Abstract
Purpose
This study aims to ascertain the characteristics of the response triggered by the global flash multifocal electroretinogram (MOFO mfERG) under various combinations of global and focal flash luminance, and to determine the optimal conditions for this measurement.
Methods
Ten normal subjects with mean age 23.2 yrs (± 1.14 yrs) were recruited for the MOFO mfERG measurement. The visual stimulation consisted of four video frames (stimulus frame with 103 scaled hexagonal focal flashes, followed by a dark frame, a global flash and then another dark frame). The focal and global flash intensities were varied independently for four levels (50, 100, 200 and 400 cd/m2). The subjects then underwent measurements with sixteen combinations of focal and global flash luminance. The direct component (DC) and induced component (IC) of the MOFO mfERG were grouped into central and peripheral regions for analysis.
Results
The central and peripheral DC amplitude increased with the focal flash luminance under constant global flash luminance. Moreover, the proportion of the global flash and focal flash intensity was shown to be important to achieve an optimal IC response. When the ratio of global flash luminance to focal flash luminance (g/f ratio) was kept at about 2:1, the central and peripheral IC amplitude reached the peak value, and further increasing the global flash luminance would not enhance the IC response magnitude. The implicit time of both central and peripheral DC generally decreased with the increase of g/f ratio. However, the implicit time of central and peripheral IC increased with the g/f ratio.
Conclusion
The g/f ratio is important in the MOFO mfERG paradigm, since the DC and IC responses change with this ratio. In order to obtain both optimal DC and IC responses, a g/f ratio of 1:1 with focal flash luminance between 100 cd/m2 and 200 cd/m2 would be recommended. As the global flash mfERG paradigm is studying the interaction triggered by both flashes, the g/f ratio is a vital parameter for measurement in future studies.
Similar content being viewed by others
Reference
Asano E, Mochizuki K, Sawada A, Nagasaka E, Kondo Y, Yamamoto T (2007) Decreased nasal-temporal asymmetry of the second-order kernel response of multifocal electroretinograms in eyes with normal-tension glaucoma. Jpn J Ophthalmol 51:379–389
Chan HH, Brown B (2000) Pilot study of the multifocal electroretinogram in ocular hypertension. Br J Ophthalmol 84:1147–1153
Chan HL, Brown B (1998) Investigation of retinitis pigmentosa using the multifocal electroretinogram. Ophthalmic Physiol Opt 18:335–350
Chan HL, Brown B (1999) Multifocal ERG changes in glaucoma. Ophthalmic Physiol Opt 19:306–316
Gerth C (2009) The role of the ERG in the diagnosis and treatment of Age-Related Macular Degeneration. Doc Ophthalmol 118:63–68
Kretschmann U, Bock M, Gockeln R, Zrenner E (2000) Clinical applications of multifocal electroretinography. Doc Ophthalmol 100:99–113
Nagy D, Schonfisch B, Zrenner E, Jagle H (2008) Long-term follow-up of retinitis pigmentosa patients with multifocal electroretinography. Invest Ophthalmol Vis Sci 49:4664–4671
Palmowski-Wolfe AM, Allgayer RJ, Vernaleken B, Schotzau A, Ruprecht KW (2006) Slow-stimulated multifocal ERG in high- and normal-tension glaucoma. Doc Ophthalmol 112:157–168
Palmowski-Wolfe AM, Todorova MG, Orguel S, Flammer J, Brigell M (2007) The ‘two global flash’ mfERG in high and normal tension primary open-angle glaucoma. Doc Ophthalmol 114:9–19
Tyrberg M, Ponjavic V, Lovestam-Adrian M (2008) Multifocal electroretinogram (mfERG) in patients with diabetes mellitus and an enlarged foveal avascular zone (FAZ). Doc Ophthalmol 117:185–189
Wolsley CJ, Silvestri G, O'Neill J, Saunders KJ, Anderson RS (2009) The association between multifocal electroretinograms and OCT retinal thickness in retinitis pigmentosa patients with good visual acuity. Eye (Lond) 23:1524–1531
Hood DC, Frishman LJ, Saszik S, Viswanathan S (2002) Retinal origins of the primate multifocal ERG: implications for the human response. Invest Ophthalmol Vis Sci 43:1673–1685
Ng YF, Chan HH, Chu PH, Siu AW, To CH, Beale BA, Gilger BC, Wong F (2008) Pharmacologically defined components of the normal porcine multifocal ERG. Doc Ophthalmol 116:165–176
Sutter EE SY, Li Y, Bearse MA (1999) Mapping inner retinal function through enhancement of adaptation components in the M-ERG. In: . Vision Science and Its Applications, 1999 OSA Technical Digest Series Vol. 1 Washington, DC: Optical Society of America: 52–55
Shimada Y, Li Y, Bearse MA Jr, Sutter EE, Fung W (2001) Assessment of early retinal changes in diabetes using a new multifocal ERG protocol. Br J Ophthalmol 85:414–419
Chu PH, Chan HH, Brown B (2006) Glaucoma detection is facilitated by luminance modulation of the global flash multifocal electroretinogram. Invest Ophthalmol Vis Sci 47:929–937
Chu PH, Chan HH, Brown B (2007) Luminance-modulated adaptation of global flash mfERG: fellow eye losses in asymmetric glaucoma. Invest Ophthalmol Vis Sci 48:2626–2633
Shimada Y, Bearse MA Jr, Sutter EE (2005) Multifocal electroretinograms combined with periodic flashes: direct responses and induced components. Graefes Arch Clin Exp Ophthalmol 243:132–141
Chu PH, Chan HH, Ng YF, Brown B, Siu AW, Beale BA, Gilger BC, Wong F (2008) Porcine global flash multifocal electroretinogram: possible mechanisms for the glaucomatous changes in contrast response function. Vision Res 48:1726–1734
Sutter EE, Bearse MA Jr (1999) The optic nerve head component of the human ERG. Vision Res 39:419–436
Sutter EE, Tran D (1992) The field topography of ERG components in man–I. The photopic luminance response. Vision Res 32:433–446
Hood DC, Bach M, Brigell M, Keating D, Kondo M, Lyons JS, Palmowski-Wolfe AM (2008) ISCEV guidelines for clinical multifocal electroretinography (2007 edition). Doc Ophthalmol 116:1–11
Acknowledgement
This study was supported by the Associated Fund (Research Postgraduate) from The Hong Kong Polytechnic University, Competitive Earmark Research Grant (PolyU 5415/06M) from The Research Grants Committee of the Hong Kong SAR, Internal Competitive Research Grant (GYF32), Departmental General Research Fund (GU352) and the Niche Areas–Myopia Research (J-BB7P) and Glaucoma Research (J-BB76) from The Hong Kong Polytechnic University. We thank Prof. Peter G Swann and Dr. Allen MY Cheong for their comments on this manuscript.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Lung, J.C.Y., Chan, H.H.L. Effects of luminance combinations on the characteristics of the global flash multifocal electroretinogram (mfERG). Graefes Arch Clin Exp Ophthalmol 248, 1117–1125 (2010). https://doi.org/10.1007/s00417-010-1346-5
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00417-010-1346-5