Abstract
Purpose:
To characterize the effect of intravitreal injection of Iodoacetic Acid (IAA) in comparison to its systemic application as a measure to induce monolateral photoreceptor degeneration.
Methods:
Seven weeks old C57BL/6J mice received either intravitreal injections of IAA (25 animals) in different concentrations (between 0.1-1 mg/kg bodyweight (BW)) or systemic treatment [intraperitoneal (8 animals, 40-70 mg/kg BW) and intravenous (3 animals, 60-70 mg/kg BW)] and were observed in the following five weeks using ERG, OCT, and histology.
Results:
Systemic application of IAA showed a mortality of 25% and toxic systemic effects with weight loss in the first two days of 10%. Intravenous application of IAA resulted in an extinction of the ERG and a thinning of the retina in the OCT. Intraperitoneal injection of IAA in mice showed no effect in the ERG or OCT for five weeks after injection. Animals that received intravitreal injections showed no weight loss after injection. Three to five days after injection the eyes developed cataracts ranging from 20% of cases at an IAA concentration of 0.1 mg/kg BW to 100% at an IAA concentration of 0.25 mg/kg BW. Higher intravitreal IAA concentrations lead to extinguished ERGs from 16% of cases at concentrations of 0.2 mg/kg BW to 90% at 0.25 mg/kg BW. Morphological signs of retinal degeneration after intravitreal injection were not observed, neither in the OCT nor in the histology.
Conclusions:
Intravitreal injection of IAA leads to dense cataracts at lower concentrations than ERG changes occurred. ERG results must be interpreted carefully in the presence of induced cataracts. Morphological signs of retinal degeneration were not seen. In summary, the intravitreal injection of IAA did not prove to be an adequate model of monocular retinal degeneration in mice.
Keywords: 503 drug toxicity/drug effects •
494 degenerations/dystrophies •
689 retina: distal (photoreceptors, horizontal cells, bipolar cells)