Animal model shows healing response of RPE after laser

REGENSBURG, Germany — An animal model designed here may help researchers study the effects of laser treatment on the retina.

In this animal model, porcine retinal pigment epithelium (RPE) with underlying choroid attached is continuously perfused on both sides with culture medium. Using the model, researchers have been able to study the healing response of the RPE and choroid to argon laser treatments.

Carsten Framme, MD, and colleagues here at the University Eye Hospital prepared the RPE with underlying choroid from enucleated porcine eyes and fixed it in a holding ring. Cultures were kept for 1, 3, 7 and 14 days and were examined histologically. Laser treatment was performed on each tissue ring by application of laser burns 1 day after culture began using different energy levels.

During laser treatment, a marked lightening of the RPE with centrifugal spreading was observed. At higher levels of energy, a contraction of the RPE toward the center of the laser spot was noticed. One day after laser photocoagulation, histology revealed destruction of the RPE. Within 3 to 7 days of culture, migration and proliferation of neighboring cells were observed in several lesions. After 7 days, the initial defect of the irradiated area was covered with dome-shaped RPE cells, and after 14 days multilayered RPE cells were showing ongoing proliferation.

The researchers note there were also cases without proliferation after laser treatment.

“After 14 days even without laser treatment a proliferative multilayered RPE was present. Although this limits the use of the system for longer than 7 days, it seems to be useful for investigation of RPE-related disorders,” the study authors reported in the November issue of Ophthalmologica.