Slit Lamp Examination
The slit lamp exam uses an instrument that provides a magnified, three-dimensional (3-D) view of the different parts of the eye. During the exam, your doctor can look at the front parts of the eye, including the clear, outer covering (cornea), the lens, the colored part (iris), and the front section of the gel-like fluid (vitreous gel) that fills the large space in the middle of the eye.
Special lenses can be placed between the slit lamp and the cornea (or directly on the cornea) to view deeper structures of the eye, such as the optic nerve, retina, and the area where fluid drains out of the eye (drainage angle). A camera may be attached to the slit lamp to take photographs of different parts of the eye.
See a picture of the structures of the eye.
Fluorescein dye eyedrops may be used during a slit lamp examination to make it easier to detect a foreign body, such as a metal fragment, or an infected or injured area on the cornea.
Why It Is Done
A slit lamp exam may be done:
How To Prepare
If you wear glasses or contact lenses, you will need to remove them before the slit lamp examination.
Eyedrops may be used to widen (dilate) your pupils and to numb the surface of your eyes. Before the test, tell your doctor if you have glaucoma or are allergic to dilating or anesthetic eyedrops.
If dilating drops are used, your eyes may be sensitive to light and you will have trouble focusing your eyes for several hours. If you know your eyes will be dilated, you may wish to arrange for someone to drive you home after the test. You also will need to wear sunglasses when you go outside or into a brightly lit room.
Talk to your doctor about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results will mean. To help you understand the importance of this test, fill out the medical test information form(What is a PDF document?).
How It Is Done
If a foreign body is present or if the cornea appears infected or injured, a test called fluorescein staining may be done along with a slit lamp examination.
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.
What Affects the Test
The inability to remain still throughout a slit lamp examination may make it hard for your doctor to check your eyes.
What To Think About
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