Slit Lamp Exam

What is a slit lamp exam?

A slit lamp exam is a test that lets an eye care specialist see every part of your eyes — including inside them. It’s a common part of a routine eye exam.

A slit lamp is a special microscope with a bright light attached to it that your eye care specialist will use to look at the different parts of your eyes. They’ll adjust the light to see into and through the layers of your eyes. They’ll check the overall health of your eyes and diagnose any issues or symptoms you’re having.

Your eye care specialist will probably dilate your pupils to perform a slit lamp exam. You can’t drive with dilated pupils, so make sure to arrange transportation or have someone pick you up after your appointment.

When is a slit lamp exam performed?

An eye care specialist will perform a slit lamp exam in their office during your routine eye exam. It’s one of the tests you’ll need to maintain your vision and eye health.

You might need slit lamp exams more often if there’s an issue with one of your eyes, or if your eye care specialist is checking for signs of a condition you might have.

People with diabetes need their eyes examined regularly and might need slit lamp exams more often.

When would I need a slit lamp exam?

You’ll probably need a slit lamp exam every few years. This will help your eye care specialist keep track of any changes in your eye and diagnose any symptoms you’re having. Your eye care specialist will use a slit lamp exam to screen for conditions that affect your eyes, including:

• Cataracts.
• Glaucoma.
• Dry eye.
• Scratched corneas (corneal abrasions).
• Corneal disease.
• Macular degeneration.
• Retinitis pigmentosa.

Your eye care specialist will tell you how often you’ll need a slit lamp exam, and which conditions or changes they’re looking for.

Who performs a slit lamp exam?

Your eye care specialist will perform a slit lamp exam in their office. You won’t need an extra appointment or to visit a special facility.

How does a slit lamp exam work?

A slit lamp is a special microscope with a bright light that your eye care specialist shines into your eye. They’ll adjust the brightness and thickness of the light’s beam to see the different layers and parts of your eye. They’ll look at the parts on the outside of your eye, including your:

• Conjunctiva.
• Sclera.
• Cornea.

Your eye care specialist will also examine the inside of your eye, including your:

• Iris.
• Pupil.
• Lens.
• Retina.
• Optic nerve.

Your eye care specialist might put dye into your eye (either with eye drops or a colored piece of paper that has stain on it). This will help them see any scratches or damage on your cornea. How quickly the dye leaves your eye can show if there are any issues affecting your tear system.

How do I prepare for a slit lamp exam?

There’s nothing you need to do to prepare for a slit lamp exam.

Your eye care specialist might dilate your pupils with special eye drops before the test. Ask your eye care specialist ahead of time if your pupils will be dilated and if you should arrange for someone to pick you up after your appointment. It usually isn’t safe to drive with dilated pupils, so make sure to arrange transportation ahead of time.

What happens during a slit lamp exam?

During a slit lamp exam, you’ll hold your head against a chinrest and forehead support. Your eye care specialist will shine a bright light into and around your eyes while they examine them.

If your eye care specialist needs to dilate your pupils, they’ll put eye drops in your eyes. These usually take a few minutes to work. After your pupils are dilated, your eye care specialist will look into your eyes again.

What should I expect after a slit lamp exam?

There’s nothing you need to do after a slit lamp exam. If your pupils were dilated, you shouldn’t drive until they return to their usual size.

Your eyes will probably be more sensitive to light while they’re dilated. It might help to wear sunglasses for a few hours after your exam. You can return to all your normal activities as soon as your pupils aren’t dilated.

What are the risks of a slit lamp exam?

There aren’t usually any risks to having a slit lamp exam.

It’s rare, but some people can have side effects from the pupil-dilating eye drops, including:

• Dizziness.
• Dry mouth.
• A flushed feeling on your face.
• Nausea or vomiting.

What type of results do you get from a slit lamp exam?

Slit lamp exams don’t have results like other kinds of tests. You won’t get a number, ratio or a positive/negative test result. Instead, your eye care specialist will tell you if they see anything that needs further tests or treatments after they look into your eyes.

If you have any issues or conditions that need to be addressed, your eye care specialist will tell you what you need and what to expect.

When should I call my doctor?

Talk to your eye care specialist if you have any side effects after your slit lamp exam.

Go to the emergency room if your vision suddenly gets worse, or you lose sight in one or both eyes after the test.

A note from Cleveland Clinic

A slit lamp exam is one of the most common tests your eye care specialist will use to help you maintain your vision and to check the health of your eyes. It’s a quick, easy test that can be done as part of your regular eye exam.

Talk to your provider about any changes in your vision or any new symptoms in or around your eyes. The sooner you have a symptom examined, the more likely it is you can catch an issue before it causes vision issues.