OCT Angiography and Ellipsoid Zone Mapping of Macular Telangiectasia Type 2 From the AVATAR Study

Skeleton density and ellipsoid zone loss are prognostic for progression in Macular Telangiectasia Type 2

Macular Telangiectasia Type 2 (MacTel) is a chronic, progressive disease of the central retina characterized by vascular and neurodegenerative changes. As there is currently no treatment for non-neovascular MacTel, there is a dearth for biomarkers identifying eyes with an increased risk for disease progression for patient counseling and clinical trial recruitment. Eyes were classified to be stable or progressive, defined by the fundus photography-based grading system by Gass and Blodi. First, structural differences between these two groups were assessed, employing optical coherence tomography (OCT) and OCT-angiography. Univariate regression analyses revealed evidence towards a lower superficial retinal layer (SRL) vessel density (VD), skeleton density (SD) and deep retinal layer (DRL) SD in progressing compared to stable eyes (p = 0.05, p = 0.05, p = 0.07). Second, a multivariable predictive model was employed to examine the predictive value of structural and functional parameters for disease progression. Baseline best corrected visual acuity (BCVA) and SRL SD are prognostic for disease progression (p < 0.001, p = 0.05). The presence of ellipsoid zone (EZ) loss is prognostic for future central retinal thickness (p < 0.01). We propose SRL SD, BCVA, and EZ loss as prognostic biomarkers and as possible outcome measures in future interventional studies in MacTel.

Endpoints for clinical trials in ophthalmology

With the identification of novel targets, the number of interventional clinical trials in ophthalmology has increased. Visual acuity has for a long time been considered the gold standard endpoint for clinical trials, but in the recent years it became evident that other endpoints are required for many indications including geographic atrophy and inherited retinal disease. In glaucoma the currently available drugs were approved based on their IOP lowering capacity. Some recent findings do, however, indicate that at the same level of IOP reduction, not all drugs have the same effect on visual field progression. For neuroprotection trials in glaucoma, novel surrogate endpoints are required, which may either include functional or structural parameters or a combination of both. A number of potential surrogate endpoints for ophthalmology clinical trials have been identified, but their validation is complicated and requires solid scientific evidence. In this article we summarize candidates for clinical endpoints in ophthalmology with a focus on retinal disease and glaucoma. Functional and structural biomarkers, as well as quality of life measures are discussed, and their potential to serve as endpoints in pivotal trials is critically evaluated.

Evaluation of Optic Disc, Retinal Vascular Structures, and Acircularity Index in Patients with Idiopathic Macular Telangiectasia Type 2

BACKGROUND

We aimed to compare the retinal, optic disc vascular density (ODVD) values, and acircularity index (AI) of patients with idiopathic macular telangiectasia type 2 (IMT) and healthy individuals using the optical coherence tomography angiography (OCTA) device.

METHODS

The study included 39 patients with IMT and 37 healthy controls. The OCTA findings of the patients and controls were examined.

RESULTS

The total, parafoveal and perifoveal vascular density of the superficial capillary plexus, choriocapillaris blood flow, inside-disc ODVD, retinal nerve fiber layer (RNFL), and retinal thicknesses were found to be statistically significantly lower, and the foveal avascular zone value was statistically significantly higher in the IMT group compared to the control group (p = 0.001, p = 0.01, p = 0.02, p = 0.01, p = 0.009, p = 0.002, p = 0.02, respectively). There was a statistically significant negative correlation between best-corrected visual acuity (BCVA) and AI (p = 0.02), and a statistically significant positive correlation between peripapillary vascular density and BCVA (p = 0.04).

CONCLUSIONS

We consider that the lower retinal, choriocapillaris, ODVD values, and retinal and RNFL thicknesses in the patients with IMT compared to the controls were due to vascular damage, remodeling, fibrosis, proliferation, and Müller cell damage. Ellipsoid zone defect, AI, and peripapillary vascular density are important indicators in the evaluation of visual acuity in these patients.

Relative Ellipsoid Zone Reflectivity in Macular Telangiectasia Type 2

Purpose

The relative ellipsoid zone reflectivity (rEZR) has been proposed as an innovative biomarker for photoreceptor integrity. This study evaluates the rEZR in macular telangiectasia type 2 (MacTel) eyes of different disease stages.

Methods

The mean rEZR (ratio ellipsoid zone [EZ]/external limiting membrane [ELM] reflectivity [arbitrary units {AUs}], grey level range = 0-1) was analyzed for an entire spectral domain optical coherence tomography volume scan (global) and for each subfield of the Early Treatment Diabetic Retinopathy Study (ETDRS) grid (topographic) in patients with MacTel and controls. MacTel disease severity was classified according to Gass and Blodi.

Results

Linear mixed-model analysis of 145 eyes of 74 patients and 50 eyes of 25 controls revealed globally lower, yet not statistically significant, rEZR values in MacTel eyes. Topographically, most pronounced decreases were found in stages 3 and 4/5 for the temporal inner (coefficient estimates [CEs] = -25.4 [-38.2; -12.6] and -34.1 [-48.7; -19.6] AU, both: P < 0.001), the inferior inner (-29.9 [-44.6; -15.6] and -35.3 [-52.1; -18.5] AU, both: P < 0.001), the nasal inner (-21.5 [-35.52; -7.4] and -31.6 [-47.6; -15.6] AU, P = 0,003 and P < 0.001), and in the superior inner subfield of stage 4/5 (-25.0 [-42.0; -7.9] AU, P = 0.004).

