Baseline characteristics of participants in the natural history study of macular telangiectasia (MacTel) MacTel Project Report No. 2

Prognostic Relevance of Relative Ellipsoid Zone Reflectivity for Ellipsoid Zone Loss in Macular Telangiectasia Type 2

Purpose

The relative ellipsoid zone reflectivity (rEZR) is an innovative biomarker for photoreceptor alterations and showed association with disease staging in macular telangiectasia type 2 (MacTel). However, its prognostic relevance for the ellipsoid zone (EZ) loss is unclear.

Methods

Longitudinal spectral-domain optical coherence tomography (SD-OCT) imaging of patients with MacTel from an observational natural history study was used for en face determination of manifest EZ loss. The rEZR was assessed globally (mean rEZR/SD-OCT volume scan) and topographically (spatially refined). Logistic and linear-mixed effect models were used to investigate the rEZR's association with EZ loss onset and the (square-root transformed) progression rate of existing EZ loss.

Results

A total of 97 eyes of 70 patients (39 women, mean age = 60.3 ± 8.9 years) were included and reviewed in a median observational period of 28.7 months (range = 20.3-49.9 months). Whereas 65 eyes of 44 patients showed manifest EZ loss (mean ± SD area = 0.44 ± 0.57 mm2) at baseline, 14 eyes of 14 patients developed EZ loss over time. Significant associations of the rEZR were only found in the topographical analyses indicated by lower rEZR values and a higher risk for EZ loss onset (odds ratio [OR] = 0.34, 95% confidence interval [CI] = 0.29 to 0.39, P < 0.001) as well as a faster EZ loss progression (coefficient estimate = -0.002, 95% CI = -0.0046 to 0.0001, P = 0.038).

Conclusions

This study demonstrates the prognostic relevance of spatially refined rEZR changes before and beyond already existing EZ loss for both its onset and progression over time in MacTel. Further analyses of the rEZR are warranted to achieve both a more tailored patient selection and a novel end point identification for clinical trials in MacTel.

Retinal pigment epithelial cells reduce vascular leak and proliferation in retinal neovessels

In multiple neurodegenerative diseases, including age-related macular degeneration, retinitis pigmentosa, and macular telangiectasia type 2 (MacTel), retinal pigment epithelial (RPE)-cells proliferate and migrate into the neuroretina, forming intraretinal pigment plaques. Though these pigmentary changes are hallmarks of disease progression, it is unknown if their presence is protective or detrimental.Here, we first evaluated the impact of pigment plaques on vascular changes and disease progression in MacTel. In a retrospective, longitudinal study, we analyzed multimodal retinal images of patients with MacTel and showed that pigment plaques were associated with decreased vascular leakage and stabilized neovascular growth. We then modeled the underlying pathomechanisms of pigment plaque formation in aberrant neovascular growth using the very-low-density lipoprotein receptor mutant (Vldlr-/-) mouse. Our data indicated that during RPE-proliferation, migration and accumulation along neovessels RPE-cells underwent epithelial-mesenchymal transition (EMT). Pharmacologic inhibition of EMT in Vldlr-/- mice decreased pigment coverage, and exacerbated neovascular growth and vascular leakage.Our findings indicate that the proliferation, migration and perivascular accumulation of RPE-cells stabilize vascular proliferation and exudation, thereby exerting a protective effect on the diseased retina. We conclude that interfering with this "natural repair mechanism" may have detrimental effects on the course of the disease and should thus be avoided.

Progressive inner retinal neurodegeneration in non-proliferative macular telangiectasia type 2

PURPOSE

Patients with non-proliferative macular telangiectasia type 2 (MacTel) have ganglion cell layer (GCL) and nerve fibre layer (NFL) loss, but it is unclear whether the thinning is progressive. We quantified the change in retinal layer thickness over time in MacTel with and without diabetes.

METHODS

In this retrospective, multicentre, comparative case series, subjects with MacTel with at least two optical coherence tomographic (OCT) scans separated by >9 months OCTs were segmented using the Iowa Reference Algorithms. Mean NFL and GCL thickness was computed across the total area of the early treatment diabetic retinopathy study grid and for the inner temporal region to determine the rate of thinning over time. Mixed effects models were fit to each layer and region to determine retinal thinning for each sublayer over time.

RESULTS

115 patients with MacTel were included; 57 patients (50%) had diabetes and 21 (18%) had a history of carbonic anhydrase inhibitor (CAI) treatment. MacTel patients with and without diabetes had similar rates of thinning. In patients without diabetes and untreated with CAIs, the temporal parafoveal NFL thinned at a rate of -0.25±0.09 µm/year (95% CI [-0.42 to -0.09]; p=0.003). The GCL in subfield 4 thinned faster in the eyes treated with CAI (-1.23±0.21 µm/year; 95% CI [-1.64 to -0.82]) than in untreated eyes (-0.19±0.16; 95% CI [-0.50, 0.11]; p<0.001), an effect also seen for the inner nuclear layer. Progressive outer retinal thinning was observed.

CONCLUSIONS

Patients with MacTel sustain progressive inner retinal neurodegeneration similar to those with diabetes without diabetic retinopathy. Further research is needed to understand the consequences of retinal thinning in MacTel.

Multilayer Retinal Correspondence of the Structural and Vascular Anomalies in Eyes With Early Macular Telangiectasia Type 2

Purpose

To assess the correspondence between interdigitation zone (IZ) reflectivity, ellipsoid zone (EZ) loss, inner retinal layer reflectivity, patterns of capillary dilation, and telangiectasia in eyes with early macular telangiectasia type 2 (MacTel).

Patients and Methods

Twenty-eight eyes of 22 patients with grade 0-2 MacTel (according to the MacTel project classification) and 28 healthy control eyes were included in this study. Multimodal imaging, including optical coherence tomography (OCT) angiography, adaptive optics flood illumination ophthalmoscopy (AO-FIO) and blue light reflectance (BLR), was performed. The EZ, IZ, and outer plexiform layer (OPL) were analyzed on the structural OCT C-scans. The vascular density (VD) was measured on the binarized and skeletonized angiograms of the superficial vascular plexus and deep capillary complex. The vascular diameter index (VDI) was calculated by dividing the binarized VD by the skeletonized VD.

Results

On AO-FIO, cone density in the MacTel zone was significantly lower in MacTel eyes than in controls, even in areas located outside the EZ loss (P < 0.001). A distinctive pattern of IZ reflectivity attenuation extended beyond the area of EZ attenuation. The shape and size of a strong OPL hyper-reflectivity corresponded to the MacTel white area (MacTel zone) seen on BLR. Capillary dilation and rarefaction were colocalized with this area, extending beyond visible telangiectasia. The VDI was higher in MacTel eyes than in controls (P < 0.001).

Conclusions

These findings suggest that in early MacTel eyes, photoreceptor signal alteration, OPL hyper-reflectivity, and capillary dilation, potentially associated with Müller cell dysfunction, precede the EZ loss.

ELLIPSOID ZONE RECOVERY IN MACULAR TELANGIECTASIA TYPE 2

PURPOSE

To describe imaging features of macular telangiectasia type 2 eyes experiencing ellipsoid zone (EZ) recovery.

METHODS

Macular telangiectasia type 2 patients with EZ recovery were identified from the Natural History and Observational Registry study and underwent retinal imaging including optical coherence tomography and fundus photography. Eyes were graded according to the classification system by Gass and Blodi, the EZ-loss area was measured, and optical coherence tomography parameters were assessed by two independent readers. Parameters were analyzed for their presence before EZ recovery.

RESULTS

Twenty-four eyes of 21 patients (12 female, 57.12%; mean age 68 ± 8.54 years) were included in this study and followed for 21.25 months ± 12.79 months. At baseline, mean EZ-loss area was 0.036 mm 2 ± 0.028 mm 2 and 0.01 mm 2 ± 0.013 mm 2 at follow-up ( P < 0.001). A persisting external limiting membrane overlaying the EZ-loss was detected in 16 cases (66%), and hyperreflective changes in the outer retina were present in 18 cases (75%). Best-corrected visual acuity was 0.23 (20/32) ± 0.33 logMAR at baseline and 0.34 (20/40) ± 0.34 logMAR at follow-up ( P = 0.3).

CONCLUSION

Distinct optical coherence tomography features precede ellipsoid zone recovery in macular telangiectasia type 2 and warrant further studies investigating implications for patient care and clinical trial interpretation.

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.

