Headaches behind the eyes: when your glasses are the cause

Glasses can cause headaches behind the eyes, and it is more common than people expect. The three usual reasons are a prescription that has drifted out of date, lenses centred in the wrong place for your pupils, and a frame that squeezes the sides of the head. All three share the same pattern: the ache builds through the day and eases when you take the glasses off.

Here is how to tell which one you have, and what to do about it.

First, rule out the serious causes

A sudden severe headache, pain with nausea or vomiting, pain in one eye only, halos around lights, or any change in your vision needs an eye hospital today, not a blog post and not an optician. Everything below assumes the dull, tiring ache that shows up mid-afternoon and goes away by bedtime.

Cause one: the prescription is old

Eyes change. A lens that was right three years ago may now be a quarter or half a dioptre off, and your eye muscles spend the day compensating. That effort is the headache.

The self-check: hold your glasses up and look at a distant sign through them. If it is sharp only when you tilt or angle the lens, the power is off. If small print on a bottle takes a moment to snap into focus, same thing. The proper check is a retest, which is free at our Lalitpur showrooms. We suggest every two years for adults, yearly if you have diabetes.

Cause two: the lenses are centred wrong

Every lens has an optical centre that should sit exactly in front of your pupil. The distance between your pupils is called the PD, and if the lab cut the lenses for a PD a few millimetres off, both eyes are looking through the edge of a prism all day. The result is a pulling feeling, sometimes mild double vision, and a headache that sits right behind the eyes.

This happens most with glasses bought without a measured PD. Our post on measuring pupillary distance at home shows the ruler method. If your measurement and the number on your order differ by more than 2 mm, that is likely your headache. We remake lenses centred correctly, and if we made the original, we do it free.

Cause three: the frame is too tight

Look at the sides of your head when you take the glasses off in the evening. Red marks or a dent above the ear mean the temples are pressing. The pressure builds into a tension headache that feels like it sits behind the eyes and at the temples.

The fix is a two-minute adjustment. Acetate temples are warmed and opened slightly; metal temples are bent. We do this free for any pair, ours or not. If the frame is simply too narrow for your head, a wider one like the Premium Round Aviator Frame at NPR 1,800 solves it for good.

The one-hour test for headaches behind the eyes

Do the same work you always do, but take the glasses off for an hour in the afternoon. If you can manage without them and the ache lifts, the glasses are involved. If it stays, look at the screen instead: distance under 50 cm, brightness far above the room, and no breaks are the usual suspects. Our post on why regular eye exams matter covers what a check-up catches beyond the prescription, and the desk setup guide covers the screen side.

What usually fixes it

Tauko dukhne and chasma: what we see in Lalitpur

A pattern from our showroom, for anyone who searches this in Nepali. The people who come in with afternoon headaches fall into three groups.

The first bought glasses at a stall or online without a proper test, and the power is simply wrong. The fix is a free retest and new lenses, often into the same frame.

The second have a correct power but a pupillary distance that was guessed. Their glasses feel fine in the morning and pull by three o'clock. We remeasure, and if the difference is more than 2 mm we recut the lenses.

The third have new progressives and are in the adaptation week. Nothing is wrong; the brain is learning the lens. We ask them to wear the glasses full time for ten days before deciding anything.

What none of them had was an eye disease. That is the reassuring part. The rare cases with sudden pain, nausea or vision loss we send straight to an eye hospital, and so should you.

In our experience the order is: retest first, because a wrong power is the most common cause; then check the PD on the order; then adjust the fit. Most afternoon headaches are gone within a week of the right lens going in. If nothing changes after new glasses and a correct fit, the cause is somewhere else and a doctor should look.