Take the Quiz - Get 20% OFF
Free shipping on orders over $50
Corneacare Logo
  • Shop
    • Shop All Products
    • Eyelid Hygiene
    • Eye Vitamins
    • Eye Drops
    • Eyecare Bundles
  • Education
    • Dry Eye Disease
      • Dry Eye 101
      • Causes & Diagnosis
      • Treatment
      • Lifestyle
      • Why It Matters
    • Eye Health & Wellness
    • Eye Glossary
    • Take The Quiz
  • Gift Guide
  • App
  • Shop Our Products
    • Shop All Products
    • Eyelid Hygiene
    • Eye Vitamins
    • Eye Drops
    • Eyecare Bundles
  • Education
    • Dry Eye
      • Dry Eye 101
      • Causes & Diagnosis
      • Treatment
      • Lifestyle
      • Why It Matters
    • Eye Health & Wellness
    • Eye Glossary
    • Take the Quiz
  • App
  • Contact Us
  • Take the Quiz

Eyecare at your fingertips. Take control of your eye health

Log In
Login
Logout
0
Take the Quiz
  • Shop
  • Quiz
  • Education
  • Gift Guide
  • Shop
  • Quiz
  • Education
  • Gift Guide
  • Shop Wholesale
  • Our App
  • Education
  • Shop Wholesale
  • Our App
  • Education

A-Z Glossary

Table of Contents

Phoropter

Vasudha Rao
Written byVasudha Rao
  • Last updated November 5, 2022

What is a Phoropter?

A phoropter is the instrument used by an eye doctor to measure the glasses prescription. The phoropter resembles the physical appearance of a butterfly. This instrument is utilized in the classic test of “1 or 2” in which eye doctors present two options of lenses and ask which lens is more clear. Many  lenses with different powers are contained in this ophthalmic diagnostic tool. A phoropter is also known as a “refractor,” and it is  used to measure the eye’s refractive power during an eye exam.

Key Takeaways

  • The phoropter is an instrument containing many lenses of different powers.
  • The phoropter is used to determine the distance and reading glasses prescription, including the amount of nearsightedness, farsightedness, and astigmatism. 
  • In some cases, the phoropter may also be used to check eye coordination and the eye’s resting position.  
Take our AI Powered Eye Quiz
Take the quiz
GET 20% OFF

Understanding the Phoropter

A phoropter is a device which has many different lenses inside of it. It has a unique design with a butterfly-shaped appearance. The patient is instructed to look through the two circular openings of the phoropter with their eyes. The doctor manually changes the lens power by moving wheels and turning knobs on the machine. In some cases the doctor may cover, or occlude, one of the eyes and evaluate the glasses prescription for each eye individually. This procedure is called a monocular subjective refraction. 

A phoropter can also be used to objectively check the glasses prescription, without any input from the patient. This procedure is called retinoscopy.  Retinoscopy can be performed with or without a phoropter. During retinoscopy, the eye doctor instructs the patient to look at a large letter on a screen. They then shine light into the eyes to evaluate the retinal reflex. The retinal reflex is neutralized with lenses. For example, a retinal reflex that moves in the same direction of the doctor’s light is neutralized with plus lenses. A retinal reflex that moves in the opposite direction is neutralized with minus lenses. Retinoscopy is a very useful technique to determine the glasses prescription for nonverbal patients. For example, children, people with cognitive impairments, or those who speak a different language. Retinoscopy is a method of obtaining the glasses prescription without the patient choosing between ‘1 or 2’.

The Steps of Refraction in Phoropters

A refraction is a procedure in which the eye doctor determines the glasses prescription. Refraction is done using a phoropter, which allows the doctor to test different lens powers. The following actions are involved in a standard phoropter refraction: 

  • Sphere power
    The initial step is to examine the patient’s sphere power. You may have noticed that your prescription for corrective lenses has “spherical” (or “SPH”) written on it. The term “sphere” simply denotes the amount of lens power required to correct nearsightedness (-) or farsightedness (+). The doctor will ask which spherical lens power looks clearer between two options (“1 or 2”.)
  • Cylindrical power
    The doctor checks for the presence or absence of astigmatism by using a cylindrical lens (“CYL”). Astigmatism indicates that a patient’s lens strength is not uniform across the eye, so different areas of the eye require different lens powers. .
  • Reading power
    Patients who are presbyopic, approximately over the age of forty, will typically require a reading glasses prescription. The eye doctor will check the reading power (“ADD”) and determine if the patient may benefit from magnifying glasses to aid in reading small print. 
  • Contact lens power
    Can also be determined using a phoropter. For patients with a moderate amount of farsightedness or nearsightedness, the glasses prescription and contact lens prescription are different. The contact lens prescription is typically ‘less strong’ than the glasses prescription because contact lenses sit closer to the front of the eye. The phoropter gives the spectacle prescription, which is then mathematically converted into the appropriate contact lens prescription.  

