Skip to content

    Eye Health Center

    Font Size

    Slit Lamp Examination

    How It Is Done continued...

    A test called fluorescein staining may be done along with a slit lamp examination.

    • During this test, your doctor applies a dye called fluorescein as an eyedrop or as a paper strip that is gently touched to the inside of your lower eyelid. The dye dissolves in your tears, coats your cornea, and collects temporarily in any scratches or other abnormal areas. The rest of the dye is washed away by your tears.
    • Your doctor shines a light onto your eye. The fluorescein dye shows up under the light, allowing the doctor to see scratches, ulcers, burns, or areas of irritation from an infection or dryness.

    A slit lamp examination takes about 5 to 10 minutes.

    How It Feels

    There normally is no discomfort involved with a slit lamp examination.

    Dilating drops may make your eyes sting and cause a medicine taste in your mouth. You will have trouble focusing your eyes for up to 12 hours after your eyes have been dilated. Your distance vision usually is not affected as much as your near vision, though your eyes may be very sensitive to light. Do not drive for several hours after your eyes have been dilated. Wearing sunglasses may make you more comfortable until the effect of the drops wears off.

    Anesthetic drops usually wear off in about 30 minutes.


    In some people, the dilating or anesthetic eyedrops can cause:

    Contact your doctor immediately if you have severe and sudden eye pain, vision problems (halos may appear around light), or loss of vision after the examination.


    The slit lamp exam uses an instrument that provides a magnified, three-dimensional (3-D) view of the different parts of the eye.

    Slit lamp examination
    • The eyelashes, eyelids, and lining of the eyelids (conjunctiva) look normal.
    • All of the structures inside of the eye look normal.
    • Cataracts camera.gif are seen.
    • Changes are found in the cornea camera.gif, such as an irregularly shaped cornea or a corneal scratch (abrasion), ulcer, or infection
    • A foreign body, such as a metal fragment, is found.
    • Infection, such as iritis or conjunctivitis camera.gif, is found.
    • Bleeding is seen between the iris camera.gif and cornea (hyphema) from a sudden break in a blood vessel or as a result of an injury to the eye.
    • Signs of glaucoma are seen.

    WebMD Medical Reference from Healthwise

    Last Updated: September 09, 2014
    This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

    Today on WebMD

    Woman holding tissue to reddened eye
    Learn about causes, symptoms, and treatments.
    Simple annoyance or the sign of a problem?
    red eyes
    Symptoms, triggers, and treatments.
    blue eye with contact lens
    Tips for wearing and caring.
    Understanding Stye
    human eye
    eye exam timing
    vision test
    is vision correction surgery for you
    high tech contacts
    eye drop