What Is a PERRLA Exam for the Eyes?

What to Expect When Undergoing This Test

PERRLA is a quick test an eye doctor performs to examine the health of your pupils. The test results can also reveal other eye, brain, and nervous system problems. Learn more about the PERRLA eye exam.

Theresa Chiechi / Verywell

Purpose of Test

A PERRLA test is an eye exam that is a common part of a routine eye checkup. Eye doctors use it to check on the health of your pupil, which is a black circle in the center of your eyes, located in the middle of the colored part of your eye called the iris.

PERRLA is actually an acronym that eye health professionals use to describe what they look for during a pupil exam. PERRLA stands for:

  • Pupils: Pupils become smaller or bigger in response to light and darkness. Eye doctors will check to ensure your pupils are in the right location in your eyes.
  • Equal: This means the eye doctors will make sure your pupils are the same size. If they are not, they may perform additional tests to help determine why they are unequal.
  • Round: Pupils are normally round in shape.
  • React to: This refers to how well the eyes should react to the following steps.
  • Light: To test your eyes' reaction to light, the eye doctor will shine a light into your eyes to measure the pupil reaction. Normally, the pupil will become a little smaller. If not, the eye doctor may want to find out why.
  • Accommodation: Typically, your pupils become bigger when you focus on something at a distance and then smaller when you focus on something close. If your pupils do not adjust or accommodate, this is considered an abnormal result.

The PERRLA eye exam monitors your pupils' health and can help doctors check for certain brain and nervous system conditions. Some conditions checked for with a PERRLA exam include:

  • Anisocoria: This is a difference in the size of your pupils, with potential causes including an aneurysm, brain tumor, cluster headache, glaucoma, multiple sclerosis, and stroke. About 20% of people have pupils that are not the same size.
  • Adie's pupil syndrome: This a neurological problem during which your pupils close slowly, not quickly, when looking at bright lights.
  • Argyll Robertson pupil: This causes your pupils to not become smaller when exposed to bright light. An Argyll Robertson pupil can indicate the presence of late-stage syphilis, among other conditions.
  • Brain tumor: A brain tumor could cause your pupils to dilate or become bigger at different speeds.
  • Eye trauma: Eye trauma can cause several changes to your eye, including a pupil that is not its usual shape.
  • Glaucoma: Affecting more than 3 million people in the United States, glaucoma could cause pupils that are not the same size, and it could affect the way pupils respond to light.
  • Horner's syndrome: This condition causes a small pupil and a drooping eyelid on one side. This occurs because of a faulty connection between nerve pathways connecting the brain and face.
  • Optic nerve problems: Your optic nerve carries sensory information from your retina to your brain. Problems that affect the optic nerve include glaucoma, optic neuritis, and stroke.

A PERRLA eye exam will not show with certainty that you have one of the conditions. Instead, the results provide a clue that may indicate the need for additional tests.

Risks and Contraindications

There are no risks involved with having a PERRLA eye exam. It can be performed on any patient.

Before the Test

Before a PERRLA eye exam, your eye doctor or other staff members may ask you general questions about your eye health. If you have noticed that your pupils look different recently, you should let them know.

The test typically takes place in an exam room at the eye doctor's office. The PERRLA test takes just a couple of minutes. Eye doctors will have the results right away, but they may need to order additional tests based on the results.

You do not need to do anything special to prepare for a PERRLA test. If you are at the eye doctor for a routine eye exam, make sure to let the office know what vision insurance or health insurance you have, if any.

During the Test

Your eye doctor will perform a PERRLA test. If the exam room is not already dim, the doctor will dim the lights. They will examine your pupil to check its size and shape.

The next step is a test called the swinging flashlight test, which involves moving a small flashlight from one eye to the other. While this happens, you are looking straight ahead. This helps to show how your pupils react to light. It can help detect disease of the retina (located in the back of your eye) or the optic nerve.

In the final step, the eye doctor will have you look at a nearby object such as their finger or a pen. As they move the object to different distances, they can measure how your eye focuses close up, at a distance, or looking from side to side.

The exam should take just a couple of minutes. You should not feel any pain, although the shining of the flashlight into your eyes may feel uncomfortable.

If the PERRLA test is part of a routine eye checkup, the eye doctor may go on to perform other tests afterward.

After the Test

You should not have any side effects from a PERRLA test.

Interpreting Results

The eye doctor should be able to give you the exam results during your appointment. Typically, the eye doctor will discuss the results with you based on the factors that are part of the PERRLA acronym.

For instance, if your pupils are not equal in size, the eye doctor may conduct other tests to figure out why they are unequal. This can help pinpoint the presence of various other health problems. Your eye doctor may be able to do those tests during that same appointment, or they may ask you to return for a future appointment.

If your eye doctor refers you to another eye specialist, make sure to ask for a summary of the PERRLA exam results or any other relevant eye tests. Although they will likely send these results to the other doctor, it is always good to have a copy for yourself.

A Word From Verywell

A PERRLA eye exam is a routine part of an eye checkup. It can help the eye doctor check for specific eye, brain, or nervous system conditions. The eye doctor may need to do some other follow-up exams. If you have any worries about taking a PERRLA eye exam, let your eye doctor know in advance.

5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. American Academy of Ophthalmology. What is anisicoria?

  2. Dichter SL, Shubert GS. Argyll Robertson pupil. StatPearls.

  3. Glaucoma Research Foundation. Glaucoma facts and stats.

  4. Stanford Medicine. Pupillary responses.

  5. Broadway DC. How to test for a relative afferent pupillary defect (RAPD)Community Eye Health. 2012;25(79-80):58-59.

By Vanessa Caceres
Vanessa Caceres is a nationally published health journalist with over 15 years of experience covering medical topics including eye health, cardiology, and more.