ABNORMAL MACULAR PIGMENT DISTRIBUTION IN TYPE 2 IDIOPATHIC MACULAR TELANGIECTASIA

Unusual morphology of foveal Müller glia in an adult human born pre-term

The fovea of the human retina, a specialization for acute and color vision, features a high concentration of cone photoreceptors. A pit on the inner retinal aspect is created by the centrifugal migration of post-receptoral neurons. Foveal cells are specified early in fetal life, but the fovea reaches its final configuration postnatally. Pre-term birth retards migration resulting in a small pit, a small avascular zone, and nearly continuous inner retinal layers. To explore the involvement of Müller glia, we used serial-section electron microscopic reconstructions to examine the morphology and neural contacts of Müller glia contacting a single foveal cone in a 28-year-old male organ donor born at 28 weeks of gestation. A small non-descript foveal avascular zone contained massed glial processes that included a novel class of 'inner' Müller glia. Similar to classic 'outer' Müller glia that span the retina, inner Müller glia have bodies in the inner nuclear layer (INL). These cells are densely packed with intermediate filaments and insert processes between neurons. Unlike 'outer' Müller glia, 'inner' Müller glia do not reach the external limiting membrane but instead terminate at the outer plexiform layer. One completely reconstructed inner cell ensheathed cone pedicles and a cone-driven circuit of midget bipolar and ganglion cells. Inner Müller glia outnumber foveal cones by 1.8-fold in the outer nuclear layer (221,448 vs. 123,026 cells/mm2). Cell bodies of inner Müller glia outnumber those of outer Müller glia by 1.7-fold in the INL (41,872 vs. 24,631 cells/ mm2). Müller glia account for 95 and 80% of the volume of the foveal floor and Henle fiber layer, respectively. Determining whether inner cells are anomalies solely resulting from retarded lateral migration of inner retinal neurons in pre-term birth requires further research.

Macular and Plasma Xanthophylls Are Higher in Age-related Macular Degeneration than in Normal Aging: Alabama Study on Early Age-related Macular Degeneration 2 Baseline

Purpose

Quantification of retinal xanthophyll carotenoids in eyes with and without age-related macular degeneration (AMD) via macular pigment optical volume (MPOV), a metric for xanthophyll abundance from dual wavelength autofluorescence, plus correlations to plasma levels, could clarify the role of lutein (L) and zeaxanthin (Z) in health, AMD progression, and supplementation strategies.

Design

Cross-sectional observational study (NCT04112667).

Participants

Adults ≥ 60 years from a comprehensive ophthalmology clinic, with healthy maculas or maculas meeting fundus criteria for early or intermediate AMD.

Methods

Macular health and supplement use was assessed by the Age-related Eye Disease Study (AREDS) 9-step scale and self-report, respectively. Macular pigment optical volume was measured from dual wavelength autofluorescence emissions (Spectralis, Heidelberg Engineering). Non-fasting blood draws were assayed for L and Z using high-performance liquid chromatography. Associations among plasma xanthophylls and MPOV were assessed adjusting for age.

Main Outcome Measures

Age-related macular degeneration presence and severity, MPOV in fovea-centered regions of radius 2.0° and 9.0°; plasma L and Z (μM/ml).

Results

Of 809 eyes from 434 persons (89% aged 60-79, 61% female), 53.3% eyes were normal, 28.2% early AMD, and 18.5% intermediate AMD. Macular pigment optical volume 2° and 9° were similar in phakic and pseudophakic eyes, which were combined for analysis. Macular pigment optical volume 2° and 9° and plasma L and Z were higher in early AMD than normal and higher still in intermediate AMD (P < 0.0001). For all participants, higher plasma L was correlated with higher MPOV 2° (Spearman correlation coefficient [Rs] = 0.49; P < 0.0001). These correlations were significant (P < 0.0001) but lower in normal (Rs = 0.37) than early and intermediate AMD (Rs = 0.52 and 0.51, respectively). Results were similar for MPOV 9°. Plasma Z, MPOV 2°, and MPOV 9° followed this same pattern of associations. Associations were not affected by supplement use or smoking status.

Conclusions

A moderate positive correlation of MPOV with plasma L and Z comports with regulated xanthophyll bioavailability and a hypothesized role for xanthophyll transfer in soft drusen biology. An assumption that xanthophylls are low in AMD retina underlies supplementation strategies to reduce progression risk, which our data do not support. Whether higher xanthophyll levels in AMD are due to supplement use cannot be determined in this study.

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.

Description of a patient cohort with Hereditary Sensory Neuropathy Type 1 without retinal disease Macular Telangiectasia type 2 - implications for retinal screening in HSN1

BACKGROUND AND AIMS

Pathogenic variants in the genes encoding serine palmitoyl transferase (SPTLC1 or SPTLC2) are the most common causes of the rare peripheral nerve disorder Hereditary Sensory Neuropathy Type 1 (HSN1). Macular telangiectasia type 2 (MacTel), a retinal disorder associated with disordered serine-glycine metabolism and has been described in some patients with HSN1. This study aims to further investigate this association in a cohort of people with HSN1.

METHODS

Fourteen patients with a clinically and genetically confirmed diagnosis of HSN1 from the National Hospital for Neurology and Neurosurgery (NHNN, University College London Hospitals NHS Foundation Trust, London, United Kingdom) were recruited to the MacTel Registry, between July 2018 and April 2019. Two additional patients were identified from the dataset of the international clinical registry study (www.lmri.net). Ocular examination included fundus autofluorescence, blue light and infrared reflectance, macular pigment optical density mapping, and optical coherence tomography.

RESULTS

Twelve patients had a pathogenic variant in the SPTLC1 gene, with p.Cys133Trp in eleven cases (92%) and p.Cys133Tyr in one case (8%). Four patients had a variant in the SPTLC2 gene. None of the patients showed clinical evidence of MacTel.

INTERPRETATION

The link between HSN1 and MacTel seems more complex than can solely be explained by the genetic variants. An extension of the spectrum of SPTLC1/2-related disease with phenotypic pleiotropy is proposed. HSN1 patients should be screened for visual symptoms and referred for specialist retinal screening, but the association of the two diseases is likely to be variable and remains unexplained. This article is protected by copyright. All rights reserved.

