VERY EARLY DISEASE MANIFESTATIONS OF MACULAR TELANGIECTASIA TYPE 2

MULTIMODAL IMAGING OF UNILATERAL IDIOPATHIC MACULAR TELANGIECTASIA TYPE 2: A FIVE-YEAR STUDY

PURPOSE

To report a rare presentation of unilateral macular telangiectasia Type 2 followed up over 5 years.

METHODS

Case report.

RESULTS

A 58-year-old man presented to us with complaints of painless progressive reduction of vision in the right eye for the past 2 years. He had no systemic illnesses. On examination, his best corrected visual acuity was 20/40 in the right eye and 20/20 in the left eye. Fundus examination in the right eye revealed loss of foveal reflex along with mild temporal graying of the fovea, and the left eye revealed results within the normal limits. Both eyes showed the presence of peripapillary myelinated nerve fibers. Multimodal imaging findings included spectral-domain optical coherence tomography, optical coherence tomography angiography, fundus autofluorescence, and fundus fluorescein angiogram, which revealed findings suggestive of exudative preproliferative variant of Mac-Tel 2 in the right eye, whereas the left eye was showed results within normal limits. After a follow-up of 5 years, spectral-domain optical coherence tomography and optical coherence tomography angiography revealed no striking differences in both eyes, with no evidence of the disease in his left eye.

CONCLUSION

This report highlights a rare advanced unilateral presentation of Mac-Tel 2 with no evidence of even early signs of the disease in the fellow eye, over a long-term follow-up.

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.

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.

OUTER FOVEAL DEFECTS IN TYPE-2 MACULAR TELANGIECTASIA

PURPOSE

To report characteristics of outer foveal defects (OFDs) in type-2 macular telangiectasia (MacTel) on spectral domain optical coherence tomography.

METHODS

This was a single-center observational study. From a registry of 745 patients with MacTel, patients with OFDs were characterized. All patients underwent multimodal imaging including color fundus photography, confocal blue reflectance, fundus autofluorescence, and spectral domain optical coherence tomography. Staging of eyes was done using the Gass and Blodi classification. Spectral domain optical coherence tomography characteristics in the central 1 mm of the macula in eyes with OFD are reported.

RESULTS

Outer foveal defect was observed in 21 eyes of 15/745 (2%) patients with MacTel. These defects were bilateral in 6/15 (40%) patients and seen in stage 2 MacTel eyes. In order of prevalence, foveal parameters seen in OFD included hyper-reflective dots in outer retina in 19/21 (90%), ellipsoid zone loss in 18/21 (86%) eyes, interdigitation zone loss in 17/21 (81%) eyes, outer retinal hyporeflective cavitation in 14 (67%) eyes, hyporeflective cavitation at foveal pit in 8 (38%) eyes, and loss of external limiting membrane in 1 (5%) eye. The mean baseline length of the foveal ellipsoid zone loss was 240.17 ± 117.249 µm. The mean baseline central subfield thickness was 155.43 ± 17.215 µm. A total of 8/11 eyes (73%) showed an increase in size of OFD on follow-up.

CONCLUSION

Outer foveal defect in MacTel eyes is characterized predominantly by foveal loss of ellipsoid zone and interdigitation zone with relative preservation of external limiting membrane.

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.

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.

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.

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.

Microvascular changes precede visible neurodegeneration in fellow eyes of patients with asymmetric type 2 macular telangiectasia

IMPORTANCE

Macular telangiectasia type 2 (MacTel) is bilateral disease with characteristic alterations of the macular capillary network along with decreased macular pigment in the parafoveal area. The purpose of this study was to highlight that some eyes show microvascular changes which precede any visible neuronal changes on spectral-domain optical coherence tomography (SD-OCT).

