Background:Cerebral oedema and elevated intracranial pressure are frequent neurologic complications of a variety of cerebral disorders. Though it carries a risk of complications, invasive intracranial pressure monitoring is the gold-standard method for monitoring intracranial pressure. Objective: Our goal was to study the reliability of ophthalmoscopy and ultrasound evaluation of optic nerve sheath diameter in relation to computed tomography brain imaging as tools for monitoring increased intracranial pressure. Methods:This prospective observational study was conducted on 57 patients with traumatic or non-traumatic brain insult admitted to the intensive care unit (ICU) at Menoufia University Hospitals. All patients underwent clinical examination, routine daily laboratory investigations, and radiological investigations (computed tomography brain, ocular ultrasound, and ophthalmoscopy). Results: There was a statistically significant association between computed tomography brain findings & optic nerve sheath diameter measurement by the ultrasound. With a sensitivity of 94%, specificity of 88%, positive predictive value of 93%, negative predictive value of 70%, and an optic nerve sheath diameter at a cut-off point of 6.55 mm on day 1, the results are impressive. The results of the ophthalmoscopic examination and the computed tomography scan of the brain showed a strong correlation on day 3.Conclusions: Clinically, optic nerve sheath diameter (ONSD) measurement is an effective, rapid, bedside, and non-invasive tool for intracranial pressure monitoring, that guides early intervention, particularly in critical settings where immediate computed tomography access may be limited.