Distribution of macular pigments in macular telangiectasia type 2 and correlation with optical coherence tomography characteristics and visual acuity

Background

To estimate macular pigment values in macular telangiectasia (MacTel) Type 2 in comparison with healthy subjects in the South Indian population across different spatial profiles and to quantify the regional differences of macular pigment optical density (MPOD) in MacTel Type 2.

Methods

In this prospective cross-sectional study, healthy controls and patients diagnosed with various stages of MacTel Type 2 underwent MPOD measurement using dual-wavelength autofluorescence technique with Spectralis HRA + OCT.

Results

Sixty eyes of 31 healthy subjects and 41 eyes of 22 MacTel type 2 patients were included. We found an overall decrease in MPOD values in MacTel type 2 patients (-0.109, -0.11, -0.001) in comparison with healthy subjects (0.38, 0.23, 0.06) at 1°, 2° & 6° foveal eccentricities (P < 0.001). In various stages of MacTel type 2, the mean MPOD was found to be higher in the peripheral region compared to the central region. We found a significantly lower mean MPOD in the central region in association with specific optical coherence tomography (OCT) parameters like inner retinal cavities (P = 0.035) and ellipsoid zone disruption (P = 0.034).

Conclusions

In MacTel type 2, MPOD distribution varies in different spatial profiles with higher MPOD levels in the peripheral region compared to the central region. The macular pigment levels are associated with inner retinal cavities and ellipsoid zone disruption seen on OCT.

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.

Lutein and Zeaxanthin Distribution in the Healthy Macula and Its Association with Various Demographic Factors Examined in Pseudophakic Eyes

The macular pigment consisting of lutein (L) and zeaxanthin (Z) protects photoreceptors via its antioxidative and barrier activities. This study aimed to determine L and Z distribution in the healthy macula and their association with various demographic factors. Macular pigment optical density (MPOD) was measured using fundus autofluorescence spectroscopy in 352 pseudophakic eyes with no fundus diseases. Pseudophakia was chosen to avoid the influence of cataract in the measurement of fundus autofluorescence. The mean patient age was 72.3 ± 8.6 years. MPOD was analyzed separately in three zones, i.e., A: a central area within a radius of 0.5°, mainly containing Z; B: a ring area with radii from 0.5° to 1.3°, containing Z and L; C: a ring area with radii from 1.3° to 9°, containing L. Multivariate analyses were performed with MPOD as the dependent variable and sex, supplement intake, smoking habits, glaucoma, diabetes, age, body mass index (BMI), skin carotenoid levels, retinal thickness, retinal volume, axial length as the independent variables. The mean total MPOD volume within 9° eccentricity was 20,121 ± 6293. Age was positively associated with MPOD in all zones. Supplement and BMI were positively and negatively associated with MPOD in zones B and C. Smoking was negatively associated with MPOD in zone A. This study revealed the standard MP values of aged Japanese, which resulted to be higher than the previously reported values in other races. Age was found to have a positive association with MP values. L in the outer foveola was affected by BMI and supplements, but Z in the foveola was not. The amount of Z in the Müller cell cone may not be changed easily by factors such as hunger and satiety in the context of preservation of homeostasis in the human body, but tobacco had a negative effect on Z.

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.

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.

Fundus Autofluorescence and Clinical Applications

Fundus autofluorescence (FAF) has allowed in vivo mapping of retinal metabolic derangements and structural changes not possible with conventional color imaging. Incident light is absorbed by molecules in the fundus, which are excited and in turn emit photons of specific wavelengths that are captured and processed by a sensor to create a metabolic map of the fundus. Studies on the growing number of FAF platforms has shown each may be suited to certain clinical scenarios. Scanning laser ophthalmoscopes, fundus cameras, and modifications of these each have benefits and drawbacks that must be considered before and after imaging to properly interpret the images. Emerging clinical evidence has demonstrated the usefulness of FAF in diagnosis and management of an increasing number of chorioretinal conditions, such as age-related macular degeneration, central serous chorioretinopathy, retinal drug toxicities, and inherited retinal degenerations such as retinitis pigmentosa and Stargardt disease. This article reviews commercial imaging platforms, imaging techniques, and clinical applications of FAF.

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.

Comparing Fluorescence Lifetime Imaging Ophthalmoscopy in Atrophic Areas of Retinal Diseases

Purpose

Fluorescence lifetime imaging ophthalmoscopy (FLIO) is a non-invasive imaging modality to investigate the human retina. This study compares FLIO lifetimes in different degenerative retinal diseases.

Methods

Included were eyes with retinal pigment epithelium (RPE) and/or photoreceptor atrophy due to Stargardt disease (n = 66), pattern dystrophy (n = 18), macular telangiectasia type 2 (n = 49), retinitis pigmentosa (n = 28), choroideremia (n = 26), and geographic atrophy (n = 32) in age-related macular degeneration, as well as 37 eyes of 37 age-matched healthy controls. Subjects received Heidelberg Engineering FLIO, autofluorescence intensity, and optical coherence tomography imaging. Amplitude-weighted mean FLIO lifetimes (τ_m) were calculated and analyzed.

Results

Retinal FLIO lifetimes show significant differences depending on the disease. Atrophic areas in geographic atrophy and choroideremia showed longest mean FLIO lifetimes. τ_m values within areas of RPE and outer nuclear layer atrophy were significantly longer than within areas with preserved outer nuclear layer (P < 0.001) or non-atrophic areas (P < 0.001).

Conclusions

FLIO is able to contribute additional information regarding differences in chronic degenerative retinal diseases. Although it cannot replace conventional autofluorescence imaging, FLIO adds to the knowledge in these diseases and may help with the correct differentiation between them. This may lead to a more in-depth understanding of the pathomechanisms related to atrophy and types of progression.

Translational Relevance

Differences between atrophic retinal diseases highlighted by FLIO may indicate separate pathomechanisms leading to atrophy and disease progression.

