LONGITUDINAL CORRELATION OF ELLIPSOID ZONE LOSS AND FUNCTIONAL LOSS IN MACULAR TELANGIECTASIA TYPE 2

Evaluation and comparison of microperimetry and optical coherence tomography findings in patients with Behçet uveitis

PURPOSE

To evaluate and compare the findings of MP and OCT in patients with inactive Behçet's uveitis (BU).

METHODS

Sixty-five eyes of 38 patients were included in this retrospective study. Ophthalmologic examination findings and OCT and MP results were recorded. The relationship between best corrected visual acuity (BCVA), duration of uveitis, central macular thickness (CMT), presence of photoreceptor zone (PZ), and/or retinal pigment epithelium (RPE) damage, macular integrity index, mean threshold and fixation stability was analyzed.

RESULTS

There was a positive correlation between BCVA and CMT (p < 0.001). The eyes with PZ and/or RPE damage had significantly lower visual acuity (p < 0.001). There was a negative correlation between BCVA and macular integrity index (p = 0.005). BCVA showed positive correlations with mean threshold and fixation stability [(BCVA vs. mean threshold, p < 0.001), (BCVA vs. P1, p < 0.001), and (BCVA vs. P2, p < 0.001)]. While there was no significant correlation between CMT and macular integrity index (p = 0.08), both mean threshold and fixation stability were significantly positively correlated with CMT [(CMT vs. mean threshold, p = 0.01), (CMT vs. P1, p = 0.008), and (CMT vs. P2, p = 0.005)]. Mean threshold and fixation stability (P1 and P2) were significantly lower in the eyes with PZ and/or RPE damage (p = 0.008, p = 0.02, and p = 0.01, respectively).

CONCLUSION

MP showed results consistent with visual acuity and morphological findings by OCT in patients with inactive BU. Although MP is promising for patient follow-up, controlled prospective studies are needed.

Proximal nailfold videocapillaroscopy findings of patients with idiopathic macular telangiectasia type 2

PURPOSE

Idiopathic macular telangiectasia type 2 (IMT) is a neurodegenerative disease characterized by bilateral, idiopathic, and perifoveal retinal telangiectatic vessel formations. We aimed to compare proximal nailfold videocapillaroscopy (NV) findings between patients with IMT and healthy individuals and evaluate the optical coherence tomography angiography (OCTA) parameters of the patients with IMT according to their NV findings.

METHODS

The study included 43 patients with IMT and 92 healthy controls of similar age and gender without any additional diseases. The OCTA and NV findings of the patients and controls were examined.

RESULTS

The mean age was 59.76 ± 5.73 years in the IMT group and 58.23 ± 4.96 years in the control group. Of the 43 patients with IMT, 19 were found to have increased capillary tortuosity, six had microhemorrhage, and 18 had bizarre capillaries (P < 0.001). In the IMT group, the total vascular density value of the superficial capillary plexus was higher among the patients with capillary microhemorrhage (P = 0.001), and the subfoveal choroidal thickness was lower among those with increased capillary tortuosity and bizarre capillaries (P = 0.04 and P = 0.07, respectively).

CONCLUSION

This is the first study in which the NV findings of patients with IMT were compared with those of a control group. We found higher rates of increased capillary tortuosity, microhemorrhage, and bizarre capillaries in the IMT group compared to the controls. We consider that this situation is caused by microvascular damage. We also think that IMT is a systemic disease that affects both proximal nailfold capillaries and eye vessels.

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.

Relative Ellipsoid Zone Reflectivity in Macular Telangiectasia Type 2

Purpose

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

Methods

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

Results

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

Conclusions

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

Divergent amino acid and sphingolipid metabolism in patients with inherited neuro-retinal disease

OBJECTIVES

The non-essential amino acids serine, glycine, and alanine, as well as diverse sphingolipid species, are implicated in inherited neuro-retinal disorders and are metabolically linked by serine palmitoyltransferase (SPT), a key enzyme in membrane lipid biogenesis. To gain insight into the pathophysiological mechanisms linking these pathways to neuro-retinal diseases we compared patients diagnosed with two metabolically intertwined diseases: macular telangiectasia type II (MacTel), hereditary sensory autonomic neuropathy type 1 (HSAN1), or both.

METHODS

We performed targeted metabolomic analyses of amino acids and broad sphingolipids in sera from a cohort of MacTel (205), HSAN1 (25) and Control (151) participants.

RESULTS

MacTel patients exhibited broad alterations of amino acids, including changes in serine, glycine, alanine, glutamate, and branched-chain amino acids reminiscent of diabetes. MacTel patients had elevated 1-deoxysphingolipids but reduced levels of complex sphingolipids in circulation. A mouse model of retinopathy indicates dietary serine and glycine restriction can drive this depletion in complex sphingolipids. HSAN1 patients exhibited elevated serine, lower alanine, and a reduction in canonical ceramides and sphingomyelins compared to controls. Those patients diagnosed with both HSAN1 and MacTel showed the most significant decrease in circulating sphingomyelins.

CONCLUSIONS

These results highlight metabolic distinctions between MacTel and HSAN1, emphasize the importance of membrane lipids in the progression of MacTel, and suggest distinct therapeutic approaches for these two neurodegenerative diseases.

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.

