In this technique, an instrument called an ophthalmoscope is used to examine the inside of the eye. You will be asked to focus on a distant object while the instrument directs a beam of light into your eye. Through the lenses in the ophthalmoscope, the ophthalmologist can examine the light-sensitive retina; the retinal blood vessels; the head of the optic nerve, which carries nerve signals from the eye to the brain; and the jelly-like vitreous humour, which fills the back of the eye. Ophthalmoscopy is painless, but if eyedrops are used to dilate the pupils, your vision may become temporarily blurred. Instead of an ophthalmoscope, a slit lamp with a lens placed in front of your eye may sometimes be used to examine structures such as the retina.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.