In vivo toxicity testing of methyl blue and aniline blue as vital dyes for intraocular surgery.
OBJECTIVE
To investigate the biocompatibility of methyl blue and aniline blue as vital dyes for vitreoretinal surgery in an in vivo rat model and to evaluate the effect of these dyes on retinal structure and function.


METHODS
Adult Brown-Norway rats received intravitreal injections of 0.1%, 0.2%, and 2% methyl blue or aniline blue dissolved in balanced salt solution with balanced salt solution serving as a control. Retinal toxicity was assessed 7 days thereafter by means of retinal ganglion cell counts, light microscopy, and electroretinography.


RESULTS
No significant decrease in retinal ganglion cell counts at concentrations up to 0.2% was observed. At 2%, however, a significant retinal ganglion cell loss was detected with both dyes (more pronounced for aniline blue). Light microscopy showed no structural changes in the central retina for concentrations up to 0.2%. Electroretinographies detected no adverse effects of methyl blue or aniline blue on rod- or cone-driven responses at concentrations up to 0.2%.


CONCLUSIONS
Methyl blue and aniline blue are very biocompatible and may, therefore, be usable for intraocular surgery. Further testing with other animal models will be necessary to confirm this. The safety margin of methyl blue is possibly higher than that of aniline blue.
Thaler
Sebastian
S
Centre for Ophthalmology, University of Tuebingen, Tuebingen, Germany. sebastian.thaler@uni-tuebingen.de
Schuettauf
Frank
F
Fiedorowicz
Michal
M
Messias
Andre
A
Schatz
Andreas
A
Choragiewicz
Tomasz J
TJ
May
Christian A
CA
Zrenner
Eberhart
E
Kampik
Anselm
A
Haritoglou
Christos
C
D000814:Aniline Compounds / Q000633:toxicity*; D000818:Animals; D001557:Benzenesulfonates / Q000633:toxicity*; D002452:Cell Count; D004396:Coloring Agents / Q000633:toxicity*; D004596:Electroretinography / Q000187:drug effects; D005456:Fluorescent Dyes / Q000633:toxicity*; D007267:Injections; D008297:Male; D051381:Rats; D011914:Rats, Inbred BN; D012160:Retina / Q000187:drug effects* / Q000473:pathology / Q000601:surgery; D012165:Retinal Ganglion Cells / Q000187:drug effects* / Q000473:pathology; D014822:Vitreous Body
D000814:Aniline Compounds; D001557:Benzenesulfonates; D004396:Coloring Agents; D005456:Fluorescent Dyes; C017006:aniline blue; C414357:Methyl Blue