Evaluation of retinal toxicity of acetylcholine in rabbit eyes.
OBJECTIVE
In vitreoretinal surgery, pupillary constriction may be required at the termination of a procedure especially if mechanical pupillary dilation was used in eyes filled with gas or silicone oil. A miotic agent instilled into the anterior chamber will sink and come into direct contact with retina in the aphakic or pseudophakic vitrectomized eye. Therefore, the retinal toxicity of acetylcholine, a miotic used for pupillary constriction, was studied.


METHODS
Eight Dutch pigmented rabbit eyes were vitrectomized, had air-fluid exchange, and were injected with a 20% mixture of SF6. Subsequently eyes were randomly selected to have injections of 0.75 ml of 10 mg/ml acetylcholine (Miochol, Iolab Corp., Claremont CA) versus 0.75 ml of lactated Ringer's solution. Short-term (2 weeks) and long-term (6 weeks) retinal toxicity was assessed by ophthalmoscopy, electroretinogram, and histology by light and electron microscopy at both times.


RESULTS
Ophthalmoscopy, electroretinographic tracings, histology, and electron microscopy disclosed no significant abnormalities.


CONCLUSIONS
Acetylcholine does not appear to have significant retinal toxicity even when undiluted solutions are in direct contact with the retina. We therefore postulate that intraoperative use of acetylcholine in previously vitrectomized eyes filled with gas or silicone is safe.
Department of Ophthalmology, University of California at San Diego, USA.
D S
DS
Ahn
M
M
Flores-Aguilar
L
L
Kirsch
D
D
Munguia
P
P
Gangan
W R
WR
Freeman
D000109:Acetylcholine / Q000633:toxicity*; D000818:Animals; D004341:Drug Evaluation; D004596:Electroretinography; D007267:Injections; D009887:Ophthalmoscopy; D011817:Rabbits; D012160:Retina / Q000187:drug effects* / Q000502:physiology / Q000648:ultrastructure; D013459:Sulfur Hexafluoride; D014821:Vitrectomy; D014822:Vitreous Body
D000109:Acetylcholine; D013459:Sulfur Hexafluoride