Why Do Headlights Look So Blinding? 4 Treatable Causes of Glare

If oncoming headlights seem blinding, or bright light leaves you squinting and looking away, you are far from alone. Glare from headlights at night is one of the most common symptoms I hear about in my cataract clinic here in the West Midlands — and it is often present for years before it's properly investigated. I'm Mr Dilraj Sahota, a consultant ophthalmic surgeon trained at Oxford and Moorfields Eye Hospital, and I perform cataract surgery regularly. The reassuring news is that in a great many cases, glare points to a specific, treatable cause. Here are the four I see most often. If it's already affecting your driving or daily life, you can schedule online for an assessment.

The most frequently overlooked cause of glare isn't inside the eye at all — it's on the surface. The tear film coating the front of your eye is an optical surface in its own right. When it's smooth and stable, light passes through cleanly. When it's thin, uneven, or breaks up quickly between blinks — as happens in meibomian gland dysfunction (MGD) and dry eye disease — it becomes an irregular, unstable refracting surface.

Think of looking out of your car windscreen: instead of being clear, it's frosted or smeared. Light scatters in multiple directions, producing glare and vision that seems to fluctuate through the day. You may feel you need to blink to clear it.

MGD is extremely common. Studies suggest it affects a significant proportion of people over 40, though the reported prevalence varies between populations and studies. What the evidence consistently shows is that it is regularly underdiagnosed.

A useful self-check — an unstable tear film may be the cause if:

• Your vision is good sometimes, but the glare varies through the day
• Your vision briefly clears when you blink
• You've been told your eyes "look normal," yet the glare persists

The good news is that this is treatable without surgery. Ask your optometrist for a tear film assessment. Warm compresses and preservative-free ocular lubricants are the established first-line therapy. 

Causes two and three are inside the eye, in the natural lens, and each produces glare in a structurally specific way.

The natural lens has many layers, like an onion. The fleshy layer around the inner core is called the cortex. Cortical cataracts form as wedge-shaped, spoke-like opacities that spread from the periphery of the lens inward — picture the spokes of a bicycle wheel. As light enters the eye and strikes these spokes, it scatters, producing glare. You might notice halos or a starburst effect around headlights when driving at night, and a washed-out quality to images in bright light.

Cortical cataract is the type most consistently associated with glare. Patients report glare as one of their main problems even when the cataract is quite early — small cortical changes can cause disproportionately significant glare, which is exactly why it's worth pursuing a diagnosis even if your general vision still seems fine. Cortical cataract accounts for around one in five age-related cataracts.

For comparison, nuclear cataract — affecting the inner core of the lens — tends to cause gradual dimming, blurring and changes to colour. Some light sensitivity can occur, but it isn't the predominant feature and isn't as intense as the glare of cortical cataract.

If your main symptom is overwhelming glare from oncoming headlights or bright sunlight, ask your optician to look specifically for cortical cataract on the slit lamp. When glare starts affecting your safety or quality of life, cataract surgery is an effective treatment, and the outcomes are usually excellent.

The third cause is a less well-known type of cataract that can be even more disabling — and it can affect people in their 40s and 50s, sometimes coming on quite rapidly.

Posterior subcapsular cataract (PSC) sits right in front of the capsule at the back of the lens. Because it occupies a central position directly along the path of light entering the eye, it produces pronounced glare in bright light, difficulty reading, and halos around bright lights. Patients often describe feeling uncomfortable driving at night and finding bright lighting intolerable. Unlike nuclear cataract, which develops over many years, PSC can come on quite quickly.

PSC has some well-established associations:

• Long-term corticosteroid use — the most established association — including steroid tablets taken long term for other conditions, steroid creams used around the eye, or steroid eye drops
• Diabetes
• Previous eye (ocular) trauma
• Short-sightedness (myopia) — I also see myopic patients develop cataracts sooner than the average population

If you or a family member take steroid medication regularly and you're experiencing glare or difficulty reading, it's worth an ophthalmic assessment. PSC can be subtle in the early stages, so don't assume it's too early or too mild to matter — if it's affecting your day-to-day life, cataract surgery is the definitive treatment.