METHODS

This observational study was conducted at a tertiary eye institute. From a registry of 630 patients with MacTel, we identified 4 patients with typical MacTel characteristics in only one eye with no visible changes on colour photographs or SD-OCT in the fellow eye. These 4 patients had findings of MacTel documented by colour fundus photograph, multicolour imaging (MCI), fundus autofluorescence (FAF), confocal blue reflectance (CBR), SD-OCT, and OCT-Angiography (OCT-A) in one eye. OCT-A was performed in MacTel patients using the High-resolution Spectralis (Heidelberg Engineering) module with a full-spectrum probabilistic approach and we employed a 30° x 15° (~8.8 mm × 4.4 mm) scan pattern covering the macula. MCI was done at the end so as to avoid fading the confocal blue reflectance hyperreflectivity seen in MacTel.

RESULTS

On OCT-A, all 4 fellow eyes showed telangiectasia and foveal avascular zone changes in the superficial and deep capillary plexuses with no changes on SD-OCT. None of the eyes showed typically increased reflectance on CBR around the foveal area.

CONCLUSION

These findings show that microvascular changes on OCT-A may occur before visible neurodegenerative changes on OCT, providing new insights into the course of the disease.

Mitochondrial Retinopathy

PURPOSE

To report the retinal phenotype and the associated genetic and systemic findings in patients with mitochondrial disease.

DESIGN

Retrospective case series.

PARTICIPANTS

Twenty-three patients with retinopathy and mitochondrial disease, including chronic progressive external ophthalmoplegia (CPEO), maternally inherited diabetes and deafness (MIDD), mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS), Kearns-Sayre syndrome, neuropathy, ataxia, and retinitis pigmentosa (NARP) syndrome, and other systemic manifestations.

METHODS

Review of case notes, retinal imaging, electrophysiologic assessment, molecular genetic testing including protein modeling, and histologic analysis of muscle biopsy.

MAIN OUTCOME MEASURES

Phenotypic characteristics of mitochondrial retinopathy.

RESULTS

Genetic testing identified sporadic large-scale mitochondrial DNA deletions and variants in MT-TL1, MT-ATP6, MT-TK, MT-RNR1, or RRM2B. Based on retinal imaging, 3 phenotypes could be differentiated: type 1 with mild, focal pigmentary abnormalities; type 2 characterized by multifocal white-yellowish subretinal deposits and pigment changes limited to the posterior pole; and type 3 with widespread granular pigment alterations. Advanced type 2 and 3 retinopathy presented with chorioretinal atrophy that typically started in the peripapillary and paracentral areas with foveal sparing. Two patients exhibited a different phenotype: 1 revealed an occult retinopathy, and the patient with RRM2B-associated retinopathy showed no foveal sparing, no severe peripapillary involvement, and substantial photoreceptor atrophy before loss of the retinal pigment epithelium. Two patients with type 1 disease showed additional characteristics of mild macular telangiectasia type 2. Patients with type 1 and mild type 2 or 3 disease demonstrated good visual acuity and no symptoms associated with the retinopathy. In contrast, patients with advanced type 2 or 3 disease often reported vision problems in dim light conditions, reduced visual acuity, or both. Short-wavelength autofluorescence usually revealed a distinct pattern, and near-infrared autofluorescence may be severely reduced in type 3 disease. The retinal phenotype was key to suspecting mitochondrial disease in 11 patients, whereas 12 patients were diagnosed before retinal examination.

CONCLUSIONS

Different types of mitochondrial retinopathy show characteristic features. Even in absence of visual symptoms, their recognition may facilitate the often challenging and delayed diagnosis of mitochondrial disease, in particular in patients with mild or nebulous multisystem 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.

Fundus autofluorescence imaging

Fundus autofluorescence (FAF) imaging is an in vivo imaging method that allows for topographic mapping of naturally or pathologically occurring intrinsic fluorophores of the ocular fundus. The dominant sources are fluorophores accumulating as lipofuscin in lysosomal storage bodies in postmitotic retinal pigment epithelium cells as well as other fluorophores that may occur with disease in the outer retina and subretinal space. Photopigments of the photoreceptor outer segments as well as macular pigment and melanin at the fovea and parafovea may act as filters of the excitation light. FAF imaging has been shown to be useful with regard to understanding of pathophysiological mechanisms, diagnostics, phenotype-genotype correlation, identification of prognostic markers for disease progression, and novel outcome parameters to assess efficacy of interventional strategies in chorio-retinal diseases. More recently, the spectrum of FAF imaging has been expanded with increasing use of green in addition to blue FAF, introduction of spectrally-resolved FAF, near-infrared FAF, quantitative FAF imaging and fluorescence life time imaging (FLIO). This article gives an overview of basic principles, FAF findings in various retinal diseases and an update on recent developments.

