Why do my sunglasses give me a headache? Six causes, in order of likelihood

A headache from sunglasses is almost always caused by the frame, not the lens. Temples that clamp the sides of the head, arms that press behind the ears, and weight bearing on one point of the nose are the three usual causes, and a frame that fits your face width removes all of them. Less often the lens is at fault: a cheaply made lens that distorts, or a tint too dark for the light you are in. Polarized lenses do not cause headaches by themselves. Here are the six causes, in order of how often they are the answer, with a test for each.

1. Temples too tight

The most common cause. A frame narrower than your head presses on the temples, just in front of the ears, and after an hour that becomes a band of ache. It is worst with plastic frames that do not adjust.

Test: take the glasses off. If the ache eases within ten to fifteen minutes and there are faint marks at the temples, this is it.

Fix: a wider frame. Frame width, hinge to hinge, should be within about 10mm of the width of your face at the cheekbones. Our measurements post shows how to measure. An optician can also gently widen most plastic frames with heat, but a frame that is the wrong size will keep creeping back.

2. Pressure behind the ears

Temple arms that bend down too sharply or too early dig in behind the ear. Same band of ache, further back.

Test: the tenderness is behind the ear rather than at the temple.

Fix: arms that bend later or more gently. This is a fit adjustment an optician can make in a minute on most frames.

3. Weight on the nose

A heavy frame, or a light one whose bridge sits on a single point rather than spreading the load, aches across the bridge of the nose and sometimes up into the forehead by afternoon.

Test: red marks or tenderness on the nose; the ache builds over the day.

Fix: a lighter frame, or a bridge that fits your nose. Plastic frames are light; metal ones with glass lenses are not. Adjustable nose pads help if the frame has them. Our slipping post covers bridge fit from the other direction.

4. Lens distortion

A poorly made lens bends light unevenly. Your eyes compensate all day, and the compensation is the headache. This is the one lens cause that is common, and it is a quality problem, not a tint problem.

Test: hold the glasses at arm's length and look through one lens at a straight edge, a door frame or a tile line, while moving the glasses slowly side to side. A good lens keeps the line straight. A bad one bends it or makes it swim.

Fix: a better lens. Distortion cannot be adjusted out. Our post on cheap sunglasses has the same test and explains what price does and does not buy.

5. Tint too dark for the light

A very dark lens worn in ordinary light, or indoors, makes your eyes work to see and can bring on an ache, especially in people prone to it. The reverse is also true: a lens too light for glare leaves you squinting, and squinting for hours is a headache in itself.

Test: the ache appears in particular light and not in others.

Fix: match the tint to the light. A medium lens for everyday, a darker one for water and snow only. The lens colour guide covers the range.

6. Adjusting to polarized

Polarized lenses do not cause headaches. What some people notice with a first polarized pair is that the world looks different: glare is gone, some screens look odd, and the change is briefly disorienting. That passes in a day or two. A headache that persists with a polarized pair is one of the causes above, not the film.

There is one exception worth naming: if the polarizing film in a cheap lens is laminated with a distortion, that is cause 4 again, and the test in cause 4 will show it.

What is not the cause

• UV. A lens with no UV protection is bad for your eyes over years, not a headache today.
• Colour. No tint colour causes headaches by itself. Brown, grey and mirrors are all fine.
• The polarizing film, as above.

Where our frame sits

The T01 is a light plastic frame with a 140mm front, which suits a face of roughly 130 to 150mm. On a narrow face it will press at the temples: cause 1. If that is you, it is the wrong frame width, and no lens will fix it. On a face it fits, the lens is laminated tri acetate cellulose, which passes the straight-line test. Every product page lists the measurements.

Frequently asked questions