The first three causes affect the natural lens. The fourth is different: it only affects people who have already had their cataract removed. If that's you, this is worth knowing about — because it's something I see regularly in clinic, and it almost always comes as a genuine relief.

If your vision was excellent after cataract surgery and is now slowly becoming less clear, with the glare returning, that is not your cataract coming back. Cataracts cannot return once they've been removed. It's almost certainly something different — and it's fixable.

The likely culprit is posterior capsular opacification (PCO), the most common complication after cataract surgery. When we remove a cataract, we leave the capsule in place — a thin membrane that holds your new artificial lens. In some people, cells gradually grow across the surface of this capsule, behind the lens, causing it to cloud over. This typically happens months or years after the original operation, and because the cloudiness sits directly behind the lens, it causes glare and haziness.

According to data from Moorfields Eye Hospital and the RNIB, around one in five patients develop PCO within three years of cataract surgery.

The treatment is YAG laser capsulotomy — a brief, painless outpatient procedure. Using a laser, we create an opening in the cloudy capsule to let light through again. There are no incisions, it's painless, and most patients notice their vision return within a couple of days. If you've had cataract surgery with good initial vision that has slowly deteriorated since, and you don't have another known eye condition, PCO is the most likely cause — and it's very treatable. Contact your ophthalmologist or surgical team.

One important distinction before you go. Everything above describes optical glare — light scattering off the eye's surface or a cloudy lens. That's different from photophobia: genuine light sensitivity, usually in an eye that is also red or painful.

⚠️ See an ophthalmologist urgently if your eye is acutely red, painful, or genuinely sensitive to light. A red, painful, light-sensitive eye is not cataract or dry eye. Important causes to exclude include uveitis (inflammation inside the eye) and a corneal ulcer (an infection of the front window of the eye).

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• Glare usually has a specific, treatable cause — you don't have to put up with it
• An unstable tear film (dry eye / MGD) is the most overlooked cause and is treatable without surgery
• Cortical cataract is the cataract most strongly linked to glare, often even when early
• Posterior subcapsular cataract can affect younger people and is linked to steroid use, diabetes, trauma and myopia
• After cataract surgery, returning glare is usually PCO — treated quickly with YAG laser, not a returning cataract
• A red, painful, light-sensitive eye needs urgent assessment

Frequently asked questions

Can glare be treated without surgery?

Often, yes. If the cause is an unstable tear film or dry eye, warm compresses and preservative-free lubricants are the established first-line treatment, with no surgery needed. Where glare is caused by a cataract or PCO, a procedure is usually required — but in the case of PCO, that's a quick, painless laser treatment.

Why do I see halos or starbursts around headlights?

Halos and starbursts appear when light scatters inside the eye instead of focusing cleanly. In cortical cataract, light strikes the spoke-like opacities spreading in from the edge of the lens and scatters; in posterior subcapsular cataract, the opacity sits centrally, directly in the path of light. Both scatter light into the halos and starbursts you notice around oncoming headlights at night.

Can a cataract come back after surgery?

No. Once a cataract has been removed it cannot return. If glare and haziness come back months or years after successful cataract surgery, the usual cause is posterior capsular opacification (PCO), which is treated with a brief YAG laser procedure.

When should I see a doctor about glare?

If glare is affecting your reading, your driving or your daily life, it's worth getting checked — you don't have to live with it. Seek urgent review if your eye is red, painful, or sensitive to light, as that points to a different problem.

This article is for general information and patient education. It is not a substitute for a personal consultation, diagnosis or treatment from a qualified clinician. If you have concerns about your eyes, please see your optometrist or an ophthalmologist.​

Last updated: June 2026