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 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.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Visual acuity after cataract surgery in Macular Telangiectasia Type 2 Stage 3 to 5

BACKGROUND

The purpose of this study was to evaluate visual acuity after cataract surgery in eyes with Macular Telangiectasia (MacTel) Type 2.

METHODS

Single-center retrospective cohort study of patients with MacTel Type 2 who underwent cataract surgery and were managed at the same institution. Patients underwent pre-operative assessment by a retinal specialist with examination and optical coherence tomography (OCT) at the same institution. The main outcome measure was the post-operative change in best corrected visual acuity (BCVA). Secondary study outcomes were achieving post-operative BCVA better than Snellen acuity of 20/40 and time to BCVA loss by two lines or more (10 or more ETDRS letters).

RESULTS

A total of 20 eyes (11 patients) underwent cataract surgery and were followed for a median of 25.5 months (IQR 17.5-44.2 months). The median post-operative BCVA improvement was 10.5 letters (IQR 3.50-20.25). Nuclear sclerosis severity [β = 8.99 (95% CI 3.35, 14.6), p = 0.00177] was associated with post-operative change in BCVA and central foveal ellipsoid zone (EZ) breaks [OR 1.33 × 10^-9 (95% CI 5.12 × 10^-10-3.43 × 10^-9), p < 0.001] on OCT was inversely correlated with post-operative BCVA > 20/40 using a multivariate generalized linear model. Central foveal EZ breaks [HR 1.77 × 10⁹ (95% CI 3.86 × 10⁸, 8.11 × 10⁹), p < 0.001] and MacTel Type 2 disease stage [HR 2.83, (95% CI 1.12, 7.12), p = 0.027] were independently associated with shorter time to vision loss of two lines or more in a multivariate Cox regression model.

CONCLUSIONS

Visual acuity significant improved after cataract surgery in eyes with MacTel Type 2 regardless of disease severity. The presence of central foveal EZ breaks may predict poorer post-operative visual acuity and subsequent vision loss from disease progression.

The effect of pegcetacoplan treatment on photoreceptor maintenance in geographic atrophy monitored by AI-based OCT analysis

PURPOSE

To investigate the therapeutic effect of intravitreal pegcetacoplan on the inhibition of photoreceptor (PR) loss and thinning in geographic atrophy (GA) on conventional spectral domain-optical coherence tomography (SD-OCT) imaging by deep learning-based automated PR quantification.

DESIGN

Post-hoc analysis of a prospective, multicenter, randomized, sham-controlled, masked phase II trial investigating the safety and efficacy of pegcetacoplan for the treatment of GA due to age-related macular degeneration.

PARTICIPANTS

Study eyes of 246 patients, randomized 1:1:1 to monthly (AM), bimonthly (AEOM) and sham (SM) treatment.

METHODS

We performed fully automated, deep learning-based segmentation of retinal pigment epithelium (RPE) loss and PR thickness on SD-OCT volumes acquired at baseline, month 2, 6 and 12. The difference in the change of PR loss area was compared between treatment arms. Change in PR thickness adjacent to the GA borders and in the whole 20 degrees scanning area was compared between treatment arms.

MAIN OUTCOME MEASURES

Square root transformed PR loss area in μm or mm, PR thickness in μm, PR loss/RPE loss ratio.

RESULTS

A total of 31,556 B-Scans of 644 SD-OCT volumes of 161 study eyes (AM: 52, AEOM: 54, SM: 56) were evaluated from baseline to month 12. Comparison of mean change in PR loss area revealed statistically significantly less growth in the AM group at month 2, 6 and 12 compared to SM (-41μm ± 219 vs. 77μm ± 126, p=0.0004; -5μm ± 221 vs. 156μm ± 139, p<0.0001; 106μm ± 400 vs. 283μm ± 226 p=0.0014). PR thinning was significantly reduced under monthly treatment compared to sham within the GA junctional zone as well as throughout the 20 degrees area. A trend towards greater inhibition of PR loss compared to RPE loss was observed under therapy.

CONCLUSIONS

Distinct and reliable quantification of PR loss using deep learning-based algorithms offers an essential tool to evaluate therapeutic efficacy in slowing disease progression. PR loss and thinning are reduced by intravitreal complement C3 inhibition. Automated quantification of PR loss/maintenance based on OCT images is an ideal approach to reliably monitor disease activity and therapeutic efficacy in GA management in clinical routine and regulatory trials.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Clinical classification, visual outcomes, and optical coherence tomographic features of 48 patients with posterior sympathetic ophthalmia

Background

To investigate the clinical manifestations, visual outcomes and optical coherence tomographic (OCT) features of patients with posterior sympathetic ophthalmia (PSO).

Methods

We performed a retrospective review of 48 patients diagnosed with PSO between January 2013 and December 2019. We compared the clinical and OCT features among different clinical types of PSO.

Results

PSO could be classified into two types according to whether the fundus exhibited serous retinal detachment (SRD) or multifocal choroiditis (MFC). There were 41 patients (85.4%) with SRD and 7 patients (14.6%) with MFC. The latent period of patients with MFC was significantly longer than that of patients with SRD (P = 0.002). The final visual acuity of patients with MFC was significantly worse than that of patients with SRD (P = 0.0001). In patients with acute SRD, OCT revealed that the mean height of retinal detachment in the fovea was 528.8 ± 437.5 μm. After treatment, the retina reattached in all patients and the band structures of the outer retina were restored in most patients (92.7%). In patients with acute MFC, the OCT images revealed inflammatory lesions on the retinal pigment epithelium layer. After treatment, the OCT images showed hyperreflective fibrosis of the lesions and loss of the outer retinal band structures in all patients.

