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Disease Entity

Disease

Macular telangiectasia (Mac Tel) is a disease that causes abnormalities of capillaries of the fovea or perifoveal region that are associated with loss of outer nuclear layers and the ellipsoid zone, Eventually, these abnormalities can progress to cystic cavitation-like changes in all retinal layers, or to development of full-thickness macular hole or subretinal neovascularization in advanced stages. It was first described by Dr. Donald Gass in 1968 as a different entity from Coats disease.

Mac Tel is divided into 3 main types:

Type 1: Congenital and unilateral. Thought to be similar to and/or possibly a variant of Coats disease. Uncommon
Type 2: Acquired and bilateral. The most common of the 3 types; usually found in middle-aged or older patients. According to the Beaver Dam Eye Study which graded only color fundus images, the average patient age was 63 years. Although the sex differences seen in type 2 were not initially described by Gass, Dr. Lawrence Yannuzzi found a slight female preponderance of 58%. The term "Mac Tel" is often used to refer to just type 2; therefore, this article will largely focus on type 2, as it has the most clinical relevance
Type 3: A rare, poorly understood primarily occlusive phenomenon

Etiology

The Mac Tel Project found that the 28% of patients with type 2 Mac Tel had concomitant diabetes mellitus (DM) and 52% had concomitant hypertension (HTN). The prevalence of HTN and DM, as well as the older age of disease onset, can point toward long-term vascular stress as the etiology for Mac Tel. These vascular changes are associated with disruption of the outer nuclear layer and ellipsoid zone and lead to pseudolamellar macular holes. Retinal pigment epithelium (RPE) hyperplasia and migration into the inner retinal layers is seen with disease progression.

General Pathology

Gass postulated that Müller cells and parafoveal neural cells may be the primary sites that are initially affected. Histopathology has shown disruption of pericytes and ectatic vessels, with dilated venules diving at a right angle into deeper retinal layers with evidence of RPE hyperplasia. As discussed above, vascular occlusion, inflammatory changes, and other neurodegenerative processes lead to loss of the outer nuclear layer and the ellipsoid zone, with later formation of cyst-like cavitations that can encompass all retinal layers.

Pathophysiology

Chronic neurodegenerative processes, vascular inflammation, occlusion, and ectatic capillary changes lead to loss of outer retinal layers and formation of pseudolamellar macular holes with cyst-like cavitations that can also be seen in the inner retinal layers. Patients can develop retinal neovascularization temporal, which can cause exudation, intraretinal and subretinal hemorrhaging, and disciform scaring.

Primary Prevention

No prevention methods have been shown to be beneficia; however, most clinicians would recommend controlling HTN and DM if present, as these 2 diseases have been shown to be prevalent in patients with Mac Tel.

Diagnosis

The diagnosis of Mac Tel is made by assessing patient history and conducting ophthalmic clinical exams. Ophthalmic imaging is also used.

History

Patients with Mac Tel type 2 often complain of metamorphopsia or scotoma. With disease progression, an increased scotoma can be perceived with decreased visual acuity (VA), as the scotoma affects the fovea and perifoveal area. However, VA rarely reaches legal blindness; the Mac Tel Project found that 50% of patients maintained a VA of 20/32 or better. However, VA can decrease if a macular hole develops. Vision can be severely diminished in Mac Tel types 1 and 3.

Physical Examination

In Mac Tel type 2, fundoscopic exam is initially significant for a decrease of foveal pit, with subsequent foveal or perifoveal ectatic vessels with possible presence of venules diving at a right angle into deeper retinal layers. Grayish discoloration of temporal perifoveal area is the earliest sign present. Ectatic vessels with evidence of venules diving at a right angle into deeper retinal layers. Of note, these findings may be subtle on routine retinal exam. Subretinal neovascularization temporal to fovea may be seen in this disease and can be associated with exudates or hemorrhage. RPE hyperplasia can also be seen at the fovea or temporal perifovea. Also, in later stages, pseudolamellar holes can develop into full-thickness macular holes.

Imaging

Fundus autofluorescence (FAF) is very useful as it allows detecting functional changes before perceivable anatomic changes. FAF shows increased foveal hyper-autofluorescence secondary to loss of foveal luteopigment (xanthophyll is probably primarily stored in Müller cells, and this could be a surrogate measure of the health and concentration of Müller cells in affected areas). In more advanced stages with increased pigmentation, areas of RPE hyperplasia will appear as hypo-autofluorescent spots.

Optical coherence tomography (OCT) shows temporal foveal pit enlargement secondary to loss of outer nuclear layer and ellipsoid zone that can progress into large cysts (often called 'cavitation') that can encompass all retinal layers. The cavitations are thought to be due to degenerative changes (which are believed to be due to Muller cells depletion within affected retina, creating structural void spaces), rather than fluid-fille cystic cavities. When the degenerative changes are pronounced, and include the inner retinal layers, only the internal limiting membrane can be visualized, leaving a characteristic "ILM drape" over the affected area. The later sign could be diagnostic. Additionally, hyperreflective areas on OCT correlate to areas of RPE hyperplasia and migration. OCT angiography (OCTA) has contributed to further understanding of the retinal vascular changes. In fact, OCTA helps by highlighting the telangiectatic changes, as well as dragging and crowding of vessels in the areas of degenerative changes.

