Bright rings or glare surrounding headlights, streetlights, or lamps at night can be distracting at best and disorienting at worst, especially while driving. Why do I see halos around lights is one of the more common questions optometrists hear, and the answer usually comes down to how light is scattering as it enters your eye.
The optometrists at OPTYX NEW YORK evaluate halo symptoms regularly, since the cause ranges from a simple, correctable refractive issue to something that benefits from closer monitoring. Here is what tends to be behind seeing halos around lights and when it is worth having examined.
How Halos Around Lights Actually Happen
A halo occurs when light entering the eye scatters instead of focusing to a single sharp point on the retina. Instead of a crisp point of light, you perceive a blurred ring or glow surrounding the source, which is most noticeable at night when the pupil dilates and lets in more light relative to the surrounding darkness. Some people also notice a starburst pattern radiating outward from the light source alongside the halo itself.
Because halos depend on how light travels through the eye’s optical structures, from the cornea to the lens, several different conditions can produce a similar visual effect for different underlying reasons. The size, color, and consistency of the halo can offer clues, though an eye exam is the only reliable way to pinpoint the exact cause.
Can Astigmatism Cause Halos Around Lights?
Astigmatism halos around lights are one of the most common combinations optometrists see, particularly in people with uncorrected or under-corrected astigmatism. Because an astigmatic cornea has an irregular curvature rather than a perfectly round shape, light entering the eye focuses at more than one point instead of a single point, producing streaking or halos around bright light sources.
This effect is often most noticeable at night, since larger pupils let more light pass through the irregularly shaped areas of the cornea. Updating an outdated glasses or contact lens prescription frequently resolves astigmatism-related halos, since the correction compensates for the uneven curvature causing the light to scatter.
Dry Eye and Halos
An unstable or insufficient tear film changes how light refracts as it crosses the surface of the eye, which can produce a halo effect similar to other causes. Unlike astigmatism or cataracts, dry-eye-related halos often fluctuate throughout the day and may improve temporarily after blinking or using lubricating drops.
Treating the underlying dry eye, rather than assuming a prescription change is needed, often reduces this particular type of halo. Lubricating drops used consistently throughout the day, rather than only when symptoms flare, tend to produce more noticeable improvement.
Other Causes Worth Knowing
A few less common but important causes can also produce this symptom and are worth ruling out during an eye exam.
- Glaucoma, particularly acute angle-closure glaucoma, can cause sudden halos along with eye pain and nausea, which requires immediate care.
- Post-LASIK glare and halos, which are common in the weeks after surgery and typically fade as the eye heals.
- Certain medications that affect pupil size or lens clarity as a side effect.
- Corneal swelling or infection, which alters how light passes through the front surface of the eye.
When Halos Around Lights Need Prompt Attention
Gradual, mild halos that have been present for a while and stay roughly consistent are usually not an emergency, though they are worth mentioning at your next eye exam. Sudden halos, especially with eye pain, nausea, headache, or a red eye, can indicate acute angle-closure glaucoma, which requires immediate treatment to prevent permanent vision loss. If glaucoma is suspected, the most accurate test for glaucoma can confirm the diagnosis quickly so treatment can begin without delay.
New halos that appear suddenly and worsen quickly, or that come with any vision loss, also warrant prompt evaluation rather than waiting for a routine appointment. Keeping track of when the halos started and whether they have changed helps your eye care professional narrow down the cause more quickly.
Schedule an Eye Exam at OPTYX NEW YORK
Whether the underlying cause turns out to be a straightforward prescription update or something that needs closer monitoring, an eye exam is the only reliable way to know for certain.
OPTYX NEW YORK has 14 locations across Manhattan, Long Island, the North Fork, the Hamptons, and Westchester. Book an eye exam to find out what is behind your halos and get the correction or treatment that actually addresses it.
Frequently Asked Questions
Why do I see halos around lights at night? Halos at night are usually caused by astigmatism, early cataracts, or dry eye, since larger pupils in low light let more scattered light through the eye’s optical structures. An eye exam can identify which of these applies to your specific case. Can astigmatism cause halos around lights? Yes. Astigmatism halos around lights occur because an irregularly shaped cornea focuses light at more than one point rather than a single sharp point. Updating your glasses or contact lens prescription often resolves this type of halo. Are halos around lights a sign of cataracts? Halos can be an early sign of cataracts, particularly if they have developed gradually over months or years and are most noticeable while driving at night. An eye exam can confirm whether cataracts are the cause. Can dry eyes cause halos around lights? Yes. An unstable tear film changes how light refracts across the surface of the eye, which can create a halo effect that often fluctuates throughout the day and improves temporarily after blinking or using lubricating drops. When should I worry about seeing halos around lights? Sudden halos accompanied by eye pain, nausea, headache, or redness should be evaluated immediately, since these can signal acute angle-closure glaucoma. Gradual, mild halos are less urgent but still worth mentioning at your next exam. Will glasses fix halos around lights? If the halos are caused by uncorrected or under-corrected astigmatism, an updated glasses or contact lens prescription typically resolves them. Halos caused by cataracts or certain other conditions require a different treatment approach. Is it normal to see halos after LASIK? Mild glare and halos are common in the first few weeks after LASIK as the eye heals, and they typically fade over time. Halos that persist well beyond the normal healing period should be evaluated by your surgeon or eye care professional.
