Author: Ameen Marashi, MD

History

Documentation of visual loss is essential, which includes the location and duration along with detailed ocular history.

Medical history obtained, such as diabetes millets, which is associated in 28 % of cases ^[1], systemic hypertension 52% along with obesity and cardiovascular disease ^[2], especially in cases of macular telangiectasia type two.

Ocular Examination

A list of ocular examination should set

1) Best-corrected visual acuity (BCVA) is an essential step that can be performed by a trained optometrist or certified ophthalmologist to document the visual impairment, which is usually around 20/40 ^[1] and rarely to 20/200 ^[3]. And this will help in the follow-up visits to assess the efficacy of the treatment.

2) A slit-lamp examination done with a thorough exam of clarity and regularity of the cornea and conjunctival abnormality such injection of conjunctival vessels should be documented. And any other inflammations of the conjunctiva or eyelids documented, along with iris exam and crystalline lens exam to rule out cataract or intraocular lens (IOL) to document the position and clarity of the posterior capsule.

3) Intra Ocular Pressure (IOP) documentation is essential as high IOP is associated with a patient with glaucoma history.

Note when high IOP spotted a corrected IOP documented after central corneal thickness measurement.

4) Bilateral dilated fundus exam is an essential and detailed examination of the optic disc, macula, posterior pole, a mid-peripheral and peripheral retinal exam with specialized indirect wide-field lenses using slit-lamp biomicroscopy or indirect ophthalmoscopy:

· Macular telangiectasia type one (exudative) features:

1. Usually unilateral 

2. Clusters of hard exudates temporal in the parafoveal area. 

3. Telangiectatic aneurysm formation

4. Macular edema with subretinal fluids 

· Macular telangiectasia type two (degenerative) features:

1. Usually bilateral 

2. Loss of retinal transparency in parafoveal area temporal to the macula, which may involve the whole parafoveal area in later stages ^[4].  (stage two)

3. Dilated capillaries in the temporal macula parafoveal area.

4. Vein does not narrow approaching the macula and even dilate while diving in the retina at a right angle into deep capillary plexus. (stage three)

5. Pigmentary changes may occur to dilated diving vein due to RPE hyperplasia  (stage four)

6. RPE pigmentary changes and neuroretina degeneration.

7. Subretinal blood, fluids, and exudates are presented only in cases of macular telangiectasia complicated with choroidal neovascularization, which is commonly located temporally.  (stage five)

Diagnostic tests

Fundus images

Fundus image is a vital tool to document the severity and to follow up macular telangiectasia, as in type one, there would be hard exudates, a telangiectatic aneurysm in the temporal parafoveal area along with macular edema and subretinal fluids, however, pigmentary and crystal deposits are rare.

Macular telangiectasia type two, which features loss of retinal transparency with dilated venule diving in a right angle into deep capillary plexus (best seen in stereoscopic images) with dilated deep capillary plexus in the temporal parafoveal area along with pigmentary changes and neuroretinal degeneration.

In contrast to macular telangiectasia type one, type two only shows hard exudates, edema, and subretinal bleeding in complicated cases with choroidal neovascularization and may induce a subretinal scar.

Optical Coherence Tomography (OCT)

In macular telangiectasia type one, OCT shows thickening of macular tissue inducing edema with the cystic formation, which can be with clear or non-clear content with subretinal fluids and hyperreflective foci resembling hard exudates.

In macular telangiectasia type two OCT shows enlarged temporal pit and thinning of retinal tissue temporally as an early sign as disease progress and neuroretinal degeneration begin as ellipsoid zone disruption (clearly evidenced on Enface OCT) as the disease progresses furthermore a formation of cavitation of outer retinal tissue which may progress further leading to atrophy or forming pseudolamellar hole leaving only ILM without an increase in retinal thickening; Pigment migration may induce hyperreflective plaque with shadowing at the level of inner retinal tissue^[5].

OCT angiography features dilated aneurysmal formation with cystic spaces mainly in deep plexus.

While in macular telangiectasia type two features temporal parafoveal capillary malformation mainly in deep capillary plexus, it may involve the superficial plexus in late stages and may show right angle dilated diving venule in superficial plexus into deep capillary plexus.

OCT angiography is a very sensitive tool to detect choroidal neovascularization in complicated cases.

Fundus Fluorescein Angiography (FFA)

In macular telangiectasia type one, FFA shows hyperfluorescence due to telangiectatic aneurysmal dilatation, and in late-stage, it shows leakage, mainly in the temporal parafoveal region.

In macular telangiectasia type two, FFA shows hyperfluorescence in deep temporal parafoveal area, which can be involved in the whole parafoveal region.

The superficial capillaries can contribute to leakage as well; FFA demonstrates the deep right angle diving venule.

FFA in macular telangiectasia is useful in detecting leakage from subretinal choroidal neovascularization.

Note that the physician should obtain signed consent explaining the rare complications of FFA, including death 1/200000, and FFA facility should have an emergency plan in situ ^[6].

Systemic evaluation

Although analysis not ordered routinely, fasting glucose, and HbA1C to rule out any systemic risk factors such as diabetes mellitus, referral to a primary care physician to rule out risks of systemic hypertension, diabetes mellitus, and cardiovascular disease, especially in cases of macular telangiectasia type two.

Management

Macular telangiectasia type one

The laser is the treatment of choice which, applied in grid fashion covering the area of leaking telangiectatic aneurysms applied 100-200 um spot size medium intensity small laser burns sparing foveal avascular zone; laser sessions can be repeated if needed ^[7].

Intravitreal Anti-VEGF, which may reduce central macular thickening, reduce leak and improve vision ^[8], intravitreal injection of Anti-VEGF used in cases when laser can’t be applied or not available, intravitreal injection repeated only if edema recurs.

Intravitreal steroids such as triamcinolone which can stabilize retinal blood barrier and downregulate VEGF; however, the effect is transit with the risk of increased intraocular pressure and cataract formation, which make intravitreal steroids not recommended as first-line treatment ^[9].

Macular telangiectasia type two

In contrast to Macular telangiectasia type one laser photocoagulation ^[10] and intravitreal Anti-VEGF ^[11] are not effective in managing cases of macular telangiectasia type two and may worsen the case; therefore, are not recommended.

Recently ciliary neurotrophic factor showed a promising effect on slowing down the progression of macular telangiectasia type two ^[12].

However, in cases of macular telangiectasia type two complicated with subretinal choroidal neovascularization, intravitreal Anti-VEGF indicated to regress neovascularization, reduce macular thickening, and improve vision ^[13].

Pars plana vitrectomy only recommended if there is a macular hole; however, the success rate is low with bad visual prognosis ^[14].

Flow chart summarizes the approach and management of macular telangiectasia

Follow up and prognosis

Macular telangiectasia has a favorable prognosis; however, in cases of macular telangiectasia type two complicated with a macular hole or subretinal scar secondary to choroidal neovascularization has poor visual prognosis.

N.B, there is a third type (occlusive) of macular telangiectasia, which is extremely rare that features capillary nonperfusion perifoveal and limited exudation ^[10], with unknown treatment. 

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These guidelines were reviewed and updated in January 2023