Abstract
Purpose
Acuity testing based on visual evoked potentials (VEPs) overestimates acuity in patients with amblyopia. We hypothesized that distortion and fragmentation of the stimulus in amblyopia impede recognition of optotypes, while it leaves the pattern onset response in the VEP mostly unaffected, resulting in overestimation of acuity.
Methods
Acuity VEPs were recorded in visually normal participants with the stimulus degraded by patterned polymethyl methacrylate panes, which induce distortion and fragmentation. For comparison, frosted panes were used to induce blur through wide-angle scattering. Standard psychophysical optotype acuity was recorded under the same conditions.
Results
With the distorted and fragmented stimuli, the VEP consistently overestimated acuity relative to psychophysical optotype acuity. With blurred stimuli, both measures were in good agreement.
Conclusions
The data support the assumption that stimulus distortion and fragmentation leave VEP-based measures of acuity relatively unaffected, resulting in a discrepancy between measures of acuity that are based on checkerboard VEPs on one hand and psychophysical optotype recognition on the other hand. The technique of stimulus degradation described here provides a simple and efficient way of imitating effects that are known from amblyopia and may thus serve as a tool in the evaluation of vision tests.
This is a preview of subscription content, log in via an institution to check access.
References
Towle VL, Harter MR (1977) Objective determination of human visual acuity: pattern evoked potentials. Invest Ophthalmol Vis Sci 16(11):1073–1076
Teping C (1981) Visusbestimmung mit Hilfe des visuell evozierten kortikalen Potentials. Klin Monatsbl Augenheilkd 179(3):169–172. doi:10.1055/s-2008-1057284
Odom JV, Hoyt CS, Marg E (1981) Effect of natural deprivation and unilateral eye patching on visual acuity of infants and children. Evoked potential measurements. Arch Ophthalmol 99(8):1412–1416. doi:10.1001/archopht.1981.03930020286018
Röver J, Bach M (1987) Pattern electroretinogram plus visual evoked potential: a decisive test in patients suspected of malingering. Doc Ophthalmol 66(3):245–251. doi:10.1007/BF00145238
Nakamura A, Akio T, Matsuda E, Wakami Y (2001) Pattern visual evoked potentials in malingering. J Neuroophthalmol 21(1):42–45
McBain VA, Robson AG, Hogg CR, Holder GE (2007) Assessment of patients with suspected non-organic visual loss using pattern appearance visual evoked potentials. Graefes Arch Clin Exp Ophthalmol 245(4):502–510. doi:10.1007/s00417-006-0431-2
Bach M, Maurer JP, Wolf ME (2008) VEP-based acuity assessment in normal vision, artificially degraded vision, and in patients. Br J Ophthalmol 92:396–403. doi:10.1136/bjo.2007.130245
Mackay AM, Bradnam MS, Hamilton R, Elliot AT, Dutton GN (2008) Real-time rapid acuity assessment using VEPs: development and validation of the step VEP technique. Invest Ophthalmol Vis Sci 49(1):438–441. doi:10.1167/iovs.06-0944
Almoqbel F, Leat SJ, Irving E (2008) The technique, validity and clinical use of the sweep VEP. Ophthalmic Physiol Opt 28(5):393–403. doi:10.1111/j.1475-1313.2008.00591.x
Wenner Y, Heinrich SP, Beisse C, Fuchs A, Bach M (2014) Visual evoked potential-based acuity assessment: overestimation in amblyopia. Doc Ophthalmol 128:191–200. doi:10.1007/s10633-014-9432-3
Hess RF, Campbell FW, Greenhalgh T (1978) On the nature of the neural abnormality in human amblyopia; neural aberrations and neural sensitivity loss. Pflügers Arch 377:201–207. doi:10.1007/BF00584273
Sireteanu R, Lagrèze WA (1993) Distortions in two-dimensional visual space perception in strabismic observers. Vision Res 33:677–690. doi:10.1016/0042-6989(93)90188-3
Thibos LN, Bradley A (1993) New methods for discriminating neural and optical losses of vision. Optom Vis Sci 70:279–287
Barrett BT, Pacey IE, Bradley A, Thibos LN, Morrill P (2003) Nonveridical visual perception in human amblyopia. Invest Ophthalmol Vis Sci 44(4):1555–1567. doi:10.1167/iovs.02-0515
Riemslag FCC, Spekreijse H (1990) Electrodiagnosis by luminance and pattern stimulation. In: Colon EJ, Visser SL (eds) Evoked potential manual: a practical guide to clinical applications. Springer, Dordrecht, pp 117–159. doi:10.1007/978-94-009-2059-0_4
Heinrich SP, Bach M (2013) Resolution acuity versus recognition acuity with Landolt-style optotypes. Graefes Arch Clin Exp Ophthalmol 251:2235–2241. doi:10.1007/s00417-013-2404-6
Kushner BJ, Lucchese NJ, Morton GV (1995) Grating visual acuity with teller cards compared with snellen visual acuity in literate patients. Arch Ophthalmol 113(4):485–493. doi:10.1001/archopht.1995.01100040107035
Bach M (1996) The “Freiburg Visual Acuity Test”—automatic measurement of the visual acuity. Optom Vis Sci 73:49–53
Dawson R (2011) How significant is a boxplot outlier. J Statist Educat 19(2), www.amstat.org/publications/jse/v19n2/dawson
Heinrich SP, Lüth I, Bach M (2015) Event-related potentials allow for optotype-based objective acuity estimation. Invest Ophthalmol Vis Sci 56(4):2184–2191. doi:10.1167/iovs.14-16228
Acknowledgements
We thank our subjects for their participation.
Author information
Authors and Affiliations
Corresponding author
Ethics declarations
Conflicts of interest
All authors certify that they have no conflicts of interest.
Ethical approval
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
Informed consent
Informed consent was obtained from all individual participants included in the study. Because no identifying information about participants is available in the article, the following statement is not included: “Additional informed consent was obtained from all individual participants for whom identifying information is included in this article.”
Human and animal research
No approval from any animal research committee was obtained for the use of several examples of the species Homo sapiens.
Rights and permissions
About this article
Cite this article
Heinrich, S.P., Bock, C.M. & Bach, M. Imitating the effect of amblyopia on VEP-based acuity estimates. Doc Ophthalmol 133, 183–187 (2016). https://doi.org/10.1007/s10633-016-9565-7
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10633-016-9565-7