ObjectiveThis study aims to report an immediate change in intraocular pressure (IOP) after the first injection of bevacizumab.Materials and methodsAn interventional case series was carried out at Isra Postgraduate Institute of Ophthalmology, Al-Ibrahim Eye Hospital, Karachi, from November 2018 to April 2020. All patients with various chorioretinal diseases requiring anti-VEGF treatment were included in the study. Patients with a history of previous anti-VEGF or steroid injections and personal or family history of glaucoma were excluded. Bevacizumab in a dose of 1.25 mg (0.05 ml) was injected intravitreally under topical anesthesia maintaining sterile aseptic conditions in the operating room. IOP was checked one hour prior to the injection, and hourly monitoring of it was continued for the next six hours. Data were analyzed using SPSS Statistics to compare the mean IOP readings before and after injection.ResultsA total of 191 eyes of 147 patients were included in the study. Among them, 92 (62.58%) were male and 55 (37.41%) were female with a mean age of 45.5 ± 8.8 years. The mean pre-injection IOP was measured as 12.12 ± 2.11 mmHg. The frequency of IOP elevation of ˃ 21 mmHg was observed in 169 (88.5%) eyes at five minutes, 104 (54.5%) eyes at 30 minutes, 33 (17.3%) eyes at one hour, and 16 (8.4%) eyes at two hours. The raised mean post-operative IOP was 30.44 ± 6.53 mmHg at five minutes, 26.27 ± 4.65 mmHg at 30 minutes, 26.12 ± 3.31 mmHg at one hour, and 25.63 ± 3.03 mmHg at two hours. The IOP reduced to pre-injection value at three hours measuring 12.12 ± 2.11 mmHg and continued to stay at that level for the next three hours.ConclusionsThe majority of the eyes receiving first-time intravitreal bevacizumab injection showed a significant increase in IOP level within five minutes to two hours post-injection.