Deep learning-based classification and segmentation of retinal cavitations on optical coherence tomography images of macular telangiectasia type 2

AIM

To develop a fully automatic algorithm to segment retinal cavitations on optical coherence tomography (OCT) images of macular telangiectasia type 2 (MacTel2).

METHODS

The dataset consisted of 99 eyes from 67 participants enrolled in an international, multicentre, phase 2 MacTel2 clinical trial (NCT01949324). Each eye was imaged with spectral-domain OCT at three time points over 2 years. Retinal cavitations were manually segmented by a trained Reader and the retinal cavitation volume was calculated. Two convolutional neural networks (CNNs) were developed that operated in sequential stages. In the first stage, CNN1 classified whether a B-scan contained any retinal cavitations. In the second stage, CNN2 segmented the retinal cavitations in a B-scan. We evaluated the performance of the proposed method against alternative methods using several performance metrics and manual segmentations as the gold standard.

RESULTS

The proposed method was computationally efficient and accurately classified and segmented retinal cavitations on OCT images, with a sensitivity of 0.94, specificity of 0.80 and average Dice similarity coefficient of 0.94±0.07 across all time points. The proposed method produced measurements that were highly correlated with the manual measurements of retinal cavitation volume and change in retinal cavitation volume over time.

CONCLUSION

The proposed method will be useful to help clinicians quantify retinal cavitations, assess changes over time and further investigate the clinical significance of these early structural changes observed in MacTel2.

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.

Retinal cavitations in macular telangiectasia type 2 (MacTel): longitudinal structure-function correlations

BACKGROUND/AIMS

To quantify retinal cavitation size over time in macular telangiectasia type 2 (MacTel) and to correlate changes with visual acuity and area of ellipsoid zone loss.

METHODS

Optical coherence tomography (OCT) macula volume scans from sham eyes included in a prospective, phase II clinical trial of human ciliary neutrophic factor for MacTel at baseline, 1 year and 2 years of follow-up were analysed. Cavitations were segmented by two independent readers. Total cavitation volume was compared with area of ellipsoid zone loss and best-corrected visual acuity (BCVA).

RESULTS

Fifty-one eyes from 51 unique patients (mean age 62 years, range 45-79 years) were included. Intraclass correlation between readers for cavitation volume was excellent (>0.99). Average cavitation volume was 0.0109 mm³, 0.0113 mm³ and 0.0124 mm³ at baseline, 1 year and 2 years, respectively. The average rate of cavitation volume change was +0.0039 mm³/year. 10 eyes (20%) had a significant change in cavitation volume during the study (3 decreased, 7 increased). Eyes with increased cavitation volume had worse BCVA compared with eyes with no change/decreased cavitation volume (71.5 vs 76.1 ETDRS letters, respectively). Cavitation volume was negatively correlated to BCVA (r=-0.37) but not to area of ellipsoid zone loss. Cavitation volume was negatively predictive of BCVA in both univariate and multivariate mixed-effects modelling with ellipsoid zone loss.

CONCLUSIONS

Retinal cavitations and their rate of change in MacTel can be reliably quantified using OCT. Cavitations are negatively correlated with visual acuity and may be a useful OCT-based biomarker for disease progression and visual function in MacTel.

Improvements in visual acuity and macular morphology following cessation of anti-estrogen drugs in a patient with anti-estrogen maculopathy resembling macular telangiectasia type 2: a pathogenic hypothesis

Background

The relationship between anti-estrogen drugs and macular telangiectasia type 2 (MacTel-2) remains unknown. Here we report a case with anti-estrogen maculopathy resembling MacTel-2 with improved visual function and macular morphology following cessation of anti-estrogen drugs.

