Effect of botulinum toxin A on the intraocular pressure and the retina in an animal model.
OBJECTIVE
The purpose of our study was to investigate the effect of an inadvertent intravitreal injection of botulinum toxin A (BTA) on the intraocular pressure (IOP) and the retina in an animal model.


METHODS
BTA was injected intravitreally in normotensive rats. IOP was measured preoperatively as well as 1, 2, and 4 weeks postoperatively. Retinas were stained in vivo using a retrograde labelling technique and the density of retinal ganglion cells (RGCs) was determined. Immunohistochemistry was performed for rhodopsin and retinal glial fibrillary acidic protein (GFAP).


RESULTS
Significant temporary IOP elevation occurred in all groups in the immediate postoperative period (ANOVA, p < 0.05). IOP changes in the intermediate period were not statistically significant (ANOVA, p > 0.05). The differences in the density of RGCs after BTA injection were not statistically significant (ANOVA, p > 0.05). All retinas displayed the same immunostaining pattern for rhodopsin and GFAP.


CONCLUSIONS
Our findings indicate that BTA has probably no severe impact on IOP and the retina after an inadvertent intravitreal injection. However, temporary rise of IOP may possibly occur in the immediate postoperative period due to a volume-effect.
Institute of Experimental Ophthalmology, University of Muenster, Muenster, Germany. zisis.gkatzioufas@uks.eu
Zisis
Z
Gatzioufas
Tobias
T
Stupp
Marilita M
MM
Moschos
Konstantinos
K
Kopsidas
Petar
P
Charalambous
Solon
S
Thanos
D000818:Animals; D019274:Botulinum Toxins, Type A / Q000008:administration & dosage*; D005260:Female; D007429:Intraocular Pressure / Q000187:drug effects*; D058449:Intravitreal Injections; D023421:Models, Animal; D051381:Rats; D017207:Rats, Sprague-Dawley; D012160:Retina / Q000187:drug effects* / Q000502:physiology
D019274:Botulinum Toxins, Type A