Conclusions

The rEZR showed association with disease severity and the predilection area of MacTel. Given the current understanding of the pathophysiological concept of MacTel, these findings underscore the value of the rEZR as a potential novel biomarker for outer retinal integrity. Longitudinal studies are demanded to better characterize its value as a biomarker for early photoreceptor alterations and disease progression in MacTel.

Macular Telangiectasia Type 2: A Classification System Using MultiModal Imaging MacTel Project Report Number 10

Purpose

To develop a severity classification for macular telangiectasia type 2 (MacTel) disease using multimodal imaging.

Design

An algorithm was used on data from a prospective natural history study of MacTel for classification development.

Subjects

A total of 1733 participants enrolled in an international natural history study of MacTel.

Methods

The Classification and Regression Trees (CART), a predictive nonparametric algorithm used in machine learning, analyzed the features of the multimodal imaging important for the development of a classification, including reading center gradings of the following digital images: stereoscopic color and red-free fundus photographs, fluorescein angiographic images, fundus autofluorescence images, and spectral-domain (SD)-OCT images. Regression models that used least square method created a decision tree using features of the ocular images into different categories of disease severity.

Main Outcome Measures

The primary target of interest for the algorithm development by CART was the change in best-corrected visual acuity (BCVA) at baseline for the right and left eyes. These analyses using the algorithm were repeated for the BCVA obtained at the last study visit of the natural history study for the right and left eyes.

Results

The CART analyses demonstrated 3 important features from the multimodal imaging for the classification: OCT hyper-reflectivity, pigment, and ellipsoid zone loss. By combining these 3 features (as absent, present, noncentral involvement, and central involvement of the macula), a 7-step scale was created, ranging from excellent to poor visual acuity. At grade 0, 3 features are not present. At the most severe grade, pigment and exudative neovascularization are present. To further validate the classification, using the Generalized Estimating Equation regression models, analyses for the annual relative risk of progression over a period of 5 years for vision loss and for progression along the scale were performed.

Conclusions

This analysis using the data from current imaging modalities in participants followed in the MacTel natural history study informed a classification for MacTel disease severity featuring variables from SD-OCT. This classification is designed to provide better communications to other clinicians, researchers, and patients.

Financial Disclosures

Proprietary or commercial disclosure may be found after the references.

Structural-vascular-functional correlation in type 2 non-proliferative macular telangiectasia

PURPOSE

To correlate the structural-vascular-functional changes in type 2 non-proliferative macular telangiectasia (MacTel) using optical coherence tomography (OCT) angiography (OCTA).

METHODS

In this retrospective study, OCTA and enface OCT image analysis of eyes with confirmed diagnosis of non-proliferative type 2 MacTel was performed. The 'MacTel area' was calculated by marking the outer boundary of an area affected by MacTel on superficial (SCP) and deep capillary plexus (DCP) on OCTA images and photoreceptor layer (PRL) on enface OCT scan. At every follow-up OCTA scan visit, best-corrected visual acuity, MacTel area and stage of disease was documented. Analyses between disease stage, MacTel area and logMAR visual acuity was carried out.

RESULTS

In total, 38 single-visit OCTA scans of 22 patients were included. The mean age was 58.9 ± 10.98 years. An increase in disease severity stage correlated positively with MacTel area in SCP segmentations slab (r = 0.334; p = 0.04) and logMAR visual acuity (r = 0.338; p = 0.038). No correlation in the DCP area or PRL area (p > 0.05) was noted with disease stage. A statistically significant positive correlation was noted between the structural changes in PRL layer with vascular changes in SCP (p = 0.021) but not in DCP (p = 0.199). No correlation of visual acuity with changes in SCP, DCP or PRL was noted (p > 0.05).

CONCLUSION

OCTA is a useful adjunct for determining disease severity in type 2 non-proliferative MacTel by assessing the structural-vascular changes. Further longitudinal studies need to be considered in future for understanding the pathomechanism of retinal damage in type 2 MacTel.

Use of OCT Angiography to Diagnose and Manage Atypical Presentations of Macular Telangiectasia Type 2

Macular telangiectasia Type 2 (MacTel) is a bilateral acquired retinal disease characterized by both vascular changes and atrophy of the retina. The purpose of this case series is to highlight the use of optical coherence tomography angiography (OCTA) as a non-invasive imaging modality to distinguish atypical MacTel from other macular conditions with similar presentations. We performed a retrospective review of patients referred to our academic retinal practice with unconfirmed or misdiagnosed MacTel between July 2017 and July 2021. Patients' OCTA imaging findings were reviewed to guide the appropriate diagnosis and management of atypical MacTel. Fifteen eyes from eight patients were included in this study. Six patients were referred with previous diagnoses of either full-thickness macular hole, lamellar hole, vitreomacular traction (VMT), postoperative cystoid macular edema (CME), or diabetic macular edema (DME). Two patients were referred to us to confirm the diagnosis of MacTel. OCTA revealed telangiectatic vessels in the temporal parafovea of all 15 eyes. OCTA also highlighted previously undiagnosed subretinal neovascularization (SRNV) in seven eyes. OCTA imaging is a valuable imaging modality to distinguish MacTel from other macular conditions, whose treatment courses vary substantially. Due to its ease of use, it holds immense potential in the future as treatments for non-proliferative MacTel emerge.

One-year follow-up of optical coherence tomography angiography microvascular findings: macular telangiectasia type 2 versus tamoxifen retinopathy

PURPOSE

To compare microstructural and microvascular changes in eyes with macular telangiectasia type 2 (MacTel2) and in those with tamoxifen retinopathy (TR) at baseline and at the 1-year follow-up using optical coherence tomography (OCT) and OCT angiography (OCTA).