FROM OUTER RETINAL NEOVACULARIZATION TO EXUDATIVE SUBRETINAL NEOVASCULARIZATION IN MACULAR TELANGIECTASIA TYPE 2

PURPOSE

To describe the progression from outer retinal neovascularization (ORNV) to exudative subretinal new vessels (SRNVs) in idiopathic macular telangiectasia type 2.

METHODS

A total of 135 patients (270 eyes) imaged with optical coherence tomography angiography were included.

MAIN OUTCOME MEASURES

Ellipsoid zone loss, outer retinal hyperreflectivity, ORNV, and SRNVs. Outer retinal neovascularization was defined as a flow signal passing through the outer plexiform layer, with or without vertical linear outer retinal hyperreflectivity on the optical coherence tomography B-scan. Subretinal new vessels were defined as an abnormal capillary network with a peripheral anastomotic arcade seen on en face optical coherence tomography angiography and a convex hyperreflectivity at the retinal pigment epithelium.

RESULTS

Subretinal new vessels were observed in 38/270 eyes (14%). Subretinal new vessels were at a fibrotic stage in 24/38 eyes and at an exudative stage in 6/38 eyes, and a progression from ORNV to SRNVs was documented in 8/38 eyes. All cases showed an ellipsoid zone loss. In seven eyes (2.5%), SRNVs were also associated with subepithelial neovascularization. No retinochoroidal anastomosis was detected. The visual acuity dropped when SRNVs were present.

CONCLUSION

In this case series, SRNVs were found in 14% of eyes. In all cases, they were associated with an ellipsoid zone loss and with outer retinal hyperreflectivity. A progression from ORNV to SRNVs was observed.

High-Resolution Imaging in Macular Telangiectasia Type 2: Case Series and Literature Review

BACKGROUND

Macular telangiectasia (MacTel), also known as idiopathic juxtafoveolar telangiectasis (IJFTs), involves telangiectatic changes in the macular capillary network. The most common variant, MacTel type 2, has distinct clinical features and management strategies.

METHODS

This study offers a comprehensive review of MacTel and focuses on a series of three patients diagnosed with MacTel type 2 in our clinic. A meticulous ophthalmological evaluation, augmented by high-resolution imaging techniques like optical coherence tomography (OCT), OCT angiography (OCT-A), fundus autofluorescence (FAF), fluorescein angiography (FA), and adaptive optics (AOs) imaging, was conducted.

RESULTS

The findings revealed normal anterior segment features and a grayish discoloration in the temporal perifoveal area on fundus examination. OCT exhibited hyporeflective cavities in the inner and outer neurosensory retina, along with other changes, while OCT-A identified retinal telangiectatic vessels in the deep capillary plexus. FAF demonstrated increased foveal autofluorescence, while FA initially detected telangiectatic capillaries followed by diffuse perilesional leakage in the later phase. Adaptive optics images showed the cone mosaic pattern. Notably, one patient developed a macular hole as a complication, which was successfully managed surgically.

CONCLUSION

This study underscores the challenges in diagnosing and managing MacTel, emphasizing the importance of a multidisciplinary approach and regular follow-ups for optimal outcomes.

Gender differences in retinal diseases: A review

Gender medicine is a medical specialty that addresses gender differences in health and disease. Traditionally, medical research and clinical practice have often been focused on male subjects and patients. As a result, gender differences in medicine have been overlooked. Gender medicine considers the biological, psychological, and social differences between the genders and how these differences affect the development, diagnosis, treatment, and prevention of disease. For ophthalmological diseases epidemiological differences are known. However, there are not yet any gender-based ophthalmic treatment approaches for women and men. This review provides an overview of gender differences in retinal diseases. It is intended to make ophthalmologists, especially retinologists, more sensitive to the topic of gender medicine. The goal is to enhance comprehension of these aspects by highlighting fundamental gender differences. Integrating gender medicine into ophthalmological practice helps promote personalized and gender-responsive health care and makes medical research more accurate and relevant to the entire population.

Self-Supervised Learning for Improved Optical Coherence Tomography Detection of Macular Telangiectasia Type 2

Importance

Deep learning image analysis often depends on large, labeled datasets, which are difficult to obtain for rare diseases.

Objective

To develop a self-supervised approach for automated classification of macular telangiectasia type 2 (MacTel) on optical coherence tomography (OCT) with limited labeled data.

Design, Setting, and Participants

This was a retrospective comparative study. OCT images from May 2014 to May 2019 were collected by the Lowy Medical Research Institute, La Jolla, California, and the University of Washington, Seattle, from January 2016 to October 2022. Clinical diagnoses of patients with and without MacTel were confirmed by retina specialists. Data were analyzed from January to September 2023.

Exposures

Two convolutional neural networks were pretrained using the Bootstrap Your Own Latent algorithm on unlabeled training data and fine-tuned with labeled training data to predict MacTel (self-supervised method). ResNet18 and ResNet50 models were also trained using all labeled data (supervised method).

Main Outcomes and Measures

The ground truth yes vs no MacTel diagnosis is determined by retinal specialists based on spectral-domain OCT. The models' predictions were compared against human graders using accuracy, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), area under precision recall curve (AUPRC), and area under the receiver operating characteristic curve (AUROC). Uniform manifold approximation and projection was performed for dimension reduction and GradCAM visualizations for supervised and self-supervised methods.

Results

A total of 2636 OCT scans from 780 patients with MacTel and 131 patients without MacTel were included from the MacTel Project (mean [SD] age, 60.8 [11.7] years; 63.8% female), and another 2564 from 1769 patients without MacTel from the University of Washington (mean [SD] age, 61.2 [18.1] years; 53.4% female). The self-supervised approach fine-tuned on 100% of the labeled training data with ResNet50 as the feature extractor performed the best, achieving an AUPRC of 0.971 (95% CI, 0.969-0.972), an AUROC of 0.970 (95% CI, 0.970-0.973), accuracy of 0.898%, sensitivity of 0.898, specificity of 0.949, PPV of 0.935, and NPV of 0.919. With only 419 OCT volumes (185 MacTel patients in 10% of labeled training dataset), the ResNet18 self-supervised model achieved comparable performance, with an AUPRC of 0.958 (95% CI, 0.957-0.960), an AUROC of 0.966 (95% CI, 0.964-0.967), and accuracy, sensitivity, specificity, PPV, and NPV of 90.2%, 0.884, 0.916, 0.896, and 0.906, respectively. The self-supervised models showed better agreement with the more experienced human expert graders.

Conclusions and Relevance

The findings suggest that self-supervised learning may improve the accuracy of automated MacTel vs non-MacTel binary classification on OCT with limited labeled training data, and these approaches may be applicable to other rare diseases, although further research is warranted.

Epiretinal neovascular membrane in Macular Telangiectasia type 2: Multimodal imaging diagnosis

PURPOSE

To characterize an epiretinal neovascular membrane (ERNM) through multimodal imaging in the context of a patient with Macular Telangiectasia type 2 (MacTel) and ipsilateral concomitant ocular ischemic syndrome (OIS).

METHODS

Case report, with ultra-wide field (UWF) retinography, fluorescein angiography (FA), swept source optical coherence tomography (ss-OCT), and OCT-angiography (OCTA). Written informed consent for patient information and images to be published was provided by the patient. Approval from the Research Ethics Committee of the Hospital was obtained for publication.

CASE REPORT

Yearly follow up of a 51 year-old-female patient with advanced bilateral MacTel showed new punctate hemorrhages in all four quadrants of her right eye (OD). OCTA showed an ERNM in the superficial capillary plexus of the same eye and FA confirmed the ERNM and demonstrated peripheral ischemia. Carotid ultrasound was performed and complete right carotid artery occlusion was confirmed. These findings allowed the diagnosis of an ERNM associated with Mactel and OIS.

CONCLUSIONS

Interestingly, this case shows an ERNM diagnosed by multimodal imaging in a patient with advanced MacTel and a concomitant OIS. Mactel is a neurodegenerative disease which in its neovascular stage has been associated with macular neovascular membranes, but also ERNM have recently been described by OCTA.

Unraveling the mysteries of macular telangiectasia 2: the intersection of philanthropy, multimodal imaging and molecular genetics. The 2022 founders lecture of the pan American vitreoretinal society

PURPOSE

Offer a personal perspective on the scientific advances on macular telangiectasia type 2 (MacTel2) since the launch of the MacTel Project in 2005.

DESIGN

Literature review and personal perspective.

METHODS

Critical review of the peer-reviewed literature and personal perspective.

