Reversibility of retinal adhesion in the rabbit.

We have studied retinal adhesion in the rabbit using a new technique for quantifying adhesiveness by the observation of how much pigment remains adherent to the photoreceptors after separation. Previous in vitro work has shown that retinal adhesiveness falls within 3 min after enucleation, is weakened by low pH or the removal of calcium and magnesium, and is increased by cold temperature. This report shows that the effects of low pH, low calcium/magnesium and temperature are all rapidly reversible. Thus, restoring normal pH or normal calcium/magnesium will restore adhesiveness to control levels, and adhesion may be repeatedly weakened or strengthened by the adjustment of temperature or the ionic environment. The actions of pH and calcium/magnesium are in part additive, while cold temperature can maintain adhesion even in low pH or low calcium/magnesium. These findings suggest that irreversible processes such as metabolic or enzymatic decay are not primarily responsible for the loss of retinal adhesion which occurs so rapidly after enucleation or death. They also suggest that retinal adhesion is a multifactorial process.