International Journal of Physiology

Open Access Open Access  Restricted Access Subscription Access
Open Access Open Access Open Access  Restricted Access Restricted Access Subscription Access

Influence of Refractory Error on the Pattern Reversal VEPs of Myopes and Hypermetropes


Affiliations
1 Assistant Professor, Dept. of Physiology, Mahatma Gandhi Institute of Medical Sciences, Sevagram, Wardha Maharashtra
2 Assistant Professor, Dept. of Anatomy. Mahatma Gandhi Institute of Medical Sciences, Sevagram, Wardha Maharashtra
3 Professor, Dept. of Physiology, AIIMS, Patna, Bihar
4 Professor, Dept. of Ophthalmology, Mahatma Gandhi Institute of Medical Sciences, Sevagram, Wardha Maharashtra
     

   Subscribe/Renew Journal


Objective: Multiple factors including age, sex, habituation, refraction, cooperation and technical variables are associated with Visual evoked potential (VEP). We attempted to evaluate the influence of refractory error on the Pattern Reversal Visual Evoked Potential (PRVEP) recordings of a cohort of Indian subjects having myopia and hypermetropia.

Material: This rural hospital based study was conducted in the Neurophysiology unit of the Department of Physiology. The study comprised of pattern reversal visual evoked potential (PRVEP) recordings from 50 hypermetropes and 50 myopes with and without glasses having age in the range of 18-40 years. The recordings were compared with those of 50 age and sex matched controls.

Methods: One channel VEP recordings were performed with the stimulus configuration consisting of the transient pattern reversal method in which a black and white checker board was generated (full field) and displayed on VEP Monitor (colour 14") by an electronic pattern regenerator inbuilt in an Evoked Potential Recorder (RMS EMG EP MARK II). P100 latency and amplitude were measured from the averaged waveforms and analysed by student's "t" test.

Results: P100 latency was increased and amplitude decreased with and without correction of refractive error. The statistical analysis revealed a significant difference (p<0.05) in latency of P100 and amplitude of P100 between controls and myopics with glasses and highly significant difference (p<0.001) in latency and amplitude of P100 between controls and myopics without glasses. The difference in P100 latency and amplitude between controls and hyperopics with glasses and those without glasses were found to be non-significant.

Conclusion: VEPs are affected in subjects with refractive error irrespective of correction given. Among the refractory errors, the VEPs seem to be more affected by myopia than hypermetropia and the probable contributory cause may be the defocusing of the image.

 


Keywords

Refractive Error,Hypermetropes, Myopes, P100 Latency, P100 Amplitude
Subscription Login to verify subscription
User
Notifications
Font Size


  • Walsh TJ. Neuro-Ophthalmology clinical signs and symptoms. 2nd ed. Philadelphia: Lea & Febiger; 1985: 303-340

  • Collins DWK, Carroll WM, Black JL, Walsh M. Effect of refractive error on the visual evoked response. Brit Med J 1979; 1(6158): 231

  • Bobak P, Bodis-Wollner I, Guillory S. The effect of blur and contrast on VEP latency: comparison between check and sinusoidal and grating patterns. Electroencephalogr Clin Neurophysiol. 1987 Jul; 68(4):247-55.

  • Bartel PR, Vos A. Induced refractive errors and pattern electroretinograms and pattern visual evoked potentials: implications for clinical assessments. Electroencephalogr Clin Neurophysiol. 1994 Jan; 92(1):78-81

  • Celesia GG, Bodis-Wollner I, Chatrian GE, Harding GFA, Sokol S, Spekreijse H. Recommended standards for electroretinograms and visual evoked potentials. Report of an International Federation of Clinical Neurophysiology (IFCN) Committee. Electroencephalogr Clin Neurophysiol 1993; 87: 421-436

  • Odom VJ, Bach M, Barber C, Brigell M, Marmor MF, Tormene AP, Holder GE, Vaegan. Visual evoked potentials standard (2004) Doc Ophthalmol 108: 115–123, 2004.