RESULTS

Generous financial support from the Lowy Medical Research Institute laid the foundations of the MacTel Project. MacTel Project investigators used state of the art multimodal retinal imaging and advanced modern biological methods to unravel many of the mysteries surrounding MacTel2. Major accomplishments includes elucidation of the pathogenic role that low serine levels, elevated 1-deoxysphingolipids and other mechanisms induce mitochondrial dysfunction which lead to Müller cell and photoreceptor degeneration; the use of objective measures of retinal structures such as the area of ellipsoid zone disruption as an outcome measure in clinical trials; the demonstration that the ciliary neurotrophic factor slows down retinal degeneration and the development of a new severity scale classification based on multimodal imaging findings.

CONCLUSIONS

MacTel2 is a predominantly metabolic disease characterized by defects in energy metabolism. Despite relatively good visual acuities, MacTel2 patients experience significant visual disability. The Mac Tel Project has been instrumental in advancing MacTel2 knowledge in the past two decades.

Longitudinal anatomical and visual outcome of macular telangiectasia type 2 in Asian patients

Limited information regarding the anatomical and visual prognosis of macular telangiectasia (MacTel) type 2 in the Asian population is currently available. Herein, we conducted a retrospective longitudinal analysis of Japanese patients diagnosed with MacTel type 2. Disease progression was evaluated using the Simple MacTel Classification developed by Chew EY et al. in 2023, and its association with visual changes was analyzed. Sixteen eyes of eight Japanese patients were included in the study, with an average follow-up period of 8.2 ± 3.9 years (range, 2.2-14.0). At the initial visit, 7 (44%) and 5 (31%) eyes were classified as Grade 2 (central ellipsoid zone break) and Grade 3 (noncentral pigment), respectively. The proportion of eyes that progressed by 1 or 2-steps in grade after 1, 3, 5, 8, and 12 years was 0%, 14%, 43%, 70%, and 100%, or 0%, 7%, 7%, 30%, and 75%, respectively. The visual acuity significantly deteriorated during the follow-up period, particularly in the two eyes with full-thickness macular holes (FTMH). Three out of 7 patients exhibited low serum serine concentrations, although no apparent correlation with anatomical or visual outcomes was observed. Overall, this cohort demonstrated chronic disease progression, both anatomically and functionally, in eyes with MacTel type 2, with FTMH potentially associated with greater visual loss.

Intraretinal pigmented cells in retinal degenerative disease

PURPOSE

Invasion of pigmented cells into the retina occurs in retinal degenerative diseases, such as macular telangiectasia type 2 (MacTel) and retinitis pigmentosa (RP). These intraretinal pigmented cells may be derived from the retinal pigment epithelium (RPE), but differences and similarities between intraretinal pigmented cells and RPE have so far not been well characterised.Clinicopathologic case report.

METHOD

Here, we compared intraretinal pigment cells with RPE cells by immunohistochemistry. Immunohistological stains for classic RPE markers (RPE65, CRALBP and KRT18) and blood vessel markers (lectin and collagen 4) were done on sections from postmortem eye tissue from two MacTel donors, an RP donor and a control donor.

MAIN OUTCOME MEASURES

Presence of specific immunohistochemistry markers on intraretinal pigmented and RPE cells.

RESULTS

We found that intraretinal pigmented cells did not express RPE65 and CRALBP, with a small subset expressing them weakly. However, they all expressed KRT18, which was also present in normal RPE cells. Interestingly, we also found clusters of KRT18-positive cells in the retina that were not pigmented.

CONCLUSIONS

Our findings suggest that RPE cells invading the retina dedifferentiate (losing classic RPE markers) and can be pigmented or unpigmented. Therefore, the number of RPE cells invading the retina in retinal degenerative disease may be underappreciated by funduscopy.

Sources and Sinks of Serine in Nutrition, Health, and Disease

Amino acid dysregulation has emerged as an important driver of disease progression in various contexts. l-Serine lies at a central node of metabolism, linking carbohydrate metabolism, transamination, glycine, and folate-mediated one-carbon metabolism to protein synthesis and various downstream bioenergetic and biosynthetic pathways. l-Serine is produced locally in the brain but is sourced predominantly from glycine and one-carbon metabolism in peripheral tissues via liver and kidney metabolism. Compromised regulation or activity of l-serine synthesis and disposal occurs in the context of genetic diseases as well as chronic disease states, leading to low circulating l-serine levels and pathogenesis in the nervous system, retina, heart, and aging muscle. Dietary interventions in preclinical models modulate sensory neuropathy, retinopathy, tumor growth, and muscle regeneration. A serine tolerance test may provide a quantitative readout of l-serine homeostasis that identifies patients who may be susceptible to neuropathy or responsive to therapy.

Co occurrance of Macular Telangiectasia type 2 with hemorrhagic polypoidal choroidal vasculopathy and response to anti-vascular endothelial growth factor

We report the case of a 57-year-old female patient who presented with defective vision in the right eye due to large hemorrhagic pigment epithelial detachment with subretinal hemorrhage near the arcades with scattered retinal pigment epithelium (RPE) alteration at the macula and minimal vitreous hemorrhage inferiorly. The left eye showed right angle perifoveal dipping venule with RPE alteration temporal to the fovea, intraretinal RPE stellate plaque at the macula area. Multimodal imaging features including color fundus photo, red-free photograph, optical coherence tomography (OCT), enhanced depth imaging OCT, fundus fluorescein angiography, indocyanine green angiography, and OCT angiography were studied along with treatment response. One eye showed features of macular telangiectasia Type 2 (MacTel 2) with polypoidal choroidal vasculopathy (PCV) (hemorrhagic type) and the other eye showed features of MacTel 2 with pachychoroid pigment epitheliopathy. This report highlights the hitherto undescribed co-occurrence of MacTel 2 with bilateral pachychoroid and with unilateral hemorrhagic PCV in one eye and its favorable outcome with anti-vascular endothelial growth factor therapy.

iPSC-derived retinal pigmented epithelial cells from patients with macular telangiectasia show decreased mitochondrial function

Patient-derived induced pluripotent stem cells (iPSCs) provide a powerful tool for identifying cellular and molecular mechanisms of disease. Macular telangiectasia type 2 (MacTel) is a rare, late-onset degenerative retinal disease with an extremely heterogeneous genetic architecture, lending itself to the use of iPSCs. Whole-exome sequencing screens and pedigree analyses have identified rare causative mutations that account for less than 5% of cases. Metabolomic surveys of patient populations and GWAS have linked MacTel to decreased circulating levels of serine and elevated levels of neurotoxic 1-deoxysphingolipids (1-dSLs). However, retina-specific, disease-contributing factors have yet to be identified. Here, we used iPSC-differentiated retinal pigmented epithelial (iRPE) cells derived from donors with or without MacTel to screen for novel cell-intrinsic pathological mechanisms. We show that MacTel iRPE cells mimicked the low serine levels observed in serum from patients with MacTel. Through RNA-Seq and gene set enrichment pathway analysis, we determined that MacTel iRPE cells are enriched in cellular stress pathways and dysregulation of central carbon metabolism. Using respirometry and mitochondrial stress testing, we functionally validated that MacTel iRPE cells had a reduction in mitochondrial function that was independent of defects in serine biosynthesis and 1-dSL accumulation. Thus, we identified phenotypes that may constitute alternative disease mechanisms beyond the known serine/sphingolipid pathway.

Tamoxifen Retinopathy and Macular Telangiectasia Type 2: Similarities and Differences on Multimodal Retinal Imaging

PURPOSE

Tamoxifen-induced retinopathy (TR) and macular telangiectasia type 2 (MacTel) share a highly similar retinal phenotype. In this study, we aimed to evaluate differences and similarities that may point toward underlying mechanisms linking both disease entities.

DESIGN

Retrospective, cross sectional study.

SUBJECTS

Patients diagnosed with MacTel or TR.

METHODS

Patients underwent multimodal retinal imaging, including color fundus photography, spectral-domain OCT, fundus autofluorescence, fluorescein angiography, and OCT angiography (if available). Age, age of onset, best-corrected visual acuity, and bilaterality of changes were evaluated. Patients' eyes were graded for different morphologic characteristics by 4 experienced graders.

MAIN OUTCOME MEASURES

Phenotypical characterization and comparison of frequencies of retinal characteristics of TR and MacTel on multimodal imaging.

RESULTS

Twenty-eight eyes of 14 patients with TR and 118 eyes of 59 patients with MacTel were included. Age, age of onset, and best-corrected visual acuity were similar in both cohorts. All but 1 patient showed bilateral changes. In patients with MacTel, neurodegenerative changes and vascular alterations were equally present, whereas in patients with TR, neurodegenerative changes usually prevailed. Predilection sites within the central retina differed between the 2 diseases: most findings in patients with TR were limited to the foveal center, whereas changes in patients with MacTel were present throughout a slightly larger region ("MacTel area"), with an epicenter temporal to the foveal center. Distinct morphologic features included the distribution of retinal crystals, the size and position of ellipsoid zone breaks, and the presence of hyperreflective changes on OCT images. Focal hyperpigmentation and neovascular membranes were only present in eyes with MacTel.