Case presentation

A 53-year-old woman presented with a 5-month history of central vision loss and anorthopia in both eyes. She had received oral tamoxifen followed by toremifene for 69 months. Funduscopy, fluorescein angiography, and optical coherence tomography (OCT) revealed MacTel-2-like findings OU. Fundus autofluorescence (FAF) showed hyper-autofluorescence at the fovea OU. Visual acuity, macular morphology on OCT, and FAF findings gradually improved after cessation of anti-estrogen drugs.

Conclusions

In the present case, visual acuity, macular morphology, and impairment of the retinal pigment epithelium (RPE) improved following cessation of anti-estrogen drugs, suggesting the relationship between retinal toxicity of anti-estrogen drugs and the development of MacTel-2-like findings. From these results and the previous observations, toxicity of both photoreceptor and RPE cells caused by anti-estrogen drugs may contribute to the development of anti-estrogen maculopathy similar to MacTel-2.

IDENTIFICATION OF INCREASED BLUE LIGHT REFLECTIVITY IN MACULAR TELANGIECTASIA TYPE 2 USING SCANNING LASER OPHTHALMOSCOPY VERSUS RED-FREE FUNDUS PHOTOGRAPHY

PURPOSE

To compare two modalities used for detection of the characteristic parafoveal hyperreflective area seen in macular telangiectasia Type 2.

METHODS

Scanning laser ophthalmoscope blue light reflectance was compared with red-free fundus photography imaging. Images were obtained as part of the international Natural History Study of Macular Telangiectasia (MacTel Study).

RESULTS

The hyperreflective area can more frequently be seen with scanning laser ophthalmoscope blue light reflectance than with red-free imaging.

CONCLUSION

Detection of the hyperreflective area might help to identify macular telangiectasia in earlier disease stages. Scanning laser ophthalmoscope blue light reflectance should be preferred as a diagnostic tool when the suspicion of macular telangiectasia arises. However, red-free imaging offers a viable option to scanning laser ophthalmoscope blue light reflectance when good quality is achieved.

Idiopathic macular telangiectasia type 2: A six-year study with multimodal imaging of a presumed unilateral case

Purpose

To present a rare manifestation of macular telangiectasia type 2 (MacTel type 2) followed up for over six years.

Methods

A 61-year-old woman with one year history of blurred vision of her left eye was referred.

Results

Whereas the funduscopy, spectral-domain optical coherence tomography (SD-OCT), fluorescein angiography (FA), and fundus autofluorescence (FAF) were normal in the right eye, they revealed noticeable findings typical of MacTel type 2 in the left eye. After over six years follow-up, OCT-angiography (OCTA) showed no remarkable difference between the two eyes, and en face OCT showed subtle abnormal change in the right eye as well as typical pathological changes in the left eye.

Conclusion

MacTel type 2 can present unilaterally and remain so for a long time. The role of multimodal imaging in diagnosis and follow-up is of utmost importance.

Stereoscopic Vision in Macular Telangiectasia Type 2

PURPOSE

To investigate stereoscopic vision in patients with macular telangiectasia (MacTel) type 2 and correlate paracentral sensitivity loss to reduced stereoscopic function.

METHODS

In a prospective single-center study, 50 patients with MacTel type 2 and 25 age-matched controls were investigated. Stereoscopic function was evaluated with Lang I, Titmus, and TNO tests. Sensitivity of the central 16° was tested using fundus-controlled perimetry (microperimetry). Functional loss was quantified as depth, size, and localization of scotomata.

RESULTS

Both the Titmus and the TNO test revealed significantly reduced stereoscopic vision in patients compared to controls (p < 0.0001 for both). This applied even to patients with only relative or monocular paracentral scotoma. A strong correlation was observed for reduced stereoscopic vision with horizontal scotoma size and with the distance of scotomata from the foveal center.

CONCLUSIONS

The results indicate that stereoscopic vision is impaired early in patients with MacTel type 2. A paracentral sensitivity loss, even if mild and limited to one eye, may considerably interfere with stereoscopic function despite normal visual acuity. Projection of paracentral scotomata within the patient's central visual field plays an important role in stereoscopic vision and should be considered when interpreting stereoscopic test results.

