What Is a PERRLA Eye Assessment Test?
Your eye doctor uses many tools to check your eye health. PERRLA is like a mental checklist the doctor runs down in her mind as she looks specifically at your pupils. PERRLA can’t diagnose eye problems, but it helps your doctor know if there’s something worth looking into.
PERRLA is an acronym that stands for the pupil qualities your doctor should review during an eye exam. The list includes Pupils, Equal, Round, Reactive (to), Light, Accomodation. What follows is an explanation of how the doctor uses each of these terms to structure her examination.
Pupils, Equal, Round
This is the part of the eye your doctor is interested in. Your pupils are the black hole in the middle of the colored part of your eye (the iris).
Normal pupils are about the same size. But, for about one in five people, one is bigger than the other. This condition is called anisocoria and may be harmless. But it can also be a sign that you have a serious health issue in your brain, blood vessels, or nerves. If you have normal, or “physiologic anisocoria,” your pupils will react to changes in light the way they should. So the doctor will check that reaction.
To find out if your anisocoria is the result of an underlying health issue, your doctor may need further tests, such as:
- Magnetic resonance imaging (MRI) -- a scan for which you lie still in a tube
- Angiography -- an X-ray of your blood or blood vessels that requires an injection of dye
- Computerized tomography angiography (CTA) -- combines CT scan (another scan that requires you to lie still in a tube) with angiography
- Doppler ultrasound -- an image a technician creates with a handheld device that uses soundwaves
Your doctor will want to know if your uneven pupils are a new symptom or something you’ve had for a long time. She’ll also want to know if you’re having other symptoms like headaches or drooping eyelids. Some of the conditions that cause uneven pupils include:
- Torn or blocked blood vessel in the neck
- Brain aneurysm
- Nerve problems in your brain
- Reaction to medications such as eye drops or motion sickness patches
Your pupils should be perfectly round circles. Abnormal pupils may look like a keyhole or a cat’s eye. Some causes for this include:
Reactive (to) Light, Accommodation
The muscles in your iris open and close your pupil in response to light. Normal pupils get smaller in brighter light and larger in the dark. Your doctor wants to make sure your pupils are reactive to the last two words in the acronym: “light” and “accommodation.”
To see how your pupils react to light, your doctor will give you a “swinging light test.” She’ll take a small light with a narrow beam and shine it first into one eye for about three seconds and then into the other. Normal pupils shrink in reaction to bright light. Both your pupils should get smaller together, even when the doctor only shines direct light into one eye at a time. Both pupils should get bigger once it’s dark again.
Your pupils should also constrict -- get smaller -- when they’re focusing on an object very close to your eye. Typically, your pupils change size as you switch from looking at something far away to something very near you.
If your eyes don’t react normally to light or close objects, or if one reacts normally and the other doesn’t, it could be a sign of several problems, including:
- Infections of your optic nerve (the nerve that goes from your brain to your eye)
- A tumor pressing on your optic nerve
- Damage to or infection in your retina
- Severe macular degeneration
If your doctor finds anything abnormal during the PERRLA check, she might want additional tests or examination.
American Academy of Ophthalmology: “Pupil,” “Pupil Irregularity.” Medscape: “Anisocoria.”
Johns Hopkins Medicine: “Pupillary Disorders Including Anisocoria.”
National Eye Institute: “Coloboma.”
Walker H., Hall W., Hurst J. Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd edition, Butterworths, 1990.
Community Eye Health: “How to test for a relative afferent pupillary defect (RAPD).”
Stanford Medicine: “Pupillary Responses.”