METHODS

We followed up patients diagnosed with MacTel2 or TR for at least 1 year. We included 17 patients with MacTel2 (31 eyes) and 15 with TR (25 eyes) who discontinued tamoxifen use after a TR diagnosis. We performed OCT and OCTA at baseline and after 1 year.

RESULTS

Patients with MacTel2 and TR showed intraretinal cavitation, ellipsoid zone (EZ) loss, and capillary telangiectasia in the superficial and deep plexuses. EZ disruption predominantly affected the temporal region in MacTel2 (32%) and was limited to the foveal center in TR (24%). Vascular density (VD) was significantly reduced within the deep temporal parafovea and superficial fovea in MacTel2 and TR eyes, respectively. After 1 year, the MacTel2 eyes showed enlarged EZ loss, proliferative vascular invasion, and increased VD (p = 0.021) in the temporal deep plexus compared with TR eyes.

CONCLUSIONS

After 1-year follow-up, the MacTel2 eyes showed proliferative vascular remodeling, particularly in the temporal parafovea of the deep plexus with EZ loss progression, whereas the TR eyes maintained their baseline capillary rarefaction.

Imaging endpoints for clinical trials in MacTel type 2

INTRODUCTION

Macular Telangiectasia type 2 (MacTel) is a bilateral neurodegenerative disease associated with dysfunction in the serine and lipid metabolism resulting in loss of Muller cells and photoreceptors. Typical structural changes include vascular abnormalities, loss of retinal transparency, redistribution of macular pigment and thinning of the central retina with photoreceptor loss. The presence and extent of photoreceptor loss, as visible on Optical Coherence Tomography (OCT) ("disease severity scale"), correlate with functional loss and the limitation of photoreceptor loss appears to be the most promising therapeutic approach. Ongoing clinical trials of ciliary neurotrophic factor (CNTF) implants for the treatment of MacTel are using this outcome to evaluate efficacy. An ideal outcome measure provides the ability to quantify the extent of the disease progression with precision and reproducibility.

METHODS

This review describes the changes and findings on different imaging techniques including fluorescein- and OCT angiography, blue light reflectance, 1- and 2-wavelength autofluorescence and OCT.

RESULTS

The possibilities of objective quantification of the severity of MacTel and correlation with functional characteristics such as best-corrected visual acuity (BCVA) and microperimetry and their applications as quantitative imaging endpoints for clinical treatment trials are discussed. OCT and especially en face OCT could be demonstrated as precise and reproducible methods to quantify the area of photoreceptor loss, which correlated highly significantly with functional loss in microperimetry.

CONCLUSION

The analysis of the area of photoreceptor loss on en face OCT is the most reliable imaging endpoint for treatment trials in MacTel. This method is already being used in ongoing randomized trials.

LONGITUDINAL ELLIPSOID ZONE AND OUTER RETINAL INTEGRITY DYNAMICS AFTER EPIRETINAL MEMBRANE SURGERY

PURPOSE

To quantify ellipsoid zone (EZ) changes in integrity after epiretinal membrane (ERM) surgery, correlate findings to visual acuity, and determine predictors for prognosis.

METHODS

A post hoc analysis of eyes undergoing ERM surgery pooled from the prospective DISCOVER intraoperative optical coherence tomography study and eyes undergoing conventional ERM surgery without intraoperative optical coherence tomography. Quantitative EZ features were extracted using a multilayer machine learning enabled automated segmentation platform after image analyst review/correction for segmentation accuracy. Visual acuity and EZ integrity were quantitatively assessed and correlated before and after ERM surgery. Multiple linear regression was performed to assess preoperative visual acuity and EZ features as predictors for improvement in visual acuity or EZ integrity.

RESULTS

There were 177 eyes from 177 subjects that underwent ERM surgery from the DISCOVER and conventional arms. Improvement in visual acuity and multiple EZ integrity features was noted after ERM surgery, including EZ partial attenuation and EZ-retinal pigment epithelium (RPE) volume (P < 0.05). A reduction in EZ partial attenuation and increase in EZ-RPE central subfield thickness (EZ-RPE CST) was significantly correlated with improved visual acuity after ERM surgery (P < 0.05). More robust EZ-RPE CST at baseline predicted visual acuity improvement after ERM peel in regression modeling (β = 0.005, P < 0.05).

CONCLUSIONS

Longitudinal assessment of EZ features demonstrates significant postoperative improvement in multiple EZ integrity metrics after ERM surgery. Improving EZ integrity was correlated to improving the visual acuity. Ellipsoid zone integrity and visual acuity were significant predictors in regression modeling and may have value in clinical prognostication.

Longitudinal Assessment of Ellipsoid Zone Integrity, Subretinal Hyperreflective Material, and Subretinal Pigment Epithelium Disease in Neovascular Age-Related Macular Degeneration

PURPOSE

To assess longitudinally the effect of anti-vascular endothelial growth factor (VEGF) treatment on ellipsoid zone (EZ) integrity, subretinal hyperreflective material (SHRM), and the sub-retinal pigment epithelium (sub-RPE) compartment in eyes with neovascular age-related macular degeneration (nAMD).

DESIGN

Post hoc analysis of the OSPREY clinical trial, a prospective, double-masked, phase 2 study comparing brolucizumab 6 mg with aflibercept 2 mg over 56 weeks.

PARTICIPANTS

Participants with treatment-naïve nAMD at the initiation of the trial were included in the analysis.