Deep longitudinal transfer learning-based automatic segmentation of photoreceptor ellipsoid zone defects on optical coherence tomography images of macular telangiectasia type 2

Photoreceptor ellipsoid zone (EZ) defects visible on optical coherence tomography (OCT) are important imaging biomarkers for the onset and progression of macular diseases. As such, accurate quantification of EZ defects is paramount to monitor disease progression and treatment efficacy over time. We developed and trained a novel deep learning-based method called Deep OCT Atrophy Detection (DOCTAD) to automatically segment EZ defect areas by classifying 3-dimensional A-scan clusters as normal or defective. Furthermore, we introduce a longitudinal transfer learning paradigm in which the algorithm learns from segmentation errors on images obtained at one time point to segment subsequent images with higher accuracy. We evaluated the performance of this method on 134 eyes of 67 subjects enrolled in a clinical trial of a novel macular telangiectasia type 2 (MacTel2) therapeutic agent. Our method compared favorably to other deep learning-based and non-deep learning-based methods in matching expert manual segmentations. To the best of our knowledge, this is the first automatic segmentation method developed for EZ defects on OCT images of MacTel2.

Contrast sensitivity and visual acuity under low light conditions in macular telangiectasia type 2

Background/Aim

Macular pigment optical density (MPOD) is centrally depleted early on in macular telangiectasia type 2 (MacTel). Contrast sensitivity (CS) might be related to MPOD, and thus impaired in early MacTel. The effect of low luminance was assessed on both CS and best corrected visual acuity (BCVA).

Methods

This is a cross-sectional study. Pelli-Robson charts were used for CS testing at 1 m in photopic (110 lux) and mesopic (1 lux) conditions. BCVA was tested with ETDRS charts and low luminance visual acuity (LLVA) with a 2.0 log unit neutral density filter. MPOD was obtained with dual-wavelength autofluorescence.

Results

One hundred and three eyes of 52 patients with MacTel (mean±SD age 62.9±10.2, range 35–77) were compared with 34 healthy eyes of 17 controls (mean±SD age 65.2±7.4, range 53–78). CS was significantly lower in the eyes with MacTel. This impairment was higher in low light conditions (low light contrast sensitivity (LL-CS)). Eyes at the early stages of MacTel had significantly lower LL-CS than controls, but normal (photopic) CS. The results were similar but less pronounced for BCVA/LLVA. Decrease in CS was correlated with loss of MPOD.

Conclusions

Low light conditions have a detrimental effect on visual performance in MacTel. Impaired CS might correlate with MPOD depletion as a pathognomonic finding in MacTel. Functional impairment might precede structural disintegration, indicating dysfunction at the cellular level. The applied tests might be useful as additional functional assessments in clinical routine and as outcome measures in future interventional clinical trials.

The anatomy of the foveola reinvestigated

Objective

In the foveola of the eye, photoreceptors and Müller cells with a unique morphology have been described, but little is known about their 3D structure and orientation. Considering that there is an angle-dependent change in the foveolar photoreceptor response for the same light beam, known as the Stiles Crawford Effect of the first kind (SCE I), which is still not fully understood, a detailed analysis of the anatomy of the foveolar cells might help to clarify this phenomenon.

Methods

Serial semithin and ultrathin sections, and focused ion beam (FIB) tomography were prepared from 32 foveolae from monkeys (Macaca fascicularis) and humans. Foveolae were also analyzed under the electron microscope. Serial sections and FIB analysis were then used to construct 3D models of central Müller and photoreceptor cells. In addition, we measured the transmission of collimated light under the light microscope at different angles after it had passed through human foveae from flat mounted isolated retinae.

