What Does 20/20 Vision Mean? Visual Acuity Explained
Quick answer: 20/20 vision means you can read at 20 feet what a person with normal vision can read at 20 feet. In metres it is written 6/6. A larger second number means weaker sharpness: 20/40 (6/12) means you need to be at 20 feet to read what normal eyes can read at 40 feet. 20/20 measures only distance sharpness, not eye health, near vision, colour vision or side vision.
Noticed this in your own eyes? Book an eye examination (NPR 400) with an optometrist at Vision Concern Lazimpat, Boudha-Tushal or Makalbari. WhatsApp +977 9841466716.
Related service: Comprehensive eye examination (NPR 400) at Vision Concern Lazimpat, Boudha-Tushal and Makalbari.
How visual acuity is measured
Visual acuity is tested with a letter chart such as a Snellen or LogMAR chart, one eye at a time, with and without glasses. The smallest line you can read gives the score. Many people see better than 20/20, for example 20/15 (6/4.5).
Common scores
- 20/20 (6/6): normal distance sharpness
- 20/40 (6/12): often the minimum standard for a driving licence in many countries
- 20/200 (6/60) or worse in the better eye with glasses: legal blindness in many countries
Why 20/20 is not the whole picture
You can have 20/20 vision and still have eye disease such as glaucoma, need reading glasses, have poor contrast or colour vision, or struggle with eye strain. A full eye examination checks focusing, eye coordination, eye pressure and eye health as well as the letter chart.
When to get urgent care
Get urgent care for any sudden drop in vision, a curtain or shadow over vision, new flashes and floaters, or sudden distortion.
How Vision Concern can help
Vision Concern optometrists in Kathmandu can examine your eyes, record what they find for comparison, update your glasses or contact lenses, and refer you to an ophthalmologist or eye hospital when medical treatment is needed. Vision Concern does not perform surgery or injections.
Frequently asked questions
Is 20/20 perfect vision?
No. It is normal distance sharpness. Many people see better, and 20/20 says nothing about eye health or near vision.
What is 6/6 vision?
It is the metric equivalent of 20/20, measured at 6 metres.
Does 20/20 mean I do not need glasses?
Not always. You may still need reading glasses or glasses for comfort, astigmatism or eye strain.
This guide is general information from the Vision Concern editorial team. It is not a diagnosis and does not replace an eye examination or medical advice.
Yes. Many visitors, particularly from Bangladesh and West Bengal (Kolkata), come to Nepal for cataract, retina, or other eye surgery at a hospital and also want new glasses, a general eye exam, or contact lenses at the same time, before or after their procedure. Vision Concern is an optical and eye-examination clinic, not a surgical hospital, so we work alongside hospitals such as Tilganga: we are happy to see you for glasses, contact lenses, or a routine check-up either side of your surgical treatment elsewhere.
No conversion is needed. Eyeglass prescriptions from Germany, France, the UK, the USA, China, Russia, and almost every other country use the same international format, SPH (sphere), CYL (cylinder), and AXIS, measured in diopters. Our opticians read this directly, so you can bring your prescription paper, a photo of it on your phone, or simply your current glasses, and we will use the same values. If your prescription is more than a year or two old, we recommend a quick, free re-check before we make your new pair.
Yes. Above roughly 3,000 metres, UV exposure increases sharply because of the thinner atmosphere and reflection off snow, and ordinary sunglasses (category 2-3) do not block enough UV to prevent snow blindness (photokeratitis). We recommend glacier glasses or category-4 sunglasses with side shields, and can fit these with your own prescription if needed. Vision Concern offers ZEISS polarized, UV400-certified sunglasses with prescription lenses, which we can prepare before you set off on your trek.