METHODS

Eyes were evaluated with spectral-domain OCT at 4-week intervals in the OSPREY trial (n = 81). Spectral-domain OCT scans collected from each visit were segmented automatically using a proprietary, machine learning-enabled higher-order feature-extraction platform for retinal layer, SHRM, and sub-RPE boundary lines, which were evaluated and corrected as needed by masked trained graders. The current analysis focused only on patients evaluated with the Cirrus (Zeiss) platform (n = 28).

MAIN OUTCOME MEASURES

Outcome measures included change from baseline in EZ-RPE (i.e., photoreceptor outer segment) volume, EZ-RPE central subfield thickness (CST), total EZ attenuation, SHRM volume, SHRM CST, and total sub-RPE volume. The correlation between each of these measures and best-corrected visual acuity (BCVA) at each visit was evaluated.

RESULTS

EZ-RPE volume and EZ-RPE CST showed significant increases, and total EZ attenuation, SHRM volume, SHRM CST, and total sub-RPE volume showed significant decreases from baseline at each visit from weeks 4 through 56 (P < 0.05 at each visit). Ellipsoid zone integrity measures and SHRM volume correlated significantly with BCVA at most visits (P < 0.05). No significant correlation was found between total sub-RPE volume and BCVA.

CONCLUSIONS

EZ integrity, SHRM, and sub-RPE disease features in eyes with nAMD showed improvement as early as week 4 of anti-VEGF treatment. EZ integrity measures and SHRM volume were predictors of visual acuity over the first year of treatment.

Retinal Fluid Volatility Associated With Interval Tolerance and Visual Outcomes in Diabetic Macular Edema in the VISTA Phase III Trial

PURPOSE

To describe longitudinal retinal fluid dynamics on spectral domain OCT and to identify imaging biomarkers that predict the worsening of DME with interval extension during anti-vascular endothelial growth factor (VEGF) therapy.

DESIGN

A post hoc sub-analysis of phase III, VISTA-DME study.

METHODS

Eyes received either intravitreal aflibercept injection 2 mg every 4 weeks (2q4) or every 8 weeks after 5 initial monthly injections (2q8), and eyes imaged with the Cirrus HD-OCT system were included. The macular cube was analyzed for 10 time-points from baseline through week 100. Retinal OCT images were evaluated using a novel software platform to extract retinal fluid features for calculation of volumetric fluid parameters, including the retinal fluid index (RFI): the percentage of retinal volume that was occupied by intraretinal fluid.

RESULTS

Fifty-five eyes were included in the 2q4 group, and 58 eyes were included in the 2q8 group. Early RFI volatility with a central macular RFI increase by ≥5 points from week 4 to 8 (P = .004, odds ratio [OR] 31.3, 95% confidence interval [CI] 3.0 to 329) and cumulative RFI volatility with an aggregate increase in macular RFI by ≥10 points from those timepoints with increased RFI between baseline to week 20, P = .005, OR 10.2, 95% CI 2.1 to 51.3) were both significant predictors for the worsening of DME and visual acuity when the treatment interval was extended to 8 weeks in the 2q8 group.

CONCLUSIONS

Early fluid dynamics as measured by (1) early RFI volatility and (2) cumulative RFI instability with aggregate increased RFI were associated with intolerance of interval extension.

CHARACTERIZING RETINAL-CHOROIDAL ANASTOMOSIS IN MACULAR TELANGIECTASIA TYPE 2 WITH OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY

PURPOSE

To characterize structural and angiographic findings in macular telangiectasia Type 2 (MacTel 2) and examine associations with visual acuity.

METHODS

MacTel 2 patients with complete ophthalmologic examination, including fundus photography, autofluorescence, spectral-domain optical coherence tomography, and projection-resolved optical coherence tomography angiography, were retrospectively evaluated.

RESULTS

There were 43 eyes of 22 patients with a mean age 63.9 (±10.3) years. Six patients had diabetes. Twenty-one eyes (48.8%) had retinal-choroidal anastomoses (RCAs) without any evidence of neovascularization extending laterally in a plane above or below the retinal pigment epithelium. None of the eyes had hemorrhage, lipid, or signs of subretinal exudation. When present, an average of 55 (±33.7) individual RCAs were clustered primarily in temporal juxtafoveal region of involved eyes. Right-angle veins were seen in all 21 eyes with RCAs, and hyperpigmentation was present in 18 (P < 0.001 for both). A conical collection of hyperreflective material spanning from Bruch membrane past external limiting membrane of ≥200-μm basal diameter was found in 21 eyes and labeled outer retinal hyperreflective lesion. Retinal-choroidal anastomoses occurred in clusters, often within the outer retinal hyperreflective lesion. This lesion colocalized with focal thinning of the outer nuclear layer and was surrounded by a larger defect in the ellipsoid zone. The presence of diabetes (P = 0.015), outer retinal hyperreflective lesion (P = 0.006), RCA (P = 0.005), and ellipsoid zone defect extent (P < 0.001) were associated with decreased visual acuity.

CONCLUSION

Retinal-choroidal anastomoses occur in eyes with MacTel 2 without signs of exudation. Retinal-choroidal anastomoses occur in numerous clusters particularly in the temporal juxtafoveal macula. Diabetes, ellipsoid zone defect extent, RCAs, and the outer retinal hyperreflective lesion predict poorer vision in MacTel 2.

Longitudinal Assessment of Ellipsoid Zone Mapping Parameters in Retinal Venous Occlusive Disease With Associated Macular Edema

Purpose:

This work evaluated the longitudinal dynamics of ellipsoid zone (EZ) integrity in retinal vein occlusion (RVO) with macular edema and their relation to outcomes.

