patients were evaluated. All examinations were consistent with reactivation of ocular toxoplasmosis with an area of active retinochoroiditis adjacent to a focal chorioretinal scar. Spectral domain OCT through areas of SRA noted on clinical examination demonstrated areas of hyperreflectivity circumscribing the affected vessel with a normoreflective lumen. Optical coherence tomography angiography and dense B-scan OCT angiography demonstrated narrowing of the intraluminal flow signal that correlated with areas of segmental hyperreflectivity on spectral domain OCT. Vascular sections proximal and distal to areas of SRA showed normal flow signal. CONCLUSION: Vessels with SRA demonstrated hyperreflectivity highlighting the vessel wall on spectral domain OCT. Optical coherence tomography angiography showed narrowing of the flow signal within these segments suggesting reduced lumen diameter. Coupling these finding with previous indocyanine green imaging findings in SRA, the collective data suggest the plaques are localized within the vessel wall to either the endothelium or the muscular tunica media without occlusion of the vessel lumen.

Exudative non-neovascular age-related macular degeneration.

PURPOSE: To describe the clinical and multimodal imaging (MMI) features of age-related macular degeneration (AMD) eyes presenting with intraretinal exudation and no evidence of neovascularization or structural alterations of native retinal vessels. METHODS: This was a retrospective review of the MMI and electronic health records for 3 consecutive patients presenting with unilateral exudative non-neovascular age-related macular degeneration. MMI included confocal color fundus photography (CFP), fundus autofluorescence (FAF), fluorescein angiography (FA), spectral domain optical coherence tomography (SD-OCT), swept-source optical coherence tomography angiography (SS-OCTA), and spectral domain optical coherence tomography angiography (SD-OCTA). Dense B-scan OCTA (DB-OCTA) patterns and implemented image post-processing were used to improve spatial resolution in the OCTA analysis and remove projection artifacts. RESULTS: Three eyes of 3 patients (1 male and 2 females, ages 72-87) developed intraretinal fluid (IRF) producing retinal edema during regular follow-up for non-neovascular AMD. FA, SS-OCTA, and DB-OCTA demonstrated no evidence of macular neovascularization or discrete retinal vascular abnormalities that could explain the IRF accumulation. Two eyes received intravitreal anti-VEGF therapy and demonstrated prompt resolution of IRF with periodic recurrences over time. CONCLUSION: Exudative non-neovascular AMD is a novel clinical phenotype characterized by the presence of non-neovascular intraretinal exudation producing macular edema. Differentiating this condition from other manifestations of AMD requires appropriate use of MMI. Further study is needed to assess the clinical impact and optimal management of exudative non-neovascular AMD.

Not cat-scratch disease: Bartonella henselae neuroretinitis associated with non-feline pet mammals.

To describe the ocurrence of Bartonella-associated neuroretinitis secondary to non-feline pet exposure, we retrospectively reviewed medical records and imaging from patients with a clinical and serologic diagnosis of Bartonella henselae (BH). Retinal imaging included color fundus photography, optical coherence tomography (OCT) and fluorescein angiography (FA). Four eyes of two patients with cat-scratch disease were included in this study, with a mean age of 35 years. The mean follow-up was 13 months, after presentation of infectious neuroretinitis. Both patients suffered from bilateral neuroretinitis after direct contact with family pets (ferret and guinea pig). All patients were treated with a long-term systemic antimicrobial therapy. Visual acuity in all improved to 20/30 or better at six months. In conclusion, humans may develop cat-scratch disease when they are exposed to Bartonella henselae (BH) in the saliva of infected cats or BH-containing flea feces reaching the systemic circulation through scratches or mucous membranes. As the cat flea (Ctenocephalides felis) may reside on non-feline mammals, Bartonella-associated neuroretinitis may result from contact with other furred family pets.

CUTICULAR DRUSEN: Risk of Geographic Atrophy and Macular Neovascularization.