The emerging roles of the macular pigment carotenoids throughout the lifespan and in prenatal supplementation

Since the publication of the Age-Related Eye Disease Study 2 (AREDS2) in 2013, the macular pigment carotenoids lutein (L) and zeaxanthin (Z) have become well known to both the eye care community and the public. It is a fascinating aspect of evolution that primates have repurposed photoprotective pigments and binding proteins from plants and insects to protect and enhance visual acuity. Moreover, utilization of these plant-derived nutrients has been widely embraced for preventing vision loss from age-related macular degeneration. More recently, there has been growing awareness that these nutrients can also play a role in improving visual performance in adults. On the other hand, the potential benefits of L and Z supplementation at very young ages have been underappreciated. In this review, we examine the biochemical mechanisms and supportive data for L and Z supplementation throughout the lifespan, with particular emphasis on prenatal supplementation. We propose that prenatal nutritional recommendations may aim at improving maternal and infant carotenoid status. Prenatal supplementation with L and Z might enhance infant visual development and performance and may even prevent retinopathy of prematurity, possibilities that should be examined in future clinical studies.

FLUORESCENCE LIFETIME PATTERNS IN MACULAR TELANGIECTASIA TYPE 2

PURPOSE

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

PARTICIPANTS

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

METHODS

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

RESULTS

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

CONCLUSION

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

Reduced foveal cone density in early idiopathic macular telangiectasia

Objective

Idiopathic macular telangiectasia (MacTel) is considered primarily a vascular disease affecting juxtafoveal retinal capillaries. However, recent evidence suggests that neuronal changes may occur early in disease development. We used high-resolution adaptive optics retinal imaging to elucidate the foveal cone photoreceptor changes at a cellular level in patients with MacTel.

Methods and analysis

We used adaptive optics scanning light ophthalmoscopy (AOSLO) to evaluate the foveal cone photoreceptors in the less-affected eye of patients with asymmetric MacTel. AOSLO images of cone photoreceptors were obtained in a 4°×4° area centred on the foveola. Individual cone positions were identified within a 2°×2° area centred on the fovea, using semiautomatic cone marking software with manual correction, permitting calculation of a map of cone density.

Results

In all participants, one eye was affected with MacTel, the fellow eye was clinically normal or near normal, with visual acuity of 20/25 or better and subtle angiographic leakage. The foveal cone mosaics were continuous with tight packing and cones exhibited normal reflectivity. However, cone density was significantly lower for all participants (mean=80 733 cones/mm²) within 0.5° than the cone density previously reported for normal eyes.

Conclusions

Foveal cone density is lower than normal in the clinically less-affected eyes of patients with asymmetric MacTel. This suggests that cone photoreceptor loss may precede classic obvious vascular changes in idiopathic MacTel.

Macular Pigment Optical Density Fluctuation as a Function of Pupillary Mydriasis: Methodological Considerations for Dual-Wavelength Autofluorescence

PURPOSE OF THE STUDY

Macular pigment (MP), comprising the dietary carotenoids lutein, zeaxanthin and meso-zeaxanthin, is believed to benefit eye health and vision. Numerous clinical and research devices and techniques are currently available to facilitate MP optical density (MPOD) measurement. One of those techniques, dual-wavelength fundus autofluorescence (AF) is being increasingly used for measurement of MP in the eye. There is substantial methodological variation across the published studies that have employed this technique, including in relation to the use of mydriasis, the possible influence of which does not appear to have been addressed in the literature. This prospective cross-sectional study was designed to investigate the effect of mydriasis on MP measurement quality and MPOD values obtained with dual-wavelength AF using the Heidelberg Spectralis HRA+OCT device.

MATERIALS AND METHODS

Twenty-one healthy participants were recruited to the study. The mean age of participants was 44.8 years (± 14.63). Pupil size and MPOD were measured in one eye for each participant, initially under natural pupil conditions and subsequently 30 minutes following instillation of one drop of 0.5% tropicamide.

RESULTS

Despite providing MPOD measurements for the majority of undilated eyes (85.7% of eyes herein), pupillary dilation resulted in statistically significant changes in MPOD (p < .001 for central eccentricities). Our results indicate that the changes in MPOD were not uniform across the spatial profile. Marked improvements were also observed in image quality post-dilation (p < .002 for central eccentricities).

CONCLUSIONS

This study clearly demonstrates that dual-wavelength AF measurements of MPOD in the same eye vary as a function of pupillary dilation status, with MPOD under-estimated across the entire spatial profile of MP for natural relative to dilated pupillary conditions. Mydriasis should, therefore, be used routinely for MPOD measurements using dual wavelength AF, pupil size should be reported and image quality optimized in order to ensure accurate MPOD quantification.

Multicolor imaging in macular telangiectasia-a comparison with fundus autofluorescence

PURPOSE

To describe various clinical features of idiopathic juxtafoveal retinal telangiectasis group 2A or idiopathic macular telangiectasia type 2 (MacTel) on multicolor imaging (MCI) and compare imaging findings of MacTel on MCI with fundus autofluorescence (FAF).

METHODS

Patients with a clinical diagnosis of MacTel based on Gass and Blodi's classification were included. FAF and MCI images were graded qualitatively for stage of disease, margins of involvement, hyperautofluorescence on FAF (corresponding retinal atrophy on MCI), and detection of crystals. FAF and MCI were graded quantitatively for the area and number of quadrants involved, hypoautofluorescene on FAF (corresponding intraretinal pigment hyperplasia or retinal pigment epithelium [RPE] atrophy on MCI), and foci of right-angled venules.

RESULTS

Seventy-eight eyes of forty five patients were included with both imaging modalities showing no difference with respect to staging of non-proliferative MacTel. Retinal crystals were recognized on MCI but not on FAF. Neurosensory retinal atrophy and  subretinal neovascular membranes were detected using MCI with 92.3 and 83.3% sensitivity, respectively. Intraretinal pigmented hyperplasia was more accurately detected (70.1 vs 58.4%) compared with RPE atrophy on MCI. MCI showed larger area of involvement, higher number of quadrants involved (p < 0.001), and better delineation of margins (p = 0.002) compared with FAF. A higher mean number of vessel dipping foci was noted on MCI in comparison with FAF (3.34 vs 3.1).

CONCLUSION

Various parameters were more easily defined using MCI compared with FAF which qualifies MCI as an enface depth-resolved imaging adjunct to conventional multimodal imaging in MacTel. The ability to detect enface as well as cross-sectional imaging features makes MCI a valuable tool in MacTel.

