Electroretinographic Assessment of Early Changes in Ocular Siderosis

Abstract

We examined a patient with an iron intraocular foreign body and recorded electroretinograms (ERGs) before and after the removal of the foreign body by vitrectomy. The amplitudes of the rod and cone ERGs and the oscillatory potentials (OPs) in the injured eye were reduced before the operation. In addition, the photopic on-responses (b wave) were more reduced than off-responses (d wave). One year after surgery, the amplitudes of the rod, cone and photopic on- and off-responses were markedly improved to within the low normal limit. However, the OP amplitudes remained unchanged with lower values. These findings suggest that iron retinotoxicity leads to a dysfunction of all layers but the changes may be reversible in the early period of the disease. The late period iron toxicity produces more severe damage to the inner retina than the outer retina.

Siderotic cataract with no signs of intraocular foreign body

“…Iron retinotoxicity leads to dysfunction of all the layers of the retina, and more severe damage occurs in the inner retina than in the outer retina in the later stages of thiscondition [8]. Rod-dominated responses are predominantly affected because they are more susceptible to iron toxicity than the cone system.…”

“…Macrophage activity is closely related to the mechanism and prognosis of ocular siderosis. According to previous studies, vision may be excellent in siderosis with ERG amplitudes of up to 50%, and complete reversal is possible following successful removal of the intraocular foreign body in the early stages of the condition and with amplitudes of up to 40% [8, 11]. Over this limit, macrophage activity may be overwhelmed by the amount of iron load, leading to direct cellular toxicity [4].…”

Vi-2 : Apport De l'ÉLECTROPHYSIOLOGIE Chez l'ADULTE : Exemples

“…Ce résultat est conforme à ce qui a été décrit par d'autres auteurs [Schechner, et al, 1990], [Imaizumi, et al, 2000].…”

“…Par contre, si le sujet consulte avec retard, il peut se constituer une cataracte sidérotique [Wu et al, 2009] et des dommages rétiniens irréversibles évoluent même si l'objet métallique est enlevé [Schechner et al, 1990]. Ce sont essentiellement les couches internes de la neurorétine qui présentent un dysfonctionnement [Schechner, et al, 1990], [Imaizumi et al, 2000]. L'objet métallique diffuse sous forme d'ions métalliques dans les milieux intérieurs de l'oeil qui, à long terme, se manifestent par des dépôts de ferritine dans le cytoplasme des cellules rétiniennes sous forme de sidérosomes [Tawara, 1986].…”

Retinal damages in turner workers of a factory exposed to intraocular foreign bodies

“…[10] Electroretinography (ERG) is among the techniques that may be used to survey the effect of IOFB on the retina because ERG can detect biochemical and functional abnormalities of the retina before a pathological change can be seen by ophthalmology or fluorescein angiography. [11–12]…”