Methods:

Clinical characteristics and optical coherence tomography data of patients with RVO and associated macular edema were collected at baseline and at 3 and 12 months. Macular cube scans were exported into EZ and retinal-layer analysis software. Longitudinal EZ parameters and visual acuity (VA) outcomes were regressed and correlated.

Results:

The study included 108 eyes of 108 patients; all eyes were treated with antivascular endothelial growth factor therapy at the baseline visit. VA improved from 20/97 at baseline to 20/52 at 3 months and 12 months ( P < .001), correlating with EZ integrity at each time point ( P < .001). At 12 months following initiation of antivascular endothelial growth factor therapy, EZ partial attenuation and EZ total attenuation improved over 12 months from 16.4% to 8.5% ( P < .001) and from 12.3% to 5.9% ( P < .001), respectively. VA improvement from baseline to 12 months correlated with improvement of EZ partial and total attenuation ( P < .001). Baseline EZ characteristics did not predict VA outcomes, but at 3 months, EZ parameters did predict improvement in visual outcomes by 12 months ( P < .01).

Conclusions:

EZ and outer retinal integrity are correlated with functional outcomes in RVO. Following treatment, EZ integrity improves and is associated with functional improvement. In RVO baseline, EZ features were not associated with 1-year VA outcomes, but evaluation of EZ integrity at 3 months was linked to 1-year outcomes.

Optical coherence tomography angiography findings of fellow eye of proliferative macular telangiectasia type 2: Long term study

PURPOSE

To report the characteristics of non-proliferative fellow eyes in patients with unilateral proliferative macular telangiectasia type 2 (MacTel).

METHODS

This was a multicenter, retrospective study and included fellow eyes of eyes with subretinal neovascular membrane (SRNVM). Multimodal imaging including fundus photography, optical coherence tomography (OCT), and OCT angiography (OCTA) was performed. OCT and OCTA measurements included central macular thickness (CMT), subfoveal choroidal thickness (SFCT), foveal avascular zone (FAZ) area and qualitative parameters such as distortion or enlargement of FAZ, increased inter-vascular spacing, dilated, tortuous vessel at margin of FAZ, crowding of vessel, and loss of choriocapillaris (CC).

RESULTS

Thirteen fellow eyes of 13 patients with mean age of 63.6 ± 12.0 years were included. Fellow eyes had various stages of the diseases - stage 2 (four eyes), 3 (six eyes), and 4 (three eyes). OCTA showed increased intervascular spacing (8; 61.5%), dilated (11; 84.6%), and elongated vessels (8; 61.5%) at the margin of the FAZ, crowding of vessels (6; 46.2%), capillary non-perfusion areas outside the FAZ (4; 30.8%), and areas of CC loss (4; 30.8%). Mean follow-up was 9.1 ± 12.9 months. Out of six eyes with follow-up of ⩾12 months, two developed SRNVM at 18 and 33 months with OCTA showing crowding and entanglement of dilated retinal vessels in deep capillary plexus at baseline which corresponded to the area affected by SRNVM.

CONCLUSION

Fellow eyes of proliferative MacTel showed established disease stages on OCTA with progressive capillary crowding and entanglement of vessels likely corresponding to the future site of SRNVM.

IMPACT OF OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY REVIEW STRATEGY ON DETECTION OF CHOROIDAL NEOVASCULARIZATION

PURPOSE

To compare optical coherence tomography angiography (OCTA) review strategies for optimizing choroidal neovascularization (CNV) detection.

METHODS

Eyes with CNV in the differential diagnosis were imaged with the Avanti RTVue XR HD (Optovue, Fremont, CA). Three modalities of review for CNV presence were used in each case: a single report generated using automated segmentation within Avanti software; a continuous slab descent video OCTA export; and a manual segmentation approach using cross-sectional OCT with decorrelation signal overlay. Scans were reviewed by two masked expert reviewers; a third reviewer was used for discrepancies.

RESULTS

The study included 421 eyes, and 350 eyes had reports deemed sufficient quality for interpretation. Choroidal neovascularization was in the differential diagnosis in 107 of 350 patients. Overall CNV was identified in 55% (59/107) eyes. In those eyes with CNV, the automated segmentation identified CNV in 56% (33/59) of cases, continuous slab descent method identified CNV in 53% (31/59) of cases, and the manual segmentation group identified CNV in 92% (54/59) of cases.

CONCLUSION

Review strategies for detection of CNV on OCTA were highest using the manual segmentation method as compared to both the automated report and continuous slab descent methods. Although the manual segmentation method had a higher rate of detection, the practical aspects of the time required for segmentation make this method challenging in routine clinical practice.

Use of OCTA Capillary Perfusion Density Measurements to Detect and Grade Macular Ischemia

BACKGROUND AND OBJECTIVE

To compare optical coherence tomography angiography (OCTA) capillary perfusion density (CPD) measurements of normal eyes and eyes with macular ischemia (MI).

PATIENTS AND METHODS

AVATAR is an institutional review board-approved, prospective, observational imaging study using the Avanti RTVue XR HD. OCTA reports were reviewed for the presence of MI. Qualitative MI grading was performed, and CPD metrics in the superficial and deep fovea and parafovea were analyzed. A normal eye cohort was identified for comparative assessment.

RESULTS

The MI and normal cohorts included 55 and 58 eyes, respectively. Compared to normal eyes, eyes with MI had significantly lower CPD values in all regions. There was a statistically significant correlation between qualitative MI grade and VA in the superficial (P = .003) and deep plexuses (P = .029). Only deep parafoveal CPD values demonstrated correlation with VA (P = .043).