CONCLUSIONS

Macular telangiectasia and TR share a highly similar retinal phenotype, especially in early disease stages. Subtle differences on multimodal retinal images may help distinguish between these 2 disease entities. Our findings indicate the involvement of Müller cells in both diseases, which may explain the observed phenotypic characteristics and similarities.

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.

Intraretinal and subretinal fluid in exudative nonproliferative macular telangiectasia type 2

A 62-year-old man presented with complaints of decreased vision in BE. His best-corrected visual acuity (BCVA) was 6/12 in both eyes (BE). Based on his fundus examination and imaging findings, he was diagnosed with BE Macular Telangiectasia type 2 (MacTel 2) and was advised of regular follow-up. Over the course of follow-up, he developed further reduction in vision in the right eye (RE) to 6/24. Spectral-domain optical coherence tomography (SD-OCT) showed the presence of a subfoveal detachment (SFD) with intraretinal cystoid edema. He was diagnosed to have an exudative variant of preproliferative MacTel 2 and underwent three intravitreal injections of bevacizumab in the RE following which there was an improvement in BCVA to 6/12 along with the complete resolution of SFD and IRF on SD-OCT. This report describes a rare case of exudative nonproliferative macular telangiectasia type 2 presenting with the presence of intraretinal fluid.

Macular Telangiectasia Type 2: A Comprehensive Review

Macular telangiectasia Type 2 (MacTel) is a gradually progressive disease that affects the quality of life by impairing both distant and near vision. It had previously been considered a vascular condition, but recent evidence suggests a neurodegenerative etiology, with primary involvement of Muller cells. Retinal pigment epithelium (RPE) hyperplasia and subretinal neovascularization (SNV) are responsible for most of the vision loss in advanced cases. Neurotrophic factors in the non-proliferative phase and intravitreal anti-Vascular Endothelial growth factor (VEGF) in the proliferative phase have shown to retard the progression of the disease. This review will discuss the pathophysiology, clinical features, important diagnostic imaging studies and available treatment options for MacTel.

Is Type 2 Macular Telangiectasia a Bilateral and Symmetrical Disease Entity?

Purpose

To study the inter-eye asymmetry in cases diagnosed with type 2 macular telangiectasia (MacTel).

Methods

Herein, type 2 MacTel cases were staged as per Gass and Blodi classification with multiple imaging techniques. Based on disease stage symmetry, two groups identified. Group 1: Symmetrical stage and Group 2: Asymmetrical stage MacTel disease. Prevalence, demography, and clinical features of MacTel cases showing inter-eye asymmetry were analyzed.

Results

Two hundred and eighty eyes of 140 patients diagnosed clinically with type 2 MacTel (84-Group 1 and 56-Group 2) were evaluated. Eighty-nine (64%) were female, and the median age of the entire cohort was 62.5 years (inter-quartile range: 57.0-68.75). MacTel disease with asymmetric stage was seen in 56 (40%) of the 140 patients. At presentation, a two-stage difference was noted in 46% (n = 26) of the patients with asymmetrical MacTel disease. A 10% conversion from symmetrical to asymmetrical disease stage was noted at the final visit. Of the 280 eyes evaluated for type 2 MacTel disease, 12 (4%) eyes showed no findings suggestive of MacTel on clinical examination and fluorescein angiography, optical coherence tomography (OCT), and OCT angiography when available and were labeled as unilateral type 2 MacTel disease.

Conclusions

Type 2 MacTel can show inter-eye disease stage asymmetry. Unilateral type 2 MacTel disease is a distinct stage in MacTel which would need further evaluation and consideration while staging.

Long term follow-up of visual acuity and incidence of subretinal neovascularization in Mactel Type 2 in 82 Eyes

PURPOSE

: To evaluate the long-term natural course of macular telangiectasia Type 2, correlation with visual acuity and the incidence of Choroidal Neovascularisation (CNV) in Indian eyes.

MATERIAL AND METHODS

: A Retrospective analysis of Patients with MacTel Type 2 was done over a period of 12 years with all patients having a minimum of 3 years follow up. The demographic details and ocular characteristics including best-corrected visual acuity (BCVA), fundus photography, fluorescein angiography, and optical coherence tomography images were studied in both proliferative and non-proliferative MacTel. Mixed models were used to estimate progression rates and a Kaplan Meier estimation of BCVA was plotted.

RESULTS

: Eighty-two eyes of 47 patients were studied over a period of mean duration of 4.5 years (range: 3 years-8.5 years). There was no difference in the demographic characteristics between the non-proliferative MacTel and proliferative MacTel groups. There were no significant risk factors observed for progression. However, patients with retinal greying had significant risk reduction for a BCVA decline. The mean logMAR BCVA decreased from 0.25 ± 0.25 at baseline to 0.46 ± 0.42 by 4 years. Twenty-eight percent of the patients maintained their vision 8 years from baseline and were unlikely to progress. The incidence of CNV was 10.6% and the mean duration for the development of CNV was 2.36 years from baseline. Seventy-Three percent (11 of 15) patients with CNV had a BCVA of <20/40.

CONCLUSION

: In patients of MacTel, the maximum vision loss occurred at the fourth year and then stabilized. The major cause of poor vision observed was CNV (active in 10.98% and scarred in 7.32%), foveal atrophy (10.98%) and central pigmented plaques (3.66%). The incidence of sight-threatening complication of CNV (10.6%) is likely to occur only in a minority of eyes.

Characterizing right-angled vessel in macular telangiectasia type 2 with structural optical coherence tomography

We investigated the structural findings on spectral-domain optical coherence tomography (SD-OCT) related to the presence of right-angled vessels (RAV) in patients with macular telangiectasia (MacTel) type 2 with severity 3 in Korea. A retrospective multicenter cross-sectional study was conducted in six tertiary hospitals in Korea; the study included 116 MacTel type 2 eyes with severity 3. The SD-OCT findings were compared between eyes with RAV on fundus photography or fluorescein angiography and those without RAV. Logistic regression was performed to determine factors associated with the presence of RAV. Fifty eyes presented with RAV and 61 eyes without RAV. More eyes presented with only inner retinal (IR) cavities on SD-OCT among eyes without RAV than among those with RAV (P < 0.001). However, eyes with RAV presented with IR disorganization, outer retinal (OR) cavity, and ellipsoid zone (EZ) disruption more frequently than eyes without RAV did (all P < 0.001). These SD-OCT findings were significantly associated with the presence of RAV. The presence of RAV was closely related to IR disorganization, OR cavities, and EZ disruption on SD-OCT. These findings suggest an advanced phase of MacTel type 2.

Fundus Autofluorescence Imaging in Macular Telangiectasia Type 2: MacTel Study Report Number 9

PURPOSE

To investigate the role of fundus autofluorescence (FAF) imaging in the diagnosis of macular telangiectasia type 2 (MacTel) and to describe disease-associated FAF patterns and their origin.

DESIGN

Cross-sectional multicenter study METHODS: FAF images were collected from the multicenter MacTel Natural History Observation and Registry Study. In a first qualitative approach, common FAF phenotypes were defined and correlated with multimodal imaging. We then evaluated how many eyes showed FAF changes, and temporal vs nasal asymmetry of FAF changes was graded. Finally, 100 eyes of MacTel patients and 100 control eyes (50 normal eyes and 50 eyes with other macular diseases) were combined and 2 masked graders assessed the presence of MacTel based on FAF images alone.

RESULTS

The study included 807 eyes of 420 patients (33 eyes were excluded owing to poor image quality). Loss of macular pigment, cystoid spaces, pigment plaques, neovascular membranes, and ectatic vascular changes commonly caused characteristic changes on FAF images. All MacTel patients had macular FAF changes in at least 1 eye. In 95% of eyes, these changes were more pronounced temporally than nasally. Common FAF patterns were increased (60%) and mixed/decreased FAF (38%) and/or visibility of vascular changes such as blunted vessels or ectatic capillaries (79%). Based on those features, high diagnostic performance was achieved for detection of the disease based on FAF alone (Youden index up to 0.91).

CONCLUSIONS

The study demonstrates that MacTel is consistently associated with disease-specific changes on FAF imaging. Those changes are typically more pronounced in the temporal parafovea.

