1. An apparatus for diagnosing optic neuropathic diseases including glaucoma, by measuring a thickness of a retinal nerve fiber layer (RNFL), the apparatus comprising: a scanning unit which scans along an optic nerve margin in the proximity of an optic nerve head; a pattern analyzing unit which analyzes a pattern of the RNFL scanned by the scanning unit; and a disease determining unit which determines a presence of the disease based on the pattern of the RNFL analyzed by the pattern analyzing unit.