The optic nerve, as a part of the central nervous system, is surrounded by a subarachnoid space and experiences the same pressure change as the intracranial compartment. The intra orbital part of the sheath, and particularly its retrobulbar segment, can distend when ICP is elevated. The study was conducted in department of emergency medicine inemergency ward and medical intensive care units. Every case was examined in detail on the lines of the proforma designed for cases of suspected raised ICP, taking in to consideration history, symptoms, clinical signs, laboratory tests,USG optic sheath and CT Scan. Present study of 100 cases left optic sheath diameter was more than 5mm in 86 cases, among them 5.1-5.5mm dimeter was observed in 56 cases and 5.6 to 6mm was observed in 30 cases. Present study of 100 cases right optic sheath diameter was more than 5mm in 86 cases,among them 5.1-5.5mm dimeter was observed in 45 cases and 5.6 to 6mm was observed in 41 cases.