Dong Heun Nam, MD (Incheon, Korea), Hyun Seung Moon, MD (Incheon, Korea), Hae Jung Paik, MD, PhD (Incheon, Korea)


To compare the effect of volume used in sub-Tenon’s anesthesia on efficacy and intraocular pressure (IOP) in vitreoretinal surgery.


A prospective, clinical trial was conducted on patients undergoing sub-Tenon’s anesthetic for vitreoretinal surgery. Patients were randomized to either 3 mL, 5 mL or 7 mL volume of anesthetic solution. IOPs were measured immediately prior to, immediately after, at 2,5 and 10 min after injection. Pain scores were assigned using a numerical visual analogue scale immediately after surgery and again the postoperative one day.


A total of 108 patients (119 eyes) were studied, including 35 eyes in the 3 mL group, 48 eyes in the 5 mL group, and 36 eyes in the 7 mL group. There was elevation in mean IOP following injection in all groups significantly and a trend for a larger rise in the group of larger volume(p<0.01). Mean IOPs were elevated after injection and reduced at all time intervals. But there was a enough reduction to the level of pre-injection in only 3 mL group. There was no significant difference in patient-reported pain scores among the groups when assessed immediately after surgery or the postoperative one day. The incidence of chemosis and high IOP elevation (40mmHg =) were more frequent in the 7 mL group (p<0.05).


Sub-Tenon’s anesthesia is effective in vitreoretinal surgery. It would appear that a 3 to 5 mL volume of anesthetic is safe when it considers the complications.