The influence of intravitreal zinc particles (1.3 mm2) in the eyes of rats caused the amplitudes of the electroretinogram to decrease to about 50% of the initial values within 24 hours, whereas the prolongation of the peak times began only on the third day after particle implantation. The removal of the zinc particles after 30 days led to only partial recovery of the amplitudes, whereas the peak times reached normal values. Dissociated behaviour of the amplitudes and peak times as described here was not found in earlier experiments with intravitreal iron, copper or lead particles of the same size. The extraction of intravitreal zinc particles (1.3 mm2) one day after implantation resulted in a recovery of the amplitudes up to 85%.

This report details the influence of the time lapse and surface area size of intravitreal copper foreign bodies on the electroretinogram (ERG) and the recovery of the potentials after removal of the particles. Pure copper wires were implanted temporarily into the vitreous body of rat eyes in the area of the ora serrata and the values of the ERG were compared with those of the intact fellow eyes. In three different procedures with groups of 12 animals each the following results were obtained: (1) The metal toxicity of small copper particles (0.3 mm2) remaining one day in the vitreous body reduced the amplitudes of the a1-, a2-, and b-wave only 10% by the end of the observation time of 260 days, (2) The loss of ERG amplitudes increased to about 25% under the influence of larger copper particles (1.3 mm2; time lapse one day); and (3) Copper particles with an active surface of 1.3 mm2 remaining two days in the vitreous body caused a permanent loss of about 50%.

On the basis of experiments with 42 rats, quantitative statements are made regarding the influence of surface area and dwelling time of intravitreal copper particles on the electroretinogram. The influence of these factors on the extent of recovery of function after extraction of the foreign body is demonstrated. The rate of mental intoxication (metallosis retinae) is indicated separately from the mechanical damage. Ophthalmoscopic findings are also described. The practical relevance of these results to the clinical situation is discussed in detail in connection with earlier reports.