Cataract Symptoms

Blurry or cloudy vision that a new prescription no longer sharpens, glare in sunlight and from oncoming headlights, haloes around lights at night, colours that look washed out or yellowed, needing more light to read, and a spectacle prescription that keeps changing. They come on over months or years rather than suddenly.

You cannot confirm one yourself, but three things are worth noticing. Cover one eye and then the other and compare — a cataract is usually further along in one eye than the other. Ask what has become harder rather than what looks blurred: night driving, a menu in dim light, telling navy from black. And ask whether a recent new prescription helped for a few months and then stopped. Any of those is a reason to have the lens looked at through a slit lamp, which is a routine part of an eye examination.

There is no single first sign, because it depends on where in the lens the clouding starts. Glare and haloes at night are often noticed before anything shows on a distance chart; in other eyes it is distance vision or colour that goes first, and in others still it is reading in ordinary light. What the early signs share is that they are gradual and easily attributed to tiredness or to needing new glasses.

Less like a smudge on a lens and more like looking through a misted window: contrast falls away, edges soften, bright lights spread rather than staying as points, and colours lose some of their separation. It is not a dark patch or a blind spot, and it does not move when you move your eye.

Lights spread. Street lamps and oncoming headlights grow haloes or starbursts, and the glare can make them hard to look at. Contrast falls too, so dark shapes on a dark road are harder to pick out. Night driving is often the first thing people notice becoming harder.

It depends on how much it affects your sight. If a cataract is affecting your vision — glare from oncoming headlights, blur, or trouble seeing the road at night — stop driving for safety reasons and consult an eye doctor soon.

It can be. Cloudy or hazy vision is how many people describe a cataract, because the lens itself is clouding. But dry eye, an out-of-date prescription and changes at the macula can make vision look cloudy too, so it is a reason to have your eyes examined rather than a diagnosis.

It can, and the pattern is distinctive: the doubling is in one eye and stays when the other eye is covered. That happens when the clouding is uneven enough to split light into more than one focus. Double vision that disappears when either eye is covered comes from the two eyes not aligning, which is a different problem and needs assessing on its own.

Not directly. A cataract is inside the eye and has no nerve supply that produces pain. What can produce headache or eye strain is the effort of working with vision that is no longer clear, or an out-of-date prescription being worn while the lens changes. Persistent headache is worth assessing on its own terms rather than being put down to a cataract.

No. A cataract is painless, which is one reason it goes unnoticed for so long. Eye pain, redness or a sudden change in vision is not a cataract symptom and should be examined promptly — those point to something else.

Yes, and it is common. A cataract is usually further along in one eye than the other, and the better eye can hide the difference for a long time — covering one eye at a time is the simplest way to notice it. Both eyes are usually affected in the end, because both are ageing. Blurry vision in one eye has other causes too, and if it came on suddenly it needs examining promptly.

No. Floaters are specks or threads in the gel at the back of the eye, and they drift as your eye moves; a cataract is in the lens and stays put. A sudden shower of new floaters, especially with flashes or a shadow across the vision, is not a cataract symptom and needs examining promptly.

Only when it is very advanced, and by then it has usually affected vision for a long time. A dense cataract can show as a grey or white appearance in the pupil. Most cataracts, including ones that are already affecting vision, look like nothing at all from the outside and are seen only through a slit lamp.

Very rarely, and there is normally a reason — an injury to the eye, for instance. Age-related cataract develops over months to years. Vision that changes over hours or days is not typical of a cataract and should be examined without waiting.

The cataract itself does not come and go, but how much you notice it can. Bright sunlight, oncoming headlights and dim rooms make it more obvious; soft, even light makes it less so. Vision that clears completely and then blurs again points to something else, such as dry eye.