Optic Nerve: Clinical Examination

Optic nerve-head examination is probably the most important step in the diagnosis of glaucoma and is also extremely important in monitoring patients with established glaucoma. There are several ways to clinically examine the optic nerve head, including direct ophthalmoscopy, indirect ophthalmoscopy, and slit lamp biomicroscopy with contact lenses (such as a Goldman lens), handheld lenses (such as a 78 or 90-diopter lens) or the Hruby lens. The advantages of slit lamp biomicroscopy, the preferred method for optic nerve evaluation, over the other methods mentioned are the quality of the stereopsis and magnifi cation provided. Although slit lamp biomicroscopy with handheld lenses can be performed through an undilated pupil, a stereoscopic view may be possible only if the pupil is dilated. In addition to slit lamp examination, optic disc stereophotography provides complimentary clinical information. For example, data from the Ocular Hypertension Treatment Study (OHTS) show that 84% of 128 cases of optic disc hemorrhages were detected on disc photographs and not on the clinical exam [1] . Clinical examination of the optic nerve should be performed with similar methodology each and every time it is executed, in order not to miss important aspects of the examination. In my view, examination of the optic nerve head should start with an evaluation of optic disc size, since disc size is extremely important in the interpretation of other optic nerve fi ndings. Even a simple subjective assessment of whether the disc is small, large, or average in size without specifi c measurements can be of value. The exam should then proceed to a careful assessment of the neuroretinal rim, looking for areas of thinning, notching, nasal cupping, M. T. Nicolela Department of Ophthalmology and Visual Sciences , Dalhousie University, Eye Care Centre , 2 West, 1278 Tower Rd , Halifax , Nova Scotia , Canada B3H 2Y9 e-mail: [email protected] Core Messages