PERRLA: What It Means for Pupil Testing
What is PERRLA?
Your eyes, besides allowing you to see the world, provide important information about your health. That’s why doctors use a variety of techniques to examine your eyes.
You may have heard your eye doctor mention “PERRLA” when discussing testing your pupils. PERRLA is an acronym used to document a common pupillary response test. This test is used to check the appearance and function of your pupils. The information can help your doctor diagnose several conditions, from glaucoma to neurological diseases.
What does it stand for?
PERRLA is an acronym that helps doctors remember what to check for when examining your pupils. It stands for:
- Pupils. The pupils are in the center of the iris, which is the colored part of your eye. They control how much light enters the eye by shrinking and widening.
- Equal. Your pupils should be the same size. If one is larger than the other, your doctor will want to do some additional testing to figure out why.
- Round. Pupils should also be perfectly round, so your doctor will check them for any unusual shapes or uneven borders.
- Reactive to. Your pupils react to your surroundings to control how much light enters your eyes. This step reminds your doctor to check your pupils’ reactions to the next two items in the acronym.
- Light. When your doctor shines a light in your eyes, your pupils should get smaller. If they don’t, there could be a problem affecting your eyes.
- Accommodation. Accommodation refers to your eyes’ ability to see things that are both close-up and far away. If your pupils are nonreactive to accommodation, it means they don’t adjust when you try to shift your focus to an object in the distance or near your face.
You can also think of PERRLA as a sentence. Pupils are equal, round, and reactive to light and accommodation.
How it’s done
To perform a pupillary exam, your doctor will have you sit in a dimly lit room. They’ll start by simply looking at your pupils, noting anything unusual about their size or shape.
Next, they’ll do a swinging eye test. This involves moving a small, hand-held flashlight back and forth between your eyes every two seconds while you look in the distance. They’ll do this several times to see how your pupils react to the light, including whether they react at the same time.
Finally, your doctor will ask you to focus on a pen or their index finger. They’ll move it toward you, away from you, and from side to side. The purpose of this is to check whether your pupils can properly focus. They should shrink when watching an object that’s shifting perspectives.
What do the results mean?
The results of a pupil exam can indicate many conditions, depending on which part of the test was unusual.
Uneven size or shape
If your pupils have a difference of more than 1 millimeter in size (called anisocoria) or aren’t perfectly round, you may have an underlying condition affecting your brain, blood vessels, or nerves. However, one out of five people with no eye health problems have pupils that are normally different sizes.
Some examples of conditions that cause differently sized pupils include:
- brain injuries, such as a concussion
- brain tumor
- brain swelling
- intracranial hemorrhage
Not reactive to light or accommodation
If your pupils aren’t responding to light or moving objects, it could indicate:
- optic neuritis
- optic nerve damage
- optic nerve tumor
- retinal infection
- ischemic optic neuropathy
- an overactive ciliary muscle, located in the middle layer of your eye
Keep in mind that the results of a pupil exam usually aren’t enough to diagnose any condition. Instead, they give your doctor a better idea of what other tests they can use to help narrow down what might be causing your symptoms.
The bottom line
Pupil eye exams are quick, noninvasive tests that doctors can use to check the health of your eyes and nervous system. PERRLA is the acronym they use to remember exactly what to check when examining your pupils.
If you look in the mirror and notice that your pupils look unusual, make an appointment with your doctor. Seek immediate medical treatment if you also start to notice severe head pain, confusion, or dizziness.