The incidence of negative ERG in clinical practice

Doc Ophthalmol. 2001 Jan;102(1):19-30. doi: 10.1023/a:1017586118749.


Introduction: A negative electroretinogram (ERG) is one in which there is a selective reduction in amplitude of the b-wave, such that it does not exceed that of the a-wave. The purpose of this study was to determine the incidence and clinical causes of negative ERGs at a tertiary referral centre. In addition, interesting and previously unreported aetiologies are described.

Patients and methods: Retrospective review of all ERGs done at Moorfields Eye Hospital from November 1995 to December 1998 under ISCEV standard conditions. Many patients had photopic ON- and OFF-response recording in addition to conventional ISCEV Standard ganzfeld ERG.

Results: A total of 2,640 ERGs were performed during the study period. 128 cases (4.8%) showed a negative ERG. The causes, where a firm clinical diagnosis was possible, include X-linked juvenile retinoschisis, congenital stationary night blindness, central retinal artery occlusion, birdshot chorioretinopathy and melanoma-associated retinopathy (MAR). Unilateral negative ERG waveforms with normal fundal appearances were seen in 7 patients. Photopic ON- responses could be selectively affected.

Conclusions: The incidence of negative ERGs over a 34-month period presenting to a large tertiary centre was almost 5%. The presence of a negative ERG may be instrumental in demonstrating the site of visual dysfunction, with many cases showing minimal or no fundus abnormality. ON- and OFF-response recording yielded additional information regarding photopic post-receptoral/phototransduction function.

Publication types

  • Case Reports

MeSH terms

  • Adult
  • Electroretinography*
  • Female
  • Humans
  • Incidence
  • Interneurons / physiology
  • Male
  • Middle Aged
  • Retina / physiopathology*
  • Retinal Diseases / diagnosis*
  • Retinal Diseases / physiopathology
  • Retrospective Studies