What's the Difference Between Vision Screening and an Eye Exam?

Medically Reviewed by Whitney Seltman, OD on June 04, 2024
5 min read

Caring for your eyes and vision are important parts of a healthy lifestyle. Vision screening is a simple test of your vision that can detect problems early.

An eye exam is a detailed check of your eyes and eye health. About one in four children in the U.S. have an undiagnosed or untreated vision problem. Poor vision and blindness are frequent in older people, too. Although there are benefits of a vision screening vs. eye exam, both are necessary for good eye health.

Vision screening is a basic test that can be done by a school nurse, family doctor, or another certified health care professional. It's a basic test that can detect eye or vision issues, but it won't diagnose an exact problem.

Vision screening aims to identify reduced vision and eye conditions that may progress to loss of vision. It can be done quickly and by people without specialized equipment. If any problems are found, you will be referred to an ophthalmologist for a complete eye examination.

The people carrying out the screening program must be trained in using age-appropriate, scientifically proven methods and devices and methods. 

Vision screenings vary widely in their procedure and thoroughness. Most often, visual acuity is tested, but other tests are also recommended:  

  • Visual acuity testing: This requires cooperation and reading ability. You or your child will be asked to identify shapes or letters from a distance. Adults and children over the age of three can be screened for visual acuity using charts placed 20 feet away. Covering one eye at a time can show visual disorders in each eye.
  • Inspection of the eye and pupils: This can be done on babies and adults. The shape and color of the eyes are assessed. The pupils should be of the same size and react to light by becoming smaller.
  • Photoscreening: This method uses a special camera and finds disorders like refractive errors and other abnormalities. The process is automated and easy to use. 

Vision screening using only charts at a distance neglect problems of near vision and eye movement disorders. An incomplete vision screening may give a false sense of security and delay the detection of serious eye diseases.

An eye examination is carried out by an optometrist or ophthalmologist. These professionals have specialized training in the detection and treatment of eye problems. They will diagnose your eye or vision problem and provide the necessary treatment.

A comprehensive eye exam can diagnose important problems:

Age-related Macular Degeneration. This is when your vision is affected over time.

Amblyopia (lazy eye). If one eye has weaker vision than the other, the brain relies on the stronger eye. The weaker eye's vision gets worse.

Cataracts. The lens inside the eye gets cloudy, reducing vision. Cataracts are common in older people, but children can have cataracts because of infections, injuries, or metabolic disorders.

Convergence insufficiency. This disorder prevents the eyes from working together when looking at near objects. It causes difficulty reading from a book, computer, or another digital device. 

Diabetic retinopathy. This is when there is damage to the retina, the light-sensitive part at the back of the eye. 

Glaucoma. This is an increase in the pressure inside the eye. This can cause complete blindness if not treated. 

Refractive errors. Refractory errors cause blurred vision. This group of disorders included myopia (nearsightedness), hyperopia (farsightedness), and astigmatism (a disorder of the cornea's shape that impairs vision). 

Strabismus (crossed eyes). The two eyes do not look in the same direction. This can cause double vision and other visual problems.

Your ophthalmologist or optometrist will want to know your medical and family history. Some eye conditions are hereditary. 

An eye exam is much more detailed than a vision screening and includes examination of:

  • The external eye and pupils
  • Refraction, which tests both your near and distant vision for sharpness
  • Dilated examination, when your pupils are dilated with medicinal drops so the doctor can look inside your eye, including the retina and optic nerve.
  • Visual acuity, where one eye at a time is tested by covering the other eye. You will read letters of diminishing sizes on a chart
  • Side vision (Peripheral vision), which assesses how well you can see to the sides when focusing ahead. Loss of peripheral vision is a sign of glaucoma.
  • Eye pressure, where the intraocular pressure (pressure inside your eyes) is measured. Glaucoma is a disorder of increased pressure, which threatens sight.
  • Binocularity, which is how well your eyes work together to judge distance
  • Color vision
  • Ocular alignment, which checks if your eyes move together in all directions

People over 65 should have an eye examination every year. When examining the eyes of seniors, ophthalmologists pay special attention to detecting diabetic retinopathy, age-related macular degeneration, glaucoma, and cataracts.

Vision screening is essential for your child's eye health. Some eye problems make children rub their eyes or squint, but others have no symptoms. Vision screening will detect many of these eye problems. 

Vision screening using an eye chart should be done as soon as your child is old enough to read the letters. Younger children may be screened by matching images or describing symbols from a set distance. Some types of screening use special tools to measure the eye position or reflection of light from the back of the eye (the red reflex).

Vision screenings can be done frequently at convenient places. They often detect eye problems in the early stages. 

But vision screening may miss some problems entirely. They're done with simple equipment, limited time, and are aimed at:

  • Identifying people likely to have an eye disease
  • Detecting eye disorders early when they can be easily treated
  • Providing vision and eye care education

Meanwhile, an eye exam is done by optometrists or ophthalmologists. They test not only vision but also the overall health of the eyes. They will diagnose any eye problems and prescribe corrective treatment. 

You should see an eye specialist regularly for a comprehensive eye exam. For your child, you can ask your pediatrician to suggest an eye specialist.

Healthy vision is important to take in the world around you. You also need good vision for working and the tasks of daily living. Children need healthy vision for learning and development. Some eye disorders can lead to permanent loss of vision if not found and treated early. 

Vision screenings are quick and easy and detect some visual disorders. However, they may miss several significant eye problems. They're not a substitute for comprehensive eye exams. Regular eye exams by an optometrist or ophthalmologist are necessary to protect your vision and keep your eyes healthy.