[Flourescein angiography and ultrastructure studies on retina after laser photocoagulation]

The fluorescein angiographs and ultrastructure changes as well as the repairable process of retina after photocoagulation were analyzed to provide scientific basis for the rationale of using laser in the treatment of retinal lesions.

Normal retinae were coagulated using I, II, III grade photic spots and were exposed to fluorescein angiography 1, 3, 7 days before the necessary exenteration in conformity with the informed consent given by 7 patients with malignant tumor of orbit. The retina from the removed globe was cut into thin sections and observed by use of electron microscope.

Fluorescein angiography: Fluorescein leaked in photic spots 1 day after photocoagulation. Leakage relieved with central small fluorescein block 3 days after photocoagulation. Leakage disappeared with central fluorescein block 7 days after photocoagulation. Ultrastructure: 1 day after photocoagulation, I grade photic spot, some retinal pigment epithelium(RPE) cells were swellen and necrotic. Partial photoreceptors were lysed and disarranged. Cells of outer nuclear layer decreased in number. II grade photic spot, RPE and photoreceptors were destroyed. Some necrotic and apoptotic cells appeared in the outer nuclear layer. Structure of outer plexiform layer became disorganized. III grade photic spot, retina was destroyed severely. 3 days after photocoagulation, cell edema and debris decreased. Phagocytes appeared, RPE and Müller cells started proliferation. 7 days after photocoagulation, proliferative RPE and Müller cells replaced the damaged areas of the retina. Retinal structure disorganization increased gradually from I to III spot.

Photocoagulation caused fluorescein leakage of retina, apoptosis of RPE and neuron, and damage to other structure. Subsequently, the proliferous RPE and Müller cells repaired the destroyed areas of retina.