Conclusions

We found that PSO could be classified according to the presence of SRD or MFC. The visual prognosis differed significantly between these types of PSO. OCT imaging is useful for clinical classification and monitoring of retinal changes after treatment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-022-02258-0.

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.

Visual function correlates with foveal slope, retinal and choroidal thickness on optical coherence tomography in type 2 Macular Telangiectasia

PURPOSE

To correlate the foveal slope angle (FSA), retinal (RT) and choroidal (CT) thickness measured using optical coherence tomography (OCT) across different stages of type 2 macular telangiectasia (MacTel) with best-corrected visual acuity (BCVA).

METHODS

A cross-sectional study of 182 gradable quality macular OCT images of 49 patients with type 2 MacTel was carried out. RT was measured on the Spectralis OCT machine from ETDRS (Early Treatment Diabetic Retinopathy Study) retinal thickness map and later used for calculating FSA. RT and CT were measured at 500-µm intervals up to 1500 µm from foveal centre manually. The change in RT, CT and FSA across five stages of type 2 MacTel was assessed. The measurements were correlated with BCVA.

RESULTS

The FSA, RT and CT were calculated quadrantwise and stagewise. The FSA and RT showed a significant negative correlation with disease stage and BCVA (p < .05) in all four quadrants. No significant correlation was noted between CT and BCVA. Multivariate linear regression analysis identified the temporal FSA to correlate best with BCVA.

CONCLUSION

BCVA correlates best with temporal FSA. Smaller the temporal FSA, poorer the vision.

Macular Telangiectasia type 2: multimodal assessment of retinal function and microstructure

PURPOSE

To assess the impact of neurodegenerative morphologic alterations due to macular telangiectasia type 2 (MacTel) on microperimetry (MP) and multifocal electroretinography (mfERG).

METHODS

Thirty-five eyes of 18 patients with MacTel were examined using spectral domain optical coherence tomography (SD-OCT), fundus autofluorescence (FAF), mfERG and MP. Software was used to match SD-OCT B-scans with the corresponding retinal sensitivity map and multifocal electroretinograms (mfERGs), thus enabling direct structure/function correlation.

RESULTS

Loss of the ellipsoid zone (EZ) had the strongest negative association with retinal sensitivity (16.77 dB versus 4.58 dB, adj. p < 0.001) of all parameters examined, and a limited negative effect on mfERGs (0.32 SD versus -1.97 SD adj. p = 0.121). Ellipsoid zone (EZ) irregularity was associated with reduced MP values but preserved mfERGs. There was a significant association between areas of inner retinal hyporeflectivity and loss of MP sensitivity (adj. p < 0.001) but the reduction in sensitivity was less than in locations with EZ loss. Areas of mfERG abnormality showed similar sensitivity loss with either inner retinal hyporeflectivity or EZ loss (adj. p = 0.063). In areas with EZ loss alone, preservation of the external limiting membrane (ELM) was associated with higher MP values than in areas with additional ELM loss; the integrity of the ELM alone was not associated with changes either in MP or mfERG. Increased FAF was observed in 51% of eyes, mixed/reduced FAF in 40%, and no abnormality was detected in 9% of eyes.

CONCLUSION

The data suggest both MP and mfERG to be useful non-invasive modalities for detecting localised macular dysfunction in MacTel. The findings suggest a different sensitivity of the two modalities to inner and outer retinal changes in macular function and are therefore complementary.

Early-stage macular telangiectasia type 2 vascular abnormalities are associated with interdigitation zone disruption

PURPOSE

To investigate the relationship between disruption in different photoreceptor layers and deep capillary plexus (DCP) telangiectasias in eyes with macular telangiectasia type 2 (MacTel).

METHODS

35 eyes (21 patients) with MacTel imaged with optical coherence tomography angiography (OCTA) were included. Circumscribed areas of DCP telangiectasia were traced from OCTA slabs and the corresponding spectral-domain OCT (SD-OCT) slabs were used to visualize the photoreceptor layer interdigitation zone (IZ) and ellipsoid zone (EZ). IZ attenuation, IZ loss, and EZ loss were graded by reviewing en face SD-OCT slabs for hypo-reflective areas and confirming their status on cross-sectional views. Total area of photoreceptor disruption and overlap with DCP telangiectasia were evaluated with respect to OCT-based MacTel stage. Longitudinal changes were evaluated in a subset of patients with follow-up imaging.

RESULTS

Overlap of DCP telangiectasia with IZ attenuation significantly decreased with MacTel severity, while overlap with IZ and EZ loss significantly increased. Overlap with IZ loss peaked in moderate MacTel (Stages 3-5). Longitudinal imaging showed that new EZ loss at 6 months was largely predicted by baseline IZ loss.

CONCLUSIONS

Worsening MacTel severity is characterized by greater overlap between DCP telangiectasia and zones of increasing severity of photoreceptor disruption, with EZ loss enlarging over time within areas of preexisting IZ disruption. We suggest that IZ disruption may indicate early photoreceptor dysfunction that eventually progresses to EZ loss, with IZ loss being a more reliable metric than IZ attenuation. Additional studies will be necessary to further explore long-term photoreceptor changes and evaluate their relationship with visual function in MacTel.

