Case Reports in Ophthalmology (Mar 2012)

Visual Dysfunction of Type I and VI Mucopolysaccharidosis Patients Evaluated with Visual Evoked Cortical Potential

  • Bruno Duarte Gomes,
  • Givago da Silva Souza,
  • Gustavo Monteiro Viana,
  • Isabel Cristina Neves de Souza,
  • Patricia do Socorro Queiroz Feio,
  • Ida Vanessa Doederlein Schwartz,
  • Diane Ruschel Marinho,
  • Manoel da Silva Filho,
  • Roberto Giugliani,
  • Luiz Carlos de Lima Silveira,
  • Luiz Carlos Santana da Silva

DOI
https://doi.org/10.1159/000337492
Journal volume & issue
Vol. 3, no. 1
pp. 104 – 112

Abstract

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Purpose: To evaluate the visual system of patients suffering from type I or VI mucopolysaccharidosis (MPS) by recording the visual evoked cortical potential (VECP). Methods: Two patients with MPS VI and 2 patients with MPS I were tested before and after enzyme replacement therapy (ERT). A control group of 20 subjects was tested for statistical comparison. VECP was elicited by monocular stimulation with 1-Hz phase-reversal checkerboard patterns at 0.5 and 2 cycles per degree and with 16° of visual field. In all patients, both eyes were tested. VECP amplitude and latency were measured and compared with tolerance limits obtained from controls. Results: MPS I and VI patients have a severe visual impairment that can be quantified by measuring VECPs. Even after several weeks of ERT, the visual impairment remained unaltered, indicating that the treatment had no significant influence on the visual conditions of MPS patients. Visual responses to high spatial frequencies were more deeply impaired than responses to low spatial frequencies. This can be explained by the kind of damage in the visual system that preferentially targets the eye optics. Conclusion: VECPs can be used to monitor the degree of visual impairment of MPS patients and to check ERT efficacy.

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