Comparison of the effect of 2 mL versus 3 mL sub-Tenon xylocaine injection on akinesia and analgesia in cataract patients at the University of Ilorin Teaching Hospital, Nigeria.

Purpose: Sub-Tenon anesthesia is a form of local anesthetic techniques used in ophthalmic procedures, especially in cataract surgery. Few studies in our environment have reported the effects of sub-Tenon anesthesia on akinesia and analgesia as well as optimum volumes of anesthetic agents that are required for effective analgesia and akinesia. The objective of this study is to determine and compare the level of analgesia and akinesia and the effect of ocular compressions after sub-Tenon injection of 2 mL versus 3 mL of xylocaine among patients booked for cataract surgery in the University of Ilorin Teaching Hospital (UITH).

Methods: A cross-sectional comparative study among cataract patients booked for surgery in the Department of Ophthalmology at UITH was carried out from March 2017 to August 2017. A total of 200 cataract patients that met the inclusion criteria were recruited into the study over 6 months. Lists of cataract patients booked for surgery formed the sampling frame. Questionnaires were administered to obtain information on sociodemographic, ocular symptoms, and other histories. Visual acuity was checked, and ocular examination was done with a pen-torch, ophthalmoscope, and slit-lamp examination with 78D. Tonometry and optic nerve assessments were done to exclude any patient with preexisting glaucoma or suspicious disc. About 200 patients were randomly allocated into one of two volume groups (Group 1 had 2 mL sub-Tenon xylocaine injection whereas Group 2 had 3 mL); level of analgesia and akinesia was checked 12 min and 15 min, respectively.

Results: The age range was 20-107 years; mean age for Group 1 was 63.8 ± 12.64, whereas the mean age of Group 2 was 64.14 ± 14.14. There was a slight female preponderance given a M:f of 1:1.4 and more than half of the patients presented with right eye (RE) cataract. Levels of analgesia 12 min after sub-Tenon injections in both groups were similar. However, two patients were found to have severe pain in Group 1, and no patients had severe pain in Group 2. The level of akinesia which was assessed 15 min after injection in both groups was found to be significantly better in Group 2.

Conclusion: There was a slight female preponderance with about two-third of the total patients being female and the percentage of females who had no pain was more than the male, more than 50% of the patients had RE cataracts. Sub-Tenon anesthesia whether with 2 mL or 3 mL led to a statistically significant rise in intraorbital pressure (IOP); however, with ocular compression, the IOP was found to decrease below the preinjection pressure in both groups. Levels of analgesia were similar in the two groups, whereas akinesia was statistically better in the group that had 3 mL injection.