[Cavity structures in the peripheral retina].
1. Lange's fold of the ora frequently found at autopsy in fetuses and infants is a purely postmortal change. 2. The 'honeycomb ora' occurring in infants and small children may sometimes be present in vivo. The extensive and larger cavities however may well have appeared only postmortally here too (they are not seen in older children). 3. Both the typical or external and the reticular or internal cystoid degeneration of the peripheral retina increase in frequency and extent with increasing age. Both occur in vivo. Biomicroscopically cystoid degenerations apparently can be demonstrated in any living eye after indentation of the ora. Basal membrane fragments and microfibrils have sometimes been shown by staining in the cyst walls (when cyst and vitreous body are connected) and mucopolysaccharides in the cystoid cavities. But there are also cystoid degenerations occurring postmortally. The picture of internal cystoid degeneration can also be seen as a fixation artefact (only) in fetuses in not yet vascularised sections of the retina. In the cystoid cavities one finds histologically sometimes reaction-free cell debris, torn fibres and isolated cell nuclei of the granular layers. Whereas the biomicroscopically found cystoid degenerations almost always end (well) in front of the equator of the eyeball, the histologically found cystoid degenerations are seen relatively often considerably behind the equator. Scotomas to be expected in vivo in these cases have not been observed so far. The periphery of the retina is histologically often torn off the ora without any reaction and displaced far forward. The picture of cystoid degeneration can also be produced quite artificially by bulging of the retina due to fixation in histology (different treatment of the two halves of the eyeball). Even without any tissue participation a picture like cystoid degeneration below the peripheral retina, between it and the pigmented epithelium, may develop in celloidin itself if too quickly hardened. 4. Retinal cysts found relatively often histologically are predominantly extensive cystoid degenerations. Exceptionally these are apparently identical with the rare cysts or retinoschisis cases visible ophthalmoscopically. 5. Small to large-cystic retinal degenerations are mostly secondary reactive changes. The situation of Lange's fold, honeycomb ora and especially cystoid degenerations depends postmortally (but also apparently in vivo) on the pull of the zonule and vitreous body fibrils as regards extent and direction. The intravitally present cavities in (honeycomb ora and) cystoid degeneration are considerably increased postmortally and apparently still more by histological preparation. In addition there seems to be an age-specific alteration in the ratio of the pull of zonule-vitreous body fibrils on the one hand and the (age-dependent) tearability of the retina on the other: in fetuses and infants we get Lange's fold, in infants and small children honeycomb ora and in later childhood increasingly extensive cystoid degenerations.