Results

In monkeys, outer segments of central foveolar cones are twice as long as those from parafoveal cones and do not run completely parallel to the incident light. Unique Müller cells are present in the central foveolae (area of 200 µm in diameter) of humans and monkeys. Light entering the fovea center, which is composed only of cones and Müller cells, at an angle of 0° causes a very bright spot after passing through this area. However, when the angle of the light beam is changed to 10°, less light is measured after transpasssing through the retina, the foveolar center becomes darker and the SCE-like phenomenon is directly visible. Measurements of the intensities of light transmission through the central foveola for the incident angles 0 and 10° resemble the relative luminance efficiency for narrow light bundles as a function of the location where the beam enters the pupil as reported by Stiles and Crawford. The effect persisted after carefully brushing away the outer segments.

Conclusion

We show that unique cones and Müller cells with light fibre-like properties are present in the center of the fovea. These unique Müller cells cause an angle dependent, SCE-like drop in the intensity of light guided through the foveola. Outer segments from the foveolar cones of monkeys are not straight.

CORRELATION OF CLINICAL AND STRUCTURAL PROGRESSION WITH VISUAL ACUITY LOSS IN MACULAR TELANGIECTASIA TYPE 2: MacTel Project Report No. 6-The MacTel Research Group

PURPOSE

To evaluate progression of macular telangiectasia Type 2 lesions and their correlation with visual acuity.

METHODS

An international multicenter prospective study with annual examinations including best-corrected visual acuity (BCVA), fundus photography, fluorescein angiography, and optical coherence tomography images graded centrally. Mixed models were used to estimate progression rates, and a generalized linear model to compute the relative risk of BCVA loss, loss of ellipsoid zone (EZ) reflectivity, development of pigment plaques, or neovascularization.

RESULTS

One thousand and fourteen eyes of 507 participants were followed for 4.2 ± 1.6 years. Best-corrected visual acuity decreased 1.07 ± 0.05 letters (mean ± SE) per year. Of all eyes, 15% lost ≥15 letters after 5 years. Of the eyes without EZ loss, 76% developed a noncentral loss. Of the eyes with noncentral loss, 45% progressed to central EZ loss. The rate of BCVA loss in eyes with noncentral EZ loss at baseline was similar to eyes without EZ loss. The rate of BCVA loss was significantly higher in eyes with central EZ loss at baseline (-1.40 ± 0.14 letters, P < 0.001).

CONCLUSION

Ellipsoid zone loss is frequently found in macular telangiectasia Type 2 and is an important structural component reflecting visual function. Its presence in the fovea significantly correlates with worse visual prognosis.

SCOTOMA CHARACTERISTICS IN MACULAR TELANGIECTASIA TYPE 2: MacTel Project Report No. 7-The MacTel Research Group

PURPOSE

To characterize scotomas in macular telangiectasia Type 2 (MacTel).

METHODS

Five of the 27 centers performed microperimetry as part of the MacTel Natural History Observation Study. Data were analyzed in the Moorfields Eye Hospital Reading Centre. The number of stimuli under a threshold of 12, 10, 8, and <0 dB were counted (thresholding) and compared with one another.

RESULTS

A total of 565 examinations were gradable, received from 632 eyes of 322 participants (age 61.1 ± 9.1 years, 62% females). The authors found absolute scotomas in 243 eyes (43%), 98% of these affected the temporal quadrant, and 99.5% were unifocal. Growth of absolute scotomas was limited to an extent of approximately 40 deg. Although transition from functionally unimpaired retina to absolute scotomas is generally steeply sloped, the larger a scotoma, the steeper it is.

CONCLUSION

Scotoma features were consistent throughout a large MacTel cohort. The temporal quadrant was confirmed as predominantly affected, which might result from vascular or metabolic asymmetry. Functional loss did not exceed an area of 5° × 8° however advanced the disorder. Different MacTel phenotypes seem likely and point toward different types of progression; identifying these would improve planning for clinical trials and might lead to better understanding patient outcome.

Optical Coherence Tomography Angiography Findings in Type-2 Macular Telangiectasia

Objectives:

To evaluate the vascular changes of idiopathic macular telangiectasia type 2 (MacTel 2) patients with optical coherence tomography angiography (OCTA) and correlate these changes with the findings of spectral domain optical coherence tomography (SD-OCT).

