Optic disk evaluation and utility of high-tech devices in the assessment of glaucoma.

BACKGROUND: Every clinician has at one time or another examined a patient who was misdiagnosed as having glaucoma or whose diagnosis of glaucoma was missed. Although glaucoma can exist with normal intraocular pressures, clinicians often rely on the presence of visual-field defects and the degree of optic disk cupping to direct care. However, assessment of cupping is but one small part of optic disk evaluation in glaucoma, and other features of the optic nerve head and retinal nerve fiber layer must be closely inspected to help diagnose borderline cases. In addition, glaucoma can exist without visual-field loss. High-tech devices offer an added dimension in the objective assessment of structure when subjective tests of function and/or ophthalmoscopic observations are equivocal. METHODS: This article details the various parameters of optic disk and retinal nerve fiber layer evaluation and their significance in the assessment of glaucoma. In addition, the role of four high-tech devices is evaluated for their utility in the assessment and progression of glaucomatous damage. CONCLUSIONS: When one attempts to classify a patient as having glaucoma, the degree of cupping and the presence or absence of visual field loss can be misleading. Prior to definitive diagnosis, a thorough evaluation of the optic disk and retinal nerve fiber layer, and appropriate use of high-tech devices, should help reduce the under-diagnosis and overdiagnosis of this disease.