BACKGROUND: Retinal contusion injury is one of the leading causes for vision impairment, and clinical treatment is difficult. Although fundus change after retinal contusion injury has been fully understood, the pathogenesis and drug treatment still remain controversial.
OBJECTIVE: To explore the apoptosis and related mechanism of optic nerve cells in rabbit model of retinal contusion injury.
METHODS: Forty-eight healthy adult rabbits without oculopathy were divided into eight groups: 1 hour, 3 hours,
1 day, 3 days, 7 days, 14 days, 28 days after contusion and normal control, with six rabbits in each group. Right eye of each rabbit was treated with Allen’s reformative hitting method as contusive retinopathy model. The eyeballs were enucleated at different time points after injury in rabbit retina. The pathological section of optic nerve 5 mm posterior to sieve plate was harvested. The morphologic changes of optic nerve were observed and number of glial cells was measured using hematoxylin-eosin staining. Electron microscope and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling technique were used to assess apoptosis.
RESULTS AND CONCLUSION: In the normal control group, glial cells presented cylinder shapes and neural fibers arranged neatly. The trend of the glial cells was as the same as the neural fibers. But the optic nerve fibers arranged in disorder and the glial cells lost polarity in the groups of 1 hour, 3 hours, 1 day, 3 days, 7 days after retinal contusion injury. The number of glial cells in 1 hour, 3 hours, 1 day, 3 days, 7 days, 14 days, and 28 days was extremely significantly reduced compared with normal control group (P < 0.01). There was cell apoptosis in
optic nerve after retinal contusion injury, but almost not observed in optic nerve from normal control group, 1 hour and
28 days after injury. The apoptotic cells were abundant at 3 hours, 1 day, 3 days, 7 days, 14 days after injury, and peaked at 3 days, showing extremely significant differences compared with normal control group (P < 0.01). Apoptosis occurs in optic nerve after contusion of retina, which may be one of the reasons for incomplete recovery of retinal function.