Can we do without mydriasis in multifocal ERG recordings?
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The purpose of this study is to determine whether mfERG recordings with natural pupils approximate recordings obtained in mydriasis if the stimulus luminance is adjusted. If so, a bright monitor could obviate pupil dilation, rendering clinical management considerably easier. In 11 eyes of six subjects, we took four mfERG recordings with a resolution of 61 scaled hexagons per eye, two with natural pupils and two in mydriasis with a luminance of 150 cd/m2 and 500 cd/m2, respectively. Conditions will be abbreviated as “LoNat, HiNat, LoDil, and HiDil,” where Lo/Hi stands for low vs. high luminance and Nat/Dil stands for natural vs. dilated pupils. Response densities and peak times were averaged for the central seven and the remaining 54 hexagons. An ANOVA found highly significant effects for both amplitude and peak time between the four recording conditions (P always <0.001). However, for the two “middle” conditions, HiNat and LoDil, amplitudes and peak times did not differ markedly. Retinal illuminances of the conditions LoNat and HiNat each differed from the conditions LoDil and HiDil, respectively, by a factor of 5.4. Amplitudes increased and peak times decreased in the order of conditions LoNat, HiNat, LoDil, HiDil. When data were corrected for the Stiles–Crawford effect, there was an inversion of effective retinal illuminances of the recordings HiNat and LoDil. The mfERG guidelines correspond to the condition LoDil; for all practical purposes, the amplitudes and peak times are the same when the HiNat condition is used. Thus, when clinical constraints render pupil dilation undesirable, the mfERG can be recorded with natural pupils when monitor luminance is increased by five times (if available).
KeywordsMultifocal electroretinogram mfERG Pupil Stiles–Crawford effect Retinal illuminance Effective retinal illuminance Troland
We gratefully thank John Robson, Thomas Meigen, and Herbert Jägle for their extensive advice and helpful critique.
- 5.Hood DC, Bach M, Brigell M, Keating D, Kondo M, Lyons JS et al (2007) ISCEV guidelines for clinical multifocal electroretinography (2007 edition). Doc Ophthalmol 116:1–11Google Scholar
- 9.Stiles WE (1937) The luminous sensitivity of monochromatic rays entering the eye pupil at different points and a new colour effect. Proc R Soc Lond B Biol Sci 123:90–118Google Scholar
- 11.Sutter EE (1997) Rapid derivation of the Stiles–Crawford function using electrophysiological responses. OSA Technical Digest Series, vol. 1. pp 1258–1261Google Scholar
- 13.Walraven PL (1996) Directional sensitivity of the cone systems in normals and anomalous color vision. In: Lakshminarayanan V (ed) Basis and clinical applications of vision science. Kluwer Academic, Dordrecht, pp 73–76Google Scholar
- 16.Wyszecki G, Stiles WS (1982) Color science: concepts and methods, quantitative data and formulae. Wiley, New YorkGoogle Scholar