Safety of intravitreal linezolid injection: electroretinographic and histopathologic studies in rabbits
Arvin Rolly D. Antipolo, MD, Ian P. Paredes, MD
Objective
This study evaluated the safety of linezolid as an alternative intravitreal drug
for the treatment of bacterial endophthalmitis.
Methods
Eight albino rabbits were divided randomly into 2 equal groups: the right
eyes were injected intravitreally with linezolid (100 mcg/0.10mL in Group 1
and 200 mcg/0.10mL in Group 2) and the left eyes were injected with 0.10mL
balanced salt solution. Indirect ophthalmoscopy before and after intravitreal
injections determined the presence of any precipitates in the vitreous. Electroretinography (ERG) and histopathology evaluated the effects in the
retina.
Results
No vitreous precipitates were found in all groups. Scotopic ERG showed a
decrease in b-wave amplitude (p < 0.05) in Group 2 between 3 hours and 2
days and between 3 hours and 7 days after injection. Histopathology showed
minimal inflammatory cells (<3 cells/hpf) in Group 2 and controls, trace
vacuolizations in the ganglion-cell layer and partial loss of photoreceptor outer
segment in Group 1 and in controls, and minimal decrease in the outer-nuclearcell density in all groups.
Conclusion
Intravitreal injection of up to 200 mcg linezolid is safe and well tolerated in
rabbit eyes and may be used in the treatment of human bacterial
endophthalmitis following further studies.
Keywords: Endophthalmitis, Intravitreal drug, Linezolid, Electroretinography, Retinal toxicity