Those spiky rays or streaks that seem to shoot outward from headlights, streetlamps, or bright screens are caused by the diffraction of light as it passes through the structures of your eye. Nearly everyone sees some version of this effect, and it becomes more pronounced at night or in dim environments when your pupils widen. While starbursts around lights are often completely normal, the severity, pattern, and sudden appearance of these lines can signal conditions ranging from dry eyes to cataracts to refractive changes that deserve attention.
How Your Eye’s Lens Creates Starburst Lines
For decades, researchers assumed that starbursts were mainly a product of optical imperfections called higher-order aberrations, particularly spherical aberration, where light passing through different zones of the lens focuses at slightly different points. That explanation turns out to be incomplete. More recent research points to the physical structure of the crystalline lens itself as the dominant source. Your eye’s natural lens is not a uniform piece of glass; it is built from long, tightly packed fiber cells that meet at junctions called sutures. These suture lines act like the struts inside a camera, diffracting incoming light and creating the characteristic spike pattern people recognize as a starburst.1Journal of the Optical Society of America A. Entopic starburst in vision: revisiting the role of diffractive lens suture patterns
This is the same physics that produces diffraction spikes in photographs of bright lights. When light squeezes past the edges of an aperture or structure, it spreads into rays along axes perpendicular to those edges. Brighter light sources produce more visible spikes, which is why you notice the lines more around oncoming headlights than around a candle across the room.2Scientific Reports. Computational Imaging Prediction of Starburst-Effect Diffraction Spikes The number and arrangement of the rays you see relates to the geometry of your own lens sutures, which varies a bit from person to person. That is why two people looking at the same streetlamp may describe slightly different starburst patterns.
Why the Lines Get Worse at Night
If you notice the lines mostly while driving after dark or walking through a parking lot, you are experiencing the effect of pupil dilation. In dim lighting, your pupil opens wider to let in more light. That wider opening means light passes through a larger area of the lens, including the outer zones where optical imperfections and suture patterns are more pronounced. The result is more prominent starbursts, halos, and streaks compared to daytime, when your pupil is small and light travels through the relatively clean center of the lens.3Optician. CPD: Why vision errors get worse at night
This also explains why younger people sometimes notice stronger starbursts than older adults in the same conditions. Younger eyes tend to dilate more widely in the dark, exposing more of the lens to incoming light. As pupils naturally become less responsive with age, the trade-off shifts: you lose some night-vision sensitivity but may also lose some starburst intensity, at least until lens aging introduces new problems like cataracts.
Dry Eyes and the Tear Film
Your tear film is the eye’s outermost optical surface, and it is surprisingly important to image quality. A smooth, stable layer of tears acts like a well-polished windshield. When that layer breaks down, which happens with dry eye disease, the irregular surface scatters incoming light and produces visual disturbances such as glare, streaks, and a sense that lights have a smeared halo. People with dry eyes often describe their vision as fluctuating with each blink because the tear film briefly smooths out and then destabilizes again.4PubMed. Mechanisms of Visual Disturbance in Dry Eye
This is worth knowing because dry eye is extremely common and often underdiagnosed. If you have noticed that lines around lights are worse at the end of a long workday, after staring at a screen for hours, or in dry air-conditioned environments, tear film instability is a strong suspect. The good news is that this is one of the most treatable causes. Lubricating drops, prescription anti-inflammatory eye drops, or even simple environmental changes like humidifiers and screen breaks can improve the optical quality of the tear layer and reduce the streaking effect.
Uncorrected or Shifting Prescriptions
An outdated glasses or contact lens prescription is one of the most mundane yet overlooked causes of prominent lines around lights. Astigmatism, where the cornea or lens is shaped more like a football than a basketball, is particularly associated with streaks and elongated halos. Even a small amount of uncorrected astigmatism can produce noticeable directional streaking, where the rays appear to radiate in a consistent orientation (often vertically or diagonally) because the asymmetry of the cornea bends light preferentially along one axis.
Research on how the eye’s optical aberrations change with focusing effort shows that the picture is dynamic. When your eye accommodates, adjusting its lens to focus on something closer, the pattern and magnitude of aberrations can shift, though the direction of change is not the same for everyone.5PubMed Central. Real-Time Measurement of Ocular Wavefront Aberrations in Symptomatic Subjects This means the lines you see may look somewhat different when you glance at a nearby phone screen versus a distant traffic light. If starbursts are bothering you and your prescription is more than a year or two old, an updated refraction may resolve or substantially reduce the problem.