Functional relevance of macular telangiectasia (MacTel) area on multicolour imaging in type 2 MacTel

PURPOSE

To analyse the correlation between area of macular telangiectasia (MacTel) involvement on multicolour (MC) imaging, disease stages and visual acuity in type 2 MacTel.

METHODS

In this retrospective analysis of MC images, confirmed cases of type 2 MacTel were graded into different disease stages as per Gass and Blodi and Yannuzzi et al classification systems. The 'MacTel area' was calculated by marking the outer boundary of an area with abnormally increased reflectivity to confocal blue wavelength light. At every follow-up visit, best-corrected visual acuity, MacTel area and stage of disease on the MC image was documented. Analyses between disease stage, MacTel area and visual acuity was carried out.

RESULTS

In total, 92 eyes of 49 patients were included in the study. The mean age was 59.6 ± 8.96 years. About 182 high-quality gradable MC images were available for analysis. There was a statistically significant difference in the visual acuity (p < 0.001) and area of involvement (p < 0.001) in the non-proliferative and proliferative type 2 MacTel groups. An increase in disease severity stage statistically correlated positively with Mactel area (r = 0.544; p < 0.001) and logMAR visual acuity (r = 0.329; p < 0.001). Over time, there was a significant increase in area of MacTel involvement (p = 0.012) with an associated decrease in the visual acuity (p = 0.023).

CONCLUSION

The MacTel area measured on MC imaging showed a strong positive correlation with disease stage and a negative correlation with visual acuity. This could serve as a useful biomarker in clinical trials and understanding the natural history of the disease.

Long-term Clinical Course of Korean Patients Diagnosed with Macular Telangiectasia Type 2

Purpose: To evaluate long-term visual prognosis and changes in the retinal microstructure in patients with macular telangiectasia type 2.Methods: Retrospective analysis of medical records were performed for 61 eyes (32 patients) diagnosed with macular telangiectasia type 2. The visual acuity at diagnosis was compared with that at the final visit. In addition, cases were classified into three grades based on optical coherence tomography (OCT) findings: grade 1, inner retinal cavities only; grade 2, outer retinal cavities with ellipsoid zone disruption; and grade 3, ellipsoid zone disruption with proliferation of retinal pigment epithelium. Change in the grade during the follow-up was verified. In addition, visual acuities were compared between eyes with and without a change in grade.Results: The mean follow-up period was 41.5 ± 33.2 months. Visual acuity had deteriorated significantly from the mean logarithm of the minimal angle of resolution 0.23 ± 0.26 at diagnosis to a mean of 0.31 ± 0.31 at the final visit (p < 0.001). When classified using OCT, 65.6%, 22.9%, and 11.5% were grades 1, 2, and 3, respectively, at diagnosis and 47.5%, 36.1%, and 16.4% at the final visit. Progression of grade was noted in 22.9%. A higher degree of visual deterioration was noted in eyes showing progression than in eyes without (p = 0.002).Conclusions: During the long-term follow-up period, visual deterioration was noted in patients with macular telangiectasia type 2. However, the degree of deterioration was not high. Progression in the disruption of the retinal microstructure was the likely cause of visual deterioration.

MERTK retinopathy: biomarkers assessing vision loss

PURPOSE

Mer tyrosine kinase-retinitis pigmentosa (MERTK-RP) causes a primary defect in the retinal pigment epithelium, which subsequently affects rod and cone photoreceptors. The study aims to identify the most appropriate MERTK-RP biomarkers to measure disease progression for deciding the optimum therapeutic trial intervention time.

MATERIALS AND METHODS

Patients' data from baseline (BL) and last follow-up (LFU) were reviewed. Best corrected visual acuity (BCVA), spectral domain-optical coherence tomography (SD-OCT), ultra-widefield fundus autofluorescence (UWF-FAF) patterns, kinetic perimetry (KP), and electroretinography (ERG) parameters were analyzed.

RESULTS

Five patients were included with the mean age of 17.7 ± 14.4 years old (6.7-42.3) at BL and mean BCVA follow-up of 8.4 ± 5.1 years. Mean BCVA at BL and LFU were 0.84 ± 0.86 LogMAR and 1.14 ± 0.86 LogMAR, respectively. The BCVA decline rate was 0.05 ± 0.03 LogMAR units/year. Ellipzoid zones (EZ) were measurable in eight eyes with mean BL length of 1293.75 ± 421.07 µm and reduction of 140.95 ± 69.28 µm/year and mean BL CMT of 174.2 ± 37.52 µm with the rate of 11.2 ± 12.77 µm declining/year. Full-field ERG (ffERG) and pattern ERG (pERG) were barely recordable. UWF-FAF showed central macular hyper-autofluorescence (hyperAF). KP (III4e and V4e) was normal in two eyes, restricted nasally in four eyes, superior wedge defect in two eyes and undetectable in two eyes. The four restricted nasally KPs became worse, while the others stayed almost unchanged.

CONCLUSIONS

This cohort showed early visual loss, moderately rapid EZ reduction and macular hyperAF. EZ, CMT, and BCVA were consistently reduced. Relative rapid decline in these biomarkers reflecting visual function suggests an early and narrow timespan for intervention.

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.

