Fundus pigmentation and the electroretinographic luminance-response function

Abstract

Dark-adapted and light-adapted electroretinographic luminance-response functions were recorded from subjects with light or dark fundus pigmentation based on digitized fundus photographs. For dark- and light-adapted electroretinograms, subjects with dark fundi had smaller b-wave amplitudes at all luminance levels. There was no significant difference in b-wave implicit time for the dark-adapted electroretinogram, but there was a significant difference for the light-adapted ERG between the two groups. The results suggest that fundus pigmentation should be considered in the interpretation of electroretinogram results. A possible mechanism for the influence of fundus pigmentation on b-wave amplitude is based on increased resistance associated with melanin.

Light- and dark-adapted electroretinograms (ERGs) and ocular pigmentation: comparison of brown- and blue-eyed cohorts

“…Our findings that some ERGs are larger from those with lighter eyes are in keeping with previous studies [2][3][4][5][6][7]. The ITs were earlier for the blue group compared with the brown group for most of ERG components, both dark-and lightadapted, which may suggest that a basic process, such as the phototransduction cascade, may be slightly accelerated in those with blue eyes.…”

“…It has been reported that human eyes with lighter fundi demonstrate larger full-field ERGs under both light-and dark-adapted conditions with normal or supranormal amplitudes in those with albinism [2][3][4][5][6][7]. Fundus pigmentation corresponds closely to iris pigmentation, iris colour and skin pigmentation [8][9][10].…”

“…Although dark-and light-skinned humans have similar amounts of melanin pigment in their retinal pigment epithelium (RPE), humans with dark skin have, on average, twice as much melanin pigment in their choroid as those with light skin [9]. Although it seems intuitive that greater light absorption by the denser choroidal pigment should reduce the effective retinal illumination and hence the ERG amplitude, this alone does not adequately explain the larger ERGs from lighter eyes [3,7].…”

Comparison of visual function in pigmented and albino rats by electroretinography and visual evoked potentials

“…Smaller b-wave amplitudes were found in patients with higher fundus pigmentation, which led to the hypothesis that this decrease could be related to a higher ocular resistance caused by melanin [52,53]. Russell-Eggitt et al [44] recorded ERGs in ocular and oculocutaneous albino Fig.…”

“…As a consequence of the reduced number of rods, an impaired post-receptoral response would also be expected. On the other hand, there are several reports that ERG amplitudes are larger in albino humans [44,[51][52][53]. Therefore, the purpose of this study was to compare the single aspects of retinal function of two closely related strains of pigmented and albino rats by comparing several ERG parameters.…”