PURPOSE: Cuticular drusen (CD) have been associated with manifestations of age-related macular degeneration such as atrophy and neovascularization in the macula. In this study, eyes with CD were followed and investigated for the estimated 5-year risk of progression to sequelae of age-related macular degeneration such as geographic atrophy (GA) and macular neovascularization (MNV). METHODS: A consecutive series of patients with CD were followed for the development of GA and MNV. Whenever possible, they were also studied retrospectively. The patients with CD were categorized into three phenotypic groups. Phenotype 1: eyes had concentrated, densely populated CD in the macular and paramacular area, Phenotype 2: eyes showed scattered CD in the posterior fundus, and Phenotype 3: involved eyes with CD mixed with large drusen (>200 µm). The 5-year incidence of progression was then estimated using a Kaplan-Meier estimator. RESULTS: A total of 63 eyes from 38 patients (35 women with a mean age at presentation of 58.9 ± 14.2 years) were studied and followed for a mean of 40 ± 18 months. Thirteen patients had single eyes with GA (84.5%; 11/13) or MNV (15.5%; 2/13) in one eye at presentation and were subsequently excluded. Geographic atrophy developed in 19.0% (12/63) of eyes and MNV in 4.8% (3/63) of eyes. The cumulative estimated 5-year risk of GA and MNV was 28.4% and 8.7%, respectively. The estimated 5-year incidence of MNV or GA was 12.6%, 50.0%, and 51.6% in Phenotype 1, Phenotype 2, and Phenotype 3, respectively (P = 0.0015, log-rank test). No difference in risk was found in the development of GA or MNV (P = 0.11) between the subgroup of patients presenting with GA or MNV in their fellow eye and those with both eyes included. CONCLUSION: When patients with CD are followed longitudinally, there was a significant risk of progression to GA or MNV for Phenotype 2 and Phenotype 3. Patients with CD are commonly first diagnosed in the fifth decade of life, and there is a female predominance. Clinicians should use multimodal imaging to detect and be aware of the risk of progression to manifestations of GA and MNV. These risks of GA and MNV suggest that patients with CD may be part of the overall spectrum of age-related macular degeneration.

RELATIONSHIP BETWEEN CHOROIDAL VASCULAR HYPERPERMEABILITY, CHORIOCAPILLARIS FLOW DENSITY, AND CHOROIDAL THICKNESS IN EYES WITH PACHYCHOROID PIGMENT EPITHELIOPATHY.

PURPOSE: To use swept-source optical coherence tomography and swept-source optical coherence tomography angiography to investigate potential relationships between choroidal vascular hyperpermeability (CVH) seen with indocyanine green angiography (ICGA), choriocapillaris flow density, and choroidal thickness in eyes with pachychoroid pigment epitheliopathy. METHODS: Patients with pachychoroid pigment epitheliopathy were prospectively imaged with 12-mm × 12-mm swept-source optical coherence tomography, 12-mm × 12-mm swept-source optical coherence tomography angiographyA, and ICGA. Binarized choriocapillaris OCTA images were superimposed with ICGA images in which CVH area had been isolated. Choriocapillaris flow density within or outside the quadrants of CVH was calculated and the ratio of these two values was determined. The presence of CVH and choroidal thickness was evaluated at 9 locations within a central 3-mm × 3-mm area to explore the relationship between these 2 factors. RESULTS: Ten eyes from 10 patients were enrolled in the present study. Choriocapillaris flow density within quadrants of CVH area was significantly lower compared with quadrants without CVH (P < 0.001). The mean choriocapillaris flow density ratio was 0.86 ± 0.10 (range: 0.65-0.99). From among the 90 locations in 10 study eyes, 48 were within areas of CVH. Choroidal thickness was greater in quadrants of CVH compared with areas without CVH (P < 0.001, 455 ± 122 µm vs. 297 ± 93 µm). CONCLUSION: Reduced choriocapillaris flow density, increased choroidal thickness, and CVH appear to co-localize in eyes with pachychoroid pigment epitheliopathy.

SEROUS MACULAR DETACHMENT IN BEST DISEASE: A Masquerade Syndrome.