Assessing the Use of Incorrectly Scaled Optical Coherence Tomography Angiography Images in Peer-Reviewed Studies: A Systematic Review

Importance

Individual differences in axial length affect the lateral magnification of in vivo retinal images and as a result can affect the accuracy of quantitative measurements made from these images. As measurements from optical coherence tomography angiography (OCTA) images are becoming increasingly used in the diagnosis and monitoring of a wide range of diseases, evaluating which studies use correctly scaled images is crucial to their interpretation.

Objective

To perform a systematic literature review to assess the percentage of articles that report correcting the scale of their OCTA images for individual differences in retinal magnification.

Evidence Review

A PubMed (MEDLINE) search was conducted for articles on OCTA retinal imaging published between June 1, 2015, and June 1, 2018. Initial results included 7552 articles. Initial exclusion criteria removed studies of animal models, as well as reviews, letters, replies, comments, and image-based or photographic essays. Articles not written in English and those that required purchase from non-English language websites were excluded. Articles that did not use OCTA for imaging the retina were also excluded. Remaining articles were reviewed in detail to assess whether the OCTA measurements required correct lateral scaling, and if so, whether axial length was reported or used to scale the images. We also determined the number of articles that mentioned the lack of correct lateral scaling as a limitation of the study.

Findings

A total of 989 articles were included in the detailed review. Of these, 509 were determined to require correct image scaling for their analyses, but only 41 (8.0%) report measuring and using axial length to correct the lateral scale of their OCTA images. Furthermore, of the 468 articles that did not correctly scale their images, only 18 (3.8%) mentioned this as a limitation to their study.

Conclusions and Relevance

These findings suggest that most peer-reviewed articles in PubMed that use quantitative OCTA measurements use incorrectly scaled images. This could call into question the conclusions of such studies and warrants consideration by OCTA manufacturers, physicians, authors, journal reviewers, and journal editors.

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.

Clinical Characteristics of Eyes Showing a Discrete Margin of Different Retinal Reflectivity

BACKGROUND AND OBJECTIVE

To evaluate the clinical characteristics of discrete margins of different retinal reflectivity (DMDRR) in ultra-widefield fundus photography.

PATIENTS AND METHODS

This DMDRR comprises a discrete border, with differing patterns of reflectivity on either side. Spectral-domain optical coherence tomography was performed on both the macula and the margin. The incidences of epiretinal membrane (ERM) and peripheral retinal pathologies of patients with a DMDRR (n = 36) were compared with a control group (n = 41).

RESULTS

An ellipsoid zone (EZ) defect at the DMDRR was detected in 34 eyes (92.2%), and vitreous traction was detected in 20 eyes (55.6%). A significantly higher proportion of eyes in the DMDRR group had an ERM, retinal hole, and cystic retinal tuft compared with the control group (P = .022, P = .010, and P < .001, respectively).

CONCLUSIONS

The DMDRR indicates EZ disruption that may originate from vitreous traction. Meticulous observation for vitreoretinal interface diseases is mandatory for these patients. [Ophthalmic Surg Lasers Imaging Retina. 2021;52:273-280.].

Outcome of Off-Label AREDS 2 Supplementation for the Treatment of Macular Degeneration in Non-Proliferative Idiopathic Type 2 Macular Telangiectasia

Purpose

To evaluate if off-label Age-Related Eye Disease Study 2 (AREDS2) supplementation prevents visual and anatomical deterioration in non-proliferative Idiopathic Macular Telangiectasia Type 2 (IMT2).

Patients and Methods

This is a single-center retrospective, comparative study of 82 IMT2 eyes treated with AREDS2 from January 1st, 2013 to January 1st, 2018. The study analysis consisted of a non-comparative arm, which included all AREDS2 eyes, and a comparative arm (27 AREDS2 and 42 untreated eyes) that only included eyes with complete follow-up data. Eyes were evaluated at baseline, 12 and 24 months. Better/worse eye sub-analysis was performed in the comparative study arm. Primary outcomes were best corrected visual acuity (BCVA) and optical coherence tomography (OCT) anatomical characteristics including largest cavitation diameter, central macular thickness (CMT), and length of ellipsoid zone (EZ) loss at 24 months.

Results

In the non-comparative arm, AREDS2 eyes showed stable BCVA (0.28 ± 0.18 logMAR at baseline vs 0.26 ± 0.19 logMAR at 24 months; p = 0.35) and OCT anatomical features after 24 months of supplementation. In the comparative arm, BCVA mean difference was greater for untreated eyes at 24 months (−0.09 ± 0.15 vs 0.03 ± 0.11 logMAR; p = <0.001). AREDS2 eyes had decreased cavitary diameter and EZ loss compared to untreated eyes at the study endpoint (p = 0.01 and p = 0.02, respectively). CMT remained stable for both cohorts throughout the study. For better/worse eye analysis, untreated eyes had worse BCVA at 24 months in both better and worse eyes (both p = 0.01). For anatomical outcomes, increases in both EZ loss (p = 0.04) and cavitary diameter (p = 0.001) among untreated eyes were only significant for eyes with worse baseline BCVA.

Conclusion

Our results suggest that off-label AREDS2 supplementation in non-proliferative IMT2 may prevent anatomical and visual deterioration in a subset of eyes.

