Correlation between Goldmann perimetry and maximal electroretinogram response in retinitis pigmentosa

Abstract

To evaluate the relationship between Goldmann perimetry and maximal electroretinographic responses in patients with retinitis pigmentosa, analyses were performed on 220 affected subjects and separately on two subgroups with autosomal dominant (n = 35) and autosomal recessive (n = 29) inheritance. Electroretinograms were recorded averaging 100 iterations elicited with a 20-lux/s, 0.5-Hz white flash ganzfeld stimulation. The peripheral isopters of the visual fields were delimited with I4e, IIIe and V4e targets, measured on conventional perimetry charts with a light pen and expressed in square centimeters. Unlike most previously published reports, this investigation showed a definite correlation (p = 0.0001) between maximal electroretinographic response amplitude and visual field areas. This correlation was more evident for I4e and IIIe isopters (r = 0.89 and 0.87, respectively) than for V4e isopter (r = 0.69). This phenomenon appears to be related to distortion occurring on standard isometric charts and to spatial summation effects in the peripheral field. Such correlations held for both the autosomal dominant and autosomal recessive subgroups. It appears that, if enough accuracy is provided, maximal electroretinographic responses and Goldmann visual fields are both good measures of the remaining functioning retina in nonsyndromic retinitis pigmentosa, irrespective of inheritance models and dystrophic patterns.

Retinitis pigmentosa: visual function and multidisciplinary management

“…1,79 Interestingly, a number of studies using this method has determined that the half-life of visual field contraction (the time over which half of the remaining field area is lost) appears to remain remarkably constant across all types of RP at about five to eight years. 3,33,34,79,80 While these data may suggest a clinically similar disease process across RP subtypes, it should be noted that most authors do not support this interpretation. 1,3,33,34,76,[79][80][81][82] It is likely that as molecular biological genotyping improves, we will be able to tease out more subtle individual differences between the multiple subgroups of RP.…”

“…3,33,34,79,80 While these data may suggest a clinically similar disease process across RP subtypes, it should be noted that most authors do not support this interpretation. 1,3,33,34,76,[79][80][81][82] It is likely that as molecular biological genotyping improves, we will be able to tease out more subtle individual differences between the multiple subgroups of RP. For the present discussion, it is clinically acceptable to state that the visual field loss in RP is about nine per cent per year.…”

“…This has been shown to be so in cone mediated conditions only. 80,83 There was a close association between the cone-mediated multifocal ERG and the cone-mediated visual field. Interestingly, no significant correlation was found between the rod-mediated multifocal ERG and the rod-mediated visual field.…”

“…Night-blindness begins earlier in the Xlinked subtype 41 and is generally appreciated before any visual field loss can be detected. 3,80,85 Histological studies have reported a loss or total absence of rod photoreceptors in the peripheral retina. 55,86 The loss of rod function is demonstrated by elevated rod dark adaptation thresholds and very slow or non-existent dark adaptation.…”

Reliability Assessment of a Rod Photoreceptor Outer Segment Grading System

“…However, in experimental studies of retinal protection against degeneration that have been performed to date, emphasis has been placed on the thickness of the outer nuclear layer (ONL) (Wang et al, 1997;LaVail et al, 1998). Interestingly, though, in a recent study (Yang et al, 2000), the rescuing effects of melatonin noted in the rds mouse in terms of ONL criteria were not matched by a measurable effect at the ERG level, which is known to be an accurate indicator of residual retinal function in patients with retinal degenerations (Iannaccone et al, 1995;Sandberg et al, 1996), nor by improved PR-OS preservation. A recent study on transgenic rats (Machida et al, 2000) demonstrated that correlation between ERG signals and retinal histology was best demonstrated when using, for the latter variable, the average product of the ONL column cell count and the PR-OS length.…”