Skip to content
My WebMD Sign In, Sign Up

Eye Health Center

Font Size

Slit Lamp Examination

How It Is Done

Most of the time, a slit lamp examination is done by an ophthalmologist or optometrist. In some situations, a family medicine doctor or an emergency medicine specialist may perform the test.

  • The doctor may put one or more types of drops in your eye. Dilating drops may be used to make the opening (pupil) in the center of the eye bigger. This makes it easier for the doctor to see the structures of your eye. Anesthetic eyedrops may be used to numb your eye if a foreign body is to be removed or if eye pressure is being measured (tonometry). In some cases, fluorescein dye is used.
  • You will sit in a chair and rest your chin and forehead against bars on the slit lamp. The lights in the room will be dimmed.
  • The slit lamp will be placed in front of your eyes, in line with the doctor's eyes. Focus your eyes in the direction requested by the doctor and try to hold your eyes steady without blinking.
  • A narrow beam of bright light from the slit lamp is directed into your eye while the doctor looks through the microscope. In some cases, a camera may be attached to the slit lamp to take photographs of different parts of the eye.

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.

WebMD Medical Reference from Healthwise

Last Updated: January 09, 2013
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

businesswoman wearing fun eyeglasses
Pink Eye Slideshow
Woman with itchy watery eyes
grilled salmon and spinach

Understanding Stye
human eye
eye exam timing

vision test
is vision correction surgery for you
high tech contacts
eye drop

Special Sections