PURPOSE: To describe the clinical and multimodal imaging findings of a series of cases of serous macular detachment (SMD) caused by Best disease (BD) masquerading as neovascular age-related macular degeneration or central serous chorioretinopathy that were inappropriately treated with intravitreal anti-vascular endothelial growth factor or laser therapy. This study will also present data to support age-related progressive choroidal thickening in BD patients, which may play a role in the development of SMD in this population. METHODS: Clinical examination and multimodal imaging findings, including color fundus photography, spectral-domain optical coherence tomography, fundus autofluorescence, fluorescein angiography, and optical coherence tomography-angiography, were reviewed and analyzed. Subfoveal choroidal thickness was also formally measured, and an age-related choroidal thickness analysis was performed and compared with a normal population. RESULTS: Twenty-six eyes of 13 patients (5 women) were included. Median age was 44 years. Nine patients presented with a history of SMD and subretinal fluid recalcitrant to various therapies, including intravitreal anti-vascular endothelial growth factor injections and photodynamic therapy. Best disease was subsequently diagnosed genetically in six patients and by detailed family history in seven. Mean logarithm of the minimum angle of resolution best-corrected visual acuity for all 26 eyes at last follow-up was +0.36 (Snellen equivalent of 20/46). Subfoveal choroidal thickness positively correlated with age for our cohort, increasing linearly at a rate of 25.6 µm per decade (R = 0.64; P < 0.001). Choroidal neovascularization was identified in four eyes on optical coherence tomography angiography, but these eyes did not respond to anti-vascular endothelial growth factor treatment. CONCLUSION: The diagnosis of BD should be considered in patients presenting with SMD and recalcitrant subretinal fluid masquerading as neovascular age-related macular degeneration or chronic central serous chorioretinopathy to avoid unnecessary treatment procedures. The positive correlation of subfoveal choroidal thickness with age in BD patients may be a factor in the pathogenesis and development of SMD in this population. Recognizing the multimodal imaging features of SMD associated with BD, described in detail in this study, will guide practitioners to the accurate diagnosis of BD and reduce the risk of unnecessary intraocular procedures with potential complications.

Masqueraders of multiple evanescent white dot syndrome (MEWDS).

PURPOSE: To describe disorders that can masquerade as multiple evanescent white dot syndrome (MEWDS). DESIGN: Retrospective, multicenter case series. PARTICIPANTS: Patients who presented with clinical findings compatible with a diagnosis of MEWDS but were ultimately diagnosed with an alternative inflammatory, infectious, or neoplastic disorder. METHODS: Clinical records and multimodal imaging findings including fundus photography, fundus autofluorescence (FAF), fluorescein angiography (FA), indocyanine green angiography (ICGA), optical coherence tomography (OCT), and OCT angiography (OCTA) were analyzed. MAIN OUTCOME MEASURES: Inclusion criteria to be defined as a masquerade syndrome for MEWDS included the presence of disseminated grayish-white outer retinal spots that were hyperautofluorescent on FAF and associated with ellipsoid zone (EZ) disruption on OCT. RESULTS: Twenty-two eyes of 13 patients were identified. All patients presented with the classic findings of MEWDS listed above. A MEWDS-like presentation was bilateral in nine of 13 patients (69%). Final diagnosis was determined on the basis of additional investigations including serologies and biopsy. These diagnoses included syphilis (three patients), lymphoma (three patients), idiopathic multifocal choroiditis (two patients), idiopathic retinal phlebitis (one patient), idiopathic acute zonal occult outer retinopathy (one patient), sarcoidosis (one patient), tuberculosis (one patient), and cancer-associated retinopathy (one patient). The outer retinal lesions and imaging findings resolved with treatment for the associated systemic disorders. CONCLUSIONS: Widespread grayish-white outer retinal spots associated with hyperautofluorescence on FAF and disruption of the EZ on OCT are not pathognomonic for MEWDS. A high index of suspicion must be maintained for masqueraders of MEWDS, which can include serious inflammatory, infectious, and neoplastic disorders.

OCT En Face Analysis of the Posterior Vitreous Reveals Topographic Relationships among Premacular Bursa, Prevascular Fissures, and Cisterns.

