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Electrophysiological findings show generalised post-photoreceptoral deficiency in macular telangiectasia type 2
  1. Anna A Ledolter1,
  2. Graham E Holder2,
  3. Robin Ristl3,
  4. Ursula Schmidt-Erfurth1,
  5. Markus Ritter1
  1. 1Department of Ophthalmology, Medical University of Vienna, Vienna, Austria
  2. 2Institute of Ophthalmology, University College London, Moorfields Eye Hospital, London, UK
  3. 3Section for Medical Statistics, Center for Medical Statistics and Informatics, Medical University of Vienna, Vienna, Austria
  1. Correspondence to Dr Markus Ritter, Department of Ophthalmology, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria; markus.ritter{at}meduniwien.ac.at

Abstract

Background Photoreceptor damage, reported in single observations, has been suggested to contribute to the disease pathogenesis in macular telangiectasia type 2 (MacTel2). The purpose of this study was to ascertain whether the photoreceptor or post-photoreceptoral function is affected in MacTel2 and could be detected using electrophysiological examination.

Methods Thirty-five eyes from 18 patients (15 men, aged 60.1±9.6 years, range 38–77 years) with MacTel2 were included in the study. All patients underwent standard ophthalmic examination followed by pattern electroretinography (PERG) and full-field ERG. The data were compared against 22 normal control subjects (10 men, age 59.83±6.28 years, range 48–76).

Results Mean PERG P50 amplitude and peak time in patients with MacTel2 did not differ significantly from control values (p>0.2) but P50 amplitude was subnormal in three patients. The mean scotopic rod b-wave amplitude was significantly lower in patients than in healthy controls (p=0.027). A lower dark-adapted 10.0 b-wave (p=0.06) but not a-wave amplitude (p=0.58) was present in patients with MacTel2. Photopic single-flash a-wave and b-wave amplitudes did not differ between patient and control groups (p=0.2 and 0.3), but 30 Hz flicker peak time was significantly later in patients with MacTel2 with no effect on amplitude (p=0.04 and 0.7).

Conclusion Both scotopic (rod system dominated) and photopic ERGs (cone system) are consistent with post-photoreceptoral dysfunction. There was no electrophysiological evidence of dysfunction at the level of the photoreceptor.

  • electrophysiology
  • macular telangiectasia type 2
  • muller cells
  • retina

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Footnotes

  • Competing interests None declared.

  • Patient consent Obtained.

  • Ethics approval Ethikkommission der Medizinischen Universität Wien.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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