Multifocal and full-field electroretinogram changes associated with color-vision loss in mercury vapor exposure

Abstract

We evaluated the color vision of mercury-contaminated patients and investigated possible retinal origins of losses using electroretinography. Participants were retired workers from a fluorescent lamp industry diagnosed with mercury contamination (n = 43) and age-matched controls (n = 21). Color discrimination was assessed with the Cambridge Colour Test (CCT). Retinal function was evaluated by using the ISCEV protocol for full-field electroretinography (full-field ERG), as well as by means of multifocal electroretinography (mfERG). Color-vision losses assessed by the CCT consisted of higher color-discrimination thresholds along the protan, deutan, and tritan axes and significantly larger discrimination ellipses in mercury-exposed patients compared to controls. Full-field ERG amplitudes from patients were smaller than those of the controls for the scotopic response b-wave, maximum response, sum of oscillatory potentials (OPs), 30-Hz flicker response, and light-adapted cone response. OP amplitudes measured in patients were smaller than those of controls for O2 and O3. Multifocal ERGs recorded from ten randomly selected patients showed smaller N1-P1 amplitudes and longer latencies throughout the 25-deg central field. Full-field ERGs showed that scotopic, photopic, peripheral, and midperipheral retinal functions were affected, and the mfERGs indicated that central retinal function was also significantly depressed. To our knowledge, this is the first demonstration of retinal involvement in visual losses caused by mercury toxicity.

The Clinical Applications of Multifocal Electroretinography: A Systematic Review

“…307 Ventura et al performed mfERG in workers of fluorescent-lamp manufacturing plants who had chronic exposure to mercury vapor. 307 It was found that the workers had significant reductions in N1 and P1 amplitudes at all retinal eccentricities and delay in P1 implicit time at the fovea compared with control. The mfERG findings provide objective evidence that chronic mercury exposure may result in retinal toxicity, causing outer segment and bipolar cell damage.…”

Method to Indentify Nonsignificant Responses at Multifocal Electroretinogram Recordings: Technical Note

“…Since the development of the mfERG technology in the 90's, it was immediately applied to different topics of clinical ophthalmology (Huang et al, 1996;Kretschmann et al, 1998;Ventura et al, 2004;Greenstein et al, 2004;Raster et al, 2011), and over 700 articles already discussed the technique. The experience of the ophthalmologist is very important in the functional mapping, but this topographical evaluation is still very subjective (Hood et al, 2003).…”

Intoxicación ocupacional por mercurio

“…Al examen con lámpara de hendidura, y también como signo temprano de intoxicación, se puede encontrar el signo de Atkinson, reflejo parduzco bilateral y simétrico en la cápsula anterior del cristalino, que no afecta la visión. Estudios actuales apoyan el hecho que la exposición a vapores de mercurio induce un cuadro sub clínico de daño en la visión de colores, inclusive en lugares de trabajo, con indicadores de exposición menor al límite actual, lo que nos permite dudar de la protección real de ese límite en lo referido a efectos del mercurio sobre la visión (12)(13)(14) . Otras alteraciones encontradas son las siguientes:…”