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MacTel 2

Introduction

MacTel2 is apart of a group of conditions known as macular telangiectasia.
Type 2 however:
- Affects 50-60 year olds without gender biases
- Presents with acute metamorphopsia
- Bilateral in nature
- Presents with occult telangiectasia, minimal exudation, foveolar atrophy, retinal crystalline deposits
- Affects 0.1% of people over age 40

Pathogenesis:
- Is a neurodegenerative condition due to the loss of Muller cells in the macular area, with vascular changes as a secondary cause of the condition
- The Muller cells provide structural support to the retina, maintains the ILM, and provides homeostatic and metabolic support
- They also maintain the PR, BRB, NV and guides light to prevent unnecessary scattering

Proliferative Pathogenesis:
- The loss of Muller cells deregulates the iBRB
- Thickens the BM of vessels, and loses pericytes
- This leads to abnormal telangiectatic capillaries
- Hypoxia, VEGF release and NV occur

Dead Giveaways

Non-Proliferative

  • Cavities are a big sign of present MacTel2

  • Without Muller cells, the PR, ONL and EZ begin to undergo atrophy

  • Note the cavities both in the inner and outer retinal layers. Red arrow points to compromised EZ, and outer retina
    Note the cavities both in the inner and outer retinal layers. Red arrow points to compromised EZ, and outer retina

  • ILM drape is seen next to the white arrow, as it is the only thing that is spared

  • Another classic feature is in the Fundus:

    • Area around the pigmented dot is slightly hyper-AF, with increased transparency temporal to the fovea. Also note the crystals.
      Area around the pigmented dot is slightly hyper-AF, with increased transparency temporal to the fovea. Also note the crystals.

    • RPE damage is associated with reduced pigmentation, typically found temporal to the fovea. Can affect the whole juxta-foveal region around 5-7th decade

    • Additionally, the foveal reflex has been lost. Hyperpigmentation refers to RPE hyperplasia

  • In angiography, telangiectatic vessels may be seen in the temporal parafovea

    • Bulbs can clearly be seen. But in late stage disease, is very diffuse and hyper-reflective
      Bulbs can clearly be seen. But in late stage disease, is very diffuse and hyper-reflective

Proliferative

  • The biggest giveaway is in the neovascularisation, with the parafoveal arteries and veins turning sharply downwards in OCT to anastomose with the choroidal circulation

The left side shows a downwards shape formed by the inner retina. That is the blood vessels sharply orienting down in pre-proliferative stage, to anastamose. The intact retinal layers appear a bit granular
The left side shows a downwards shape formed by the inner retina. That is the blood vessels sharply orienting down in pre-proliferative stage, to anastamose. The intact retinal layers appear a bit granular

  • This leads to sub-retinal neovascularisation, that can cause fibrosis or subretinal haemorrhages

    Shows the vessels pointing downwards, as well as the subretinal haemorrhage or neovascularisation. Foveal pit is very distorted here
    Shows the vessels pointing downwards, as well as the subretinal haemorrhage or neovascularisation. Foveal pit is very distorted here

  • Vessels are best visualised using OCT-A

    • Shows new vessel proliferation in an fovea, which shouldn't have vessels
      Shows new vessel proliferation in an fovea, which shouldn't have vessels

  • Fundus pics can reveal fibrovascular scars

    • Fibrovascular scar and haemorrhage in late-stage MacTel2. By this stage, the crystals have disappeared
      Fibrovascular scar and haemorrhage in late-stage MacTel2. By this stage, the crystals have disappeared

diagnostic features

3 Types of MacTel

T1:

  • Affects 40 year old males prodominantly

  • Unilateral

  • Clinically visible telangiectasia, macular oedema and hard exudates

  • Developmental Origin (only one that isn't acquired)

T2:

  • Affects 50-60 year olds with no gender bias, presenting with acute metamorphopsia (unless very early)

  • Bilateral in nature

  • Presents with occult telangiectasia, minimal exudation and foveolar atrophy, retinal crystalline deposits

  • Acquired

T3:

  • Very rare, affecting 50 year old with unknown gender bias

  • Unilateral in nature

  • Visible telangiectasia, minimal exudation, progressive obliteration of the perifoveolar capillary network, capillary occlusion and optic disc pallor

  • Acquired


Symptoms:

  • In pre-proliferative, Px reports slow progressive vision loss due to PR loss

  • During proliferative Px reports rapid and severe vision loss possibly due to subretinal neovascularisation

  • Affecting the macular will lead to associated scotomas (more nasal), as well as metamorphopsia, which influences QoL


Summary of Clinical Signs:

  • Clinically:

    • Mild reduction of VA and metamorphopsia

  • Fundus:

    • Lack of foveal pit reflex

    • Bilateral retinal changes temporal to fovea

    • Distortion of pit

    • Reduces transparency

    • Retinal pigment hyperplasia

    • Thinning of retina

  • OCT:

    • Outer retinal layer involvement

    • Hyper-reflective areas

    • Pigment migration

    • Atrophy of outer retinal layers

    • Intraretinal cystic spaces


MacTel 2 FAF

  • Though not a defining feature, can be noted

  • Retinal atrophy appears hypo-AF on FAF



2025, made by Eric Qin. UNSW. SOVS

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