March 2014

Case of the Month


Author: James Leong
Editor: Adrian Fung

Figure 1a

Figure 1a.
Colour fundus photographs reveal subtle abnormalities temporal to both foveae.

 

A 60-year-old caucasian female was referred by her optometrist for further evaluation having presented with difficulty reading and reduced visual acuity.

 

Case History

A 60-year-old caucasian female was referred with complaints of a gradual reduction in her visual acuity and difficulty reading over the last 12 months.  She had no significant past ocular history although there was a family history of glaucoma. Past medical history included diet controlled diabetes mellitus and hypertension.

On examination her visual acuities were 6/18 pinhole 6/12 in the right eye (OD) and 6/7.5 (pinhole no improvement) in the left (OS). Intraocular pressures were 16mmHg OD, 14mmHg OS. Anterior segment examination was normal. Examination of both maculae demonstrated loss of the foveolar reflex and reduced retinal transparency, yellow crystalline spots and mild intraretinal pigment hyperplasia. Mildly telangiectatic capillaries with right angle venules were evident temporal to the foveae (Figs 1a and b).

 

Figure 1b.

Figure 1b.
Magnified image of the right macula demonstrates the following changes temporal to the fovea: reduced retinal transparency, yellow crystals, intraretinal pigmentation and telangiectatic vessels with right angle venules.

 

 

What is your diagnosis?

 

 

Differential diagnosis

A) Telangiectatic vessels

  • Diabetic retinopathy
  • Branch retinal vein occlusion
  • Radiation Retinopathy
  • Macular Telangiectasia

B) Crystalline retinopathy

  • Ocular disease
    • Calcified macular drusen
    • Macular Telangiectasia
    • Bietti’s crystalline dystrophy
  • Systemic disease
    • Oxalosis
    • Cystinosis
  • Drug toxicity
    • Tamoxifen
    • Methoxyflurane
    • Canthoxanthine
    • Talc retinopathy

C) Yellow spot

  • Solar retinopathy
  • Cystoid macular oedema
  • Vitreomacular traction syndrome
  • Adult vitelliform macular dystrophy
  • Alkyl Nitrite ‘popper’ retinopathy

 

Additional history and investigations

Optical coherence tomography demonstrated hyporeflective cavities and outer retinal loss temporal to both foveae (Fig 2). Red free photography highlighted the telangiectatic vessels and area of reduced retinal transparency (Fig 3). On fundus autofluorescence there was a reduction in the normal foveal hypoautofluorescence (Fig 4). On fluorescein angiography, telangiectatic vessels were prominent in the early phase and increasing hyperfluorescence seen in the late phase (Fig 5).

 

Figure 2.

Figure 2.
Horizontal optical coherence tomography (OCT) raster scans through the right and left maculae demonstrate hyporeflective inner retinal cavities and outer retinal loss temporal to the foveae.

 

Figure 3.

Figure 3.
Red free photograph of the right macula (A and B, magnified view) reduced retinal transparency, crystals and telangiectatic vessels with right angle venules.

 

Figure 4.

Figure 4.
Fundus autofluorescence of the right macula in the affected patient (left) and a normal eye (right). In the affected patient there is reduced hypoautofluorescence that is usually seen at the fovea.

 

Figure 5.

Figure 5.
Fluorescein angiography shows increasing hyperfluorescence temporal to the right fovea.

 

Diagnosis

(Idiopathic) Macular Telangiectasia Type 2 (“MacTel”). This is also known as juxtafoveal or perifoveal telangiectasia.

Clinical Course

The clinical findings, diagnosis and prognosis were discussed at length with the patient. This included the characteristic slowly progressive nature of the condition. It was explained that at present no therapy has been proven effective in reducing the retinal loss.  An Amsler grid was provided to allow self-monitoring between regular ophthalmic reviews. The patient was enrolled in the Macular Telangiectasia Project Study (https://web.emmes.com/study/mactel/).  In light of the asymmetrical cup to disc ratio and family history of glaucoma the patient underwent further evaluation for glaucoma.

Discussion

Macular Telangiectasia Type 2 is an uncommon bilateral neurodegenerative condition affecting the maculae. Prevalence in epidemiological studies varies from 0.005%- 0.01% of the population.1 It typically becomes symptomatic in patients 6th and 7th decade of life, with the most common complaints being difficulty reading and metamorhopsia.2 There may be an association with diabetes mellitus, hypertension (as was the case in this patient) and cardiovascular disease.3

Clinical features, particularly in early stages, can be subtle. Findings are initially found in the temporal parafoveal area in a characteristic oval distribution. The most common macula signs include: loss of the foveolar reflex, reduced retinal transparency (graying), fine telangiectatic capillaries, right angle venules, intraretinal pigment hyperplasia and migration, crystalline deposits and foveal atrophy.4,5 Less commonly there is a yellow spot at the fovea.

