Examination of Optic Nerve

Examination of optic nerve

• Optic disc evaluation is of fundamental importance in the management of glaucoma.

• Clinical examination of the optic disc is best performed with slit lamp biomicroscopy, utilizing contact or handheld lenses.

• Subjective assessment or measurement of optic disc size is paramount, as there is a strong correlation between optic disc size and optic cup size.

• Great attention should be paid to neuroretinal rim contour, as well as the presence of retinal nerve fiber layer defects and optic disc hemorrhages, which can easily be missed.

• Over time, disc changes are better to identify with optic disc photographs or automated devices.The rate of disc changes in glaucoma is quite variable in different individuals and depends upon the stage of the disease, among other things.

• A large proportion of individuals with optic disc hemorrhages will present with progressive changes in the optic nerve fiber layer or optic disc within 2 years of hemorrhage, and these individuals should be monitored closely.

How Should I Examine the Optic Nerve?

The 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 Goldmann 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 magnification 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 stereo photography provides complementary clinical information.

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The cranial nerve examination involves a number of steps as you are testing all 12 of the nerves in one station. Be certain to know which nerve is being tested next and what tests you must perform for each specific nerve.

This guide will take you through each nerve systematically, but personal techniques may be adopted for this station so that it flows best for you. It can seem like a daunting station as there are many steps to it but hopefully, this guide will help.

Subject steps

The following equipment is required for a cranial nerve examination:

Handwash
Item with distinct odour (e.g. orange/lemon peel, coffee, vinegar, etc)
Cotton ball
Pen torch
Fundoscopy
Tuning fork
Neurological reflex hammer
Snellen charts
Ishihara plates