Electroretinograms in patients with achromatopsia

Abstract

Eleven patients with X-linked and 9 patients with autosomal recessive achromatopsia were examined with full-field electroretinograms. In the standard full-field ERG's, normal rod responses were obtained, but the amplitude of the cone b-waves was not detectable. With computer averaging and narrow bandpass filtering, residual cone b-wave responses could be detected in 10 of the 20 patients. The residual cone b-wave amplitudes were markedly different in the 3 families with X-linked achromatopsia. In two of them, residual cone b-wave responses were seen in all patients examined. In contrast, such responses were seen only in 2 of 7 patients in the third family. There were also differences in other clinical observations (mainly in the visual acuity and refractive error) and we therefore suggest that there are at least two forms of X-linked achromatopsia. The ratios of the cone response amplitudes to 30 Hz flickering orange and blue-green light suggested that the defect in the X-linked achromatopsia patients was of the protanope type, whereas in the autosomal patients, both the protanope and the deutanope type was seen. In conclusion, measurements of the residual cone b-wave amplitude responses are of diagnostic and may possibly be of prognostic value when examining children and other members of families with achromatopsia.

A 19-month-old girl with nystagmus, paradoxical pupillary response and low vision

“…7 As a result, cone and cone-driven ERG responses to full-field stimuli are markedly attenuated or non-detectable, but rod and rod-driven responses are normal or mildly decreased. 8,9 In our patient although achromatopsia is the most likely diagnosis, a progressive retinal disorder cannot be ruled out completely. For this reason regular ophthalmic follow-up is recommended.…”

Electroretinographic findings in day-blind dogs

“…In cd, ERG alterations are only limited to the cone responses (Aguirre and Rubin, 1975;Andréasson and Tornqvist, 1991;Hurn et al, 2003;Shamir et al, 2010;Genead et al, 2011;Narfström and Petersen-Jones, 2013;Dixon, 2016). It has been shown that the function and number of cones decrease with age (Aguirre and Rubin, 1974;Long and Aguirre, 1991).…”

“…Throughout life, in animals with cd no fundoscopic lesions are observed and pupillary light reflexes (PLR) are normal under all light conditions (Rubin, 1971a,b;Narfström and Petersen-Jones, 2013). The results of electroretinography (ERG) in the course of cd demonstrate normal values for rod-driven responses, while cone-driven responses are markedly reduced or even absent (Aguirre and Rubin, 1975;Andréasson and Tornqvist, 1991;Hurn et al, 2003;Shamir et al, 2010;Genead et al, 2011;Narfström and Petersen-Jones, 2013;Dixon, 2016).…”

Educational paper

“…A hypermetropic refractive error is common, and fundal appearance is usually normal, although retinal pigment abnormalities may be present [26]. ERG testing shows normal rod function, but absent cone responses [5]. More recent high-resolution retinal imaging with optical coherence tomography (OCT) has revealed abnormalities in cone outer photoreceptor structure which can progress to photoreceptor loss with advancing age, despite visual symptoms remaining stable [41,42].…”