FUNCTIONAL AND STRUCTURAL EFFECTS OF NONDAMAGING RETINAL LASER THERAPY FOR MACULAR TELANGIECTASIA TYPE 2: A Randomized Sham-Controlled Clinical Trial

PURPOSE

Macular telangiectasia (MacTel) Type 2 is a progressing neurovascular disease of the macula, currently lacking effective treatment. This study assessed the effect of nondamaging retinal laser therapy (NRT) compared with sham.

METHODS

Twelve MacTel patients were enrolled in this double-masked, controlled, randomized clinical trial. For the nine patients with both eyes eligible, one eye was randomized to NRT or sham and the other received alternate treatment. For three patients with only one eye eligible, that eye was randomly assigned either NRT or sham. Ellipsoid zone disruption, best-corrected visual acuity, and macular automated perimetry at 12 months served as structural and functional measures.

RESULTS

Eleven eyes were randomized to sham and 10 to NRT. Baseline best-corrected visual acuity was 66 letters (20/50) for sham and 72 letters (20/40) for NRT (P = 0.245). Ellipsoid zone disruption area was 298 µm2 in sham and 368 µm2 in NRT (P = 0.391). At 12 months, ellipsoid zone disruption increased by 24% in sham and decreased by 34% in NRT (P < 0.001). Best-corrected visual acuity measures remained stable during follow-up compared with baseline. At 1 year, the mean macular sensitivity was 28 dB in the NRT group, compared with 26 dB in sham.

CONCLUSION

Nondamaging retinal laser therapy was safe and well tolerated in patients with MacTel and resulted in structural and functional improvements, which could represent a protective effect of laser-induced hyperthermia. Longer follow-up and larger number of patients should help corroborate these effects.

Functional Relevance of Hyper-Reflectivity in Macular Telangiectasia Type 2

Purpose

The purpose of this study was to quantify hyper-reflective lesions on en face optical coherence tomography (OCT) and study its functional relevance in macular telangiectasia type 2 (MacTel).

Design

This was a retrospective, cross-sectional cohort study.

Methods

Baseline image and functional data from participants of a phase II clinical trial (NCT01949324) that studied the effect of Ciliary Neurotrophic Factor in patients with MacTel were analyzed. The projection of hyper-reflectivity within different layers on OCT was used to generate an en face view and measure the en face size of hyper-reflectivity. Ellipsoid zone (EZ)-loss was additionally evaluated, and en face images were superimposed onto microperimetry sensitivity maps, allowing to estimate mean retinal sensitivity within areas displaying hyper-reflectivity and EZ-loss, respectively. Best-corrected visual acuity (BCVA) and reading speed were also analyzed.

Results

Fifty-two eyes from 52 patients were analyzed. Hyper-reflectivity was present in 32 eyes (62%), and EZ-loss in 50 (96%) eyes. Mean lesion size was 0.11 mm² (range = 0.01-0.26) for hyper-reflectivity and 0.51 mm² (range = 0.02-1.34) for EZ-loss, and lesion sizes correlated strongly (Spearman r = 0.79, P < 0.001). Although both hyper-reflectivity and EZ-loss were associated with a significant decrease in retinal sensitivity, mean sensitivity thresholds differed significantly between lesions (0.9 dB vs. 16.3 dB; P < 0.001), indicating an almost complete loss of sensitivity in hyper-reflective areas. No correlations were found between the size of hyper-reflectivity and BCVA (r = 0.09) or reading speed (r = -0.17).

Conclusions

En face OCT can be used to quantify the area of hyper-reflective lesions in MacTel. Hyper-reflectivity in MacTel is associated with severe functional impairment, leading to an almost complete loss of retinal sensitivity as observed on microperimetry.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Incidence and phenotypical variation of outer retina-associated hyperreflectivity in macular telangiectasia type 2

BACKGROUND

Macular telangiectasia type 2 (MacTel) is a neurodegenerative disease resulting in photoreceptor loss. Optical coherence tomography (OCT) reveals outer retina-associated hyperreflectivity (ORaH) as part of this process. The purpose of this study was to describe the incidence and phenotypical variation of ORaH.

METHODS

Different parameters of ORaH were analysed: OCT characteristics (Spectralis SD-OCT), correlation with vascular changes (OCT angiography; OCTA 3×3 mm Optovue) and correlation with hyperpigmentation (autofluorescence/fundus images). ORaH was also evaluated regarding the grade of severity of photoreceptor loss (Disease Severity Scale).

RESULTS

Of 220 eyes with MacTel type 2, 106 demonstrated ORaH. On OCT, the size, the extension into the inner retina and the contact with retinal pigment epithelium (RPE) of the ORaH were variable. On OCTA neovascularisation (NV) in the outer retina (OR) was present at the location of the ORaH in 97.6%. Increasing size of NV correlated with progressive photoreceptor loss. In 86.6% with NV, the flow signals were visible between the OR and the choriocapillaris. In 85.7%, the ORaH was associated with hyperpigmentation on autofluorescence and fundus colour images.

CONCLUSIONS

The presence of ORaH is associated with increasing photoreceptor loss and disease severity. In these more advanced cases of the present study, a variable presentation of ORaH in respect to size and form was seen, but in most cases, ORaH was in contact to the RPE. Additionally, ORaH was associated with hyperpigmentation and OR NV on OCTA. These results are consistent with the concept of ORaH representing fibrovascular OR-NV with RPE proliferation after contact with the RPE.