After LASIK or Cataract Surgery
Complaints about lines, halos, and starbursts around lights are one of the most common concerns people bring up after refractive or lens-replacement surgery. In LASIK, a laser reshapes the cornea to correct vision, and that reshaping can introduce subtle irregularities at the boundary between treated and untreated corneal tissue. These irregularities act as diffraction edges, scattering light into streaks, especially when the pupil dilates beyond the treated zone at night. One study of 250 eyes found a small but statistically meaningful increase in higher-order aberrations after modern wavefront-guided LASIK, with the pattern of those aberrations linked to eye movement during the laser treatment.6PubMed Central. Higher-Order Aberrations Following Ray Trace LASIK and the Impact of Eye Movement on Coma
Cataract surgery involves removing the clouded natural lens and replacing it with an artificial intraocular lens, and the visual side effects after this procedure have their own name: dysphotopsias. Patients describe them as glare, streaks, starbursts, arcs, rings, and halos. The immediate numbers are striking: up to two-thirds of patients notice these effects right after surgery. But the vast majority resolve on their own. Persistent symptoms lasting beyond a year affect only about 2% of patients.7PubMed Central. Dysphotopsias or Unwanted Visual Phenomena after Cataract Surgery So if you recently had cataract surgery and are seeing prominent rays around every light, patience is the most evidence-based response, though flagging it to your surgeon is still wise.
Multifocal intraocular lenses, designed to reduce the need for reading glasses after cataract surgery, tend to produce more noticeable halos and starbursts than simpler monofocal lenses. The reason is built into the design: multifocal lenses split light into multiple focal points, and that splitting creates concentric rings of unfocused light around bright sources. For some people the trade-off is worth it; for others, particularly those who drive frequently at night, a monofocal lens with reading glasses may be a better fit. This is worth discussing with your ophthalmologist before surgery rather than after.
Cataracts and Other Lens Changes
If the lines around lights have been gradually worsening over months or years, especially if you are over fifty, early cataracts are a likely explanation. A cataract is a clouding of the natural lens, and it does not have to be visually dramatic to affect how light passes through the eye. In the early stages, the clouding is often uneven, creating zones of different density that scatter light in much the same way a dirty windshield does. People often report that night driving becomes harder long before their daytime vision seems obviously impaired.
Cataracts develop at different rates and in different parts of the lens. A posterior subcapsular cataract, which forms at the back surface of the lens, is especially known for causing glare and starbursts because of its position directly in the light path. Nuclear cataracts, which develop in the center of the lens, may initially cause a temporary improvement in near vision (the so-called “second sight”) before the increasing density starts scattering light. The type, location, and density all influence whether you see diffuse halos, directional streaks, or a general washed-out glare around lights.
When the Lines Come from Your Brain, Not Your Eyes
Not all visual disturbances originate at the eye’s optical surface. Migraine with aura is a neurological condition that can produce its own version of visual light phenomena. The classic migraine aura involves flashing lights, zigzag lines, or shimmering patterns that typically build over several minutes and then resolve, often followed by a headache. These symptoms arise from a wave of altered electrical activity that slowly sweeps across the visual cortex at the back of the brain, disrupting normal visual processing as it goes.8PubMed Central. Neuro-ophthalmology and migraine: visual aura and its neural basis
The visual effects of migraine aura are quite different from optical starbursts. Migraine aura typically affects part of the visual field (not just the area around a light source), moves or expands over minutes, and appears whether your eyes are open or closed. If you close your eyes and still see shimmering zigzag lines, that is a strong clue the origin is neurological. Optical starbursts, by contrast, are anchored to the light source: they follow the light when you move your head and disappear when you close your eyes or look away. This distinction matters because the causes and treatments are entirely different.