  • American Clinical Neurophysiology Society. Guideline 5: guidelines for standard electrode position nomenclature. J Clin Neurophysiol 2006; 23:107–110

  • Oken BS, Chiappa KH, Gill E. Normal temporal variability of the P100. Electroencephalogr Clin Neurophysiol 1987; 68:153-156

  • Tumas V, Sakamoto C. Comparison of the mechanisms of latency shift in pattern reversal visual evoked potential induced by blurring and con trast reduction. Electroencephalogr Clin Neurophysiol. 1997 Jan; 104(1):96-100

  • Marre JE, Harvey R, Ainsworth JR. Association of high hypermetropia in childhood. Eye 2003; 17: 436-437

  • Ludlam WM, Meyers RR. The use of visual evoked responses in objective refraction. Transactions of the New York Academy of Sciences. 1972 Feb; 34: 154-170

  • Lee SM, Kim C, Ahn JK. The change of visual evoked potentials in patients with myopia in correction of refraction. J Korean Acad Rehab Med Dec 2002; 26(6): 734-738

  • Zislina NN, Sorokina RS. Possibilities of the use of visual evoked potentials in the evaluation of visual acuity in congenital myopia in children. Vestn Oftalmal 1992 Jan-Feb; 108(1):35-37

  • Millodot M, Riggs LA. Refraction Determined Electrophysiologically Responses to Alternation of Visual Contours. Arch Ophthalmol. 1970; 84(3):272-278.

  • Sherman J. Visual evoked potential (VEP): basic concepts and clinical applications. J Am Optom Assoc 1979; 50:19–30

  • Anand A, De Moraes CG, Teng CC, Liebmann JM, Ritch R, Tello C. Short-duration transient visual evoked potential for objective measurement of refractive errors.Doc Ophthalmol 2011 Dec;123(3):141-7


Abstract Views: 881

PDF Views: 0




  • Influence of Refractory Error on the Pattern Reversal VEPs of Myopes and Hypermetropes

Abstract Views: 881  |  PDF Views: 0

Authors

Ruchi Kothari
Assistant Professor, Dept. of Physiology, Mahatma Gandhi Institute of Medical Sciences, Sevagram, Wardha Maharashtra
Pradeep Bokariya
Assistant Professor, Dept. of Anatomy. Mahatma Gandhi Institute of Medical Sciences, Sevagram, Wardha Maharashtra
Ramji Singh
Professor, Dept. of Physiology, AIIMS, Patna, Bihar
Smita Singh
Professor, Dept. of Ophthalmology, Mahatma Gandhi Institute of Medical Sciences, Sevagram, Wardha Maharashtra

Abstract


Objective: Multiple factors including age, sex, habituation, refraction, cooperation and technical variables are associated with Visual evoked potential (VEP). We attempted to evaluate the influence of refractory error on the Pattern Reversal Visual Evoked Potential (PRVEP) recordings of a cohort of Indian subjects having myopia and hypermetropia.

Material: This rural hospital based study was conducted in the Neurophysiology unit of the Department of Physiology. The study comprised of pattern reversal visual evoked potential (PRVEP) recordings from 50 hypermetropes and 50 myopes with and without glasses having age in the range of 18-40 years. The recordings were compared with those of 50 age and sex matched controls.

Methods: One channel VEP recordings were performed with the stimulus configuration consisting of the transient pattern reversal method in which a black and white checker board was generated (full field) and displayed on VEP Monitor (colour 14") by an electronic pattern regenerator inbuilt in an Evoked Potential Recorder (RMS EMG EP MARK II). P100 latency and amplitude were measured from the averaged waveforms and analysed by student's "t" test.

Results: P100 latency was increased and amplitude decreased with and without correction of refractive error. The statistical analysis revealed a significant difference (p<0.05) in latency of P100 and amplitude of P100 between controls and myopics with glasses and highly significant difference (p<0.001) in latency and amplitude of P100 between controls and myopics without glasses. The difference in P100 latency and amplitude between controls and hyperopics with glasses and those without glasses were found to be non-significant.

Conclusion: VEPs are affected in subjects with refractive error irrespective of correction given. Among the refractory errors, the VEPs seem to be more affected by myopia than hypermetropia and the probable contributory cause may be the defocusing of the image.

 


Keywords


Refractive Error,Hypermetropes, Myopes, P100 Latency, P100 Amplitude

References