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.

Local Abundance of Macular Xanthophyll Pigment Is Associated with Rod- and Cone-Mediated Vision in Aging and Age-Related Macular Degeneration

Purpose

We assessed the association between the abundance of macular xanthophyll carotenoid pigment using dual-wavelength autofluorescence and multimodal vision testing including rod-mediated dark adaptation (RMDA), a measure of retinoid re-supply, in adults ≥60 years old with and without age-related macular degeneration (AMD).

Methods

AMD severity was determined using the nine-step Age-Related Eye Disease Study grading. Tests probed cones (best-corrected visual acuity, contrast sensitivity), cones and rods (low-luminance visual acuity, low-luminance deficit, mesopic light sensitivity), or rods only (scotopic light sensitivity, RMDA). Signal attenuation by macular pigment optical density (MPOD) was estimated using a ratio of blue and green autofluorescence signal to yield mean MPOD in a 1°-diameter fovea-centered disk, mean MPOD in a 2°-diameter disk centered on a perifoveal RMDA test location, and macular pigment optical volume (MPOV, or integrated MPOD) in a 4°-diameter fovea-centered disk. Age-adjusted associations between vision and imaging measures were determined.

Results

In 88 eyes of 88 subjects (age, 74.9 ± 5.8 years) with normal eyes (n = 32), early AMD (n = 23), or intermediate AMD (n = 33), foveal and perifoveal MPOD and MPOV were higher in the AMD eyes than in the normal eyes. At the RMDA test location, higher MPOD was unrelated to AMD severity but was associated with faster RMDA.

Conclusions

In older adults with and without AMD, higher macular xanthophyll concentrations are associated with better best-corrected visual acuity and RMDA. Data are consistent with a model of cone resilience and rod vulnerability in aging and AMD and can be further explored in a larger sample study.

Functionally validated imaging endpoints in the Alabama study on early age-related macular degeneration 2 (ALSTAR2): design and methods

Background

Age-related macular degeneration (AMD), a leading cause of irreversible vision impairment in the United States and globally, is a disease of the photoreceptor support system involving the retinal pigment epithelium (RPE), Bruch’s membrane, and the choriocapillaris in the setting of characteristic extracellular deposits between outer retinal cells and their blood supply. Research has clearly documented the selective vulnerability of rod photoreceptors and rod-mediated (scotopic) vision in early AMD, including delayed rod-mediated dark adaptation (RMDA) and impaired rod-mediated light and pattern sensitivity. The unifying hypothesis of the Alabama Study on Early Macular Degeneration (ALSTAR2) is that early AMD is a disease of micronutrient deficiency and vascular insufficiency, due to detectable structural changes in the retinoid re-supply route from the choriocapillaris to the photoreceptors. Functionally this is manifest as delayed rod-mediated dark adaptation and eventually as rod-mediated visual dysfunction in general.

Methods

A cohort of 480 older adults either in normal macular health or with early AMD will be enrolled and followed for 3 years to examine cross-sectional and longitudinal associations between structural and functional characteristics of AMD. Using spectral domain optical coherence tomography, the association between (1) subretinal drusenoid deposits and drusen, (2) RPE cell bodies, and (3) the choriocapillaris’ vascular density and rod- and cone-mediated vision will be examined. An accurate map and timeline of structure-function relationships in aging and early AMD gained from ALSTAR2, especially the critical transition from aging to disease, will identify major characteristics relevant to future treatments and preventative measures.

Discussion

A major barrier to developing treatments and prevention strategies for early AMD is a limited understanding of the temporal interrelationships among structural and functional characteristics while transitioning from aging to early AMD. ALSTAR2 will enable the development of functionally valid, structural biomarkers for early AMD, suitable for use in forthcoming clinical trials as endpoint/outcome measures. The comprehensive dataset will also allow hypothesis-testing for mechanisms that underlie the transition from aging to AMD, one of which is a newly developed Center-Surround model of cone resilience and rod vulnerability.

Trial registration

ClinicalTrials.gov Identifier NCT04112667, October 7, 2019.

Spatial distribution of macular pigment estimated by autofluorescence imaging in elderly Japanese individuals

PURPOSE

To determine the spatial distribution types of macular pigment (MP) in elderly Japanese individuals and to consider their origin.

STUDY DESIGN

Observational case series.

METHODS

Local MP optical density (MPOD) at some eccentricities and MP volume were measured using the MPOD module of a MultiColor Spectralis in 96 pseudophakic eyes of 96 participants (age range, 52-86 years; mean age, 72.8 ± 8.3 years). The MP distribution types were determined from the MP spatial profiles. The retinal thickness (RT) at the foveal center, at both 0.5° and 0.9° eccentricities, and the foveal width were measured using optical coherence tomography.

RESULTS

The mean local MPOD at the foveal center was 0.79. Spatial distribution was classified into four types: central peak (24.0%), ring-like (40.6%), intermediate (22.9%), and central dip (12.5%). The ring-like type was the most frequent in these Japanese participants. The central-peak type showed lower MPOD than did the other types in the area outside 0.9°. The ring-like type occurred frequently in eyes with small RT at 0.5° and wider foveal width. A rough contour of the Müller cell cone was found more frequently in the central-dip type than in the other types.

CONCLUSIONS

The present characteristics of the different distribution patterns could be explained by the hypothesis that MP presents mainly in the Müller cell cone within 0.5° and in Müller cells in the outer and inner plexiform layers in the area outside 0.5°. The anatomic characteristics of Müller cells at the fovea and parafovea likely affect the MP distribution.

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.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

RETINAL-CHOROIDAL ANASTOMOSIS IN MACULAR TELANGIECTASIA TYPE 2

PURPOSE

To investigate the deep retinal vascular changes potentially present in macular telangiectasis Type 2 (MacTel 2) with projection resolved optical coherence tomography angiography including volume rendering.

METHODS

Retrospective consecutive evaluation of patients with MacTel 2 in a community-based retinal referral practice with a comprehensive ophthalmologic examination to include optical coherence tomography and projection-resolved optical coherence tomography angiography with volume rendering. Main outcome measures were the characterization of vessel presence and anatomical arrangement in the outer retina.

