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

Timing of ocular examination and retinal imaging for the diagnosis of type 2 macular telangiectasia (MacTel)

PURPOSE

To report a case demonstrating the relevance of ocular examination and retinal imaging timing in type 2 macular telangiectasia (MacTel).

CASE DESCRIPTION

A 55-year-old-female complained of blurring of vision in the left eye for the last 6 months. Corrected visual acuity was 20/20, N6 and 20/30, N8 in the right and left eye respectively. Anterior segment examination was normal in both eyes. Her both eyes' fundus was seen initially by the general ophthalmologist and was subsequently referred to the retinal specialist.

RESULTS

Dilated fundus examination of the right eye appeared normal while the left eye showed no specific retinal pathology except for a dull foveal reflex. Retinal imaging with optical coherence tomography and confocal blue reflectance (CBR) imaging were not conclusive of any specific clinical diagnosis. A fluorescein angiography and repeat CBR imaging was done on the following day which now clearly showed the features of type 2 MacTel.

CONCLUSION

Specific clinical and imaging features in type 2 MacTel are observed better in the absence of light exposure. Retinal imaging with CBR should not be performed immediately after dilated retinal examination in a suspected case of type 2 MacTel.

Non-vasogenic cystoid maculopathies

Besides cystoid macular edema due to a blood-retinal barrier breakdown, another type of macular cystoid spaces referred to as non-vasogenic cystoid maculopathies (NVCM) may be detected on optical coherence tomography but not on fluorescein angiography. Various causes may disrupt retinal cell cohesion or impair retinal pigment epithelium (RPE) and Müller cell functions in the maintenance of retinal dehydration, resulting in cystoid spaces formation. Tractional causes include vitreomacular traction, epiretinal membranes and myopic foveoschisis. Surgical treatment does not always allow cystoid space resorption. In inherited retinal dystrophies, cystoid spaces may be part of the disease as in X-linked retinoschisis or enhanced S-cone syndrome, or occur occasionally as in bestrophinopathies, retinitis pigmentosa and allied diseases, congenital microphthalmia, choroideremia, gyrate atrophy and Bietti crystalline dystrophy. In macular telangiectasia type 2, cystoid spaces and cavitations do not depend on the fluid leakage from telangiectasia. Various causes affecting RPE function may result in NVCM such as chronic central serous chorioretinopathy and paraneoplastic syndromes. Non-exudative age macular degeneration may also be complicated by intraretinal cystoid spaces in the absence of fluorescein leakage. In these diseases, cystoid spaces occur in a context of retinal cell loss. Various causes of optic atrophy, including open-angle glaucoma, result in microcystoid spaces in the inner nuclear layer due to a retrograde transsynaptic degeneration. Lastly, drug toxicity may also induce cystoid maculopathy. Identifying NVCM on multimodal imaging, including fluorescein angiography if needed, allows guiding the diagnosis of the causative disease and choosing adequate treatment when available.

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.

Comparison of Macular Pigment Optical Density in Glaucoma Patients and Healthy Subjects - A Prospective Diagnostic Study

Purpose

To evaluate the relationship between macular pigment optical density (MPOD) and glaucoma.

Methods

Forty-three patients with an established glaucoma diagnosis (25 females, 18 males, mean age 70 (range 34–84)) and 43 healthy controls (28 females, 15 males, mean age 62 (range 30–87)) were included in this prospective diagnostic case-control study. All subjects underwent detailed eye examination including ophthalmoscopy, best-corrected visual acuity, biomicroscopy, measurement of the axial length of the eye, objective refraction, lens status, central foveal thickness on spectral-domain optical coherence tomography (SD-OCT). In all glaucoma patients, a visual field assessment and a measurement of the retinal nerve fibre layer (RNFL) on SD-OCT were done. MPOD was determined using the macula pigment module of the Spectralis HRA+OCT (Heidelberg Engineering GmbH, Heidelberg, Germany) at 0.51°, 1.02° and 1.99° retinal eccentricity using two-wavelength autofluorescence imaging.

Results

In the glaucoma group, the median of the visual field mean defect was 5.1 db (quartiles 3.0 and 13.5) and the mean RNFL-thickness global was 65.9 µm (SD ± 16.1). Median MPOD measured at 0.51°, 1.02° and 1.99° retinal eccentricity in the glaucoma group was 0.42 DU, 0.34 DU and 0.13 DU, in the control group 0.40 DU, 0.35 DU and 0.12 DU respectively. There was no statistically significant difference of median MPOD between glaucomatous and control eyes (p=0.510, 0.735, 0.481). No significant relation between MPOD at 1.02 retinal eccentricity and the presence of glare symptoms was found (p=0.948). However, age seems to correlate with median MPOD measured at 1.02 retinal eccentricity (p=0.017).

Conclusion

There was no evidence for lower MPOD levels in our glaucoma patients; lower MPOD was not related to the presence of glare symptoms. However there seems to be a positive correlation between age and MPOD at 1.02° retinal eccentricity. To further investigate the relation between glare reported by glaucoma patients and glare disability linked to lower MPOD levels, additional studies are necessary that include both detailed inquiry of the quality of glare and a glare quantification and precise analysis of MPOD levels in glaucoma patients.

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.

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.

[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.