Abstract
Purpose: :
As occurs in other parts of the CNS, retinal damage induced by laser photocoagulation is multiplied by secondary degeneration processes whereby tissues adjacent to the primary lesion are destroyed. Earlier studies have shown a natural self-repair immune reaction as a physiological response to CNS injury. Under normal conditions these reactions are insufficient to overcome trauma and the secondary neurodegeneration. However, these beneficial reactions may be boosted by an appropriate preconditioning via a reversible injury to the retina. Thus, we evaluated the neuroprotective effect of intravitreal saline injection on reducing the spread of laser-induced retinal damage in animals that served as control groups for other studies.
Methods: :
Standard argon laser lesions (514 & 544 nm, 200 µm, 0.1 W, 0.05 second) were created in 36 DA pigmented rats that received saline either by intravitreal (5µl, n=18) or intravenous (0.5 ml, n=18) injection seven days before the laser session. The intravitreal injection was performed with a 30-gauge needle of a Hamilton syringe through the temporal posterior sclera and retina. The laser-induced lesions were evaluated histologically and morphometrically 3, 20 and 60 days after exposure to laser.
Results: :
After intavitreal injection of saline the laser induced cell loss was reduced (P < 0.05) and the laser lesion diameter decreased (P < 0.05), as compared to intravenous treatment at all the time-points examined.
Conclusions: :
The results show that pre-treatment by intravitreal saline injection has a neuroprotective effect in the rat retina. The mechanism of action should be evaluated and the clinical applicability of this effect should be tested both morphologically and functionally.
Keywords: neuroprotection • laser • retina