CONCLUSIONS

Eyes with MI determined by masked qualitative OCTA grading demonstrated significantly reduced CPD values compared to normal eyes. Categorical assessment of MI severity correlated with VA. [Ophthalmic Surg Lasers Imaging Retina. 2020;51:S30-S36.].

Perivenular Capillary Loss: An Early, Quantifiable Change in Macular Telangiectasia Type 2

Purpose

To evaluate differences in parafoveal vascular density surrounding arterioles and venules in type 2 macular telangiectasia (MacTel).

Methods

Thirty-seven eyes (20 subjects) diagnosed with MacTel and 16 healthy eyes (10 subjects) were imaged with optical coherence tomography angiography between March 2016 and June 2019 in this single-center, observational, cross-sectional study. Arterioles and venules were manually identified, and perivascular density was generated using a custom MATLAB code. The primary outcome measure was the ratio of periarteriolar to perivenular vascular density (arteriovenous [A/V] capillary ratio) in the superficial and deep capillary plexuses across MacTel stages. The main secondary outcome measures were overall parafoveal vascular density (VD), periarteriolar VD, and perivenular VD.

Results

In the superficial capillary plexus (SCP), the A/V capillary ratio was significantly higher in MacTel subjects than controls (0.914 vs. 0.892; P = 0.0044). The greatest differences occurred between controls and nonproliferative MacTel subjects without optical coherence tomography evidence of disease (P = 0.0055). A/V capillary ratios progressed in a nonlinear fashion with MacTel severity, increasing from nonproliferative disease (0.912) to intraretinal proliferative disease (0.931), then decreasing in subretinal proliferative disease (0.905). Parafoveal VD in the SCP was lower in MacTel subjects than controls only in subretinal proliferative disease (P = 0.0130).

Conclusions

The A/V capillary ratio of the SCP is a quantifiable metric of vascular pathology in MacTel that occurs earlier than decline in parafoveal VD. Elevated A/V capillary ratios in MacTel are consistent with an early, disproportionately perivenular disruption in the SCP.

Translational Relevance

Findings inform MacTel pathogenesis through revealing early perivenular capillary loss and offer a new quantitative metric for earliest stage MacTel.

Optical Coherence Tomography Angiography in Monitoring Proliferative Macular Telangiectasia Type 2 Treatment Response

BACKGROUND AND OBJECTIVE

Difficulty exists in the follow-up of proliferative macular telangiectasia type 2 (MacTel 2) cases after anti-vascular endothelial growth factor (VEGF) treatment due to staining in fluorescein angiography (FA) and alteration in retinal layers by optical coherence tomography (OCT). Herein, the authors report three cases in which OCT angiography (OCTA) could resolve this issue.

PATIENTS AND METHODS

In this retrospective, observational case series, diagnosis of MacTel 2 was made based on clinical examination, FA, OCT, and OCTA at presentation. Regression of neovessels was monitored by OCT and OCTA.

RESULTS

OCTA could delineate neovessels before treatment in all cases and facilitate differentiation between active and regressed lesions after treatment. Simultaneous OCT images were less easily appreciated due to altered retinal structure secondary to degenerative nature of the disease.

CONCLUSION

OCTA could be the tool of choice to monitor neovascular response to anti-VEGF treatment in proliferative MacTel 2. [Ophthalmic Surg Lasers Imaging Retina. 2019;50:485-491.].

Higher-Order Assessment of OCT in Diabetic Macular Edema from the VISTA Study: Ellipsoid Zone Dynamics and the Retinal Fluid Index

PURPOSE

To investigate retinal fluid features and ellipsoid zone (EZ) integrity dynamics on spectral-domain OCT (SD-OCT) in eyes with diabetic macular edema (DME) treated with intravitreal aflibercept injection (IAI) in the VISTA-DME study.

DESIGN

A post hoc subanalysis of a phase III, prospective clinical trial.

PARTICIPANTS

Eyes received either IAI 2 mg every 4 weeks (2q4) or every 8 weeks after 5 initial monthly doses (2q8).

METHODS

All eyes from the VISTA Phase III study in the IAI groups imaged with the Cirrus HD-OCT system (Zeiss, Oberkochen, Germany) were included. The OCT macular cube datasets were evaluated using a novel software platform to generate retinal layer and fluid boundary lines that were manually corrected for assessment of change in EZ parameters and volumetric fluid parameters from baseline. The retinal fluid index (i.e., proportion of the retinal volume consisting of cystic fluid) was also calculated at each time point.

MAIN OUTCOME MEASURES

The feasibility of volumetric assessment of higher-order OCT-based retinal parameters and its correlation with best-corrected visual acuity (BCVA).

RESULTS

Overall, 106 eyes of 106 patients were included. Specifically, 52 eyes of 52 patients were included in the IAI 2q4 arm, and 54 eyes of 54 patients were included in the IAI 2q8 arm. Ellipsoid zone integrity metrics significantly improved from baseline to week 100, including central macular mean EZ to retinal pigment epithelium (RPE) thickness (2q4: 26.6 μm to 31.6 μm, P < 0.001; 2q8: 25.2 μm to 31.4 μm, P < 0.001). At week 100, central macular intraretinal fluid volume was reduced by >65% (P < 0.001) and central macular subretinal fluid volume was reduced by >99% in both arms (P < 0.001). Central macular retinal fluid index (RFI) significantly improved in both arms (2q4: 17.9% to 7.2%, P < 0.001; 2q8: 19.8% to 4.2%, P < 0.001). Central macular mean EZ-RPE thickness (i.e., a surrogate for photoreceptor outer segment length) and central RFI were independently correlated with BCVA at multiple follow-up visits.

