[Early changes in the bioelectrical activity of retina after eyeball contusion]

Characteristic signs of changes in the bioelectrical activity of the retina soon after contusion of the eyeball supplement the functional criteria used for accurate diagnosis of the severity of contusion (classification of the injury). The most sensitive indicator of electroretinography is the amplitude of the electroretinogram (ERG) a-wave, which is sharply suppressed during the first three days in injury of any severity. Recovery of the bioelectrical activity of photoreceptors is delayed in comparison with the time course of the function of the second-order neurons (more rapid recovery of the b-wave in comparison with the a-wave). The reactivity of Müller cells increases in severe contusion, which is shown by a more pronounced decrease in the ERG b-wave amplitude and less expressed changes in low-frequency ERG. Analysis of the time course of biopotentials during repeated examinations of the patients helps control the efficacy of treatment. The results indicate that electroretinographic examinations are the most desirable 5-7 days after the contusion, because at this period the differences in the bioelectrical activity of the retina are the most expressed. The most informative parameters of electroretinography are the time course of total ERG a- and b-waves and the low-frequency rhythmic ERG.