COLOR PATTERN-REVERSAL VISUAL EVOKED POTENTIALS IN ACUTE ELEVATION OF THE INTRAOCULAR PRESSURE

Title COLOR PATTERN-REVERSAL VISUAL EVOKED POTENTIALS IN ACUTE ELEVATION OF THE INTRAOCULAR PRESSURE
Author, Co-Author Julie Prud'homm, Helene Kergoat, John Lovasik O.D.
Topic
Year
1992
Day
Monday
Program Number
Poster 37
Room
Great Hall
Affiliation
Abstract Berninger et al. (1989) suggested using chromatic stimuli to improve the diagnostic power of evoked potentials for ocular disease. Shih et al. (1991) reported attenuated and delayed chromatic visual evoked cortical potentials (CVECPs) for ocular hypertensives (OH) and glaucoma patients. We investigated the response of CVECPs to a short-term, acute increase of the intraocular pressure (IOP) to evaluate differential vulnerability of CVECPs elicited by different color combinations. Ten volunteers with normal IOP and brachial blood pressure participated in 2, 45 min test sessions. The IOP was elevated via body inversion (baseline vs. 40! declination). The luminance matched (40 cd/m2) stimuli were white/black, red/black and blue/black 38 minarc checks phase-reversing at 1 Hz and 7 Hz (1st & 2nd session) on a high-res RGB monitor. A Nicolet CA-1000 was used to amplify, filter and record the CVECPs. Increased IOP did not attenuate the 1Hz CVECP for any of the colors used (p> 0.05). However, the implicit time was prolonged for the red/black checks (p= 0.0055). For 7 Hz checkerboards, increasing the IOP attenuated the white/black (p= 0.0146) and blue/black (p= 0.0323) CVECPs. One subject showed decreased amplitudes and prolonged latencies for all test colors during elevated IOPs. Our data indicate that an acute, short-term increase in the IOP can decrease the amplitude and prolong the implicit time of CVECPs, some individuals showing a greater vulnerability. This data suggest that a transient increase in the IOP may be useful clinically to identify 'normals' and patients at risk for IOP induced visual dysfunction. This form of provocative test may be particularly useful for identifying OH who are likely to develop glaucoma.
Affiliation of Co-Authors
Outline