Limiting photoreceptor death and deconstruction during experimental retinal detachment: The value of oxygen supplementation

PURPOSE: To assess the role of hypoxia in causing the death and deconstruct ion of photoreceptors in detached retinas and the effectiveness of suppleme ntal oxygen in limiting such damage. METHODS: Retinal detachment was induced surgically in the right eye of each of 10 cats. The cats were allowed to survive surgery for 3 days. Two were kept for these 3 days in normoxia (room air, 21% oxygen) and eight in hyper oxia (70% oxygen). The retinas were examined for cell death by use of label s for normal and fragmenting DNA, with antibodies and a cone sheath-specifi c lectin to demonstrate the status of their inner and outer segments, the s ynaptic structures of the outer plexiform layer, and the distribution of ba sic fibroblast growth factor (bFGF) and with in situ hybridization to demon strate bFGF mRNA. RESULTS: Retinal detachment without oxygen supplementation caused the death of some photoreceptors; the loss of cytochrome oxidase from the inner segm ents and the collapse of the outer segments of surviving photoreceptors; th e loss of synaptophysin profiles from the outer plexiform layer; and the lo ss of bFGF protein from retinal neurons and neuroglia but not from retinal vessels. Oxygen supplementation (hyperoxia) during detachment mitigated all these changes, reducing photoreceptor death, maintaining the specialized s tructures of surviving photoreceptors, and stabilizing the bFGF within the retina. CONCLUSIONS: In experimental retinal detachment, hypoxia caused by the sepa ration of outer retina from its normal source of nutrients is a factor in i nducing the death and deconstruction of photoreceptors as well as in the lo ss of bFGF from the detached retina, Hyperoxia offered to human patients be tween diagnosis of retinal detachment and surgery may enhance the function of the reattached retina. (C) 1999 by Elsevier Science Inc. All rights rese rved.