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.

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.

Quantitative analysis of retinal microvascular changes in macular telangiectasia type 2 using optical coherence tomography angiography

PURPOSE

To evaluate retinal vascular changes on optical coherence tomography angiography (OCTA) in patients with macular telangiectasia type 2 (MacTel 2) and to assess their correlation with visual acuity.

METHODS

Twenty-six patients (52 eyes) with MacTel 2 and 20 age-matched controls (40 eyes) were included. Fundus examinations, including fundus autofluorescence, swept-source optical coherence tomography, and OCTA, were performed. Differences in the vascular density in the fovea and parafovea, the area of the foveal avascular zone, and the diameter of the ellipsoid zone defect of the two groups were analyzed.

RESULTS

The foveal vascular density of the superficial capillary plexus was significantly lower in the MacTel 2 group than in the control group (p = 0.027). The vascular density in the entire deep capillary plexus was also significantly less in the MacTel 2 group than in the control group (all p < 0.05). The mean diameter of ellipsoid-zone disruption on OCT in the MacTel 2 group was 634.6 ± 104.3 𝜇m. The foveal avascular zone areas of the superficial and deep capillary plexuses were significantly enlarged in the MacTel 2 group compared to those in the control group (0.45 ± 0.12 mm2 vs. 0.27 ± 0.08 mm2, p < 0.001; 0.56 ± 0.15 mm2 vs. 0.40 ± 0.14 mm2, p = 0.001). In addition, the enlarged foveal avascular zone of the superficial and deep plexus was negatively correlated with best corrected visual acuity (logMAR) in MacTel 2 patients (p = 0.013, r = -0.642 and p = 0.042, and r = -0.511, respectively).

CONCLUSIONS

Retinal vascular density changes occur in the superficial fovea and in the entire deep capillary plexus of patients with MacTel 2. The enlarged foveal avascular zone areas of the superficial and deep plexuses were prominent in the MacTel 2 group, and this enlargement correlates with worsened visual acuity.

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.

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.

Serine and Lipid Metabolism in Macular Disease and Peripheral Neuropathy

BACKGROUND

Identifying mechanisms of diseases with complex inheritance patterns, such as macular telangiectasia type 2, is challenging. A link between macular telangiectasia type 2 and altered serine metabolism has been established previously.

METHODS

Through exome sequence analysis of a patient with macular telangiectasia type 2 and his family members, we identified a variant in SPTLC1 encoding a subunit of serine palmitoyltransferase (SPT). Because mutations affecting SPT are known to cause hereditary sensory and autonomic neuropathy type 1 (HSAN1), we examined 10 additional persons with HSAN1 for ophthalmologic disease. We assayed serum amino acid and sphingoid base levels, including levels of deoxysphingolipids, in patients who had macular telangiectasia type 2 but did not have HSAN1 or pathogenic variants affecting SPT. We characterized mice with low serine levels and tested the effects of deoxysphingolipids on human retinal organoids.

RESULTS

Two variants known to cause HSAN1 were identified as causal for macular telangiectasia type 2: of 11 patients with HSAN1, 9 also had macular telangiectasia type 2. Circulating deoxysphingolipid levels were 84.2% higher among 125 patients with macular telangiectasia type 2 who did not have pathogenic variants affecting SPT than among 94 unaffected controls. Deoxysphingolipid levels were negatively correlated with serine levels, which were 20.6% lower than among controls. Reduction of serine levels in mice led to increases in levels of retinal deoxysphingolipids and compromised visual function. Deoxysphingolipids caused photoreceptor-cell death in retinal organoids, but not in the presence of regulators of lipid metabolism.

CONCLUSIONS

Elevated levels of atypical deoxysphingolipids, caused by variant SPTLC1 or SPTLC2 or by low serine levels, were risk factors for macular telangiectasia type 2, as well as for peripheral neuropathy. (Funded by the Lowy Medical Research Institute and others.).

Progression of vascular changes in macular telangiectasia type 2: comparison between SD-OCT and OCT angiography

PURPOSE

To investigate the different appearances of vascular changes in macular telangiectasia type 2 (MacTel) and to describe their possible progression, the vascular patterns in different retinal layers were analyzed with optical coherence tomography angiography (OCT-A) and the findings were correlated with a spectral-domain OCT (SD-OCT) disease severity scale based on the extent of ellipsoid zone (EZ) loss.

METHODS

Participants from the MacTel Study Group in Muenster and a healthy cohort were investigated with OCT-A using RTVue XR Avanti. After segmentation of the superficial capillary network, the deep capillary network, and the outer retina (OR), flow density was analyzed using Optovue software. Then, the images were exported using the software Fiji (National Institute of Mental Health, Bethesda, MD, USA) and analyzed with the automated MATLAB program (Mathworks, Version R2014b). Four parameters (total vessel length, number of vessel branches, number of vessel segments, and fractal dimension) were examined on the vascular skeletons (temporal, foveal, nasal, and total fields of the ETDRS grid). In addition, linear and area measurements of EZ loss were performed on SD-OCT volume scans. Progression characteristics and correlation between linear and area measurements were analyzed using linear mixed effects models.