RESULTS

There were 26 eyes of 13 patients with a mean age of 64.9 (±11.3) years, and 6 were men. The mean visual acuity was logMAR 0.4 (Snellen equivalent 20/50). No eye had signs of choroidal neovascularization or exudation. Focal hyperpigmentation was seen in 13 (50%) and right-angle veins in 17 (65%) eyes. Retinal-choroidal anastomoses were seen in 17 (65%) eyes. These anastomoses typically occurred in multiple clusters of small vessels. The presence of anastomoses was associated with pigment (P < 0.001), although the anastomoses did not necessarily colocalize with the pigment, and right-angle veins (P < 0.001), which were found in every eye with a retinal-choroidal anastomosis.

CONCLUSION

Retinal-choroidal anastomoses were commonly observed in eyes with MacTel 2 using projection-resolved optical coherence tomography angiography. One animal model for MacTel 2 uses very low-density lipoprotein receptor mutant mice and shows multiple retinal-choroidal anastomoses in the disease pathogenesis as well. These findings suggest MacTel 2 is more than just a neurodegenerative disease with secondary vascular abnormalities, as the choroid may be involved in the disease process.

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.

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.

Review of clinical approaches in fluorescence lifetime imaging ophthalmoscopy

Autofluorescence-based imaging techniques have become very important in the ophthalmological field. Being noninvasive and very sensitive, they are broadly used in clinical routines. Conventional autofluorescence intensity imaging is largely influenced by the strong fluorescence of lipofuscin, a fluorophore that can be found at the level of the retinal pigment epithelium. However, different endogenous retinal fluorophores can be altered in various diseases. Fluorescence lifetime imaging ophthalmoscopy (FLIO) is an imaging modality to investigate the autofluorescence of the human fundus in vivo. It expands the level of information, as an addition to investigating the fluorescence intensity, and autofluorescence lifetimes are captured. The Heidelberg Engineering Spectralis-based fluorescence lifetime imaging ophthalmoscope is used to investigate a 30-deg retinal field centered at the fovea. It detects FAF decays in short [498 to 560 nm, short spectral channel (SSC) and long (560 to 720 nm, long spectral channel (LSC)] spectral channels, the mean fluorescence lifetimes (τm) are calculated using bi- or triexponential approaches. These are meant to be relatively independent of the fluorophore's intensity; therefore, fluorophores with less intense fluorescence can be detected. As an example, FLIO detects the fluorescence of macular pigment, retinal carotenoids that help protect the human fundus from light damages. Furthermore, FLIO is able to detect changes related to various retinal diseases, such as age-related macular degeneration, albinism, Alzheimer's disease, diabetic retinopathy, macular telangiectasia type 2, retinitis pigmentosa, and Stargardt disease. Some of these changes can already be found in healthy eyes and may indicate a risk to developing such diseases. Other changes in already affected eyes seem to indicate disease progression. This review article focuses on providing detailed information on the clinical findings of FLIO. This technique detects not only structural changes at very early stages but also metabolic and disease-related alterations. Therefore, it is a very promising tool that might soon be used for early diagnostics.

No association between sleep apnoea and macular telangiectasia type 2 and its markers of severity and progression: a case-control study and retrospective cohort study

IMPORTANCE

Idiopathic Macular Telangiectasia Type 2 (MacTel) is an uncommon, progressive retinal disease usually affecting both eyes. Currently there is no know treatment however with similar comorbidities to Obstructive Sleep Apnoea (OSA) there is plausibility of an association which may accelerate disease progression.

BACKGROUND

To identify an association between MacTel and OSA and whether OSA may result in increased disease progression.

DESIGN

Matched case-control study and retrospective cohort analysis.

PARTICIPANTS

Fifty-seven patients with MacTel and 165 matched controls from the Busselton Health Study.

METHODS

MacTel participants were matched based on age, gender and body mass index (BMI) (and where possible hypertension and diabetes) on a 3:1 ratio with controls from the Busselton Health Study. Participants undertook a sleep questionnaire using a previously validated questionnaire. In a subset sleep apnoea severity was objectively measured via overnight ambulatory polygraphy (30 cases and 83 matched controls; ApneaLink device; ResMed, Sydney, Australia). In a retrospective analysis of the suspected MacTel cases we assessed whether major markers of OSA severity and MacTel progression were associated.

MAIN OUTCOME MEASURES

Apnoea Hypopnea Index along with key markers of MacTel progression.

RESULTS

MacTel patients did not have a higher risk of sleep apnoea when compared to age, sex and BMI -matched controls (mean ± SD Apnoea hypopnea index [AHI] cases 9.6 ± 14.7 vs. controls 9.7 ± 10.8, P = 0.95). No markers of disease progression in the cases were associated with any marker of OSA severity.

CONCLUSIONS AND RELEVANCE

Sleep apnoea does not increase the risk or accelerate the progression of MacTel.

Fluorescence Lifetime Imaging Ophthalmoscopy: A Novel Way to Assess Macular Telangiectasia Type 2

PURPOSE

Macular Telangiectasia Type 2 (MacTel) is an uncommon, late-onset complex retinal disease that leads to central vision loss. No causative gene(s) have been identified so far, resulting in a challenging clinical diagnostic dilemma because retinal changes of early stages are often subtle. The objective of this study was to investigate the benefit of fluorescence lifetime imaging ophthalmoscopy (FLIO) for retinal imaging in patients with MacTel.

DESIGN

Cross-sectional study from a tertiary-care retinal referral practice.

SUBJECTS AND CONTROLS

42 eyes of 21 patients (mean age 60.5±13.3 years) with MacTel as well as an age-matched healthy control group (42 eyes of 25 subjects, mean age 60.8±13.4 years).

METHODS

A 30° retinal field centered at the fovea was investigated using FLIO. This camera is based on a Heidelberg Engineering Spectralis system. Fundus autofluorescence (FAF) decays were detected in short (498-560 nm, SSC) and long (560-720 nm, LSC) spectral channels. The mean fluorescence lifetime, τm, was calculated from a 3-exponential approximation of the FAF decays. For MacTel patients, macular pigment (MP), OCT, blue light reflectance, fluorescein angiography, as well as fundus photography, were also recorded.

