title: A sub-Tenon's capsule injection of lidocaine induces extraocular muscle akinesia and mydriasis in dogs.
abstract: The effect of local anaesthetic on the extraocular muscles was investigated in dogs by injecting lidocaine into the space between Tenon's capsule and the sclera. A cross-over design was used with both eyes from five Beagle dogs randomly injected, under general anaesthesia, with 1 mL of 2% lidocaine (1 mL-lidocaine group), 2 mL of 2% lidocaine (2 mL-lidocaine group) or 2 mL of normal saline (control group). Each eye was assigned to all treatments with a minimum 14 day interval between injections. Changes in eye position, pupil diameter, and intraocular pressure (IOP) were evaluated during the procedure. All eyes in the 2 mL-lidocaine group exhibited akinesia and mydriasis (pupil diameter >10mm) with an onset time of 6.5 ± 4.9 and 4.2 ± 4.3 min, respectively. In the 1 mL-lidocaine group, akinesia was induced in nine eyes and mydriasis occurred in seven eyes at 10.7 ± 5.8 and 5.4 ± 2.4 min after the injection, respectively. No changes in eye position or pupil diameter were observed in the control group. Akinesia was maintained for 44.3 ± 26.7 min in the 1 mL-lidocaine group and for 88.5 ± 17.2 min in the 2 mL-lidocaine group. Duration of mydriasis was 51.7 ± 28.9 min in the 1 mL-lidocaine group and 82.9 ± 15.6 min in the 2 mL-lidocaine group. Marked chemosis and sub-conjunctival haemorrhage occurred in 16/30 and 15/30 eyes, respectively. No significant change in IOP was observed between the mean pre- and post-injection values in all groups. These results suggest that a sub-Tenon's injection of 2 mL of 2% lidocaine provided effective extraocular muscle akinesia and mydriasis in dogs.
authors.affiliation: Department of Veterinary Surgery and Ophthalmology, College of Veterinary Medicine, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-742, Republic of Korea.
authors.forename: J S
authors.initials: JS
authors.lastname: Ahn
authors.forename: M B
authors.initials: MB
authors.lastname: Jeong
authors.forename: Y W
authors.initials: YW
authors.lastname: Park
authors.forename: Y S R
authors.initials: YS
authors.lastname: Lee
authors.forename: E R
authors.initials: ER
authors.lastname: Lee
authors.forename: S H
authors.initials: SH
authors.lastname: Kim
authors.forename: I
authors.initials: I
authors.lastname: Lee
authors.forename: K
authors.initials: K
authors.lastname: Seo
mesh_terms: D000779:Anesthetics, Local / Q000009:adverse effects*; D000818:Animals; D018592:Cross-Over Studies; D004285:Dogs; D005123:Eye / Q000187:drug effects*; D005260:Female; D056965:Injections, Intraocular / Q000379:methods* / Q000662:veterinary; D007429:Intraocular Pressure / Q000187:drug effects; D008012:Lidocaine / Q000009:adverse effects*; D008297:Male; D009799:Ocular Physiological Phenomena / Q000187:drug effects; D013508:Ophthalmologic Surgical Procedures / Q000379:methods* / Q000662:veterinary; D058475:Tenon Capsule / Q000187:drug effects
chemical_list: D000779:Anesthetics, Local; D008012:Lidocaine