Acetylcholine effectively contracts pupils in cataract surgery
MedWire News: Intracameral acetylcholine is an effective pupil-contractant in patients whose pupils have been dilated during phacoemulsification cataract surgery, say researchers.
The Swedish team says the study should reassure cataract surgeons of the safety and comfort of using intracameral mydriatics, even if pupil contraction is subsequently needed.
Gunnie Bäckström (Örnsköldsviks Hospital, Sweden) and co-workers evaluated the efficacy and safety of using acetylcholine to contract the pupils in patients given intracameral hydriatics in phacoemulsification surgery.
"Some cataract surgeons might not feel comfortable and safe in using intracameral mydriatics to dilate the pupil if the efficacy of acetylcholine is not confirmed," they explain.
This study therefore aimed to assess whether acetylcholine contracts the pupil to the same extent after intracameral mydriatics as with topical mydriatics.
Bäckström's team recruited 60 patients into the study and randomly assigned them to one of two groups: one group received topical placebo and an intracameral mydriatic solution (cyclopentolate 0.1%, phenylephrine 1.5%, and xylocaine 1%) while the other group received topical mydriatics (cyclopentolate 0.85% and phenylephrine 1.5%) and xylocaine 1% intracamerally at the start of surgery.
After intraocular lens implantation, all patients received 0.15 mL of 1% acetylcholine given intracamerally.
Writing in Acta Ophthalmologica, the researchers report that pupil contraction 30 seconds after acetylcholine injection was similar in the intracameral and topical mydriatic groups, at 1.0 versus 0.9 mm.
Similarly, there was no difference in pupil size 30 seconds after acetylcholine between the intracameral and topical mydriatic groups, at 4.8 versus 5.2 mm.
Both these parameters remained similar between the groups at 2 minutes and 1 day after acetylcholine injection, the authors add. Furthermore, pupil size following evacuation of the ophthalmic viscosurgical device was similar in the two groups (5.8 versus 6.1 mm).
"We here show that intracameral acetylcholine contracts pupils as effectively after dilatation with intracameral mydriatics as after dilatation with topical mydriatics," the researchers conclude.
"Cataract surgeons can feel comfortable using intracameral mydriatics for pupil dilatation even if a situation requiring pupil constriction with intracameral acetylcholine occurs."
By Joanna Lyford