MAIN OUTCOME MEASURES

Mean FAF lifetime (τm) images.

RESULTS

FLIO of MacTel patients shows a unique pattern of prolonged τm at the temporal side of the fovea in patients with MacTel in the "MacTel area" within 5-6° of the foveal center. In early stages, this region appears crescent-shaped, while advanced stages show a ring-like pattern. This pattern corresponds well with other imaging modalities and gives an especially high contrast of the affected region even in minimally affected individuals. Additionally, FLIO provides a novel means to monitor the abnormal MP distribution. In one case, FLIO showed changes suggestive of MacTel within a clinically normal parent of two MacTel patients.

CONCLUSIONS

FLIO detects retinal changes in patients with MacTel with high contrast, presenting a distinctive signature that is a characteristic finding of the disease. The non-invasive properties of this novel imaging modality provide a valuable addition to clinical assessment of early changes in the disease that could lead to more accurate diagnosis of MacTel.

Fluorescence Lifetime Imaging Ophthalmoscopy (FLIO) of Macular Pigment

Purpose

To describe different patterns of macular pigment (MP) seen in fluorescence lifetime imaging ophthalmoscopy (FLIO) and to analyze ex vivo fluorescence characteristics of carotenoids.

Methods

A total of 31 eyes of young healthy subjects, 4 eyes from patients with albinism, 36 eyes with macular telangiectasia type 2 (MacTel), 24 eyes with retinitis pigmentosa, and 1 eye with a macular hole were included in this clinic-based, cross-sectional study. All subjects underwent Heidelberg Engineering FLIO and MP measurements (dual-wavelength autofluorescence). Fundus autofluorescence (FAF) lifetimes of a 30° retinal field were detected in two spectral channels (SSC: 498-560 nm; LSC: 560-720 nm), and amplitude-weighted mean fluorescence lifetimes (τm) were calculated. Additionally, autofluorescence lifetimes of known dilutions of lutein and zeaxanthin were measured in a cuvette in free- and protein-associated states.

Results

MP shows a significant inverse correlation to foveal FAF lifetimes measured with FLIO (SSC: r = -0.608; P < 0.001). Different distribution patterns can be assigned to specific disease-related changes. Two patients with albinism, who did not have MP, were found to be missing short FAF lifetimes. In solvent, lutein and zeaxanthin show very short autofluorescence lifetimes (∼50-60 ps; SSC), as do their respective binding proteins (∼40-50 ps; SSC). When combining carotenoids with their specific binding proteins, the decay times shift to longer means (∼70-90 ps; SSC).

Conclusions

This study expands upon previous findings of an impact of MP on short FAF lifetimes by describing ex vivo autofluorescence lifetimes of carotenoids and different in vivo autofluorescence patterns that can be associated with certain diseases.

VASCULAR DISTORTION AND DRAGGING RELATED TO APPARENT TISSUE CONTRACTION IN MACULAR TELANGIECTASIS TYPE 2

PURPOSE

To examine the alterations in retinal vascular morphology over an extended follow-up in eyes with macular telangiectasis Type 2 (MacTel2).

METHODS

Eyes with high-quality digital photographs were evaluated. The geometric distortion in baseline images required to emulate the follow-up images was determined and vectors were made that represented the direction and magnitude of changes, to create a warp field. Optical coherence tomography and optical coherence tomography angiography evaluation of the retina was performed.

RESULTS

There were 7 eyes of 4 patients, who had a mean age of 70.25 years, which were followed for a mean of 8.8 years. The eyes showed increasing grayish opacification in the temporal macula with straightening and displacement of the macular vessels, even those in the nasal macula. The warp field vectors pointed to the temporal juxtafoveal macula. There was never any cavitation at the epicenter of the retinal distortion in any patient, although cavitations were found around this area. Optical coherence tomography imaging showed a circumscribed region of hyperreflectivity in the temporal macula. Optical coherence tomography angiography showed a deep angular condensed network of vessels within the hyperreflective region. One eye showed marked atrophic changes including full-thickness macular hole formation, but no increase in graying of the retina, loss of retinal laminations, pigmentary infiltration, or alteration in the retinal vessels.

CONCLUSION

Tissue contraction with retinal vascular displacement and contortion seem to be integral aspects of disease manifestation in MacTel2. The induced vascular changes may lead to secondary effects that increase morbidity in this disease.

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.

ABNORMAL RETINAL REFLECTIVITY TO SHORT-WAVELENGTH LIGHT IN TYPE 2 IDIOPATHIC MACULAR TELANGIECTASIA

PURPOSE

Macular telangiectasia Type 2 (MacTel) is a bilateral, progressive, potentially blinding retinal disease characterized by vascular and neurodegenerative signs, including an increased parafoveal reflectivity to blue light. Our aim was to investigate the relationship of this sign with other signs of macular telangiectasia Type 2 in multiple imaging modalities.

METHODS

Participants were selected from the MacTel Type 2 study, based on a confirmed diagnosis and the availability of images. The extent of signs in blue-light reflectance, fluorescein angiographic, optical coherence tomographic, and single- and dual-wavelength autofluorescence images were analyzed.

RESULTS

A well-defined abnormality of the perifovea is demonstrated by dual-wavelength autofluorescence and blue-light reflectance in early disease. The agreement in area size of the abnormalities in dual-wavelength autofluorescence and in blue-light reflectance images was excellent: for right eyes: ρ = 0.917 (P < 0.0001, 95% confidence interval 0.855-0.954, n = 46) and for left eyes: ρ = 0.952 (P < 0.0001, 95% confidence interval 0.916-0.973, n = 49). Other changes are less extensive initially and expand later to occupy that area and do not extend beyond it.

CONCLUSION

Our findings indicate that abnormal metabolic handling of luteal pigment and physical changes giving rise to increased reflectance are widespread in the macula throughout the natural history of the disease, precede other changes, and are relevant to early diagnosis.

ELECTROPHYSIOLOGICAL CHARACTERIZATION OF MACULAR TELANGIECTASIA TYPE 2 AND STRUCTURE-FUNCTION CORRELATION

PURPOSE

To investigate the electrophysiological features of macular telangiectasia Type 2 and their relationship to structure as determined by optical coherence tomography imaging.

