In rats, lasering of half the retina, but not a quarter, leads to significant deficits in outer retinal functions over a 2-month period. Thereafter some recovery occurs, presumably as a result of migration of photoreceptors from undamaged areas and their retinal remodeling.

The course of a laser-induced retinal lesion is gradual: the photoreceptors are damaged first and the damage then spreads to other layers and to the adjacent retina. By day 3, the damage spreading stops, and adjacent cells begin to fill in and remodel the area of the lesion.

ABSTRACT.Purpose: NAP is the smallest active element of activity-dependent neuroprotective protein (ADNP) in the non-myelinated neural tissue. This study evaluated the neuroprotective effect of NAP in reducing the spread of laser-induced retinal damage in rat. Methods: Laser lesions were created in 72 DA pigmented rats. Two groups were treated by one intravenous or intravitreal injection of NAP immediately after exposure to laser. Two control groups were similarly administered saline injection. Histological and morphometrical evaluations of the lesions were preformed 3, 20 and 60 days after photocoagulation. Results: After intravitreal treatment with NAP, a significant reduction in the diameter of the laser-induced lesions was found 3 days after photocoagulation (p < 0.001) but not after 20 and 60 days while the systemic treatment significantly reduced lesion diameter 20 and 60 days after photocoagulation (p = 0.001). Significant difference in photoreceptor cell loss was found in eyes treated intravitreally only 3 days after photocoagulation (p = 0.002). In the systemically treated animals such effect was found only after 20 and 60 days (p < 0.001). Conclusions: Treatment with NAP ameliorates laser-induced retinal lesions. Intravitreal treatment had an early short-term effect while the effect of systemic administration was delayed and prolonged. This treatment may be of clinical significance in reducing laser-induced retinal injuries in humans.

Immunization with PN-277 has an ameliorative effect in neural tissue such as the retina. This type of immunization may be of clinical significance in reducing laser-induced retinal injuries in humans.