Materials and Methods:

Simultaneous SD-OCT and OCTA images of 10 eyes of 6 patients who were diagnosed as MacTel 2 in Ankara University Faculty of Medicine, Department of Ophthalmology were obtained and graded according to the OCTA grading system for MacTel 2.

Results:

Ten eyes of 6 patients were included. Four (66%) patients were female and 2 (34%) were male. The disease was grade 0 in 2 eyes, grade 1 in 2 eyes, grade 2 in 3 eyes, grade 3 in 1 eye, grade 4 in 1 eye, and grade 5 in 1 eye. The most common findings in grade 1, 2, and 3 non-proliferative disease were thinning of the outer retinal layers, presence of intraretinal hyporeflective layers and inner limiting membrane draping. In cases with subretinal choroidal neovascularisation (CNV) in OCTA, CNV or CNV scar was present in the B-scan SD-OCT images. In a case in which OCT was within normal limits, vascular changes consistent with grade 1 disease were observed in OCTA. On the contrary, 2 patients with significant foveal atrophy and macular hole in B-scan showed changes of early disease in OCTA. In some of the eyes, OCTA revealed an intact superficial vascular layer despite visible changes in the deep layer and the presence of neovascularisation.

Conclusion:

OCTA yields findings which are important for understanding the pathogenesis of the disease and providing better follow-up. Contrary to fundus fluorescein angiography, changes in the deep arterial plexus in the early disease and CNV can be clearly observed with OCTA. To achieve the best results in clinical practice, en face flow maps should be evaluated together with B-scan SD-OCT images.

Correlation Between Macular Integrity Assessment and Optical Coherence Tomography Imaging of Ellipsoid Zone in Macular Telangiectasia Type 2

Purpose

To correlate ellipsoid zone (EZ) defects on spectral-domain optical coherence tomography (SD-OCT) with retinal sensitivity loss on macular integrity assessment (MAIA) microperimetry in macular telangiectasia type 2 (MacTel).

Methods

Macular SD-OCT volumes and microperimetry maps were obtained during the international, multicenter, randomized phase 2 trial of ciliary neurotrophic factor for type 2 MacTel on two visits within 5 days of one another. Software was developed to register SD-OCT to MAIA scanning laser ophthalmoscopy images and to overlay EZ defect areas on the microperimetry maps generated from microperimetry sensitivity values at specific points and from interpolated sensitivity values. A total of 134 eyes of 67 patients were investigated.

Results

The semiautomated registration algorithm was found to be accurate, both qualitatively by visual inspection of the nearly perfect overlap of the retinal vessels and quantitatively as assessed by interobserver reliability metrics performed in 98 eyes of 49 patients (intraclass correlation of aggregate retinal sensitivity loss >0.99). Aggregate retinal sensitivity loss within the EZ defect area was highly correlated with EZ defect area (Pearson correlation coefficient 0.93 and 0.92 at screening and baseline for noninterpolated maps; both were 0.94 for interpolated maps; P values <0.001).

Conclusions

With our software and image processing algorithms, there is nearly perfect correlation between retinal sensitivity on microperimetry and EZ defect area on SD-OCT. Our software allows determination of functional and structural changes with increasing disease severity and demonstrates that functional loss on microperimetry may be used as a surrogate marker of EZ loss on SD-OCT in type 2 MacTel.

VOLUME-RENDERED ANGIOGRAPHIC AND STRUCTURAL OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY OF MACULAR TELANGIECTASIA TYPE 2

PURPOSE

To evaluate multimodal imaging including volume-rendered angiographic and structural optical coherence tomography of macular telangiectasia Type 2 (MacTel2) for right-angle vein complexes, macular cavitations, and signs of deeper retinal vascular invasion.

METHODS

Retrospective review of imaging performed in a community-based retinal referral center. The eyes were scanned using optical coherence tomography using split-spectrum amplitude-decorrelation techniques to derive flow information. These data were extracted and used to create volume-rendered images of the retinal vasculature with integrated structural information derived from the component optical coherence tomographic images.

