It is used to examine the retina and optic nerve.
It is part of the routine eye examination. It is done in two different ways.
Direct ophthalmoscopy
It is done with a device called ophthalmoscope. The optic nerve, retinal vessels, macula, and other areas of the retina can be examined.
Especially in cases where the pupil is enlarged dilated (mydriasis), most of the retina can be examined.
Indirect ophthalmoscopy
It is an advanced form of examination and is performed with a special instrument called indirect ophthalmoscope.
Using high numbered lenses, the bottom of the eye can be seen with two eyes and a clearer image is obtained.