Is macular telangiectasia always bilateral?

Macular Telangiectasia Type 2 Is Almost Always Bilateral

Macular telangiectasia type 2 (MacTel 2) is characteristically bilateral in presentation, though it may be asymmetric between the two eyes. 1

Understanding Macular Telangiectasia Type 2

Macular telangiectasia type 2, also known as idiopathic perifoveal telangiectasia or juxtafoveolar retinal telangiectasis type 2A, is a bilateral neurodegenerative macular disease that typically manifests during the fifth or sixth decades of life. It is characterized by:

• Minimal dilatation of parafoveal capillaries
• Graying of the affected retinal area
• Lack of lipid exudation
• Right-angled retinal venules
• Refractile deposits in the superficial retina
• Hyperplasia of the retinal pigment epithelium
• Foveal atrophy
• Potential subretinal neovascularization

Epidemiology and Prevalence

MacTel 2 has a prevalence of approximately 0.1% in persons 40 years and older 2. The disease may be underdiagnosed due to its subtle clinical presentation in early stages.

Bilateral Nature of MacTel 2

The bilateral nature of MacTel 2 is a key diagnostic feature that distinguishes it from other macular diseases:

• MacTel 2 is "typically bilateral" according to the corneal ectasia preferred practice pattern 1
• The natural history section of the guideline specifically states: "Corneal ectasia is usually bilateral, and it varies in severity from clinically undetectable, or 'subclinical,' to advanced disease." 1

This is in contrast to macular telangiectasia type 1 (MacTel 1), which "almost always occurs unilaterally" 3. The bilateral presentation is so characteristic of MacTel 2 that when a unilateral presentation is observed, alternative diagnoses should be considered.

Clinical Presentation and Imaging

MacTel 2 may present with asymmetric involvement between the two eyes. Diagnostic imaging findings include:

• Optical Coherence Tomography (OCT): Demonstrates intraretinal hyporeflective spaces that are usually not related to retinal thickening or fluorescein leakage 4, 5
• Fluorescein Angiography: Shows deep intraretinal hyperfluorescent staining in the temporal parafoveal area that may eventually involve the whole parafoveal area but typically does not extend to the center of the fovea 6
• Fundus Autofluorescence: Reveals a unique depletion of macular pigment in the central retina 2

Differential Diagnosis

When evaluating a patient with suspected macular telangiectasia, it's important to differentiate between:

• MacTel 1: Almost always unilateral, associated with cystoid macular edema, responds variably to treatment 3
• MacTel 2: Almost always bilateral, characterized by neurodegenerative changes, minimal response to treatments 5
• Other macular diseases: Diabetic maculopathy, retinal vein occlusions, and radiation retinopathy may present with similar features but typically have different clinical contexts

Clinical Implications

The bilateral nature of MacTel 2 has important implications for:

1. Diagnosis: When evaluating a patient with macular telangiectasia, bilateral involvement strongly suggests MacTel 2
2. Monitoring: Both eyes should be carefully examined and followed, even if symptoms are initially unilateral
3. Prognosis: Long-term prognosis for central vision is generally poor due to the development of subretinal neovascularization or macular atrophy 6

Management Considerations

Currently, there is no known effective treatment for the underlying cause of MacTel 2. Management focuses on:

• Monitoring for complications such as subretinal neovascularization
• Anti-VEGF therapy may be considered for neovascular complications, though clinical trials have shown limited efficacy for non-neovascular disease stages 2
• Patient education regarding the bilateral and progressive nature of the condition

Key Takeaway

When evaluating a patient with macular changes suggestive of telangiectasia, the bilateral presentation is a strong indicator of MacTel 2. Even in cases where symptoms or clinical signs appear asymmetric, careful examination of both eyes will typically reveal bilateral involvement, which is characteristic of this condition.