Abstract
We present the case of a 59-year-old male patient with progressive vision impairment and consecutive visual field narrowing (“tunnel view”) for 7 years and a known retinitis pigmentosa for 5 years. The remaining Goldmann perimetric visual field at time reported was less than 5°. A request for blindness-related social benefits was rejected because an ophthalmologic expert assessment suggested malingering. This prompted us to assess an objective determination of the visual field using multifocal VEPs. Objective visual field recordings were performed with a four-channel multifocal VEP-perimeter using 58 stimulus fields (pattern reversal dartboard stimulus configuration). The correlated signal data were processed using an off-line method. At each field, the recording from the channel with the maximal signal-to-noise ratio (SNR) was retained, thus resulting in an SNR optimized virtual recording. Analysis of VEP signals was performed for each single field and concentric rings and compared to an average response measured in five healthy subjects. Substantial VEP responses could be identified in three fields within the innermost ring (eccentricity, 1.7°) for both eyes, although SNR was generally low. More eccentric stimuli did not elicit reliable VEP responses. The mfVEP recording was correlated with perimetric visual field data. The current SNR optimization by using the channel with the largest SNR provides a good method to extract useful data from recordings and may be appropriate for the use in forensic ophthalmology.
References
Tost F, Gass C (2007) Legal aspects of ophthalmological expert assessment—part 1. Klin Monatsbl Augenheilkd 224:57–76
Tost F, Gass C (2007) Legal aspects of ophthalmological expert assessment—part 2. Klin Monatsbl Augenheilkd 224:111–130
Klistorner A, Graham SL (2000) Objective perimetry in glaucoma. Ophthalmology 107:2283–2299
Hood DC, Zhang X, Hong JE, Chen CS (2002) Quantifying the benefits of additional channels of multifocal VEP recording. Doc Ophthalmol 104:303–320
Baseler HA, Sutter EE, Klein SA, Carney T (1994) The topography of visual evoked response properties across the visual field. Electroenceph clin Neurophysiol 90:65–81
Baseler HA, Sutter EE (1997) M and P components of the VEP and their visual field distribution. Vision Res 37:675–690
Odom VJ, Odom JV, Bach M, Barber C, Brigell M, Marmor MF, Tormene AP, Holder GE, Vaegan (2004) Visual evoked potentials standard (ISCEV). Doc Ophthalmol 108:115–123
Graham SL, Klistorner A, Goldberg I (2005) Clinical application of objective perimetry using multifocal visual evoked potentials in glaucoma practice. Arch Ophthalmol 123:729–739
Hood DC, Holopigian K (2007) The use of multifocal electroretinograms and visual evoked potentials in diagnosing optic nerve disorders. In: Chan JW (ed) Optic nerve disorders, chapter 11. Springer, Berlin
Watanabe K, Ohde H (2007) Discordance between subjective perimetric visual fields and objective multifocal visual evoked potential-determined visual fields in patients with hemianopsia. Am J Ophthalmol 143:295–304
Acknowledgment
This study is financial supported by DFG SFB 539.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Kaltwasser, C., Horn, F.K., Kremers, J. et al. Objective visual field determination in forensic ophthalmology with an optimized 4-channel multifocal VEP perimetry system: a case report of a patient with retinitis pigmentosa. Doc Ophthalmol 123, 121–125 (2011). https://doi.org/10.1007/s10633-011-9283-0
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10633-011-9283-0