PURPOSE: To characterize the topographic relationships among vitreous structures, including the premacular bursa, prevascular vitreous fissures, cisterns, and lacunae, in healthy participants using en face and cross-sectional swept-source (SS) OCT. DESIGN: Prospective, comparative study. PARTICIPANTS: Sixty eyes of 60 healthy participants (age range, 4-35 years). Eyes of individuals younger than 20 years (n = 29) were compared with eyes of individuals 20 years of age or older (n = 31). METHODS: From each study eye, 12 × 12-mm SS OCT volume scans comprising 1024 × 1024 A-scans centered at the fovea were acquired. MAIN OUTCOME MEASURES: En face and cross-sectional data were analyzed to characterize topographic relationships between hyperreflective spaces anterior to the vitreoretinal interface. RESULTS: Prevascular vitreous fissures are an almost universal feature of human eyes. Cisterns became more prevalent over the course of the first 20 years (r = 0.49; P = 0.002). In 97% of eyes in individuals older than 20 years, en face and cross-sectional SS OCT showed the premacular bursa and prepapillary gap merge at a distance superior to the optic nerve and then follow a superonasal course anteriorly. However, only 69% of individuals younger than 20 years demonstrated such a connection (P = 0.01). A close topographic relationship of vitreous fissures and cisterns to the underlying vasculature of the posterior pole was visible on en face projections. En face imaging readily distinguished these spaces. Degenerative, eyewall-parallel fissure planes and their course were described for the first time in a 3-dimensional manner. The fissure planes were rare in younger eyes (12%) and significantly more common in older eyes (42%; P < 0.001). CONCLUSIONS: En face SS OCT demonstrated that (1) premacular bursa and Cloquet's canal are not connected in younger patients, but are connected in older patients; (2) prevascular vitreous fissures overly the retinal vessels; and (3) cisterns are continuous with prevascular fissures.

The Fate and Prognostic Implications of Hyperreflective Crystalline Deposits in Nonneovascular Age-Related Macular Degeneration.

Purpose: To explore patterns of disease progression in nonneovascular age-related macular degeneration (AMD) associated with hyperreflective crystalline deposits (HCDs) in the sub-retinal pigment epithelium-basal laminar space. Methods: Retrospective review of medical records, multimodal imaging, and longitudinal eye-tracked near-infrared reflectance (NIR) and optical coherence tomography (OCT) spanning ≥2 years. NIR/OCT images were analyzed with ImageJ software to identify HCD morphology and location. Associated macular complications were reviewed from the time of HCD detection to the most recent follow-up, using NIR/OCT. Results: Thirty-three eyes with HCDs from 33 patients (mean age: 72 ± 7.5 years) had 46.7 months (95% confidence limits: 33.7, 59.6) of serial eye-tracked NIR/OCT follow-up. Baseline best-corrected visual acuity (BCVA) was 0.44 logMAR (Snellen equivalent 20/55). At a mean of 11.3 months (3.1, 19.6) after HCD detection, 31/33 (93.9%) eyes had developed macular complications including de novo areas of complete retinal pigment epithelium and outer retinal atrophy (cRORA) in 21/33 (64%) eyes, enlargement of preexisting cRORA in 4/33 (12%) eyes, and incident macular neovascularization in 3/33 (9%) eyes. Movement and clearance of HCDs in 9/33 (27%) eyes was associated with enlargement of preexisting cRORA (r = 0.44, P = 0.02). BCVA at the last follow-up visit had decreased to 0.72 logMAR (20/105). Conclusions: Eyes with nonneovascular AMD demonstrating HCDs are at risk for vision loss due to macular complications, particularly when movement and clearance of these structures appear on multimodal imaging. HCD reflectivity and dynamism may be amenable to automated recognition and analysis to assess cellular activity related to drusen end-stages.

Long-Term Multimodal Imaging of Solar Retinopathy.

This is a rare, multimodal imaging report spanning a decade of monitoring in a patient with chronic solar retinopathy showing the natural course of the disease. Spectral-domain optical coherence tomography (SD-OCT) showed mild widening of subfoveal loss of ellipsoid and interdigitation zones bilaterally, progressive retinal pigment epithelial thinning in the right eye, and hyperplasia in the left eye. Structural en face OCT showed subfoveal tissue loss bilaterally. There was no leakage on fluorescein angiography and OCT angiography (OCTA), and dense B-scan OCTA images were unremarkable. Microperimetry revealed bilateral decreased central sensitivity and eccentric fixation in the left eye. Vision remained stable throughout. [Ophthalmic Surg Lasers Imaging Retina. 2019;50:388-392.].

Focal Choroidal Excavation Following Blunt Trauma.