Phoropters’ Key Benefits

  • Quick prescription determination
    Since the phoropter contains a wide range of lens powers (+16.75 to -19.00) , changing lens powers is significantly quicker than with demonstrating each trial lens individually by hand. 
  • Lightweight
    Patients do not feel any pressure or weight from testing high powered lenses, because the lenses are not sitting directly on their face. 
  • Jackson Cross-Cylinder
    There are many different phoropter parts. The Jackson Cross-cylinder (JCC) is the part of the phoropter that determines astigmatism. It tests for the magnitude and direction of astigmatism. Astigmatism simply means that the eye does not have one single power since it is not perfectly round. It is a common finding in approximately half of all Americans. 
  • No lens smear
    Because patients cannot touch the lenses that are encased in the phoropter, they remain relatively clean and free of smudges or fingerprints. 
  • Risley prisms
    This apparatus allows eye doctors to measure the natural eye alignment (phoria). Prism works by bending light, and moving the location of a perceived image. Prism testing can determine if the eye coordination is robust and is used to evaluate symptoms of double vision, eye strain, or headaches.  
  • Computerization
    Some clinics use automatic, digital phoropters, which are fast and intuitive to use, while still maintaining prescription accuracy.

Sources

  1. Moe, Myron. Taking the Mystery out of Refraction “a Basic Overview.”
  2. Editor, By Jane Cole, Contributing. “Your Phoropter on Steroids?” Www.reviewofoptometry.com, www.reviewofoptometry.com/article/ro0917-your-phoropter-on-steroids.
  3. “Phoropter | What Is a Phoropter | EyeGlass Guide.” Www.eyeglassguide.com, www.eyeglassguide.com/my-visit/vision-testing/phoropter.aspx.

Related Terms

Loading...

Iris Nevus

is a clump of melanocytes on the iris

Eye Stroke

also called ischemic optic neuropathy, is a dangerous condition caused by a lack of blood flow to the optic nerve

Computer Vision Syndrome

is the result of prolonged digital device use and can cause symptoms including headaches and tired eyes

Argyll Robertson Pupil

is a condition that affects the pupils. It may cause symptoms such as light sensitivity, loss of balance, or tingling toes

Tonic Pupil

is a pupil abnormality in which the pupil is dilated and does not respond to light appropriately

Enophthalmos

is when one eye is displaced deeper into the eye socket compared to the other eye

Related Articles

Loading...
  • Causes & Diagnosis

Eye Exercises for Double Vision 

5 min read

Discover effective eye exercises for double vision and how they may help improve vision, strengthen eye muscles, and restore clarity.
Picture of Heather Cottrell

Heather Cottrell

  • Eye Health & Wellness

Can Sinus Pressure Cause Eye Pain?

6 min read

Sinus pressure can cause eye pain, blurry vision, and strain. Learn how to relieve symptoms and protect your eye health.
Picture of Heather Cottrell

Heather Cottrell

  • Eye Health & Wellness

How to Lighten Eye Color: Get the Facts

6 min read

Learn how to lighten eye color, discover how it works, explore various methods, and get essential eye care tips to keep your vision healthy and bright.
Picture of Heather Cottrell

Heather Cottrell

CorneaCare Logo Pink


  • Shop
  • Wholesale
  • Education
  • Community
  • App
  • Eye Glossary
  • Shop
  • Wholesale
  • Education
  • Community
  • App
  • Eye Glossary
  • Contact
  • Terms of service
  • Privacy policy
  • Shipping & Returns
  • Contact
  • Terms of service
  • Privacy policy
  • Shipping & Returns
  • Education
  • Shop
  • Wholesale
  • Contact
  • Terms of service
  • Privacy policy
  • Shipping & Returns
  • Education
  • Shop
  • Wholesale
  • Contact
  • Terms of service
  • Privacy policy
  • Shipping & Returns
  • Education
  • Shop
  • Wholesale
  • Contact
  • Terms of service
  • Privacy policy
  • Shipping & Returns
  • Education
  • Shop
  • Wholesale
  • Contact
  • Terms of service
  • Privacy policy
  • Shipping & Returns
Instagram Facebook Icon Youtube Twitter Tiktok

Copyright – © 2024 CorneaCare, Inc. ⚡️ All rights reserved

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease

Wholesale inquiry

Please fill out the form below, and we will be in touch shortly.



Sample inquiry

Please share your address where samples should be sent and what you are interested in trying.