What Is a PERRLA Eye Exam?

A PERRLA eye exam is a key part of a comprehensive eye exam that checks how your pupils respond to light and focus. It helps doctors evaluate the size, shape, and reaction of your pupils, which can reveal valuable insights about your eye health and even your nervous system.

At EFE Glasses, we believe that understanding how eye exams work empowers you to take better care of your vision.

What Does PERRLA Stand For?

PERRLA stands for Pupils Equal, Round, Reactive to Light and Accommodation.
This acronym describes the normal findings of a healthy pupil reaction test:

• Pupils are equal in size and round in shape.

• When light shines into one eye, both pupils constrict.

• Each eye shows an equal response when light is directed at it.

• Pupils shrink when focusing on something close, such as reading a book or using a phone.

If these responses differ, it could signal an underlying eye or neurological condition, making early detection through a PERRLA test crucial.

How Is the PERRLA Eye Exam Performed?

The PERRLA test is typically performed in a dimly lit room using a flashlight or penlight and a nearby target. Here’s what happens during the exam:

1. Observation: The doctor checks if your pupils are round, equal in size, and react properly under different lighting conditions.

2. Light Reaction: A light is shone into each eye to see if the illuminated pupil constricts (direct response) and if the other eye reacts similarly (consensual response).

3. Swinging Flashlight Test: The light moves back and forth between both eyes to test how equally they react.

4. Accommodation Test: You’ll focus on a far object, then quickly shift your gaze to a near one. The doctor observes whether your pupils constrict properly.

This pupil dilation test helps identify any irregularities in your light response or focus adjustment.

Understanding the Results

Normal PERRLA Results

• Pupils are equal and round in both bright and dim light.

• Both constrict equally when exposed to light.

• Pupils constrict appropriately during the swinging flashlight test and when focusing on near objects.

Abnormal PERRLA Results

• Pupils appear unequal or irregularly shaped.

• One pupil reacts differently to light.

• Pupils fail to constrict when focusing near.

• A Marcus Gunn pupil (also called an afferent pupillary defect) occurs when one pupil enlarges instead of shrinking during the swinging flashlight test.

Abnormal results may suggest optic nerve issues, brain disorders, or eye muscle damage—conditions that need prompt attention from an eye care professional.

What Can an Abnormal PERRLA Test Indicate?

An irregular result from a PERRLA eye exam might point to conditions such as:

• Anisocoria: Unequal pupil sizes, which can be harmless or linked to nerve problems.

• Afferent Pupillary Defect (Marcus Gunn Pupil): Unequal constriction due to retinal or optic nerve damage.

• Horner Syndrome: Characterized by a small pupil, drooping eyelid, and reduced sweating on one side of the face.

• Adie Pupil: A large, light-insensitive pupil often associated with blurred near vision or light sensitivity.

• Cranial Nerve III Disease: Causes double vision and drooping eyelid—considered a medical emergency if accompanied by a dilated pupil.

• Argyll Robertson Pupil: Small, irregular pupils that don’t react to light but constrict during close focus, often linked to untreated syphilis.

• Iris Injury: Caused by trauma or eye surgery, temporarily altering pupil shape.

• Pharmacologic Causes: Certain medications or chemicals (e.g., nasal sprays, painkillers, or glaucoma drops) can also alter pupil reactions.

These conditions emphasize why routine eye exams at trusted clinics—and reliable eyewear brands like EFE Glasses—play a vital role in protecting your long-term eye health.

When Should You See a Doctor?

If you suddenly notice unequal pupils or any of these symptoms, seek medical attention immediately:

• Loss or double vision

• Dizziness or slurred speech

• Trouble walking or balancing

• Muscle weakness

• Severe headache or neck pain

While many cases of unequal pupils are harmless, others can indicate serious health conditions like stroke or nerve damage. Always err on the side of caution.

The Importance of Regular Eye Exams

The PERRLA eye exam might seem simple, but it provides essential insights into how your eyes and brain communicate. At EFE Glasses, we encourage everyone to schedule comprehensive eye exams regularly—not only to detect potential problems early but also to ensure your prescription is accurate for optimal comfort and clarity.

Your eyes are extraordinary tools, constantly adapting to light and focus. By understanding tests like the PERRLA eye exam, you take a proactive step toward maintaining sharp, healthy vision—something that stylish, protective eyewear from EFE Glasses is proud to support every day.