The authors report a case of nonconforming focal choroidal excavation (FCE) identified in an eye following blunt, nonperforating trauma to the globe. Multimodal imaging was undertaken including color fundus photographs, enhanced depth imaging optical coherence tomography, fluorescein angiography, and fundus autofluorescence. This shows that FCE may result from blunt ocular trauma. The authors hypothesize that loss of structural support provided by an intact Bruch's membrane may be a key factor in precipitating the specific morphological changes associated with FCE occurring in a range of clinical settings. [Ophthalmic Surg Lasers Imaging Retina. 2019;50:187-190.].

A proposed mechanism influencing structural patterns in X-linked retinoschisis and stellate nonhereditary idiopathic foveomacular retinoschisis.

OBJECTIVE: To explore the structural differences between X-linked retinoschisis (XLR) and stellate nonhereditary idiopathic foveomacular retinoschisis (SNIFR) using swept-source optical coherence tomography angiography (SS-OCTA). METHODS: A case series of two patients, a 9-year-old male with XLR and a 58-year-old woman with SNIFR were imaged with swept-source optical coherence tomography angiography (SS-OCTA; PLEX Elite 900, Carl Zeiss Meditec, Inc, Dublin, CA). Automated segmentation was manually adjusted to include the areas of retinoschisis within en face flow and structural slabs. The flow data were binarized using ImageJ 1.51s (Wayne Rasband, National Institutes of Health, USA, http://imagej.nih.gov.ij ) and superimposed onto the structural slab. RESULTS: In the eye with XLR, OCTA flow data superimposed on the structural slab demonstrated flow signal within numerous bridging structures connecting the inner and outer plexiform layers containing the intermediate (ICP) and deep (DCP) capillary plexuses. In contrast, the same technique applied to the eye with SNIFR demonstrated an absence of flow signal in the cystic retinal spaces within Henle's fiber layer. CONCLUSIONS: The vascular pattern of bridging vessels between the ICP and DCP is closely related to the structural "retinoschisis" pattern of XLR and appears to be structurally different from that seen in SNIFR. Moreover, the connecting vessels appear to be highly represented and regularly distributed, thereby supporting a serial arrangement of the retinal capillary plexuses within the perifoveal macula.

Association of Optical Coherence Tomography Angiography of Collaterals in Retinal Vein Occlusion With Major Venous Outflow Through the Deep Vascular Complex.

Importance: Analysis of collateral vessel formation following retinal vein occlusion may advance our understanding of the venous outflow anatomy in the macula. Objective: To determine the location of collateral vessels with optical coherence tomography (OCT) angiography imaging. Design, Setting, and Participants: Observational retrospective cohort study. Collateral vessel formation was studied with OCT angiography (OCTA) in patients with retinal vein occlusion (RVO). The study took place at 2 retinal practices (Vitreous Retina Macula Consultants of New York and Stein Eye Institute, University of California, Los Angeles), with patient records retrieved from March 2015 to August 2017. Data analysis was completed in November 2017. Exposures: Collaterals identified with fundus photography and/or fluorescein angiography were analyzed with OCTA to determine their course through the superficial vascular plexus (SVP) and the deep vascular complex (DVC). Main Outcomes and Measures: Collateral vessel pathways through the SVP and DVC were analyzed with cross-sectional and en face OCT and OCTA segmentation and color-coded volume renderings prepared from raw OCTA voxel data. Results: From 23 eyes (22 branch and 1 hemispheric retinal vein occlusion ) of 23 patients (mean [SD] age, 73 [11] years), 101 collateral vessels were identified and analyzed (mean [SD], 4.4 [2.0]; range, 2-9 collateral per eye). On OCTA, the collaterals appeared as curvilinear dilated flow signals that connected veins across the horizontal raphe or veins on opposite sides of an occluded venous segment within the same retinal hemisphere. Of the 101 collaterals analyzed, all showed greater flow signal in the DVC, and all had some portion of their course identified within the DVC. No collaterals were found exclusively in the SVP. Volume renderings for 3 cases confirmed qualitatively that retinal collateral vessels course through the retina predominantly at the level of the DVC. Conclusions and Relevance: Based on a limited number of cases, all collateral vessels associated with retinal vein occlusion were found to course through the DVC. The absence of collaterals isolated to the SVP supports a serial arrangement of the SVP and DVC, with venous drainage predominantly coursing through the DVC.