RESULTS

There were 24 eyes of 16 patients who had a mean age of 61.8 years. Right-angle veins seemed in association with vascular proliferation external to the deep vascular plexus. The origin of a right-angle vein was surrounded by a stellate arrangement of radiating retinal vessels apparently caused by contraction of surrounding tissue in the temporal macula. Cavitations were found in the fovea and varied in size and configuration from one examination to the next. Many smaller cavitations, called microcavitations, were seen in the surrounding macula. Vascular invasion occurred into the subretinal space.

CONCLUSION

There are contractile features of the tissue in the temporal macula and the number, size, and temporal variations in the cavitations have not been in not mentioned in previous published descriptions of MacTel2. Vascular invasion of deeper layers occurred in the temporal macula through the outer nuclear layer. Volume-rendered angiographic and structural optical coherence tomography offers unprecedented ability to examine the vascular interrelationships their associations with cavitations in the macula.

EFFECT OF DARK ADAPTATION AND BLEACHING ON BLUE LIGHT REFLECTANCE IMAGING IN MACULAR TELANGIECTASIA TYPE 2

PURPOSE

In patients with macular telangiectasia Type 2, blue light reflectance imaging reveals an oval, parafoveal area in the macula that has increased reflectance compared with its surrounding. Here, we examine how dark adaptation and photobleaching can affect the blue light reflectance imaging pattern.

METHODS

Prospective study of patients with macular telangiectasia enrolled in the MacTel Natural History Observation Study. After dark adaptation, a sequence of images was obtained with a confocal scanning laser ophthalmoscope at 488 nm. Change of reflectance patterns was analyzed over time.

RESULTS

Eighteen eyes from 16 patients were analyzed. Initially, increased reflectivity in the parafoveal area resulted in higher gray values compared with the paramacular surrounding on blue light reflectance imaging. The difference between parafoveal and paramacular reflectance intensity decreased steadily during imaging, from 17.7 gray-value units (95% confidence interval: 12.1-23.2) down to 2.8 (95% confidence interval: -0.8 to 6.5) after around 30 seconds, and recovered after 5 minutes of dark adaptation.

CONCLUSION

A bleaching effect was evident in our study. Understanding these changes is important for both diagnosis and assessment of blue light reflectance phenotype in patients with macular telangiectasia and could also provide further insights into the pathophysiology of this disease.

VISUAL FUNCTION CORRELATES OF FOVEAL SLOPE CHANGES ON OPTICAL COHERENCE TOMOGRAPHY IN MACULAR TELANGIECTASIA TYPE 2

PURPOSE

To evaluate changes in foveal and parafoveal thickness measured using optical coherence tomography across five stages of macular telangiectasia 2 (MacTel 2) and to correlate the foveal slope angle with best-corrected visual acuity (BCVA).

METHODS

A multicentered, cross-sectional study of 90 patients with bilateral MacTel 2 was carried out. We reviewed medical records of patients who had undergone optical coherence tomography. Mean retinal thickness foveal and subfoveal were noted from ETDRS (Early Treatment Diabetic Retinopathy Study) mapping and later used for calculating foveal slope angle. The change in retinal thickness and foveal angle across five stages of MacTel 2 was assessed. Central foveal thickness and foveal slope angle were correlated with BCVA.

RESULTS

The foveal slope angles were calculated quadrantwise and stagewise. The mean slope angle was minimum in temporal quadrant (6.29°) followed by inferior (7.13°), superior (7.54°), and nasal (7.93°). The slope angles were 9.27°, 7.95°, 6.70°, 6.10°, and 6.31° in Stages 1, 2, 3, 4, and 5, respectively. Statistically significant correlation noted between the temporal, superior, inferior slope angles and BCVA (in logarithm of the minimum angle of resolution) with r = -0.18, -0.19, and -0.25, respectively (P < 0.05). No statistically significant correlation was noted between central retinal thickness and BCVA.

CONCLUSION

The BCVA correlates better with slope angles than central retinal thickness. This implies that, change in both foveal and parafoveal regions accounts for vision change. Greater the foveal slope angle, the better the vision.