Eye, examination of

An inspection of the structures of the eyes, either as part of a vision test or to make a diagnosis when an eye disorder is suspected. An eye examination usually begins with inspection of the external appearance of the eyes, lids, and surrounding skin. A check of eye movements is usually performed and the examiner looks for squint. A check of the visual acuity in each eye using a Snellen chart follows. Refraction testing (using lenses of different strengths) may be performed to determine what glasses or contact lenses, if any, may be needed. A test of the visual fields may be performed, especially in suspected cases of glaucoma or neurological conditions. Colour vision may be checked because loss of colour perception is an indication of certain disorders of the retina or optic nerve. To check for abrasions or ulcers, the conjunctiva and cornea may be stained with fluorescein. Applanation tonometry is an essential test for glaucoma. The ophthalmoscope is an instrument used to examine the inside of the eye, particularly the retina. The slit-lamp microscope, with its illumination and lens magnification, allows examination of the conjunctiva, cornea, front chamber of the eye, iris, and lens. For a full view of the lens and the structures behind it, the pupil must be widely dilated with eye-drops.