CONCLUSIONS

Intravitreal aflibercept injection resulted in significant improvement in EZ integrity and quantitative fluid metrics in both 2q4 and 2q8 arms and correlated with visual function.

Overlap between telangiectasia and photoreceptor loss increases with progression of macular telangiectasia type 2

OBJECTIVES

To examine the topographical correlation between ellipsoid zone loss and telangiectasia in the deep capillary plexus in patients with macular telangiectasia type 2 (MacTel).

METHODS

38 eyes (20 subjects) diagnosed with MacTel were imaged with OCTA between March 2016 and June 2019 in this single center, cross-sectional observational study. The en face OCTA and OCT were evaluated for areas of deep capillary plexus telangiectasia and ellipsoid zone loss, respectively, and their outlines were superimposed to study their overlap (mm2). The primary outcome was percentage of overlap and its relationship to MacTel stage. Secondary outcomes included the relationship between neovascularization and hyperreflective foci as well as correlations between ellipsoid zone loss, deep capillary plexus telangiectasia and visual acuity.

RESULTS

In nonproliferative MacTel stage, ellipsoid zone loss was localized to margins of telangiectatic areas (mean overlap = 15.2%). In proliferative stages, ellipsoid zone loss showed a higher degree of overlap with telangiectatic areas (mean overlap = 62.8%). Overlap increased with advancing MacTel stages, with an overall average of 45.3%. Overlap correlated highly with ellipsoid zone loss (r = 0.831; p<0.0001). Telangiectasia was present in all 38 eyes (range: 0.08mm2-0.99mm2), while ellipsoid zone loss was absent in 6 (range: 0.00-3.32mm2). Visual acuity correlated most strongly with ellipsoid zone loss (r = 0.569; p = 0.0002), followed by overlap (r = 0.544; p = 0.0004), and finally, telangiectasia (r = 0.404; p<0.0118). Presence of hyperreflective foci on OCT correlated with the presence and intraretinal location of neovascularization.

CONCLUSIONS

Ellipsoid zone loss occurs at the margins of deep capillary plexus telangiectasia in nonproliferative MacTel, with progressively increasing overlap as MacTel advances, peaking in proliferative disease. Deep capillary plexus telangiectasia and its overlap with ellipsoid zone loss are two promising markers of nonproliferative MacTel, while hyper-reflective foci are markers for proliferative MacTel.

Evaluation of 1-year follow-up results of macular telangiectasia type 2 cases by optical coherence tomography angiography

The results of 1-year follow-up with optical coherence tomography angiography (OCTA) of 3 patients with macular telangiectasia type 2 (MacTel 2) were evaluated. The 3X3 mm OCTA imaging was performed in January 2017 and February 2018. The superficial and deep capillary plexus vascular density changes of the whole area, the parafoveal temporal and parafoveal nasal areas were examined. The mean whole, parafoveal temporal, and parafoveal nasal vessel densities at superficial capillary plexus were 51.31, 50.39, 54.57 at baseline and 49.93, 46.79, 51.83 at 1-year follow-up, respectively. The mean whole, parafoveal temporal and parafoveal nasal vessel densities at deep capillary plexus were 59.06, 59.05, 63.39 at baseline and 52.18, 54.68, 57.9 at 1-year follow-up, respectively. In this case series, it was shown quantitatively that vessel densities of MacTel2 patients markedly decreased over time, more pronounced in the deep capillary plexus.

Optical Coherence Tomography Angiography in Eyes with Indeterminate Choroidal Neovascularization: Results from the AVATAR study

OBJECTIVE

To evaluate the use of optical coherence tomography angiography (OCTA) to detect choroidal neovascularization (CNV) in eyes with indeterminate CNV features on conventional imaging.

DESIGN

The AVATAR study is a prospective observational study of OCTA in patients undergoing routine spectral-domain optical coherence tomography (SD-OCT) for macular disease.

PARTICIPANTS

Subjects enrolled in the AVATAR study for which CNV was considered as part of a differential diagnosis based on clinical exam and/or prior imaging, but in whom the presence of CNV was not definitive on SD-OCT and fluorescein angiography (FA) imaging.

INTERVENTIONS

All patients were imaged with the Avanti RTVue XR HD (Optovue, Fremont, CA) and the Cirrus HD-OCT (Zeiss, Oberkochen, Germany) systems.

MAIN OUTCOME MEASURES

OCTA scans were assessed for the presence or absence of CNV. SD-OCT scans were assessed for the presence of fluid, hyperreflective material, serous pigment epithelial detachment (PED), shallow irregular PED, vitreomacular adhesion, epiretinal membrane, retinal pigment epithelium atrophy and central subfield retinal thickness. Univariate and multivariate logistic regression analyses were performed to identify features on SD-OCT associated with the presence of CNV on OCTA.

RESULTS

Twenty-nine eyes of 29 patients met the criteria for inclusion. A CNV lesion was detected on OCTA in 8 (28%) eyes; 21 (72%) eyes were negative for CNV. After adjusted for age, gender and central subfield retinal thickness, the presence of shallow irregular PED [odds ratio, 148; 95% confidence interval, 3.22-6830; p = 0.011], as well as the combinations of intraretinal fluid and sub-retinal pigment epithelium material [odds ratio, 16.8; 95% confidence interval, 1.43-198; p = 0.025] on SD-OCT were significantly associated with the presence of CNV on OCTA.

