Background: Sub-tenon anaesthesia is a form of local anaesthetic techniques used in ophthalmic procedures especially in cataract surgery. Few studies in our environment have reported the effects of Subtenon anaesthesia on intra-ocular pressure (IOP), akinesia and analgesia as well as optimum volumes of anaesthetic agents that is required for effective analgesia and akinesia. Objectives: To determine and to compare the change in IOP, the level of analgesia and akinesia and the effect of ocular compressions after Subtenon injection of 2ml versus 3ml of xylocaine among patients booked for cataract surgery in UITH. Methodology: A cross sectional comparative study among cataract patients booked for surgery in UITH, department of Ophthalmology 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 six months. Lists of cataract patients booked for surgery formed the sampling frame. Questionnaires were administered to obtain information on socio-demographic, ocular symptoms and other histories. Visual acuity was checked and ocular examination done with a pen-torch, ophthalmoscope and slit lamp examination with 78D. Tonometry and optic nerve assessments were done in order to exclude any patient with pre-existing glaucoma or suspicious disc. About 200 patients were randomly allocated into one of two volume groups(group1 had 2ml Subtenon xylocaine injection while group2 had 3ml),IOP was measured using Perkins Tonometer pre injection,5mins post- injection of xylocaine and after ocular massage(using a metal weight 0.42kg) which was applied for 2min.Level of analgesia and akinesia were checked 12min and 15min respectively. Results: Patients were randomly allocated into 2groups of 100 each, the age range was 20 107years, mean age for group1 was 63.8±12.64 while the mean age of group2 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 RE cataract. There was a rise in IOP in both groups, percentage IOP rise were 7.26% in group1 and 12.83% in group2 and percentage IOP reduction were -15.40% for group1 and -13.01% for group2 with ocular compression. The fall in IOP after ocular compression was found to be statistically significant as the IOP fell below the pre-injection level. Levels of analgesia 12minutes after Subtenon injections in both groups were similar. However, 2patients were found to have severe pain in group1, no patients had severe pain in group2. The level of akinesia which was assessed 15minutes after injection in both groups was found to be significantly better in group2.