Documenta Ophthalmologica

, Volume 118, Issue 3, pp 225–231 | Cite as

ERG evaluation of daily, high-dose sildenafil usage

  • Christopher I. Zoumalan
  • Roham T. Zamanian
  • Ramona L. Doyle
  • Michael F. Marmor
Case Report


Purpose Sildenafil can cause transient, mild ERG changes in healthy individuals taking large single doses. Although the drug was originally intended for intermittent use in erectile dysfunction, it has now been approved for chronic use in subjects with pulmonary arterial hypertension (PAH). The purpose of our study is to investigate possible ERG changes in subjects using large doses of sildenafil on a chronic daily basis. Methods We examined five subjects with PAH taking sildenafil daily for 1–4 years. Full-field electroretinogram (ERG), multifocal ERG (mfERG), and color testing were performed. Three of the subjects returned on a later date for challenge off and on the medication. Results On chronic daily sildenafil, color vision testing was normal, and ERG and mfERG amplitudes were normal; however, cone implicit times on drug were modestly lengthened. There were no consistent full-field ERG changes when off the drug, but the mfERG showed a small amplitude increase and implicit time decrease, which returned 1 h after re-dosing. Conclusion There was a modest lengthening of cone implicit time on chronic daily doses of sildenafil and a hint that some of these changes may be reversible in the short term. It does not appear that chronic sildenafil usage at these dosage levels is seriously toxic or threatening to vision.


Electroretinogram Multifocal electroretinogram Viagra Sildenafil Pulmonary hypertension 



We thank Lorella Cabael for assistance with the experiments and data preparation.

Proprietary interest:

MFM has been a consultant to Eli Lilly Co. and Pfizer Inc. RTZ is a recipient of an Actelion-Entelligence career development grant and a consultant to Actelion, United Therapeutics, and Gilead Pharmaceuticals.


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Copyright information

© Springer-Verlag 2008

Authors and Affiliations

  • Christopher I. Zoumalan
    • 1
  • Roham T. Zamanian
    • 2
    • 3
  • Ramona L. Doyle
    • 2
    • 3
  • Michael F. Marmor
    • 1
  1. 1.Department of OphthalmologyStanford University School of MedicineStanfordUSA
  2. 2.Division of Pulmonary & Critical Care MedicineStanford University School of MedicineStanfordUSA
  3. 3.Vera Moulton Wall Center for Pulmonary Vascular DiseaseStanfordUSA

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