Fluorescein angiography (FA) mainly shows temporal foveal telangiectatic vessels in Mac Tel type 2 that leak in later frames. Evidence of venules diving at a right angle into deeper retinal layers can also be seen. Subretinal neovascularization, when present, is though to be of primary retinal in origin as FA shows a feeding arteriole and a draining venule.

Proposed Staging

Five distinct stages has been proposed to layout the progressive nature of Mac Tel:

Stage 1: characterized by normal fundus, with very subtle changes on FAF.
Stage 2: characterized by loss of retinal transparency manifesting as greying of the affected area clinically and hyperFAF, as well as appearance of mild telangiectatic changes, without exudation. Crystalline deposits at the level of the vitreoretinal interface (sub-ILM) could also be present.
Stage 3: characterized by moderate telangiectatic changes, right angle venules, and capillaries remodeling in the outer retinal layers, without exudation.
Stage 4: characterized by presence of pigmentary changes due intraretinal RPE migration and hyperplasia, that is thought to be secondary to the underlying degenerative changes.
Stage 5: characterized by presence of retino-choroidal anastomosis leading to exudation and hemorrhage.

Differential diagnosis

Differential diagnosis of retinal capillary telangiectasia include branch retinal vein occlusion, diabetic retinopathy, radiation retinopathy. In cases of neovascularization, age-related macular degeneration should also be ruled out.

Management

There has been no randomized clinical study for this entity. In non-neovascular cases, laser, intravitreal anti-VEGF or steroid has not been shown to be effective in controlling the disease. For neovascular cases, intravitreal anti-VEGF are the mainstay of treatment, although transpupillary therapy and photodynamic therapy have been used in the past. Neuroprotective agents are currently being investigated. A Phase II trial studying intraocular delivery of ciliary neurotrophic factor (CNTF) in eyes with Mac Tel type 2 found decreased ellipsoid zone loss, increased macular thickness, and stable reading speed when compared to controls. Phase III multi-center Renexus (NT-501) Trial tested the safety and efficacy of using an intravitreal ocular implant designed to deliver therapeutic doses of ciliary neurotrophic factor (CNTF) in patients with macular telangiectasia type 2. Associated full thickness macular holes may be treated with pars plana vitrectomy surgery, membrane peeling and gas tamponade, but are likely to have a lower-than-average closure rate, and postoperative visual acuity.

Prognosis

According to the Mac Tel Project, 60% of type 2 patients with have a visual acuity of 20/50 or better, with a mean visual acuity of 20/40. Mac Tel can rarely lead to 20/200 or worse vision (~4% with severe visual loss) especially when associated with full-thickness macular hole or retinal neovascularization associated with disciform scaring. However, about 79% of eyes with neovascularization, and about 78% of eyes with macular hole have visual acuities better than 20/200. Interestingly, eyes with visual acuity ≤ 20/200 (consider to be advanced disease) were reported to have pigmentary plaques, which are though to be a surrogate marker for photoreceptor degeneration.

Additional Resources

Turbert D. What is macular telangiectasia? American Academy of Ophthalmology. https://www.aao.org/eye-health/diseases/macular-telangiectasia-list. Published September 23, 2024. Accessed April 21, 2025.
Porter D. Blood pressure. American Academy of Ophthalmology. https://www.aao.org/eye-health/anatomy/blood-pressure-list. Published February 27, 2018. Accessed April 21, 2025.

References

1. Clemons TE, Gillies MC, Chew EY, et al; for the Macular Telangiectasia Project Research Group. Medical characteristics of patients with macular telangiectasia type 2 (MacTel type 2): MacTel Project Report No. 3. Ophthalmic Epidemiol. 2013;20(2):109-113.

2. Wu L, Evans T, Arevalo JF. Idiopathic macular telangiectasia type 2 (idiopathic juxtafoveolar retinal telangiectasis type 2A, Mac Tel 2). Surv Ophthalmol. 2013;58(6):536-559.

3. Charbel Issa P, Gillies MC, Chew EY, et al. Macular telangiectasia type 2. Prog Retin Eye Res. 2013;34:49-77.

4. Kedarisetti KC, Narayanan R, Stewart MW, et al. Macular telangiectasia type 2: a comprehensive review. Clin Ophthalmol. 2022;16:3297-3309.

5. Heeren TFC, Chew EY, Clemons T, et al; MacTel Study Group. Macular telangiectasia type 2: visual acuity, disease end stage, and the MacTel Area: MacTel Project Report Number 8. Ophthalmology. 2020;127(11):1539-1548.