Related Experiment Videos
Artificially increasing intraocular pressure causes flicker sensitivity losses
V Van Toi1, P A Grounauer, C W Burckhardt
1Engineering Design Department, Tufts University, Medford, Massachusetts 02155.
Investigative Ophthalmology & Visual Science
|August 1, 1990
Summary
Elevated intraocular pressure (IOP) significantly reduces flicker sensitivity in normal eyes, particularly at lower frequencies. This suggests psychophysical flicker testing is a sensitive method for detecting early ocular hypertension effects.
Area of Science:
- Ophthalmology
- Neuroscience
- Vision Science
Background:
- Ocular hypertension and glaucoma are known to affect visual electrophysiologic responses.
- Elevated intraocular pressure (IOP) has been shown to impair electrophysiologic responses.
Purpose of the Study:
- To investigate the effect of varied intraocular pressure (IOP) levels on psychophysical flicker sensitivity in normal subjects.
- To determine if psychophysical flicker sensitivity is a sensitive indicator of IOP variations.
Main Methods:
- Ten normal subjects underwent temporary IOP elevation using a novel ophthalmodynamometer.
- Flicker sensitivity was measured at different IOP levels, including physiological and artificially elevated states.
Main Results:
- Increasing IOP led to a loss of flicker sensitivity, especially at frequencies below 20 Hz for moderate IOP elevation (27.2 +/- 2.1 mm Hg) and above 5 Hz for higher IOP (40.7 +/- 2.1 mm Hg).
- The critical flicker frequency remained unaffected.
- A "curtain phenomenon" was observed, where high flicker frequency stimuli could disappear at critical IOP levels.
Conclusions:
- Psychophysical flicker sensitivity measurement is a sensitive technique for evaluating the impact of IOP variations.
- The "curtain phenomenon" warrants further investigation into ocular hypertension mechanisms.