Flashes of Light vs. Starburst Lines
People sometimes confuse starbursts with flashes of light, but these are distinct phenomena with different implications. A flash, or photopsia, is a brief burst of light that appears even when no external light source is present. You might see it as a lightning bolt in your peripheral vision or a quick arc near the edge of your sight. The most common cause in middle-aged and older adults is posterior vitreous detachment, where the gel inside the eye shrinks and tugs on the retina. In a study of patients with this condition, the flashes were overwhelmingly seen in the peripheral (temporal) field, lasted only seconds at a time, and appeared as vertically oriented streaks.9PubMed. Discriminate characteristics of photopsia in posterior vitreous detachment, retinal tears and retinal detachment
Posterior vitreous detachment is usually harmless, but the same tugging that causes flashes can occasionally tear the retina, and a retinal tear can lead to a retinal detachment if untreated. New flashes, especially when accompanied by a sudden increase in floaters or a shadow creeping across your vision, warrant an urgent eye exam. Starbursts around headlights, on the other hand, are usually a chronic optical issue rather than an emergency. The key question to ask yourself is: does the light disturbance happen only when I am looking at a bright light source, or does it happen in the dark or with my eyes closed? The answer separates optical starbursts (tied to a light source) from flashes (generated by the retina or brain).
How Glasses, Contacts, and Coatings Affect Starburst Appearance
Your eyewear can either reduce or worsen lines around lights, depending on its condition and fit. Scratched lenses are a surprisingly common culprit. Each scratch acts as a tiny diffraction edge, scattering light into streaks. Smudges and fingerprints have a similar but more diffuse effect, producing halos and general glare rather than defined rays. If your starbursts are worse with your glasses on than with them off, the lenses themselves deserve inspection.
Anti-reflective coatings, when in good shape, help reduce the internal reflections within a lens that can produce ghost images and additional starburst-like artifacts. But these coatings degrade over time, especially when cleaned with abrasive materials, and a damaged coating can actually make glare worse than no coating at all. Contact lenses can affect starbursts too, particularly if they are depositing protein buildup, fitting poorly, or drying out on the eye. A well-fitted, clean contact lens that fully covers the pupil typically reduces starbursts compared to wearing nothing at all, because it smooths out mild corneal irregularities.
Telling Normal from Concerning
Given how many causes can produce lines around lights, the practical question is when to simply accept them as a quirk of your visual system and when to bring them up with an eye care provider. Some guidelines are useful here.
- Longstanding and stable: If you have always seen mild starbursts around bright lights and the pattern has not changed, this is likely just how your lens sutures diffract light. No action needed.
- Worse after screen time or in dry environments: Dry eye is the most probable cause. Try preservative-free lubricating drops and see if the effect improves.
- Gradually worsening over months: An outdated prescription or early cataracts are worth checking. A routine eye exam can catch both.
- New after surgery: Post-LASIK or post-cataract starbursts are common in the early recovery period. Mention them at your follow-up, but know that most resolve within weeks to months.
- Sudden onset with floaters or a visual shadow: This pattern suggests possible retinal involvement. See an eye doctor the same day or the next.
- Accompanied by eye pain, redness, or colored halos: Halos with a rainbow tint and eye pain can indicate a sudden rise in eye pressure, which is an emergency. Go to an urgent care or emergency room.
A standard comprehensive eye exam, which includes dilation, can evaluate your tear film, corneal surface, lens clarity, retina, and optic nerve in one visit. If the cause is not obvious from a routine exam, your provider may use wavefront aberrometry, a test that maps the specific optical imperfections of your eye to identify what is driving the light disturbance. This kind of targeted testing is especially helpful when the complaint does not match the usual suspects.
The Role of Screen Habits and Modern Lighting
Something that rarely comes up in clinical discussions but matters in daily life is how modern lighting affects the perception of starbursts. LED headlights, now standard on most new vehicles, emit a bluer, more intense beam than older halogen headlights. Blue light scatters more than warmer wavelengths as it passes through optical imperfections, which means the same degree of corneal or lens irregularity produces more noticeable streaking from an LED headlight than from a halogen one. If you feel like night driving has gotten harder over the past several years even though your prescription has not changed, the shift in headlight technology may be part of the explanation.
Prolonged screen use also contributes indirectly. People blink about half as often when staring at a screen, which accelerates tear film breakdown and increases the surface irregularities that scatter light. The effect accumulates over the day: someone who has spent eight hours at a computer may find that their evening drive home involves noticeably worse starbursts than their morning commute, even though their eyes and prescription are exactly the same. This daily cycle of worsening and recovery is a hallmark of tear-film-related light disturbance, and recognizing it can save you an unnecessary worry about cataracts or other progressive conditions.