LONGITUDINAL FLUORESCENCE LIFETIME IMAGING OPHTHALMOSCOPY ANALYSIS IN PATIENTS WITH MACULAR TELANGIECTASIA TYPE 2 (MacTel)

PURPOSE

Fluorescence lifetime imaging ophthalmoscopy (FLIO) shows characteristic patterns in macular telangiectasia Type 2 (MacTel). This study investigates FLIO changes over time to better understand disease progression.

METHODS

Thirty-three patients with MacTel (age 60 ± 15 years) were followed at the Moran Eye Center with a prototype Heidelberg Engineering FLIO. The mean follow-up time was 19 ± 8 months (range 6-34 months). Fundus autofluorescence was excited at 473 nm, and FLIO lifetimes were recorded in in short (498-560 nm) and long (560-720 nm) spectral wavelengths channels.

RESULTS

Autofluorescence lifetimes imaging ophthalmoscopy lifetimes from the MacTel area prolonged significantly over time (subfield T1, baseline: short spectral channel 210 ± 54 ps, long spectral channel 269 ± 58 ps; follow-up: short spectral channel 225 ± 59 ps, P < 0.001, long spectral channel 282 ± 64 ps, P < 0.01). The average 12-months prolongation of FLIO lifetimes was 9 ps (short spectral channel) and 8 ps (long spectral channel). Autofluorescence lifetimes changes correlated positively with ellipsoid zone loss and negatively with changes in retinal thickness.

CONCLUSION

Autofluorescence lifetimes in MacTel slowly prolong over time, and temporal patterns progress to full rings. Detailed knowledge about FLIO changes will aid in understanding disease development and progression.

Choroidal vascularity index: an enhanced depth optical coherence tomography-based parameter to determine vascular status in patients with proliferative and non-proliferative macular telangiectasia

KEY MESSAGES

The pathogenesis of subretinal neovascularization (SRNV) due to macular telengiectasia (MacTel 2) has not fully elucidated. This optical coherence tomography (OCT)-based method can provide better understanding of the pathogenesis of SRNV due to MacTel 2.

PURPOSE

To evaluate the choroidal vascular index (CVI) through optical coherence tomography (OCT) on eyes with proliferative macular telangiectasia type 2 (MacTel 2) or non-proliferative MacTel 2, and in healthy individuals.

METHODS

Macular enhanced depth imaging OCT scans on 42 eyes of 21 patients with non-proliferative MacTel 2, on 32 eyes of 20 patients with proliferative MacTel 2, and on 38 eyes of 32 control patients were analyzed by adjusting for age-gender-axial length. Proliferative MacTel 2 was diagnosed when subretinal neovascularization (SRNV) was simultaneously observed in the non-proliferative phase. Binarization methods of ImageJ software were used to analyze images, and total choroid area (TCA), luminal area (LA) and stromal area (SA) were obtained. CVI was characterized as the ratio of LA to TCA.

RESULTS

The mean TCA and SA were significantly higher in group 1 and group 2 when compared with group 3 (3.36 ± 0.29 mm² vs. 3.27 ± 0.76 mm² vs. 2.49 ± 0.24 mm², p < 0.001; 1.15 ± 0.31 mm² vs. 1.10 ± 0.69 mm² vs. 0.35 ± 0.23 mm², respectively; p < 0.001). Although LA was relatively higher in group 1 and group 2 than group 3, no statistically significant difference was observed (2.22 ± 0.14 mm² vs. 2.17 ± 0.15 mm² vs. 2.13 ± 0.21 mm²) (p = 0.088). CVI was significantly lower in group 1 than other groups (0.65 ± 0.01 vs 0.67 ± 0.02 vs 0.68 ± 0.02) (p < 0.001).

CONCLUSION

As an OCT screening method, CVI may be used to assess the vascular status of the choroid on the eyes which are naive for or were exposed to SRNV secondary to MacTel 2, and to elucidate the pathogenesis of this disease.

Morphological characteristics preceding exudative neovascularisation secondary to macular telangiectasia type 2

AIMS

To identify morphological characteristics preceding the development of exudative neovascularisation secondary to Macular Telangiectasia type 2 (MacTel) using multimodal retinal imaging.

METHODS

In this retrospective study, eyes with a minimum observation period of 6 months prior to the de novo diagnosis of an exudative neovascularisation secondary to MacTel were analysed. Morphological changes preceding the formation of neovascularisation were evaluated using colour fundus photography, infrared imaging, fluorescein angiography, macular pigment measurement and optical coherence tomography (OCT). OCT-angiography (OCT-A) images were additionally available in a subset of patients.

RESULTS

Twenty eyes from 20 patients were examined over a median period of 17 months (range: 6-100 months). Eyes were characterised by an accelerated progression of ellipsoid zone loss (median of 0.013 mm²/month), increased thickness of the temporal parafovea and hyper-reflective lesions on OCT. The latter underwent morphological changes preceding the development of exudative neovascularisation, including an increase in size and density, and expansion to outer retinal layers and the retinal pigment epithelium. All eyes showed a foveal depletion of macular pigment. On OCT-A, a focal increase in blood flow was observed at the level of the outer retina/choriocapillaris, and retinal-retinal and retinal-choroidal anastomoses preceded the formation of exudative neovascularisation.

CONCLUSIONS

Multimodal imaging allows the identification of prognostic morphological features preceding the formation of exudative neovascularisation in MacTel. Eyes exhibiting these characteristics should be monitored closely and patients should be alert for emergent symptoms in order to detect and treat neovascularisation early and, thereby, prevent irreversible visual loss.

Genetic disruption of serine biosynthesis is a key driver of macular telangiectasia type 2 aetiology and progression

Background

Macular telangiectasia type 2 (MacTel) is a rare, heritable and largely untreatable retinal disorder, often comorbid with diabetes. Genetic risk loci subtend retinal vascular calibre and glycine/serine/threonine metabolism genes. Serine deficiency may contribute to MacTel via neurotoxic deoxysphingolipid production; however, an independent vascular contribution is also suspected. Here, we use statistical genetics to dissect the causal mechanisms underpinning this complex disease.

Methods

We integrated genetic markers for MacTel, vascular and metabolic traits, and applied Mendelian randomisation and conditional and interaction genome-wide association analyses to discover the causal contributors to both disease and spatial retinal imaging sub-phenotypes.

Results

Genetically induced serine deficiency is the primary causal metabolic driver of disease occurrence and progression, with a lesser, but significant, causal contribution of type 2 diabetes genetic risk. Conversely, glycine, threonine and retinal vascular traits are unlikely to be causal for MacTel. Conditional regression analysis identified three novel disease loci independent of endogenous serine biosynthetic capacity. By aggregating spatial retinal phenotypes into endophenotypes, we demonstrate that SNPs constituting independent risk loci act via related endophenotypes.

Conclusions

Follow-up studies after GWAS integrating publicly available data with deep phenotyping are still rare. Here, we describe such analysis, where we integrated retinal imaging data with MacTel and other traits genomics data to identify biochemical mechanisms likely causing this disorder. Our findings will aid in early diagnosis and accurate prognosis of MacTel and improve prospects for effective therapeutic intervention. Our integrative genetics approach also serves as a useful template for post-GWAS analyses in other disorders.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13073-021-00848-4.

Identification of genetic factors influencing metabolic dysregulation and retinal support for MacTel, a retinal disorder

Macular Telangiectasia Type 2 (MacTel) is a rare degenerative retinal disease with complex genetic architecture. We performed a genome-wide association study on 1,067 MacTel patients and 3,799 controls, which identified eight novel genome-wide significant loci (p < 5 × 10^-8), and confirmed all three previously reported loci. Using MAGMA, eQTL and transcriptome-wide association analysis, we prioritised 48 genes implicated in serine-glycine biosynthesis, metabolite transport, and retinal vasculature and thickness. Mendelian randomization indicated a likely causative role of serine (FDR = 3.9 × 10^-47) and glycine depletion (FDR = 0.006) as well as alanine abundance (FDR = 0.009). Polygenic risk scoring achieved an accuracy of 0.74 and was associated in UKBiobank with retinal damage (p = 0.009). This represents the largest genetic study on MacTel to date and further highlights genetically-induced systemic and tissue-specific metabolic dysregulation in MacTel patients, which impinges on retinal health.

FLUORESCENCE LIFETIME PATTERNS IN MACULAR TELANGIECTASIA TYPE 2

PURPOSE

Type 2 idiopathic macular telangiectasia (MacTel) is a rare bilateral neurodegenerative disease characterized by alterations in the macular capillary network leading to central vision loss. The purpose of this study was to quantify disease-specific retinal fluorescence lifetime patterns in patients with MacTel using fluorescence lifetime imaging ophthalmoscopy.

