Visual acuity test
Informed by recognized medical guidance
Overview
A visual acuity test measures how clearly you can see details at a distance. It is the most common part of an eye exam and uses an eye chart with letters, numbers, or symbols.
Key facts
- It checks the sharpness of your distance vision, often expressed as a fraction like 20/20.
- The test is painless and takes only a few minutes.
- You will be asked to read letters from a chart placed a set distance away, usually 20 feet (6 metres).
Yes, visual acuity testing is a routine part of almost every eye exam, done for people of all ages.
It affects everyone who has an eye exam, from children to older adults. It helps detect vision problems early.
Symptoms
- Sudden loss of vision in one or both eyes
- Seeing flashes of light or a curtain-like shadow over your vision
- Eye pain with redness or nausea
- ⚠New or sudden onset of double vision
- ⚠Eye injury or chemical splash
- ⚠Seeing many new floaters (dark spots or lines) suddenly
Common symptoms
- Blurred or fuzzy vision when looking at things far away or up close
- Squinting or straining to see clearly
- Frequent headaches or eye strain after reading or using screens
- Difficulty recognising faces or reading road signs
Symptoms in children
- Squinting or tilting the head to see better
- Rubbing the eyes often
- Avoiding activities that require clear vision, like reading or drawing
- Complaining of headaches or saying things look blurry
Symptoms in older adults
- Needing brighter light for reading or close work
- Difficulty seeing at night or in dim light
- Colours appearing less bright or faded
- Frequent changes in eyeglass prescription
Causes
Main causes
- Refractive errors: the shape of your eye prevents light from focusing directly on the retina (nearsightedness, farsightedness, astigmatism)
- Age-related changes: presbyopia (difficulty focusing up close) after about age 40
- Eye diseases: cataracts, glaucoma, macular degeneration, diabetic retinopathy
Risk factors
- A family history of vision problems or eye diseases
- Age (over 40 for presbyopia, over 60 for age-related conditions)
- Certain health conditions like diabetes or high blood pressure
- Prolonged close work (reading, computer use) without breaks
- Previous eye injury or surgery
When to see a doctor
See a doctor urgently if:
- Sudden changes in vision, even if temporary
- Eye pain, redness, or discharge
- Seeing flashes, floaters, or a curtain in your vision
Book a routine appointment if:
- Regular eye exams: every 1–2 years for adults over 50, every 2–4 years for adults under 50
- Children should have vision screening at school entry and as recommended
Diagnosis
A visual acuity test is performed as part of a comprehensive eye exam. You sit a set distance from a chart and read letters, numbers, or symbols, first with one eye covered, then the other. The smallest line you can read accurately determines your visual acuity.
Tests that may be done
- Snellen chart (traditional letter chart)
- LogMAR chart (more precise, often used in research)
- Tumbling E chart or picture charts for children or people who cannot read letters
- Near vision card to test reading distance vision
What to expect at your appointment
The test is quick and painless. You'll be asked to cover one eye at a time and read out what you see. You may also be asked to look through a pinhole device – this helps check if your vision can be improved with glasses. Your results are usually given as a fraction (e.g., 20/20 means you see at 20 feet what a person with normal vision sees at 20 feet). Your eye doctor will explain what your results mean.
Treatment
Treatment depends on the cause of any vision problem found. Often, refractive errors can be corrected with glasses or contact lenses. Other conditions may need medical or surgical treatment.
Self-care at home
- Take regular breaks from close work (follow the 20-20-20 rule: every 20 minutes, look at something 20 feet away for 20 seconds)
- Use good lighting when reading or doing detailed work
- Wear sunglasses outdoors to protect your eyes from UV rays
- Keep your eyeglass or contact lens prescription up to date
Medical treatments
Depending on the diagnosis, treatment may include prescription eyeglasses or contact lenses, eye drops for conditions like dry eye or glaucoma, or medications for underlying health problems like diabetes. Laser procedures can reshape the cornea (such as LASIK) for some refractive errors. Always follow your eye doctor's recommendations; never use someone else's prescription or eye drops.
When is surgery considered?
Surgery may be recommended for cataracts (cloudy lens replaced with an artificial one), advanced glaucoma, or certain retinal conditions. Your doctor will discuss the risks and benefits.
Living with this condition
If you have a vision problem, adapt your environment: use larger print, increase screen font size, and keep floors clear of obstacles. Ask for assistance when needed.
Lifestyle tips
- Schedule regular eye exams: at least every two years, or as advised
- Wear prescribed glasses or contacts as directed
- Manage other health conditions like diabetes and high blood pressure
- Avoid smoking, which increases risk of macular degeneration and cataracts
Diet and exercise
A balanced diet rich in leafy greens, citrus fruits, and fish may support eye health. Exercise helps control conditions like diabetes and high blood pressure that can harm vision. Talk to your doctor before starting a new exercise routine.
Mental health and emotional wellbeing
Vision loss can affect your mood and confidence. It's normal to feel frustrated or anxious. Tell your doctor if you feel down – they can connect you with resources and support groups.
Prevention
Not all vision problems can be prevented, but you can reduce your risk by getting regular eye exams, protecting your eyes from injury, and managing health conditions.
Screening programmes
Routine vision screening is recommended for all children, especially before starting school. Adults should have a comprehensive eye exam every 2 years, or more often if they have risk factors like diabetes.
Complications
If left untreated
- Worsening of vision that may not be fully correctable with glasses
- Increased risk of falls and accidents due to poor vision
- Eye conditions like glaucoma or cataracts can cause permanent vision loss if not treated
Long-term outlook
Most vision problems found through a visual acuity test can be successfully managed with glasses, contacts, or treatment. Even if vision cannot be fully restored, many people adapt well with support and low vision aids.
Find support
Local organisations
- Your local optician or eye clinic · Local
External links open third-party websites. Ruqelo Health is not responsible for external content. Listing an organisation does not imply endorsement.
Always verify with your doctor
Health guidelines vary by country and region. The information in this article is based on international clinical guidelines but may not reflect the specific guidelines, medications, or practices in your country. Always discuss your health concerns with your own doctor or healthcare provider, and refer to your local national health guidelines where available.
Important notice This information is for educational purposes only. It does not replace professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider about your specific situation. If you are experiencing a medical emergency, call your local emergency services immediately.
Related conditions
Sources and guidance
This article is educational and is prepared with reference to recognized health information and clinical guidance sources where available. Specific source links may vary by topic.
Last updated: July 16, 2026
Educational note: This information is for education only and is not a diagnosis.
Use it to support, not replace, advice from a licensed clinician.
If symptoms are severe, worsening, or urgent, call your local emergency number or seek emergency care.
Guidance may differ by country or region. Confirm local recommendations with a qualified healthcare provider.