Comparison of metal and flexible sub-Tenon cannulas.
OBJECTIVE
To compare metal posterior, flexible posterior, and flexible medium sub-Tenon cannulas for akinesia and anesthesia.


METHODS
King Khaled Specialist Eye Hospital, Riyadh, Saudi Arabia.


METHODS
Prospective blind randomized comparison.


METHODS
Patients having cataract surgery under sub-Tenon block received a mixture of bupivacaine and lidocaine with hyaluronidase. The patients were divided into 3 groups based on whether a metal posterior sub-Tenon cannula, flexible posterior sub-Tenon cannula, or flexible medium sub-Tenon cannula was used. Pain during injection, akinesia, anesthesia, and complications were recorded.


RESULTS
The study enrolled 159 patients. The akinesia score, superior oblique muscle activity, lid movements, and pain during injection were significantly lower in the metal posterior cannula group 2 minutes after injection (P=.002, P=.008, P=.097, and P=.001, respectively); there was no significant difference at 4 minutes, 6 minutes, 8 minutes, and 10 minutes. The incidence of intraoperative pain was low in all groups (P=.607). Chemosis was significantly less in the flexible posterior cannula group (P=.003); however, there was no significant difference in the site of chemosis (P=.460). There was no significant difference in the incidence, site, or severity of subconjunctival hemorrhage (P=.087, P=.072, and P=.331, respectively). No serious complications occurred.


CONCLUSIONS
Rigid posterior, flexible posterior, and flexible medium cannulas produced effective and equivalent anesthesia. The flexible cannulas may be safer than the rigid cannulas.


BACKGROUND
No author has a financial or proprietary interest in any material or method mentioned.
Department of Anesthesia, King Khaled Eye Specialist Hospital, Riyadh, Saudi Arabia.
Waleed
W
Riad
Nauman
N
Ahmad
Chandra M
CM
Kumar
D000772:Anesthesia, Local / Q000295:instrumentation*; D019162:Anesthetics, Combined / Q000008:administration & dosage; D000779:Anesthetics, Local / Q000008:administration & dosage*; D002045:Bupivacaine / Q000008:administration & dosage; D057785:Catheters; D004311:Double-Blind Method; D005133:Eye Movements / Q000502:physiology*; D058447:Eye Pain / Q000175:diagnosis*; D005143:Eyelids / Q000502:physiology; D005260:Female; D006801:Humans; D019654:Lens Implantation, Intraocular; D008012:Lidocaine / Q000008:administration & dosage; D008297:Male; D008670:Metals; D008875:Middle Aged; D019148:Neuromuscular Blockade; D009801:Oculomotor Muscles / Q000502:physiology; D010147:Pain Measurement; D018918:Phacoemulsification; D011446:Prospective Studies; D015607:Stents; D058475:Tenon Capsule
D019162:Anesthetics, Combined; D000779:Anesthetics, Local; D008670:Metals; D008012:Lidocaine; D002045:Bupivacaine