PARTICIPANTS

Both eyes of 14 patients (mean age ± SEM, 67.8 ± 6.4 years) with a clinical diagnosis of MacTel Type 2 and 14 healthy age-matched controls (age 69.8 ± 6.4 years) were included in this study.

METHODS

All participants were imaged with a fluorescence lifetime imaging ophthalmoscope (Heidelberg Engineering, Germany). Mean retinal fluorescence lifetimes (Tm) were obtained in the short spectral channels (498-560 nm) and long spectral channels (560-720 nm). Clinical features, fundus images, fundus autofluorescence intensity images, spectral domain optical coherence tomography, and corresponding macular pigment optical density measurements using a modified confocal scanning laser ophthalmoscope (mpHRA) were further analyzed. Patients were classified into five phenotypic subgroups using the Gass and Blodi classification.

RESULTS

Mean fluorescence lifetimes were significantly prolonged temporal to the fovea in patients with MacTel compared with healthy controls (mean ± SEM: short spectral channels 543 ± 61 ps vs. 304 ± 9 ps; P < 0.0001; long spectral channels: 447 ± 26 ps vs. 348 ± 11 ps; P < 0.0001), and appeared as a crescent or ring-shaped pattern. Prolonged lifetime patterns correlated with decreased macular pigment density on macular pigment optical density measurements. Follow-up examinations were performed in four MacTel patients, which revealed an increase of short spectral channel Tm of 22% over 2.1 years in the temporal fovea.

CONCLUSION

This study confirms that fundus autofluorescence lifetimes display characteristic patterns in patients with MacTel Type 2 disease and provide information about macular pigment and possibly photoreceptor loss. Fluorescence lifetime prolongation correlates with disease severity and may therefore be a useful addition to other imaging modalities for assessing disease progression in MacTel Type 2.

Demographic and Multimodal Imaging Features of Macular Telangiectasia Type 2: Korean Macular Telangiectasia Type 2 Study - Report No. 2

Purpose: To investigate the demographic and multimodal imaging features of macular telangiectasia (MacTel) type 2 in Korea and their relationship with visual acuity and the clinical stage.Methods: A retrospective multicentre cross-sectional study was conducted in six tertiary hospitals in Korea and the study included 84 patients. Demographic data and imaging data of fundus photography, fundus autofluorescence (FAF), confocal blue-light reflectance (CBR), fluorescein angiography (FAG), and optical coherence tomography (OCT) were collected.Results: The Korean patients with MacTel type 2 were predominantly female (75%), and the mean logMAR visual acuity was 0.282 ± 0.280 at initial presentation. Most commonly presented signs were the loss of retinal transparency in fundus photographs (68.3%); increased autofluorescence in FAF (83.6%); increased blue reflectance involving the centre in CBR (68.0%); telangiectatic vessels in FAG (88.2%); and hyporeflective cavities in OCT (77.7%). The eyes diagnosed in the first half of the study period (2009-2014) showed a tendency to be diagnosed at more advanced severe stages than those diagnosed in the second half of the study period (2015-2019), using new severity scales based on FAG, FAF and OCT findings.Conclusion: The clinical features of MacTel type 2 in Korean patients assessed by newer imaging modalities suggest that Korean patients and the Caucasian-dominant population show similar presentations. This study showed that MacTel type 2 can be diagnosed in the earlier phase of the disease by using new imaging modalities and through better understanding of the disease.

Prevalence and Severity of Diabetic Retinopathy in Patients with Macular Telangiectasia Type 2

PURPOSE

To study the prevalence and severity of diabetic retinopathy (DR) in patients with macular telangiectasia type 2 (MacTel 2).

DESIGN

Retrospective case series.

PARTICIPANTS

Patients with a diagnosis of MacTel 2 treated at the Rotterdam Eye Hospital or Erasmus Medical Center between 2014 and 2018 were included.

METHODS

The following information was retrieved from patient files: demographics, history of diabetes mellitus and hypertension, presence of DR, and severity of DR, that is, mild, moderate, severe, or proliferative. Presence of diabetic macular edema (DME) was assessed using OCT.

MAIN OUTCOME MEASURES

Presence and severity of DR.

RESULTS

Two hundred six eyes of 103 patients were included. At the onset of MacTel 2, the mean age was 61 years (standard deviation [SD], 9.8 years) and 64 (62%) were women. Mean follow-up was 71 months (SD, 60 months). Diabetes mellitus type 2 was present in 50 patients (49%) and hypertension was present in 47 patients (46%). Mild DR was present in 22 eyes (11%), of which 14 eyes (7%) showed signs at baseline and 8 eyes (4%) showed signs at a later time during follow-up. Ten eyes (5%) demonstrated remission of mild DR during follow-up. Both eyes (1%) in 1 patient progressed to moderate DR. Severe DR, proliferative DR, and DME did not occur.

CONCLUSIONS

Although diabetes mellitus was highly prevalent among MacTel 2 patients, no patients showed severe or proliferative DR or DME. These findings suggest that MacTel 2 could have a protective effect on the progression of DR. We hypothesize that our results may be explained by the role of Müller cells in the development of MacTel 2 and DR, and therefore a link between both diseases warrants additional studies.

Morphological features of macular telangiectasia type 2 in Japanese patients

PURPOSE

This study aimed to demonstrate the clinical course of Japanese patients with macular telangiectasia type 2 (MacTel-2).

METHODS

This retrospective observational case series included 16 eyes of 8 Japanese patients (3 men and 5 women) with MacTel-2. The mean age and follow-up duration was 66.9 years and 42.8 months, respectively. Differences in best-corrected visual acuity (BCVA), funduscopic macular findings, central macular thickness (CMT), and the length of macular ellipsoid zone (EZ) loss were compared between the initial/baseline and final visits. Optical coherence tomographic changes in CMT by ≥ 20% and in EZ loss by ≥ 20% or ≥ 100 μm were defined as improved or worsened.

RESULTS

Numerical changes in BCVA and EZ loss during follow-up were not statistically significant. However, the mean CMT at baseline, which was lower than that of healthy control eyes (P < 0.001), significantly increased during follow-up (P = 0.041). A certain proportion of eyes showed improvement in several parameters: funduscopic findings (both parafoveal retinal graying and foveal retinal pigment epithelium depigmentation) in 29% of eyes, CMT in 21% of eyes, and EZ loss in 43% of eyes.

CONCLUSIONS

The non-negligible proportion of eyes with improved parameters, marked especially by macular EZ loss, suggests that Japanese patients with MacTel-2 have milder clinical features than Caucasian patients reported in the literature.

Long-Term Outcomes in Macular Telangiectasia Type 2 With Subretinal Neovascularization

Purpose:

This work reports long-term outcomes in macular telangiectasia type 2 (MacTel) with subretinal neovascularization (SRNV).

Methods:

A retrospective, single-center review of medical records was performed on all patients with a diagnosis of MacTel presenting between May 2004 and October 2019. Medical and ocular history, best-corrected visual acuity (BCVA) at baseline and final visit, optical coherence tomography data, and treatment history of SRNV secondary to MacTel were recorded.

Results:

A total of 471 eyes were diagnosed with MacTel. SRNV was present in 44 eyes (9.3%), of which 38 eyes met inclusion criteria for SRNV. Average follow-up duration in the SRNV group was 78.4 months. All SRNV patients underwent antivascular endothelial growth factor (anti-VEGF) therapy. There was no significant change from mean baseline (0.59 ± 0.45) to final (0.70 ± 0.49) BCVA in the SRNV group as a whole ( P = .13). Subgroup analysis revealed 17 of 38 eyes had SRNV at diagnosis and received immediate anti-VEGF treatment. In this subgroup mean pretreatment BCVA was 0.89 ± 0.43 and the mean final BCVA was 0.87 ± 0.61 ( P = .84). The remainder (21 of 38 eyes) developed SRNV during follow-up. In this subgroup, final BCVA after initiation of treatment was 0.56 ± 0.32, an improvement in BCVA from SRNV onset ( P = .04) and a decrease from pre-SRNV onset baseline BCVA ( P = .008).

Conclusions:

Visual acuity is maintained, not improved, in long-term follow-up of MacTel with SRNV treated with anti-VEGF. Patients presenting with SRNV have a worse prognosis than those who develop SRNV during follow-up.

Longitudinal Assessment of Remnant Foveal Cone Structure in a Case Series of Early Macular Telangiectasia Type 2

Purpose

To determine the extent of remnant cone structure within early foveal ellipsoid zone (EZ) lesions in macular telangiectasia type 2 longitudinally using both confocal and split detector adaptive optics scanning light ophthalmoscopy (AOSLO).

