Influence of visual angle on pattern reversal visual evoked potentials
Purpose: The aim of this study was to find whether the visual evoked potential (VEP) latencies and amplitude are altered with different visual angles in healthy adult volunteers or not and to determine the visual angle which is the optimum and most appropriate among a wide range of check sizes for t...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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Wolters Kluwer Medknow Publications
2014-01-01
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| Series: | Oman Journal of Ophthalmology |
| Subjects: | |
| Online Access: | http://www.ojoonline.org/article.asp?issn=0974-620X;year=2014;volume=7;issue=3;spage=120;epage=125;aulast=Kothari |
| _version_ | 1819144187655749632 |
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| author | Ruchi Kothari Smita Singh Ramji Singh A K Shukla Pradeep Bokariya |
| author_facet | Ruchi Kothari Smita Singh Ramji Singh A K Shukla Pradeep Bokariya |
| author_sort | Ruchi Kothari |
| collection | DOAJ |
| description | Purpose: The aim of this study was to find whether the visual evoked potential (VEP) latencies and amplitude are altered with different visual angles in healthy adult volunteers or not and to determine the visual angle which is the optimum and most appropriate among a wide range of check sizes for the reliable interpretation of pattern reversal VEPs (PRVEPs).
Materials and Methods: The present study was conducted on 40 healthy volunteers. The subjects were divided into two groups. One group consisted of 20 individuals (nine males and 11 females) in the age range of 25-57 years and they were exposed to checks subtending a visual angle of 90, 120, and 180 minutes of arc. Another group comprised of 20 individuals (10 males and 10 females) in the age range of 36-60 years and they were subjected to checks subtending a visual angle of 15, 30, and 120 minutes of arc. The stimulus configuration comprised of the transient pattern reversal method in which a black and white checker board is generated (full field) on a VEP Monitor by an Evoked Potential Recorder (RMS EMG. EPMARK II). The statistical analysis was done by One Way Analysis of Variance (ANOVA) using EPI INFO 6.
Results: In Group I, the maximum (max.) P100 latency of 98.8 ± 4.7 and the max. P100 amplitude of 10.05 ± 3.1 μV was obtained with checks of 90 minutes. In Group II, the max. P100 latency of 105.19 ± 4.75 msec as well as the max. P100 amplitude of 8.23 ± 3.30 μV was obtained with 15 minutes. The min. P100 latency in both the groups was obtained with checks of 120 minutes while the min. P100 amplitude was obtained with 180 minutes. A statistically significant difference was derived between means of
P100 latency for 15 and 30 minutes with reference to its value for 120 minutes and between the mean value of P100 amplitude for 120 minutes and that of 90 and 180 minutes.
Conclusion: Altering the size of stimulus (visual angle) has an effect on the PRVEP parameters. Our study found that the 120 is the appropriate (and optimal) check size that can be used for accurate interpretation of PRVEPs. This will help in better assessment of the optic nerve function and integrity of anterior visual pathways. |
| first_indexed | 2024-12-22T12:38:09Z |
| format | Article |
| id | doaj.art-0d6aec10a7294d139d7741830ec889aa |
| institution | Directory Open Access Journal |
| issn | 0974-620X |
| language | English |
| last_indexed | 2024-12-22T12:38:09Z |
| publishDate | 2014-01-01 |
| publisher | Wolters Kluwer Medknow Publications |
| record_format | Article |
| series | Oman Journal of Ophthalmology |
| spelling | doaj.art-0d6aec10a7294d139d7741830ec889aa2022-12-21T18:25:31ZengWolters Kluwer Medknow PublicationsOman Journal of Ophthalmology0974-620X2014-01-017312012510.4103/0974-620X.142593Influence of visual angle on pattern reversal visual evoked potentialsRuchi KothariSmita SinghRamji SinghA K ShuklaPradeep BokariyaPurpose: The aim of this study was to find whether the visual evoked potential (VEP) latencies and amplitude are altered with different visual angles in healthy adult volunteers or not and to determine the visual angle which is the optimum and most appropriate among a wide range of check sizes for the reliable interpretation of pattern reversal VEPs (PRVEPs). Materials and Methods: The present study was conducted on 40 healthy volunteers. The subjects were divided into two groups. One group consisted of 20 individuals (nine males and 11 females) in the age range of 25-57 years and they were exposed to checks subtending a visual angle of 90, 120, and 180 minutes of arc. Another group comprised of 20 individuals (10 males and 10 females) in the age range of 36-60 years and they were subjected to checks subtending a visual angle of 15, 30, and 120 minutes of arc. The stimulus configuration comprised of the transient pattern reversal method in which a black and white checker board is generated (full field) on a VEP Monitor by an Evoked Potential Recorder (RMS EMG. EPMARK II). The statistical analysis was done by One Way Analysis of Variance (ANOVA) using EPI INFO 6. Results: In Group I, the maximum (max.) P100 latency of 98.8 ± 4.7 and the max. P100 amplitude of 10.05 ± 3.1 μV was obtained with checks of 90 minutes. In Group II, the max. P100 latency of 105.19 ± 4.75 msec as well as the max. P100 amplitude of 8.23 ± 3.30 μV was obtained with 15 minutes. The min. P100 latency in both the groups was obtained with checks of 120 minutes while the min. P100 amplitude was obtained with 180 minutes. A statistically significant difference was derived between means of P100 latency for 15 and 30 minutes with reference to its value for 120 minutes and between the mean value of P100 amplitude for 120 minutes and that of 90 and 180 minutes. Conclusion: Altering the size of stimulus (visual angle) has an effect on the PRVEP parameters. Our study found that the 120 is the appropriate (and optimal) check size that can be used for accurate interpretation of PRVEPs. This will help in better assessment of the optic nerve function and integrity of anterior visual pathways.http://www.ojoonline.org/article.asp?issn=0974-620X;year=2014;volume=7;issue=3;spage=120;epage=125;aulast=KothariPattern reversalP100 latencyP100 amplitudeVEPvisual angle |
| spellingShingle | Ruchi Kothari Smita Singh Ramji Singh A K Shukla Pradeep Bokariya Influence of visual angle on pattern reversal visual evoked potentials Oman Journal of Ophthalmology Pattern reversal P100 latency P100 amplitude VEP visual angle |
| title | Influence of visual angle on pattern reversal visual evoked potentials |
| title_full | Influence of visual angle on pattern reversal visual evoked potentials |
| title_fullStr | Influence of visual angle on pattern reversal visual evoked potentials |
| title_full_unstemmed | Influence of visual angle on pattern reversal visual evoked potentials |
| title_short | Influence of visual angle on pattern reversal visual evoked potentials |
| title_sort | influence of visual angle on pattern reversal visual evoked potentials |
| topic | Pattern reversal P100 latency P100 amplitude VEP visual angle |
| url | http://www.ojoonline.org/article.asp?issn=0974-620X;year=2014;volume=7;issue=3;spage=120;epage=125;aulast=Kothari |
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