Wir berichten über 22 Patienten mit 3–12-monatiger Nachkontrolle, bei denen wegen subfovealer Neovaskularisation bei altersabhängiger oder myoper Makuladegeneration eine limitierte Translokation nach de Juan durchgeführt wurde. Unter Berücksichtigung der z. Z. publizierten Ergebnisse der photodynamischen Therapie mit Verteporfin scheint die Indikation für diese Operation vor allem bei der myopen Degeneration und mit Einschränkung bei kleinen okkulten Membranen bei altersabhängiger Degeneration zu liegen.

The retina of the Royal College of Surgeons (RCS) strain of rat, which is being used as an animal model for human retinal degenerations, has been employed in the study of the function of second order neurons. By about the 33rd postnatal day the dendritic branching of isolated bipolar cells is more sparse than in bipolar cells of the normal rat retina, but their GABA channels are as in the normal rat retina. The normally occurring light-induced distal potassium increase has been used as the indicator of the functional competence of second order neurons in the isolated RCS rat retina. These are dependent upon the integrity of ionotropic and metabotropic synapses. At about the 22nd postnatal day MgCl2 enlarges the light-induced distal potassium increase in the young RCS rat retina as in the normal rat retina. It seems that MgCl2 does not block the metabotropic synapses of on-bipolar cells. At about postnatal day 33, at which time the photoreceptors of the RCS rat retina had become severely damaged, the size of this light-induced distal potassium increase was not changed, but it was abolished by MgCl2. This indicates that bipolar cells are still active but that the synaptic function of on-bipolar cells has become vulnerable to MgCl2. The conclusion is that at a time when photoreceptor degeneration is already severe bipolar cells are still active, but that on-bipolars, mainly rod bipolar cells, have some functional deficit.

ERG and light-induced extracellular potassium ([K+]o) changes have been measured in isolated retinas of bothRana esculenta and Rana temporaria. The conditions of the preparations have been varied. Isolated frog retinas kept receptor side-upward in a moist chamber without perfusion showed the well-known slow PIII in the ERG. Retinas superfused from the receptor side, with O2 enrichment at their vitreal surface, however, exhibit a slow cornea-positive potential in the ERG. The slow ERG-potentials relate to different light-induced potassium changes in the proximal retina. There was a long lasting and larger proximal potassium increase in adequately maintained retinas but a smaller and shorter one in preparations lacking superfusion and oxygen. There was no significant difference between the size of potassium decrease around receptors of retinas supervised from their vitreal side and those supervised from receptor side. A reduction of slow PIII should therefore not be responsible for the slow cornea-positive potential. The long lasting and larger (by 59%) potassium increase in the proximal retina may counteract the potential in the Mu¨ller cells caused by the potassium decrease around receptors and thereby cancel slow PIII and generate a third component of the electroretinogram c-wave.

A c-wave-like cornea-positive potential in the isolated rabbit retina has been described. In this study, frog retinas were investigated to see if the neural retina contributes a slow cornea-positive component to the c-wave of the electroretinogram. The eye cups of both Rana esculenta and Rana temporaria exhibited a normal electroretinogram with c-wave, a larger proximal light-induced extracellular potassium increase, a small distal extracellular potassium increase and an extracellular potassium decrease around photoreceptors. Isolated frog retinas kept receptor side-upward in a moist chamber without perfusion showed the well-known slow PIII generated by the potassium decrease around receptors. If the isolated retinas were well perfused, the slow PIII was not seen, but a cornea-positive d.c. potential sometimes appeared after the b-wave. The different slow potentials seemed to relate to different light-induced potassium changes in the proximal retina. There was a long-lasting proximal potassium increase in the superfused retinas but a quick return of the proximal potassium increase to the baseline in the retinas lacking oxygen at the vitreal side. The lasting proximal potassium increase in adequately maintained retinas may counteract the potassium decrease around receptors and cancel slow PIII.