METHODS

Forty-two eyes from 21 patients enrolled in the Macular Telangiectasia Natural History Observation Study were reviewed. All patients had full-field and pattern electroretinography (ERG; PERG) with some patients additionally having multifocal electroretinography (mfERG; N = 15) or electrooculography (N = 12). Multiple linear regression modeling assessed the relationship between the ellipsoid zone break size on optical coherence tomography and the central mfERG response.

RESULTS

Full-field ERG and electrooculography were normal in all eyes. Six eyes (14%) from five patients had subnormal PERG P50 amplitudes. Twenty-two of 30 eyes (73%) had reduced central or paracentral stimulus on mfERG. There was a significant correlation between ellipsoid zone break size and both the P1 amplitude (R = 0.37, P = 0.002) and P1:N1 ratio (R = 0.32, P = 0.002) of the central response on mfERG.

CONCLUSION

The electrophysiological findings in macular telangiectasia Type 2 are those of localized central dysfunction and are consistent with the structural data available from imaging and histologic studies. The ellipsoid zone break size correlates with mfERG reduction. The reduced mfERG P1:N1 ratio is consistent with inner retinal dysfunction.

CHARACTERISTICS OF PIGMENTED LESIONS IN TYPE 2 IDIOPATHIC MACULAR TELANGIECTASIA

PURPOSE

Pigment in the midretina is a characteristic sign in Type 2 idiopathic macular telangiectasia (MacTel) and is considered to characterize the late stage of the disease. Our aim was to investigate its incidence, and relationship with risk factors for MacTel, including outer retinal vascularization and subretinal neovascular proliferation (SRNV).

METHODS

Pigment extent was measured in fundus autofluorescence images of 150 eyes of 75 MacTel probands, using the Region Finder tool of Heidelberg Eye Explorer. A linear mixed model was used to analyze the dynamics of pigment and its associations with other features of the phenotype. The relative incidence of pigment and of outer retinal outer retinal vascularization and SRNV was analyzed within the full MacTel Study cohort (1,244 probands).

RESULTS

Mean pigment area at baseline was 0.157 mm (range = 0-1.295 mm, SD = 0.228 mm, n = 101). Progression demonstrated a nonlinear pattern (P < 0.001) at an overall rate of 0.0177 mm/year and was associated with the initial plaque size and with SRNV. There was a strong correlation between fellow eyes (P ≤ 0.0001). In approximately 25% of all SRNV cases, SRNV may coincide with or precede pigment.

CONCLUSION

Our data may be useful for refining the current system for staging disease severity in MacTel.

MACULAR PIGMENT DISTRIBUTION RESPONSES TO HIGH-DOSE ZEAXANTHIN SUPPLEMENTATION IN PATIENTS WITH MACULAR TELANGIECTASIA TYPE 2

PURPOSE

To analyze macular pigment (MP) amount and distribution in patients with macular telangiectasia Type 2 receiving oral zeaxanthin supplementation in a randomized, open-label, interventional trial.

METHODS

Eight macular telangiectasia Type 2 patients were randomized to 10 mg or 20 mg of zeaxanthin per day. At each visit, best-corrected visual acuity, contrast sensitivity, fundus biomicroscopy, color fundus photography, autofluorescence imaging, optical coherence tomography, and serum carotenoid levels were tested. Patients were assessed at baseline and after 6, 12, 18, and 24 months of zeaxanthin supplementation. Concentration of MP was analyzed and calculated from autofluorescence imaging obtained at 488-nm excitation wavelength. Serum carotenoid levels were obtained using high-performance liquid chromatography.

RESULTS

The majority of patients had definite increases in the intensity of hypofluorescent ring of MP, but none of them deposited MP centrally at the fovea. Although some patients noted subjective improvements in vision, no objective improvements could be documented, and there were no changes in foveal optical coherence tomographic features. Yellowish, hypofluorescent crystals appeared in one patient's macular region with no change in visual acuity. These inner retinal crystals disappeared several months after discontinuing her 20-mg zeaxanthin supplement.

CONCLUSION

Based on the current study, zeaxanthin supplementation does not result in any visual benefit in patients with macular telangiectasia Type 2 and does not reestablish a normal peaked distribution of MP in the fovea. One patient developed a novel, reversible, crystalline maculopathy in response to zeaxanthin supplementation that was reminiscent of canthaxanthin crystalline maculopathy.

CORRELATION OF OPTICAL COHERENCE TOMOGRAPHY AND MACULAR PIGMENT OPTICAL DENSITY MEASUREMENTS IN TYPE 2 IDIOPATHIC MACULAR TELANGIECTASIA

PURPOSE

Macular telangiectasia is associated with neurodegenerative changes including focal outer retinal atrophy and a loss of macular pigment (MP). We aimed to investigate whether an association between spectral domain optical coherence tomography neurodegenerative signs and MP abnormalities can be detected.

METHODS

Forty-seven eyes of 27 macular telangiectasia Type 2 patients (mean age 66.7 years, range 50-82 years, 12 male) were investigated. An MP pattern was recorded using a dual-wavelength autofluorescence method and classified according to severity (I-III). Outer plexiform, inner nuclear, and photoreceptor layer thickness values were measured in Spectralis spectral domain optical coherence tomography scans. Thickness values were compared with those of a control group of 14 healthy age-matched eyes.

RESULTS

Macular pigment redistribution was found to be Class I in 11 eyes, Class II in 28 eyes, and Class III in 8 eyes. More advanced stages of MP loss were associated with a greater, statistically significant thinning of the outer plexiform and inner nuclear layer complex and photoreceptor layers (P ≤ 0.001). Lower absolute levels of MP were also associated with a thinning of the photoreceptor layer. Thinning was restricted to within the parafovea, more severe at temporal eccentricities.

CONCLUSION

Our findings support the hypothesis that in macular telangiectasia Type 2 cellular degenerative processes leading to a thinning of these layers also result in reduction and redistribution of MP.

