Early magnocellular loss in glaucoma demonstrated using the pseudorandomly stimulated flash visual evoked potential

J Glaucoma. 1999 Apr;8(2):140-8.


Purpose: Components of the pseudorandomly stimulated flash visual evoked potential (VEP) have now been identified that appear to arise predominantly from each of the magnocellular (M-cell) and parvocellular (P-cell) systems. In this study, the relative damage to magnocellular and parvocellular systems at different stages of glaucoma using pseudorandomly stimulated flash VEP was investigated.

Methods: Pseudorandomly stimulated flash VEP was recorded in 15 normal eyes and 28 eyes with different stages of glaucoma using the VERIS-3 recording system (Electro-Diagnostic Imaging, San Francisco, CA). Two levels of luminance contrast of the stimulus (32% and 99%) were tested. The first slice of the second-order kernel from only the central (8 degrees) stimulated area was extracted for analysis.

Results: Data recorded from normal eyes demonstrated early saturation of the response/contrast function of the first slice of the second-order kernel. The ratio of the VEP amplitude recorded at 32% and 99% of the luminance contrast was close to unity. In eyes with early glaucoma, although the amplitude of the responses to both low- and high-contrast stimulation decreased, the relative reduction of the low-contrast VEP (M-cell) was more prominent. However, the amplitude of the high-contrast response (P-cell) declined more rapidly later in the disease.

Conclusion: These results are consistent with relatively earlier damage of the magnocellular pathway in glaucoma.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Evoked Potentials, Visual*
  • Geniculate Bodies / pathology
  • Glaucoma, Open-Angle / pathology*
  • Glaucoma, Open-Angle / physiopathology
  • Humans
  • Middle Aged
  • Photic Stimulation
  • Prognosis
  • Retinal Ganglion Cells / pathology*
  • Severity of Illness Index