Pathologically there are changes in the macular capillary network as well as retinal atrophy with loss of Müller cells and photoreceptors.6 The exact aetiology of the condition is still incompletely understood but both genetic and environment factors likely play a role.4

Fundus imaging is especially useful in assisting with the diagnosis. Optical coherence tomography (OCT) changes can include an asymmetric foveal contour, hyporeflective inner retinal cavities, outer retinal atrophy and hyperreflective spots.4,7 Autofluorescence imaging in eyes with normal macula pigment demonstrates central foveal masking (Figure 4, right image).  In Macular Telangiectasia Type 2 there is either a reduction and/or redistribution in the macula pigment such that the normal central masking is lost.1,4 Early phases of the FFA usually demonstrate characteristic telangiectatic capillaries temporal to the fovea.  In the later phases of the angiogram these are associated with diffuse hyperfluorescence.4

The natural course of the disease may be complicated by the development of intra- or subretinal neovascularisation.3 Anti-VEGF therapy may be of benefit for this8, but does not appear to be useful in non-neovascular disease9,10. Macular Telangiectasia Type 2 can also be associated with lamellar or full thickness macula holes for which the surgical outcomes are not as favourable as with typical idiopathic full thickness macular holes. This is likely related to underlying neurosensory atrophy.11

At present there is no effective therapy to slow the neurodegeneration however neuroprotection may be possible in the future with further understanding of the pathophysiology of the disease.

 

Take home points

  • (Idiopathic) Macular Telangiectasia Type 2 is an uncommon macular disease.
  • It usually presents in middle-aged to elderly patients with difficulty reading and slowly progressive loss of vision.
  • Clinical findings are subtle and are focussed on the temporal parafoveal region. These include: loss of the foveolar reflex, reduced retinal transparency (graying), fine telangiectatic capillaries, right angle venules, intraretinal pigment hyperplasia and migration, crystalline deposits and foveal atrophy.
  • Fundus imaging is invaluable in assisting with diagnosis.
  • Although there is no current treatment, intravitreal anti-VEGF agents may be useful in cases complicated by subretinal neovascularisation.

 

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References:

1. Chew EY. How prevalent is macular telangiectasia type 2? Ophthalmic Epidemiology 2012;19:183-4.
2. Heeren TF, Holz FG, Charbel Issa P. First Symptoms and their age of onset in Macular Telangiectasia Type 2. Retina 2013.
3. Clemons TE, Gillies MC, Chew EY, et al. Medical characteristics of patients with macular telangiectasia type 2 (MacTel Type 2) MacTel project report no. 3. Ophthalmic Epidemiology 2013;20:109-13.
4. Charbel Issa P, Gillies MC, Chew EY, et al. Macular telangiectasia type 2. Progress in Retinal & Eye Research 2013;34:49-77.
5. Gas JD, Blodi BA. Idiopathic Juxtafovelar Retinal Telangiectasis: Update of Classification and Follow-up Study. Ophthalmology 1993;100:1536-46.
6. Powner MB, Gillies MC, Zhu M, Vevis K, Hunyor AP, Fruttiger M. Loss of Muller’s cells and photoreceptors in macular telangiectasia type 2. Ophthalmology 2013;120:2344-52.
7. Baumuller S, Charbel Issa P, Scholl HP, Schmitz-Valckenberg S, Holz FG. Outer retinal hyperreflective spots on spectral-domain optical coherence tomography in macular telangiectasia type 2. Ophthalmology 2010;117:2162-8.
8. Narayanan R, Chhablani J, Sinha M, et al. Efficacy of anti-vascular endothelial growth factor therapy in subretinal neovascularization secondary to macular telangiectasia type 2. Retina 2012;32:2001-5.
9. Charbel Issa P, Finger RP, Kruse K, Baumuller S, Scholl HP, Holz FG. Monthly ranibizumab for nonproliferative macular telangiectasia type 2: a 12-month prospective study.[Erratum appears in Am J Ophthalmol. 2011 Jul;152(1):151]. American Journal of Ophthalmology 2011;151:876-86.e1.
10. Toy BC, Koo E, Cukras C, Meyerle CB, Chew EY, Wong WT. Treatment of nonneovascular idiopathic macular telangiectasia type 2 with intravitreal ranibizumab: results of a phase II clinical trial. Retina 2012;32:996-1006.
11. Karth PA, Raja SC, Brown DM, Kim JE. Outcomes of Macular Hole Surgeries for Macular Telangiectasia Type 2. Retina 2013.