ASSOCIATION BETWEEN CHANGES IN MACULAR VASCULATURE IN OPTICAL COHERENCE TOMOGRAPHY- AND FLUORESCEIN- ANGIOGRAPHY AND DISTRIBUTION OF MACULAR PIGMENT IN TYPE 2 IDIOPATHIC MACULAR TELANGIECTASIA

PURPOSE

We investigate the association between morphologic findings in optical coherence tomography angiography (OCTA) as a new method offering the visualization of deeper layers of retinal vasculature and fluorescein angiography (FA) and macular pigment imaging and in Type 2 macular telangiectasia.

METHODS

Fourty-two eyes of 21 patients with macular telangiectasia (38-68 years, 14 female) were examined by FA and OCTA and 24 eyes additionally with dual-wavelength autofluorescence. Early and late FA, macular pigment density images, and (after segmentation of retinal vasculature into superficial and deep capillary network and outer) OCTA images were graded into standardized categories. Agreement between the methods was evaluated statistically.

RESULTS

In OCTA, a reduction of density of superficial capillaries, dilated vessels in the deep capillary network, anastomoses toward the superficial capillary network, and "new" vessels in the outer retina layers can be detected. The described anatomical features, especially in the deep capillary plexus and outer retina corresponded well with changes in FA. Classes of macular pigment distribution correlated most with classes of changes in OCTA superficial capillary plexus.

CONCLUSION

Progressive changes in macular telangiectasia apparent in FA and macular pigment imaging are most obvious in the deep capillary network and outer retina in OCTA. Optical coherence tomography angiography offers a noninvasive technology to analyze vascular changes in the retina and choroid of patients with macular telangiectasia.

When is macular edema not macular edema? An update on macular telangiectasia type 2

Macular telangiectasia type 2 (Mac Tel 2) also known as idiopathic perifoveal telangiectasia and juxtafoveolar retinal telangiectasis type 2A is an enigmatic disease of unknown etiology. It manifests both neurodegenerative and vasculopathic characteristics.

It manifests itself during the fifth or sixth decades of life. Clinical characteristics include minimally dilated parafoveal capillaries with loss of the retinal transparency in the area involved, absence of lipid exudation, right-angled retinal venules, superficial retinal refractile deposits, hyperplasia of the retinal pigment epithelium (RPE), foveal atrophy and subretinal neovascularization (SRNV). Optical coherence tomography (OCT) images typically demonstrate outer retinal abnormalities and the presence of intra-retinal hyporeflective spaces that are usually not related with retinal thickening or fluorescein leakage. The typical fluorescein angiographic finding is a deep intraretinal hyperfluorescent staining in the temporal parafoveal area. With time this fluorescein hyperfluorescence involves the whole parafoveal area but does not extend to the center of the fovea. Long-term prognosis for central vision is poor, because of the development of SRNV or macular atrophy. Its pathogenesis remains unclear but multi-modality imaging with fluorescein angiography, spectral domain OCT, adaptive optics, confocal blue reflectance, short wave fundus autofluorescence, OCT angiography, and clinicopathological correlations implicate Müller cells. Currently there is no known treatment for this condition.

Macular telangiectasia--changes in macular pigment optical density during a 5-year follow-up

PURPOSE

To quantitatively analyze the distribution of macular pigment (MP) over a period of 5 years and for monitoring progression of macular telangiectasia.

METHODS

Macular pigment concentration (autofluorescence, excitation wavelengths: 488 and 514 nm) was determined at baseline and after 5 years in 43 eyes of 22 subjects (46-80 years; mean, 65.6 years; 10 men) participating in the macular telangiectasia project.

RESULTS

Mean MP density at 0.5° declined in the segment (one eighth of a circle) with the highest MP optical density (-0.04 density units; P= 0.015), where density units (DU), and also averaged in the 2 segments that divided segments with detectable MP from those in which MP was no longer detectable (-0.04 density units; P = 0.0005). In the first segment mentioned, 2° values decreased to a lesser extent and not significantly. The diameter of MP loss expanded horizontally from 2.64 mm to 2.74 mm (P = 0.0001) but not vertically. Macular pigment density in the "halo" of peripheral MP at a mean of 5.44° (4.53-6.21°) increased (+0.01 DU; P= 0.01).

CONCLUSION

Five years of follow-up resulted in central (0.5°) reduction and peripheral (4.53-6.21°) accumulation of MP. Longer period of follow-up may disclose significant changes in paracentral locations. The area of central MP loss expands in particular in a horizontal direction and less vertically. Centrifugal movement of MP during disease may explain our findings.

[Morphological characteristics in macular telangiectasia type 2]

Macular telangiectasia type 2 is characterized by atrophic alterations of the central retina which is accompanied by a defined vascular phenotype. The disease manifests within an oval central retinal area the size of approximately two disc diameters, with a topographic predisposition temporal to the foveal center. Funduscopy reveals reduced retinal transparency, crystalline deposits, mildly ectatic capillaries, thickened venules and retinal pigment plaques. Secondary neovascularization and macular holes may occur during the disease course. Fluorescein angiography usually shows a diffuse leakage and often ectatic capillaries. On optical coherence tomography (OCT) examination, hyporeflective cavities and focal atrophy of the photoreceptor layer represent a frequent finding. A characteristic sign is an increased (para) central signal on fundus autofluorescence imaging due to a reduced density of macular pigment.

Pseudocystic foveal cavitation in tamoxifen retinopathy

PURPOSE

To present 3 cases of tamoxifen-induced foveal cavitation and review previous prospective and cross-sectional studies.

DESIGN

Observational case series.

METHODS

Retrospective analysis of patients presenting to a single institution with evidence of tamoxifen-induced maculopathy.

RESULTS

Three patients presented with pseudocystic foveal cavitation similar in appearance to macular telangiectasia type 2 on spectral-domain optical coherence tomography (SD OCT) imaging.

CONCLUSIONS

Tamoxifen maculopathy is characterized by cavitation in the central macula with or without typical cystoid macular edema. Pathogenesis involves toxicity to retinal Müller cells. It can occur with low daily and cumulative doses of the drug, and in the absence of subjective visual complaints or crystalline retinopathy. Prospective research with SD OCT imaging will be required to gain a more accurate estimate of the incidence of tamoxifen retinopathy.