May 2003
Volume 44, Issue 13
ARVO Annual Meeting Abstract  |   May 2003
Sildenafil Increases Persistence of Vision
Author Affiliations & Notes
  • J.D. Mollon
    Experimental Psychology, Cambridge University, Cambridge, United Kingdom
  • B.C. Regan
    Experimental Psychology, Cambridge University, Cambridge, United Kingdom
  • R. Foo
    Clinical Pharmacology Unit, Department of Medicine, Cambridge University, Cambridge, United Kingdom
  • B.J. Morris
    Clinical Pharmacology Unit, Department of Medicine, Cambridge University, Cambridge, United Kingdom
  • Footnotes
    Commercial Relationships  J.D. Mollon, Pfizer Ltd F; B.C. Regan, Pfizer Ltd F; R. Foo, Pfizer Ltd F; B.J. Morris, Pfizer Ltd F.
Investigative Ophthalmology & Visual Science May 2003, Vol.44, 4097. doi:
  • Views
  • Share
  • Tools
    • Alerts
      This feature is available to authenticated users only.
      Sign In or Create an Account ×
    • Get Citation

      J.D. Mollon, B.C. Regan, R. Foo, B.J. Morris; Sildenafil Increases Persistence of Vision . Invest. Ophthalmol. Vis. Sci. 2003;44(13):4097.

      Download citation file:

      © ARVO (1962-2015); The Authors (2016-present)

  • Supplements

Abstract: : Purpose: Subjective reports from patients taking sildenafil citrate (Viagra®) suggest that this drug may increase the persistence of visual sensations. We asked whether such an effect could be demonstrated when visual persistence was estimated by means of a performance measure, that is, when we do not ask the subject to describe his phenomenological sensations but rather measure his accuracy in an objective test. Methods: In psychopharmacological experiments an impairmentof performance can often be attributed to non-specific factors. So we designed a task in which enhanced visual persistence would lead to better performance. Stimuli were presented on a computer-controlled monitor running at a refresh rate of 160 Hz. On each trial, two successive arrays of white dots were presented on a dark background. When the interval between the two arrays was brief, the subject could combine these two sub-arrays and identify a ring of dots randomly placed within the total array. His task was to report the position of a gap in the ring. Of the 11 dots making up the ring, 5 occurred in one sub-array and 6 in the other. In total, the two arrays contained 50 dots. The independent variable in the experiment was the number of milliseconds between the presentations of the two sub-arrays. The computer program adaptively adjusted this temporal separation to find the inter-stimulus interval (ISIc) at which the subject failed to identify the position of the gap. We used a Latin-square, double-blind, cross-over design with five conditions, corresponding to oral doses of 25, 50, 100 and 200 mg of sildenafil, plus a placebo condition. There were 16 young healthy adult male volunteer subjects, who gave informed consent. One subject did not complete all conditions and is excluded from the analysis. Results: A related measures ANOVA showed a highly significant dependence of ISIc on dose (F=8.43, p<.0001). After ingestion of 100 mg of sildenafil citrate (the maximal clinical dose), the value of ISIc was modestly greater [by approximately 20%] than that found in placebo or pre-test conditions. The effect was fully reversible. Conclusions: Sildenafil citrate increases persistence of vision in that it enhances performance in a task where two stimuli must be integrated across a time interval.

Keywords: temporal vision • photoreceptors: visual performance • pharmacology 

This PDF is available to Subscribers Only

Sign in or purchase a subscription to access this content. ×

You must be signed into an individual account to use this feature.