[Evaluation of toxicity of manganese ions to rabbit retina].

Objective: To research the Mn(2+) toxicity in vivo rabbit retina. Mn(2+) is used as a tracer in MRI.
Methods: It was an experimental study. Sixty pigmented rabbits (120 eyes) were divided into 5 groups randomly. Manganese chloride solution 25 µl of 10, 15, 20, 30, 40 mmol/L were injected intravitreally in one eye of each rabbit respectively as 5 experimental groups (n = 12). The saline (0.9%) 25 µl was injected intravitreally in other eye of each rabbit as control group (60 eyes). After intravitreal injections, all eyes were examined by color fundus camera, fluorescein angiography, flash electroretinography, light microscopy, and transmission electron microscopy on the 0(th), 7(th), and 28(th) day.
Results: On the 7(th) day after intravitreal injection, the average of the F-ERG b-wave amplitude was reduced significantly from 337 µV to 189 µV in the group of 15 mmol/L (F = 20.43, P < 0.05), but the amplitude was returned to normal on the 28(th) day. On the 7(th) day after intravitreal injections, the F-ERG b-wave amplitude was reduced significantly in the group of ≥ 20 mmol/L, and the amplitude was not returned to normal on the 28(th) day. There were abnormal changes in the structure of the retina in ≥ 20 mmol/L group at difference time after intravitreal injections.
Conclusion: MnCl(2) as a tracer in vivo optic nerve, the concentration of ≤ 15 mmol/L caused only reversible changes in retinal function; The concentration of ≥ 20 mmol/L appears, damages in retinal function and morphology appeared.