Methods

Spectral domain optical coherence tomography (SDOCT), confocal and split detector AOSLO were acquired from seven patients (10 eyes) with small (early) EZ lesions on SDOCT secondary to macular telangiectasia type 2 at baseline, 6 months, and 12 months. The presence of cone structure on AOSLO in areas of EZ loss as well as cones at 1° eccentricity, and their change over time were quantified.

Results

By split detector AOSLO, remnant cone structure was identified within and on the borders of all foveal EZ lesions. Within the extent of these lesions, cone spacing ranged from 4.97 to 9.95 µm at baseline, 5.30 to 6.10 µm at 6 months, and 4.99 to 7.12 µm at 12 months. Four eyes with significantly smaller EZ lesions showed evidence of recovery of EZ reflectivity on SDOCT B-scans. Remnant cone structure was identified in some areas where EZ reflectivity recovered at the following time point. Eyes that showed recovery of EZ reflectivity had a continuous external limiting membrane.

Conclusions

Remnant cone structure can persist within small SDOCT-defined EZ lesions, which can wax and wane in appearance over time. AOSLO can help to inform the interpretation of SDOCT imaging.

Translational Relevance

The absence of EZ in early macular telangiectasia type 2 and other retinal conditions needs careful interpretation because it does not always indicate an absence of underlying cone structure. The integrity of the external limiting membrane may better predict the presence of remnant cone structure and recovery of EZ reflectivity.

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.

Optical coherence tomography-angiography for monitoring neovascularisations in macular telangiectasia type 2

PURPOSE

To evaluate the utility of optical coherence tomography-angiography (OCT-A) for monitoring activity, progression and response to therapy of neovascularisations (NVs) secondary to macular telangiectasia type 2 (MacTel).

METHODS

In a retrospective analysis, eyes with NVs secondary to MacTel were reviewed over a period of ≥8 months. Examinations at monthly intervals included visual acuity testing, dilated funduscopy, spectral domain-OCT and OCT-A. Eyes were treated with intravitreal VEGF (vascular endothelial growth factor)-inhibitors following a pro-re-nata (PRN) regime, and treatment decisions were based on morphological signs of activity as determined by B-scan OCT and funduscopy. Signs of neovascular activity were defined as an increase in retinal thickness, presence/increase of intraretinal/subretinal fluid and haemorrhages.

RESULTS

A total of 19 eyes from 17 patients were analysed. Patients were evaluated over a mean period of 13.4 months (range: 8.9 to 24.2). OCT-A permitted the monitoring of both treatment effects (regression) and progression (growth) of NVs, but not neovascular activity. The growth of neovascular vessels was detectable in OCT-A before signs of activity occurred on OCT. NVs showed a progressive growth over time despite PRN-treatment and preferentially grew and extended within areas characterised by a focal reduction of choriocapillaris perfusion.

CONCLUSIONS

The results indicate that OCT-A represents a useful imaging modality for monitoring NV-progression and treatment effects in MacTel. We demonstrate its advantages over conventional B-scan OCT imaging, including an earlier detection of NV-progression, and propose an adjustment of the current OCT-controlled PRN treatment regime in order to prevent NV-progression and subsequent functional loss in neovascular MacTel.

Case report: internal limiting membrane drape sign masking by foveal detachment in macular telangiectasia type 2

BACKGROUND

Internal limiting membrane (ILM) drape sign is an important OCT characteristic of Macular telangiectasia type 2 (MacTel 2). Described here is a case where masking of the ILM drape sign occurred with bilateral foveal detachments in a patient with MacTel 2.

CASE PRESENTATION

A 64-year old female was diagnosed with MacTel 2, four years prior to the current presentation on the basis of an OCT demonstrating bilateral ILM drape sign. Fluorescein angiography showed bilateral dilated, ectatic capillaries and late phase dye leak. At the current presentation there was bilateral gradual visual impairment over two months due to bilateral foveal detachments. Treatment with intravitreal Bevacizumab resulted in unmasking of the pre-existing ILM drape sign at 12 weeks. Visual acuity was reduced to counting fingers in the left eye with the neovascular membrane as a consequence of sub-retinal fibrosis, while the right eye maintained a vision of 6/12. A difference in the stage of the disease at presentation determined the long-term visual outcome after seven years of observation.

CONCLUSION

Foveal detachment can influence the OCT detectability of pre-existing foveal cystoid lesions. Visual prognosis at the final follow up was consistent with the interocular disparity of the disease stage at presentation.

Macular Telangiectasia Type 2: Visual Acuity, Disease End Stage, and the MacTel Area: MacTel Project Report Number 8

PURPOSE

To report the visual acuity measures from the macular telangiectasia type 2 (MacTel) registry and to investigate and describe phenotypic findings in eyes with substantial vision loss resulting from MacTel.

DESIGN

Cross-sectional multicenter study.

PARTICIPANTS

Participants in the MacTel Natural History Observation Registration Study.

METHODS

Best-corrected visual acuity (BCVA) data, retinal imaging data, and clinical data were accessed from the MacTel Study databases in May 2019.

MAIN OUTCOME MEASURES

Frequency distribution of BCVA and its relationship to age; morphologic changes in eyes with very late disease stages, defined by a BCVA of 20/200 or worse; average retinal thickness of macular subfields on OCT; and dimensions of the area affected by MacTel (i.e., the MacTel area).

RESULTS

Best-corrected visual acuity was 20/50 or worse in 37.3% and 20/200 or worse in 3.8% of 4449 eyes of 2248 patients; 18.4% and 0.7% of all patients showed bilateral BCVA of 20/50 or worse and 20/200 or worse, respectively. Asymmetry between right and left eyes was present (median BCVA, 71 letters vs. 74 letters), a finding supported by more advanced morphologic changes in right eyes. Participant age correlated with BCVA, but the effect size was small. If a neovascularization or macular hole were present, bilateral occurrence was frequent (33% or 17%, respectively), and BCVA was better than 20/200 (79% or 78%, respectively) or 20/50 or better (26% or 13%, respectively). Eyes with advanced disease (BCVA, ≤20/200) showed the following characteristics: (1) atrophy of the foveal photoreceptor layer with or without associated subretinal fibrosis; (2) an affected area, termed MacTel area, limited to a horizontal diameter not exceeding the distance between the temporal optic disc margin and foveal center, and the vertical diameter not exceeding approximately 0.8 times this distance (exceptions were eyes with large active or inactive neovascular membranes); (3) reduced retinal thickness measures within the MacTel area; and (4) less frequent retinal greying and more frequent hyperpigmentations compared with eyes that have better BCVA.

CONCLUSIONS

Severe vision loss is rare in MacTel and is related to photoreceptor atrophy in most people. Results indicate disease asymmetry with slightly worse vision and more advanced disease manifestation in right eyes. MacTel-related neurodegeneration does not spread beyond the limits of the MacTel area.

FLUORESCENCE LIFETIME IMAGING OPHTHALMOSCOPY (FLIO) PATTERNS IN CLINICALLY UNAFFECTED CHILDREN OF MACULAR TELANGIECTASIA TYPE 2 (MACTEL) PATIENTS

PURPOSE

Macular telangiectasia Type 2 (MacTel) is an inherited retinal disease following an autosomal dominant pattern with late onset and reduced penetrance. Fluorescence lifetime imaging ophthalmoscopy (FLIO) enhances diagnosis by showing distinct changes in MacTel. This study investigates FLIO-associated changes in clinically unaffected family members.

METHODS

Eighty-one patients with MacTel (61 ± 12 years), 33 clinically healthy children under age 40 years of these MacTel patients (MacTel-C; 31 ± 6 years), 27 other family members (children over age 40 years, siblings, and parents) and 30 controls were investigated with the Heidelberg FLIO. All subjects underwent multimodal conventional imaging, including optical coherence tomography, blue-light reflectance, fluorescein angiography, and macular pigment imaging.

RESULTS

All 81 patients with MacTel showed typical FLIO patterns. Of the 33 investigated MacTel-C with completely normal eye examinations and conventional imaging, 12 (36%) show FLIO patterns consistent with early MacTel.

CONCLUSION

Prolonged FLIO lifetimes in the parafoveal area within the short spectral channel, especially temporally, are MacTel-specific. Fluorescence lifetime imaging ophthalmoscopy detects these lifetime patterns in over one-third of clinically unaffected MacTel-C. Although further studies will be necessary to determine the specificity of FLIO, it may help diagnose MacTel before conventional imaging modalities show changes or patients experience visual disturbances. Early detection may facilitate future gene discovery studies and interventional trials.

