Documenta Ophthalmologica

, 119:51 | Cite as

The mfERG response topography with scaled stimuli: effect of the stretch factor

  • Charlotte M. Poloschek
  • Michael BachEmail author
Original Research Article


In multifocal electroretinogram recordings, the stimulus array is usually scaled with eccentricity to compensate for cone density changes. The strength of this scaling is parameterized by the so-called “stretch factor” (SF). In this study, we determined the quantitative influence of the SF striving for equal response densities over the entire stimulus area. VERIS 4.8 software was used to record multifocal ERGs from 11 normals with 61 hexagons and a 60° stimulus diameter. Six recordings were obtained per subject with SFs 0, 12, 23, 25, 27, and 29. For analysis, we calculated the mean hexagon area per eccentricity and the average amplitude for elements of equal eccentricity (rings 1–5 = R1–R5), normalized to R2. As expected, recordings with SF = 0 showed the steepest amplitude drop-off with eccentricity (relative amplitudes of 1.90 (R1/R2), 1.0 (R2/R2), 0.67 (R3/R2), 0.51 (R4/R2), 0.38 (R5/R2). Using the preset SF = 12 in our set-up resulted in R1-amplitudes 1.7× larger than the peripheral amplitudes (relative amplitudes 1.39, 1.0, 0.88, 0.87, 0.82). SF = 23 compensated best for eccentricity, yielding relative amplitudes of 1.2, 1.0, 1.02, 1.08, and 1.11. Deviations increased again with higher SFs. To minimize amplitude variability over the stimulated retinal area, the optimal SF needs to be adjusted to the individual recording set-up.


Multifocal electroretinogram mfERG Response topography Stretch factor Stimulus scaling Signal-to-noise ratio Cone density 



We thank Antje Fuchs for her assistance in data recording.


  1. 1.
    Sutter EE, Tran D (1992) The field topography of ERG components in man—I. The photopic luminance response. Vision Res 32:433–446. doi: 10.1016/0042-6989(92)90235-B PubMedCrossRefGoogle Scholar
  2. 2.
    Østerberg GA (1935) Topography of the layer of rods and cones in the human retina. Acta Ophthalmol (Copenh) 13:1–97CrossRefGoogle Scholar
  3. 3.
    Curcio CA, Sloan KR, Kalina RE, Hendrickson AE (1990) Human photoreceptor topography. J Comp Neurol 292:497–523. doi: 10.1002/cne.902920402 PubMedCrossRefGoogle Scholar
  4. 4.
    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. doi: 10.1136/bjo.85.4.414 PubMedCrossRefGoogle Scholar
  5. 5.
    Bearse MA Jr, Han Y, Schneck ME, Adams AJ (2004) Retinal function in normal and diabetic eyes mapped with the slow flash multifocal electroretinogram. Invest Ophthalmol Vis Sci 45:296–304. doi: 10.1167/iovs.03-0424 PubMedCrossRefGoogle Scholar
  6. 6.
    Shimada Y, Horiguchi M (2003) Stray light-induced multifocal electroretinograms. Invest Ophthalmol Vis Sci 44:1245–1251. doi: 10.1167/iovs.02-0527 PubMedCrossRefGoogle Scholar
  7. 7.
    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. doi: 10.1007/s00417-004-1072-y PubMedCrossRefGoogle Scholar
  8. 8.
    Chen JC, Brown B, Schmid KL (2006) Slow flash multifocal electroretinogram in myopia. Vision Res 46:2869–2876. doi: 10.1016/j.visres.2006.02.021 PubMedCrossRefGoogle Scholar
  9. 9.
    Lai TY, Ngai JW, Chan WM, Lam DS (2006) Visual field and multifocal electroretinography and their correlations in patients on hydroxychloroquine therapy. Doc Ophthalmol 112:177–187. doi: 10.1007/s10633-006-9006-0 PubMedCrossRefGoogle Scholar
  10. 10.
    Schimitzek T, Bach M (2006) The influence of luminance on the multifocal ERG. Doc Ophthalmol 113:187–192. doi: 10.1007/s10633-006-9028-7 PubMedCrossRefGoogle Scholar
  11. 11.
    Chen JC, Brown B, Schmid KL (2006) Retinal adaptation responses revealed by global flash multifocal electroretinogram are dependent on the degree of myopic refractive error. Vision Res 46:3413–3421. doi: 10.1016/j.visres.2006.03.013 PubMedCrossRefGoogle Scholar
  12. 12.
    Chen JC, Brown B, Schmid KL (2006) Changes in implicit time of the multifocal electroretinogram response following contrast adaptation. Curr Eye Res 31:549–556. doi: 10.1080/02713680600744869 PubMedCrossRefGoogle Scholar
  13. 13.
    Lai TY, Lai RY, Ngai JW, Chan WM, Li H, Lam DS (2008) First and second-order kernel multifocal electroretinography abnormalities in acute central serous chorioretinopathy. Doc Ophthalmol 116:29–40. doi: 10.1007/s10633-007-9075-8 PubMedCrossRefGoogle Scholar
  14. 14.
    Klemp K, Lund-Andersen H, Sander B, Larsen M (2007) The effect of acute hypoxia and hyperoxia on the slow multifocal electroretinogram in healthy subjects. Invest Ophthalmol Vis Sci 48:3405–3412. doi: 10.1167/iovs.06-0471 PubMedCrossRefGoogle Scholar
  15. 15.
    Maertz NA, Kim CB, Nork TM, Levin LA, Lucarelli MJ, Kaufman PL, Ver Hoeve JN (2006) Multifocal visual evoked potentials in the anesthetized non-human primate. Curr Eye Res 31:885–893. doi: 10.1080/02713680600899648 PubMedCrossRefGoogle Scholar
  16. 16.
    Rudolph G, Kalpadakis P, Bechmann M, Haritoglou C, Kampik A (2003) Scanning laser ophthalmoscope-evoked multifocal ERG (SLO-mfERG) in patients with macular holes and normal individuals. Eye 17:801–808. doi: 10.1038/sj.eye.6700502 PubMedCrossRefGoogle Scholar
  17. 17.
    World Medical Association (2000) World Medical Association Declaration of Helsinki: ethical principles for medical research involving human subjects. JAMA 284:3043–3045. doi: 10.1001/jama.284.23.3043
  18. 18.
    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. doi: 10.1007/s10633-007-9089-2 PubMedCrossRefGoogle Scholar
  19. 19.
    Lyons JS, Severns ML (2008) Using multifocal ERG ring ratios to detect and follow Plaquenil retinal toxicity: a review. Doc ophthalmol 118:29–36. doi: 10.1007/s10633-008-9130-0 PubMedCrossRefGoogle Scholar
  20. 20.
    Farber DB, Flannery JG, Lolley RN, Bok D (1985) Distribution patterns of photoreceptors, proteins and cyclic nucleotides in the human retina. Invest Ophthalmol Vis Sci 26:1558–1568PubMedGoogle Scholar
  21. 21.
    Ahnelt PK, Kolb H, Pflug R (1987) Identification of a subtype of cone photoreceptor, likely to be blue sensitive, in the human retina. J Comp Neurol 255:18–34. doi: 10.1002/cne.902550103 PubMedCrossRefGoogle Scholar

Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  1. 1.Sektion Funktionelle SehforschungUniversitäts-AugenklinikFreiburgGermany

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