Abstract
Purpose: :
To assess rabbit retinal toxicity to triamcinolone acetonide vehicle, benzyl alcohol, when injected intravitreally.
Methods: :
This prospective comparative experimental study included 24 pigmented rabbits assigned into 2 groups; group 1 (experiment, n=12) received intravitreal 0.1ml of benzyl alcohol (BA), and group 2 (control, n=12) received intravitreal 0.1ml of balanced salt solution (BSS); all injections were done in the right eyes. Electroretinograms (ERGs) were recorded on both eyes of all available rabbits of both groups at 3, 7, 14, 28 and 42 days following injections. Three rabbits from each group were killed at 7, 14, 28 and 42 days and both eyes were sent for either light or electron microscopic examination.
Results: :
ERG recordings showed an absent b wave with markedly depressed a wave at day 3 and 7 in 11 BA–injected eyes of group 1. These ERG responses continued to be recorded in the unkilled rabbits up to 6 weeks with no recovery. In group 2: only 2 BSS–injected eyes showed abnormal b wave at 3 and 7 days with complete recovery by 6 weeks. Light microscopy showed severely reduced ganglion cell layer GCL, mild to moderate reduction of inner (INL) and outer (ONL) nuclear layers, and mild architectural changes of photoreceptors layers (PRL) in group 1. In group 2: no structural changes seen except for mild reduction of GCL in the 2 rabbit with ERG changes. Electromicroscopy showed intracellular irreversible changes in the GCL, INL, ONL, and PRL at 6 weeks in group 1, with no significant changes in group 2.
Conclusions: :
Triamcinolone Acetonide's Vehicle, benzyl alcohol, produced severe irreversible ERG and structural damage to rabbit neurosensory retinal following intravitreal injection.
Keywords: drug toxicity/drug effects • electroretinography: clinical • pathology: experimental