Early diagnosis of glaucoma is critical to prevent permanent structural damage and irreversible vision loss. Detection of glaucoma typically relies on examination of structural damage to the optic nerve combined with measurements of visual function. To aid the clinician in evaluation of visual function and structure, computer-based devices such as confocal scanning laser ophthalmoscopy, scanning laser polarimetry, and optical coherence tomography provide quantitative assessments of structural damage, and visual function testing includes standard automated perimetry as well as selective techniques, including short-wavelength automated perimetry and frequency-doubling technology perimetry are available. This article will review current literature on diagnostic modalities available for glaucoma with emphasis on the best evidence available in the literature to support their use in clinical practice.