Sunglasses and UV: choosing a pair that protects
A darker lens doesn't mean more protection, and an expensive pair isn't always better. What to look for in sunglasses, according to eye care and public health bodies.
Guides A to Z
Eye terms, symptoms and exercises explained in plain words. General information, not advice: your eye doctor is the one to ask about your eyes.
Free tools
Take a short screen break or start a clearer record while you read. Free, right in your browser.
- Screen break timerA 20-20-20 timer that reminds you to look away from the screen, with a 20-second break countdown.Free
- Eye photo journalTake your eye photos the same way each time and keep them dated, for your eye doctor.Free
- Eye tracking journalTrack how your eyes feel day by day: symptoms, screen time, sleep and drops, in seconds.Free
- Shade HuntSpot the tile that is a slightly different colour.60 seconds
- Dot ChaseFollow the dot and catch it when it changes.2 minutes
- Edge SpotEyes on the centre, catch what appears at the edges.About 2 minutes
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- 20-20-20 rule
- A screen-break habit: every 20 minutes, look about 20 feet (6 metres) away for 20 seconds. Read the guide →
A
- Accommodation
- The eye's ability to change focus between far and near.
- Amblyopia
- Reduced vision in one eye that develops in childhood, often called lazy eye.
- Astigmatism
- An uneven curve of the cornea or lens that can blur vision at any distance.
B
- Blink rate
- How often you blink. People tend to blink less while looking at a screen.
- Blue light
- Light from the sun and from screens. What blue light glasses can and can't do, according to research. Read the guide →
- Blurry vision
- When things look out of focus, up close, far away or both. Read the guide →
- Brock string
- A bead-and-string tool some eye care professionals prescribe for practising convergence. Read the guide →
C
- Cataract
- A clouding of the eye's natural lens, more common with age.
- Conjunctivitis
- Inflammation of the thin layer over the white of the eye, often called pink eye.
- Contact lens care
- Everyday habits, from handwashing to never sleeping in lenses, that lower the risk of eye infection. Read the guide →
- Contrast sensitivity
- How well you can tell an object apart from a background of a similar shade.
- Convergence
- Both eyes turning inward together to look at something close.
- Convergence insufficiency
- When the eyes find it hard to turn inward together for close work, which can make reading tiring. Read the guide →
D
- Diabetic eye screening
- Regular checks of the back of the eye for people with diabetes, often before any symptoms. Read the guide →
- Diplopia
- The medical word for double vision. See Double vision
- Double vision
- Seeing two of one object, side by side or one above the other. New double vision needs urgent care. Read the guide →
- Drooping eyelid
- An upper eyelid that sits lower than usual, also called ptosis. Read the guide →
- Dry eyes
- Eyes that feel gritty, burning or scratchy, often worse at a screen or in dry air. Read the guide →
E
- Exercise log
- A simple record of the exercises your eye care professional prescribed. Read the guide →
- Eye drops
- Drops for the eyes, from lubricating drops to prescribed medicine. Read the guide →
- Eye exercises
- Movements or tasks for the eyes, and what research does and doesn't show about them. Read the guide →
- Eye exercise myths
- Common claims about eye exercises and what the evidence says. Read the guide →
- Eye strain
- Tired, aching or uncomfortable eyes after long close work, also called digital eye strain. Read the guide →
- Eye test
- A check of your vision and eye health by an optometrist or optician, and how often to have one. Read the guide →
- Eye twitching
- A small, repeated flicker of the eyelid, also called myokymia. Read the guide →
F
- Floaters
- Small specks or threads that drift across your vision. A sudden shower of new floaters or flashes of light needs urgent care.
G
- Glaucoma
- A group of conditions that damage the optic nerve, often without early symptoms, which is why regular eye exams matter.
H
- Headache
- Pain in the head, which people sometimes notice alongside eye strain. Read the guide →
- Hyperopia
- Long-sightedness: things up close look less clear than things far away.
L
- Light sensitivity
- Discomfort in bright light, also called photophobia. Read the guide →
M
- Myopia
- Short-sightedness: things far away look less clear than things up close. Read the guide →
O
- Ophthalmologist
- A medical doctor who specialises in eyes and eye surgery.
- Optometrist
- An eye care professional who examines eyes, tests vision and prescribes glasses or contact lenses.
- Orthoptist
- An eye care professional who assesses eye movements and how the two eyes work together.
P
- Pencil push-ups
- A near-focus exercise where a pencil is moved slowly toward the nose. Read the guide →
- Photophobia
- The medical word for light sensitivity. See Light sensitivity
- Presbyopia
- The gradual loss of near focus with age, usually noticed after about 40. Read the guide →
- Ptosis
- The medical word for a drooping eyelid. See Drooping eyelid
R
- Red eye
- Redness in the white of the eye. A red eye with pain or changed vision needs urgent care. Read the guide →
S
- Screen time
- The hours spent looking at phones, computers and other screens. Read the guide →
- Sleep
- How long and how well you slept, which many people note next to how their eyes feel. Read the guide →
- Strabismus
- When the eyes don't point in the same direction, also called a squint.
T
- Tear film
- The thin layer of tears that covers and protects the front of the eye.
- Tired eyes
- Eyes that feel heavy, achy or worn out, often late in the day. Read the guide →
U
- UV protection
- Shielding the eyes from ultraviolet light, for example with sunglasses that block 100% of UV. Read the guide →
V
- Visual acuity
- How clearly you see detail, usually measured with a letter chart.