Getting Used to New Glasses: What’s Normal in the First Two Weeks and When to Come Back
13 October 2026
07:18
Astigmatism is one of those words that sounds far more alarming than it is. People hear it at the end of an eye test, assume it is a condition they have developed, and occasionally go home and look it up expecting bad news.
It is not a disease. It is a description of shape. And it is so common that a large proportion of the people reading this have some degree of it, whether or not anyone has ever mentioned it to them.
What it does do is explain a specific and very recognisable set of complaints, particularly at night, which is why it comes up so often in our night driving article and why it deserves a proper explanation of its own.
They were not, and it is one of the most common and consequential misunderstandings we come across.
Diabetic eye screening is an excellent programme and everybody eligible should attend. It is also a narrow test that was never designed to do the job of an eye examination, and a great many people with diabetes are attending one and skipping the other without realising there is a gap.
A well-shaped eye is curved evenly, like the surface of a football. Light entering it comes to a single sharp focus.
An eye with astigmatism is curved slightly unevenly, more like the surface of a rugby ball: more steeply curved in one direction than the other. Light passing through it does not come to one focus. It comes to two, in slightly different places, and the result is that nothing is ever perfectly sharp — there is always a small amount of smearing in one direction.
That is the whole of it. Most astigmatism comes from the shape of the cornea, the clear front surface of the eye. Some comes from the lens inside. It is usually present from early life, it tends to be stable, and it is very often inherited.
Astigmatism is not caused by reading in poor light, sitting close to screens, squinting, or anything else you may have been told as a child. None of those cause it.
This is the part that explains almost everything people find confusing about their own vision.
In bright conditions your pupil is small. A small pupil only lets light through the central part of the cornea and lens, which acts rather like the small aperture on a camera: it increases depth of focus and masks small optical imperfections. Your brain does the rest, sharpening up an image that is not quite perfect.
At dusk and at night, your pupil opens wide. Now light passes through much more of the eye, including the peripheral parts where the uneven curvature has more effect. The imperfection that daylight was hiding is suddenly doing real work, and every bright point of light — a headlight, a street lamp, a traffic signal — smears into a streak, a star or a cross.
Which is why so many people say the same sentence: my eyes are fine, it is just driving at night that has got harder.
What you notice | Why astigmatism causes it | What helps |
|---|---|---|
Headlights streak or starburst at night | Wide pupil exposes uneven focus | Accurate correction plus AR coating |
Squinting to sharpen distant text | Squinting narrows the effective aperture | Glasses or toric lenses |
Eye strain after reading or screens | Constant effort to compensate | Correction; check working distance |
Headaches late in the day | Sustained focusing effort | Correction; rule out binocular causes |
Tilting the head to see clearly | Aligning with the clearer meridian | Correction |
Vision fine by day, poor at dusk | Pupil size changes with light | Correction; this is the classic pattern |
Being told “only a small amount” | Small amounts still matter at night | Worth correcting for driving at least |
The last row is worth dwelling on. “Only a small amount” is true as a description of the number and misleading as a description of the effect, because the effect is concentrated exactly where you need vision most: low light, high contrast, moving.
Astigmatism shows up as two extra numbers alongside your main prescription: a cylinder value and an axis.
A common source of confusion: a high axis number does not mean severe astigmatism. It is a compass bearing, not a severity score. Our article on understanding your glasses prescription breaks down the full set of numbers.
Straightforward. The lens is made with a matching uneven curvature that cancels out the eye’s, which is why astigmatic lenses have to be fitted in the correct orientation and why the axis matters so much.
One thing to expect: if you have been uncorrected for a long time, new astigmatic correction can feel odd for a few days. Floors can seem to slope slightly, or doorways lean. It settles quickly as the brain recalibrates, and it is not a sign the prescription is wrong. Tell us if it persists beyond a week.
Yes, and this is worth saying loudly because a great many people were told otherwise years ago.
Toric contact lenses correct astigmatism and are now widely available, including as daily disposables. They are weighted or shaped so that they settle into a consistent orientation on the eye rather than rotating freely. If you were turned away from lenses because of astigmatism at some point in the past, that advice is very likely out of date. Our contact lens guide covers the options, and the contact lens service page explains fitting.
Two things help, and they are cumulative. An accurate correction, and an anti-reflective coating on the lenses, which cuts the internal reflections that would otherwise add their own ghosting on top. Details on lens options are in advanced lenses.
Worth a specific note, because children do not report it.
A child with uncorrected astigmatism has no idea that anyone sees differently. What shows up instead is behaviour: reluctance with reading, head tilting, squinting, difficulty copying from a board, or being described as not concentrating. Significant astigmatism in early childhood can also affect visual development if it goes uncorrected, which is one of the reasons for testing children before they can read.
Our children’s eye test guide covers what age to start and what gets checked, and the children’s eyecare page explains how we test young children.
If any of the signs in the table are familiar, particularly the night-driving pattern, an eye examination is the way to find out. Ours run forty minutes, and refraction is done carefully rather than quickly, because small astigmatic corrections are precisely the thing a rushed appointment rounds off.
Tell us what you have noticed rather than waiting to be asked. “Headlights have started streaking” directs the examination far better than “fine, thanks”. Our walkthrough of what happens at an eye test explains each stage if you want to know what to expect.
Book your comprehensive eye examination or eyewear styling consultation with
Mosspark Opticians today.
Astigmatism means the eye is curved slightly unevenly, more like a rugby ball than a football, so light comes to two focal points instead of one. It is a description of shape rather than a disease. It is very common, usually present from early life, often inherited, and it does not damage the eye.
Mostly the natural shape of the cornea, the clear front surface of the eye, and sometimes the lens inside. It is frequently inherited and usually present from early life. It is not caused by reading in poor light, screen use, squinting or any habit, despite what many people were told as children.
Because pupil size changes. In bright light your pupil is small, which increases depth of focus and masks small optical imperfections. At night the pupil widens, light passes through more of the eye including the peripheral parts, and the uneven curvature starts to matter. That is why headlights streak while daytime vision seems perfectly good.
Yes. Toric contact lenses correct astigmatism and are widely available, including as daily disposables. They are designed to settle into a consistent orientation rather than rotating on the eye. If you were told years ago that astigmatism ruled out lenses, that advice is very likely out of date.
Two values appear alongside your main prescription. The cylinder (CYL) is how much astigmatism there is, and the axis is its orientation, written between 1 and 180. The axis is a direction, not a severity score, so a high axis number does not mean severe astigmatism.
It is usually fairly stable through adult life. Changes do happen, which is one reason examinations are recommended every two years, but steady progressive deterioration is not the typical pattern. In children it can change as the eye develops.
If you have been uncorrected for a long time, new astigmatic correction can make floors seem to slope or doorways lean for a few days. It is the brain recalibrating and it settles quickly. It is not a sign the prescription is wrong, but tell your optometrist if it persists beyond about a week.
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