Factors Affecting the Foveal Avascular Zone Area in Healthy Eyes among Young Chinese Adults

Purpose

To evaluate the influence of systemic and ocular factors on the foveal avascular zone (FAZ) area in young Chinese subjects' healthy eyes.

Methods

The current observational, cross-sectional study included 344 eyes from 172 healthy individuals (103 women, 69 men). Optical coherence tomography angiography realized with the split-spectrum amplitude-decorrelation angiography (SSADA) algorithm was used to assess the area of superficial FAZ. To determine the related factors and to reveal their potential correlations with the FAZ area, comprehensive examinations including both systemic and ocular ones were executed. Systemic examination involved factors including age, gender, and body mass index, while ocular examination involved factors including BCVA, refractive error, intraocular pressure, axial length (AL), anterior chamber depth, and central corneal thickness. Especially for fundus examination, central macular thickness (CMT), retinal volume, mean retinal thickness, macular blood flow area/vessel density in the superficial retinal layer (SRL) and deep retinal layer (DRL), mean retinal nerve fiber layer (RNFL) thickness, ganglion cell layer (GCL) thickness, C/D rate, rim area, and subfoveal choroid thickness were assessed, using mixed-effects regression models to appropriately account for intereye correlation. Subgroup analyses were performed based on gender and high myopia categories.

Results

The mean FAZ area was 0.30 ± 0.11 mm² and varied significantly across gender (P = 0.0024). AL, CMT, and RNFL thickness were found significantly correlated with the FAZ area in the univariate regression analysis (AL, P = 0.0005; CMT, P < 0.0001; and RNFL thickness, P = 0.0461). According to the multivariate results, CMT and macular blood flow in SRL were negatively correlated with FAZ (CMT: P < 0.0001; macular blood flow in SRL: P = 0.00223). Mean retinal thickness, mean GCL thickness, and macular blood flow in DRL were positively correlated with FAZ (mean retinal thickness: P = 0.0005; mean GCL thickness: P < 0.0001; and macular blood flow in DRL: P = 0.0099). Correlation results among these filtered factors and FAZ were more pronounced in non-high-myopic eyes than in high-myopic eyes and had a significant difference when data of male and female subjects were processed separately from each other.

Conclusion

The present cross-sectional study performed comprehensive systemic and ocular examinations in young Chinese adults and filtered factors affecting FAZ. We indicated that among all the assessed candidate factors, gender, AL, retinal thickness, macular blood flow, RNFL, and GCL thickness affected the FAZ area most significantly. Such findings would facilitate future research concerning the role of FAZ variation in fundus diseases.

Binocular Inhibition of Reading in Macular Telangiectasia Type 2

Purpose

To assess the presence of binocular gain in macular telangiectasia type 2 (MacTel) and its correlation to paracentral scotomas.

Methods

Sixty-eight patients with MacTel were consecutively recruited for a cross-sectional analysis. Best-corrected visual acuity (BCVA), reading acuity, and reading speed were tested monocularly and binocularly. Macular retinal sensitivity was examined with fundus-controlled perimetry (microperimetry). Scotomas were quantified by their size, their depth, and their proximity to the fovea.

Results

Binocular reading speed and acuity were lower than monocular reading speed and acuity in the functionally better eye (142 vs. 159 words per minute and 0.43 vs. 0.28 log reading acuity determination, P < 0.001). Magnitude of binocular inhibition of reading speed was correlated to the degree of interocular functional difference (R2 = 0.61, P < 0.001). This correlation was not found for reading acuity or BCVA (R2 < 0.03). Binocular reading speed was negatively correlated to size of right and left eye scotomas, with bigger effect size for left eye scotomas. The magnitude of binocular inhibition was correlated to size of left eye scotomas, but not of right eye scotomas. When both eyes had similar scotoma characteristics, the right eye was more frequently the better reading eye.

Conclusions

We provide evidence for the presence of binocular inhibition of reading performance in MacTel, likely due to binocular rivalry. This may result from the characteristic paracentral scotomas in noncorresponding retinal fields and, in particular, a disruptive projection of scotomas in reading direction arising from the left eyes. Patients may benefit from occluding one eye while reading.

Evaluation of Choroidal Thickness in Patients with Proliferative and Non-Proliferative Macular Telangiectasia Using Enhanced Depth Imaging Optical Coherence Tomography

Purpose: To compare subfoveal choroidal thickness (SFCT) in eyes with non-proliferative macular telangiectasia (MacTel) type 2 with or without subretinal neovascularization (SRNV) and healthy control eyes.Methods: Consecutive patients with non-proliferative and proliferative MacTel type 2 were included in the current study. For comparisons subjects with no ocular pathology were recruited and used as controls. Best corrected visual acuity (BCVA), central macular thickness (CMT), and subfoveal choroidal thickness (SFCT) were evaluated. Since axial length (AL) may affect choroidal thickness, AL measurements were performed to avoid confusion in SFCT between the groups.Results: Of the 63 eyes of 38 MacTel type 2 patients, 38 eyes had only MacTel type 2 (group 1) and 25 eyes had SRNV caused by MacTel type 2 (group 2). Fourty eyes of 20 subjects served as controls (group 3). BCVA was found to be significantly higher in control group compared with group 1 and group 2 (p < .005). Whereas, no difference was detected between group 1 and group 2 (p = .75). No difference was noted in CMT between the groups (p = .35). Axial length measurement was very similar among all three groups (p = .62). After adjusting for age and axial length SFCT was significantly thinner in group 3 than the other groups (p < .001), but no statistically significant difference was found between group 1 and group 2.Conclusions: Choroidal thickness did not vary between eyes with MacTel type 2 with SRNV and without SRNV. Choroid was significantly thicker in MacTel type 2 with SRNV and without SRNV than healthy eyes.

DARK ADAPTATION IN MACULAR TELANGIECTASIA TYPE 2

PURPOSE

To evaluate dark adaptation (DA) in patients with macular telangiectasia Type 2 (MacTel).

METHODS

After a local photobleach (4 × 4° size, 83% bleach), DA was measured using a test stimulus (2° diameter) projected at 5° eccentricity horizontal from the foveal center within the temporal parafovea. Cone plateau, rod intercept time, and rod recovery rate (S2) were calculated from the resulting DA curves. Findings were correlated with disease stages (according to Gass and Blodi), the area of ellipsoid zone loss in optical coherence tomography, and macular pigment loss ("MP-Classes 1-3").

RESULTS

Fifty-nine eyes of 59 patients were compared with 18 eyes of 18 healthy controls. Dark adaptation was significantly impaired in patients with MacTel. Although differences were most pronounced for parameters indicating rod-mediated recovery, cone-mediated recovery was also decreased, yet to a lesser extent. Dark adaptation parameters were only weakly associated with disease stages and ellipsoid zone loss. A better association was found between rod-mediated recovery (S2 and rod intercept time) and macular pigment loss (Kendall's tau for rod intercept time: 0.69 and S2: -0.51; both P < 0.0001).

CONCLUSION

Dark adaptation is significantly impaired in patients with MacTel. Our results indicate an association of reduced macular pigment and rod dysfunction in MacTel.

Progression characteristics of ellipsoid zone loss in macular telangiectasia type 2

PURPOSE

To investigate the progression characteristics of ellipsoid zone (EZ) loss in eyes with macular telangiectasia type 2 (MacTel) as reflected by area and linear measurements, and their relevance for visual acuity.

METHODS

Participants were selected from the MacTel Study cohort. Linear and area measurements of EZ loss were performed in Spectral-Domain Optical Coherence Tomograph (SD-OCT) volume scans. Progression characteristics and correlations between linear and area measurements were analysed using linear mixed effects models.

RESULTS

A total of 134 eyes of 70 patients were included (85 eyes with follow-up, mean 4.7 years, range: 1.4-8 years). Ellipsoid zone (EZ) loss significantly progressed at a mean annual increment of 0.057 mm² (p = 0.005). The progression rate was non-linear and interacted significantly with initial EZ lesion size indicating an exponential growth before reaching a plateau. There was a strong heterogeneity in area sizes between fellow eyes. EZ break length had a significant linear effect on EZ break area (b = 1.06, p < 0.001) and could predict it. The location of the EZ break had a significant impact on visual acuity.

CONCLUSION

Ellipsoid zone (EZ) loss in MacTel has a non-linear progression characteristic, and its rate depends on area size at baseline, which must be taken into account at sample selection in clinical trials. Our results show a good correlation of linear and area measures of EZ loss and a segregation of best-corrected visual acuity by EZ location, which may help routine clinical practice.