HEPATIC RETINOPATHIA - CHANGES IN RETINAL FUNCTION

In patients suffering from hepatic failure, the brain is subject to de fined morphological and functional changes known as hepatic encephalop athia (HE). The morphological changes are dominated by glial cells (Al zheimer-type II astrocytes). It has recently been possible to demonstr ate, that the retinal glia (Muller) cells undergo similar morphologica l changes, The present study was carried out in order to reveal if the se Muller cell changes cause any characteristic functional deficits, W e examined 11 patients with different stages of HE due to liver cirrho sis. Six patients were at stage 0 or 1 (group I) and five at stage 2 o r 3 (group II), They underwent ophthalmological routine examination, c olour vision testing and standard ERG recording. None of the patients reported impaired vision, in daylight or at night. There were no fundu s abnormalities except very mild changes of the pigment epithelium and abnormal reflexes of the inner limiting membrane, especially in the h igher HE stages. The number of confusions in the colour arrangement te st increased with the higher stages of HE, preferably in the tritan ax is. The scotopic a- and b-waves of the electroretinogram (ERG) were al most unchanged in group I and significantly decreased and delayed in g roup II, The photopic ERG b-wave amplitudes were changed in a similar fashion. Oscillatory potentials proved to be most sensitive to hepatot oxic changes. Their latencies were significantly delayed even in group I. Amplitudes were decreased significantly only in group II. Patients suffering from hepatic failure and accompanying HE display functional abnormalities of the retina. These are best demonstrated by the ERG, and correlate well with the degree of HE. A hypothesis is presented th at relates the observed functional changes to altered neurotransmitter levels and impaired retinal glial-neuronal interaction, due to Muller cell damage caused by elevated ammonia levels. (C) 1997 Elsevier Scie nce Ltd.