Halos, Glare and Starbursts After Cataract Surgery

If you're researching IOL options — or you've already had surgery and you're staring at streetlights wondering if this is permanent — you've probably run into the word dysphotopsia. It's the umbrella term for the unwanted visual effects some patients see around light sources at night: halos, glare, and starbursts. I get more questions about this topic than almost any other, so let's go through it properly: how common it really is, why the numbers you read online are all over the place, what causes it, and — most importantly — what you can actually do about it.

It's not just an IOL problem

Here's something that surprises most people: night dysphotopsias aren't exclusive to intraocular lenses. Healthy, phakic (natural-lens) eyes experience them too. I have significant hyperopia and astigmatism myself, and when I'm not wearing correction, I see a starburst pattern around lights at night. My wife is moderately myopic, and she sees halos instead. Cataracts, dry eye, and uncorrected refractive errors like myopia, hyperopia, or astigmatism can all produce these effects on their own. So when a patient reports halos after implant surgery, the first question isn't "which lens did they get" — it's "is this even coming from the lens."

That said, once we're specifically talking about IOLs, there are three recognizable patterns:

• Glare — a general brightening/scattering around a light source
• Halo — a distinct ring around the light
• Starburst — spikes radiating outward from the light source

Multifocal and EDOF lenses are the designs most associated with these effects, because of how they split or stretch light to create multiple focal points. But — and this is the part people skip — even the simplest monofocal lens can produce some degree of dysphotopsia in some patients.

One more distinction worth knowing before your surgery, because it comes up in consent forms and consultations: everything above — glare, halo, starburst — falls under what ophthalmology formally calls positive dysphotopsia: unwanted extra light your visual system perceives. There's a separate, less commonly discussed category called negative dysphotopsia — a dark shadow or crescent, usually in your peripheral vision, that some patients notice after IOL surgery. It's a genuinely different phenomenon with a different likely mechanism (related to how light interacts with the edge of the IOL optic rather than how it scatters), and it doesn't respond to the same "wait for neuroadaptation" advice in quite the same way for every patient. If what you're experiencing is a shadow rather than a ring or a burst of light, say that specifically to your surgeon — it changes the conversation.

Why does "how common is it" get such wildly different answers?

If you go looking for hard numbers, you'll find studies reporting anywhere from 5% to 25% of patients experiencing night dysphotopsias. That's an enormous range for the same phenomenon, and the reason is entirely about methodology, not biology.

Two things move the number a lot:

1. The patient's own personality and how they process the sensation. Some people notice a faint ring and shrug; others fixate on it.
2. How the question is asked. Ask "Are you satisfied with your vision?" and most patients say yes. Ask "Do you see circles or rings around lights while driving at night?" — a directed question — and the positive-response rate jumps sharply. Same patients, same eyes, different framing.

So when you see a scary percentage quoted somewhere, ask yourself which kind of question generated it.

The number that actually matters: how many people get the lens removed over this

How often a symptom is noticed is not the same as how often it is severe. Study numbers vary because questionnaires, lens designs and follow-up periods differ. Persistent symptoms that affect driving or daily life deserve a proper examination; they should not be dismissed because most patients adapt.

What each lens type actually looks like at night

Rather than describe this abstractly, it helps to compare real patient-reported simulations across lens families:

• Monofocal IOL — clean image, essentially no disturbance
• Monofocal-plus (e.g. Eyhance-type) — slight change in the settings, but visually unaffected in practice
• Trifocal (e.g. PanOptix-type) — a noticeable halo ring around light sources
• EDOF, diffractive design (e.g. Symfony-type) — less halo, more of a glare pattern
• Hybrid multifocal (e.g. Synergy-type) — a different signature again, closer to a web or starburst

These simulations come from real patient-reported experience, not marketing renders — but treat them as a general shape, not a promise. Two patients with the identical lens can describe their night vision completely differently, because so much of this is processed by the brain, not just the optics.

Where does it actually come from?

We don't have a single clean answer for why one patient gets dysphotopsia and another with the same lens doesn't. But there are recognized contributing factors:

• Corneal irregularities
• Pupil size and pupil abnormalities
• IOL decentration
• Refractive surprises after calculation and implantation — this is probably the single most common driver

And underneath all of that is your visual cortex. In a young, healthy eye, the natural lens changes shape to focus at different distances — true accommodation. An artificial IOL can't do that. Instead, presbyopia-correcting lens designs manipulate light to spread focus across distances, which is an unnatural pattern for your brain to process. Your brain has to learn it. This is called neuroadaptation, and for most patients it genuinely works: halos and glare fade in intensity over the following months, and a meaningful share of patients report the effects disappearing almost entirely.

The trade-off nobody can engineer around

If you remember one sentence from this article, make it this one: there is no free lunch. A monofocal lens gives you the sharpest, clearest image at one fixed distance, with the lowest chance of dysphotopsia — but you'll need reading or intermediate glasses. A presbyopia-correcting lens (EDOF or multifocal) gives you spectacle independence across distances — but that comes at the cost of some contrast sensitivity and/or some level of night dysphotopsia. Every "premium" lens is a negotiated trade, not a miracle cure, and understanding which trade you're signing up for before surgery is the whole point of my work.

What actually helps if you're already dealing with it

The first step is to check treatable causes: dry eye, residual prescription error, corneal irregularity, IOL position, posterior capsule opacification and retinal disease. Neuroadaptation can make some optical effects less noticeable over weeks or months, but it is not the only answer. If symptoms are severe, worsening, one-sided, or make driving unsafe, contact your surgeon rather than trying to ignore them.

Before you choose a lens

There is no universally best IOL. The useful question is which trade-off fits your life: maximum distance contrast and night-driving comfort, more intermediate range, or greater independence from reading glasses. IOL exchange is possible in selected cases, but it is another intraocular procedure with additional risk — a reason to clarify priorities before the first surgery.

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