RESULTS

Twenty eyes of healthy probands (20 OCT-A and 20 SD-OCT scans) and 122 eyes of 61 MacTel patients were included. In order to classify the severity of the disease, MacTel eyes were assigned to a SD-OCT "disease severity scale" (grade 1 = no EZ loss; grade 2 = EZ loss temporal to the fovea; grade 3 = EZ loss including the fovea and the region nasal to the fovea). Flow density and total vessel length showed only limited differences between healthy eyes and different grades of MacTel, but particularly the numbers of branches and vessel segments, as well as the fractal dimension values, demonstrated significant and progressive reduction in the superficial and deep capillary networks of the temporal, nasal, and total ETDRS fields. Moreover, the outer retina showed a progressive presence of hyperreflective material in SD-OCT grades 2 and 3 eyes with associated vascular patterns in the OR on OCT-A.

CONCLUSIONS

In SD-OCT, the severity of MacTel is characterized by progressive EZ loss, which may be used as a simple clinical "disease severity scale". In addition, OCT-A enables visualization and quantification of vascular patterns with mathematical methods. The morphological progression of the disease correlated significantly with progressive vascular changes, especially in respect of the numbers of branches and vessel segments as well as fractal dimension. This suggests that the severity of neurodegenerative and neurovascular changes develops in parallel and that the analysis and quantification of the vascular changes in the superficial and deep capillary networks may become an additional parameter for future treatment trials. Moreover, the significant association between hyperreflective material progressively visible on SD-OCT in the OR, which most often contains vessels in OCT-A, and advancing SD-OCT severity grades, as well as vascular changes in OCT-A, supports the concept of retinal neovascularization in the OR in patients with advanced MacTel.

Estimating Retinal Sensitivity Using Optical Coherence Tomography With Deep-Learning Algorithms in Macular Telangiectasia Type 2

IMPORTANCE

As currently used, microperimetry is a burdensome clinical testing modality for testing retinal sensitivity requiring long testing times and trained technicians.

OBJECTIVE

To create a deep-learning network that could directly estimate function from structure de novo to provide an en face high-resolution map of estimated retinal sensitivity.

DESIGN, SETTING, AND PARTICIPANTS

A cross-sectional imaging study using data collected between January 1, 2016, and November 30, 2017, from the Natural History Observation and Registry of macular telangiectasia type 2 (MacTel) evaluated 38 participants with confirmed MacTel from 2 centers.

MAIN OUTCOMES AND MEASURES

Mean absolute error of estimated compared with observed retinal sensitivity. Observed retinal sensitivity was obtained with fundus-controlled perimetry (microperimetry). Estimates of retinal sensitivity were made with deep-learning models that learned on superpositions of high-resolution optical coherence tomography (OCT) scans and microperimetry results. Those predictions were used to create high-density en face sensitivity maps of the macula. Training, validation, and test sets were segregated at the patient level.

RESULTS

A total of 2499 microperimetry sensitivities were mapped onto 1708 OCT B-scans from 63 eyes of 38 patients (mean [SD] age, 74.3 [9.7] years; 15 men [39.5%]). The numbers of examples for our algorithm were 67 899 (103 053 after data augmentation) for training, 1695 for validation, and 1212 for testing. Mean absolute error results were 4.51 dB (95% CI, 4.36-4.65 dB) when using linear regression and 3.66 dB (95% CI, 3.53-3.78 dB) when using the LeNet model. Using a 49.9 million-variable deep-learning model, a mean absolute error of 3.36 dB (95% CI, 3.25-3.48 dB) of retinal sensitivity for validation and test was achieved. Correlation showed a high degree of agreement (Pearson correlation r = 0.78). By paired Wilcoxon rank sum test, our model significantly outperformed these 2 baseline models (P < .001).

CONCLUSIONS AND RELEVANCE

High-resolution en face maps of estimated retinal sensitivities were created in eyes with MacTel. The maps were of unequalled resolution compared with microperimetry and were able to correctly delineate functionally healthy and impaired retina. This model may be useful to monitor structural and functional disease progression and has potential as an objective surrogate outcome measure in investigational trials.

Macular Pigment Distribution as Prognostic Marker for Disease Progression in Macular Telangiectasia Type 2

PURPOSE

To evaluate macular pigment distribution pattern as a prognostic marker for disease progression in patients with macular telangiectasia type 2 (MacTel).

DESIGN

Retrospective cohort study.

METHODS

In this single-center study, 90 eyes of 47 patients were analyzed. Macular pigment optical density (MPOD) was measured with dual-wavelength fundus autofluorescence. Eyes were graded into MPOD distribution classes 1 to 3 with increasing loss of macular pigment and grading was performed masked by 2 independent graders. Best-corrected visual acuity, reading acuity, total scotoma size in fundus-controlled perimetry (microperimetry), and break of the ellipsoid zone (EZ) in optical coherence tomography (en face measurement) were defined as functional and morphologic outcome parameters and evaluated at baseline and after 60 months.

RESULTS

After a mean review period of 59.6 months (±standard deviation 5.2 months), no change between MPOD classes was observed compared to baseline. Morphologic and functional deficits were limited to the area of MPOD loss. At last follow-up, a significant mean decrease of visual acuity and reading acuity as well as a significant mean increase of scotoma size and EZ break were observed in eyes assigned to MPOD classes 2 and 3, while outcome parameters remained stable in eyes of class 1.

CONCLUSIONS

The results indicate that MPOD and its distribution may serve as a prognostic marker for disease progression and functional impairment in patients with MacTel.

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.

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.