CONCLUSIONS

OCTA enabled the identification of CNV that was otherwise indeterminate with prior imaging in select eyes. The presence of a shallow irregular PED as well as intraretinal fluid combined with sub-retinal pigment epithelium material were both associated with the presence of CNV. OCTA may be a valuable adjunct to conventional SD-OCT and FA imaging in the detection and surveillance of CNV, particularly in diagnostic dilemmas.

Assessment of inner and outer retinal layer metrics on the Cirrus HD-OCT Platform in normal eyes

Purpose

Ellipsoid zone (EZ) and outer retinal integrity are strongly linked to visual prognosis, but quantitative normative data is lacking. This study evaluates the EZ, outer retina, and inner retina in eyes without macular disease across a wide age spectrum.

Methods

An IRB-approved study was performed for eyes without macular pathology undergoing Spectral Domain Optical Coherence Tomography (SD-OCT) scans on the Cirrus HD-OCT system (Carl Zeiss Meditec, Oberkochen, Germany). Scans were analyzed using a previously described automated EZ mapping tool with line-by-line manual verification. Segmentation included internal limiting membrane (ILM), outer nuclear layer/Henle fiber layer complex (ONL/HFL), EZ, and the retinal pigment epithelium (RPE). The output included metrics for the inner retina (ILM-OPL/HFL), outer retina (ONL/HFL-RPE), EZ-RPE area and volume, and en face EZ mapping. EZ-RPE attenuation on en face mapping was defined as EZ-RPE thickness < 20 um, and total attenuation was 0 um. Imaging parameters were assessed for the group and compared to age, sex, visual acuity and spherical equivalent.

Results

167 eyes from 167 subjects were included. Mean age was 49.7 years (range 10–84 years). The mean foveal retinal thickness was 200.58 ± 19.22 um. Mean inner retinal thickness was 21.47 ± 13.60 um. Mean outer retinal thickness was 179.11 ± 18.52 um. Mean EZ-RPE thickness was 50.58 ± 6.01um. The mean EZ-RPE volume was 1.20 ± 0.10 mm³. Mean EZ attenuation percentage per macular map area was 0.87% ± 1.13% and mean percentage total attenuation was 0.12% ± 0.14%. Total and inner retinal thickness metrics decreased with age. Mean outer retinal thickness increased with age. EZ-RPE parameters were unchanged with age. However, EZ attenuation was negatively correlated with age.

Conclusion

This study provides important information for inner and outer retinal parameters. Future research on quantitative EZ integrity can utilize this data for comparison.

Retinal pigment epithelium hyperplasia overlying pigment epithelial detachment in age-related macular degeneration can masquerade as neovascularization on optical coherence tomography angiography

Purpose

To report the image artifacts due to retinal pigment epithelium (RPE) hyperplasia overlying retinal pigment epithelial detachment (PED) in age-related macular degeneration (AMD), which can masquerade as neovascularization on optical coherence tomography angiography (OCTA).

Methods

A hospital-based, retrospective, and cross-sectional study. Twenty-two eyes from 16 patients with non-vascularized PED related to AMD were included in this study. All patients were examined by OCTA, spectral-domain optical coherence tomography, fluorescence angiography, and indocyanine green angiography. Vascular flow signals (VFS) on both the outer retinal slab of en face OCTA and cross-sectional OCTA and their correspondence with RPE hyperplasia were evaluated.

Results

Fifteen eyes (68.2%) showed VFS on both the outer retina slab of en face OCTA and cross-sectional OCTA, all corresponding to the RPE hyperplasia overlying PED. Among them, 12 eyes with lump RPE hyperplasia outside foveal avascular zone (FAZ) all showed obvious VFS on the outer retina slab of OCTA, and 3 eyes with scattered RPE hyperplasia outside FAZ showed VFS fragments. Of note, 4 eyes had accompanied RPE hyperplasia inside FAZ, and 7 eyes without RPE hyperplasia overlying PED showed no corresponding VFS on the outer retina slab of OCTA. Additionally, a round-like dark band at the edge of PED was observed in the outer retina slab on en face OCTA in 17 eyes (77.3%).

Conclusions

RPE hyperplasia overlying PED in AMD can masquerade as neovascularization on OCTA. To avoid misdiagnosis and unnecessary treatment, this RPE hyperplasia-related image artifact should be considered when interpreting OCTA images.

Late-Stage Sjögren-Larsson Syndrome Maculopathy Imaged With OCT Angiography

Three adult siblings with Sjögren-Larsson syndrome (SLS) demonstrated signs of late-stage SLS maculopathy, including intraretinal crystals, atrophic changes, and lipofuscin deposition. This first report of SLS maculopathy imaged with optical coherence tomography angiography revealed decreased retinal capillary density, vessel dilation, and increased flow voids in the superficial and deep capillary plexuses. [Ophthalmic Surg Lasers Imaging Retina. 2018;49:e78-e82.].

Automated detection of photoreceptor disruption in mild diabetic retinopathy on volumetric optical coherence tomography

Diabetic retinopathy is a pathology where microvascular circulation abnormalities ultimately result in photoreceptor disruption and, consequently, permanent loss of vision. Here, we developed a method that automatically detects photoreceptor disruption in mild diabetic retinopathy by mapping ellipsoid zone reflectance abnormalities from en face optical coherence tomography images. The algorithm uses a fuzzy c-means scheme with a redefined membership function to assign a defect severity level on each pixel and generate a probability map of defect category affiliation. A novel scheme of unsupervised clustering optimization allows accurate detection of the affected area. The achieved accuracy, sensitivity and specificity were about 90% on a population of thirteen diseased subjects. This method shows potential for accurate and fast detection of early biomarkers in diabetic retinopathy evolution.