Cataract surgery is one of the most performed — and most successful — operations in all of medicine. Millions are done every year, and the overwhelming majority go smoothly, with patients seeing better the very next day. That is the honest baseline, and you should know it.
But "very safe" is not the same as "risk-free," and a site that only told you the good news would not be honest. This article covers the real complications: what they are, how rare each one is, what your surgeon does to prevent them, and — most importantly — the warning signs that mean you should call.
Perspective first: why surgeons call this safe
A modern cataract operation takes about ten to fifteen minutes, uses a tiny self-sealing incision, and requires no stitches in routine cases. The eye is numbed with drops, you go home the same day, and serious complications are uncommon. When surgeons quote safety figures, they are drawing on enormous experience — this is among the most studied procedures in medicine.
Still, every eye is different, and certain factors raise risk: very dense or long-standing cataracts, prior eye trauma or surgery, severe nearsightedness, glaucoma, diabetic eye disease, and weak zonules (the fibers holding the lens in place). A good surgeon will tell you plainly if any of these apply to you — which is one reason asking the right questions before surgery matters so much.
Infection inside the eye (endophthalmitis)
This is the complication surgeons fear most, because it can threaten vision fast. Bacteria entering the eye during or shortly after surgery can cause a severe internal infection. The good news: with modern sterile technique and antibiotic drops, it is rare — well under one in a thousand cases.
Prevention is layered: sterile draping and instruments, antibiotic drops before and after surgery, and a carefully constructed self-sealing incision. Your job is to use every drop exactly as prescribed, keep tap water out of the eye in the early days, skip eye makeup as instructed, and never rub the eye.
Warning signs: increasing pain (not just mild scratchiness), worsening redness, discharge, or vision that gets worse instead of better in the first days after surgery. These warrant an immediate call — do not wait for your next scheduled visit.
Retinal detachment
Cataract surgery slightly raises the lifetime risk of retinal detachment, and the risk is higher for very nearsighted people, whose retinas are already more vulnerable. Even so, detachment after cataract surgery is uncommon.
This one matters because it is time-sensitive: a detached retina is repairable, but sooner is better. Warning signs: a sudden shower of new floaters, flashes of light, or a dark curtain or shadow spreading across part of your vision. These need same-day evaluation — call your surgeon or go to an emergency eye service immediately.
Swelling of the macula (cystoid macular edema)
The macula is the center of your retina — the part responsible for sharp, detailed vision. After cataract surgery, it can swell, usually showing up weeks later as blurry or wavy central vision. This is one of the more common treatable complications, and it often responds well to anti-inflammatory drops, occasionally requiring an injection.
Surgeons watch for it at post-op visits, and certain patients — those with diabetes or prior retinal vein problems, for example — are watched more closely. If your central vision seems to blur or distort weeks after an initially good result, report it at your follow-up rather than assuming it is normal healing.
Clouding behind the lens ("secondary cataract")
Months or years after surgery, the thin membrane that holds your new lens can turn cloudy, gradually blurring vision again. This is called posterior capsule opacification, and it is common over time — but it is not the cataract returning, and it is not a failure of the surgery.
The fix is a quick, painless in-office laser procedure called a YAG capsulotomy that takes minutes. We cover it fully in Can Cataracts Come Back After Surgery?
Droopy eyelid (ptosis)
Some patients notice the upper eyelid sits lower after surgery. This is most often temporary — caused by the eyelid speculum that holds the eye open during the procedure, or by the bright microscope light — and it typically improves over weeks to months. A droop that does not improve should be evaluated, but patience is usually the right first step.
Other complications worth knowing
A few more, briefly: corneal swelling (usually clears in days; persistent swelling is uncommon and treatable), lens position issues (minor shifts may need no treatment; significant ones can be repositioned), temporary pressure spikes (checked at post-op visits, usually manageable with drops — glaucoma patients are watched more closely), and very rarely dropped lens fragments requiring a second procedure by a retina specialist.
The bottom line on risk: serious complications are uncommon, most are treatable when caught early, and catching them early depends on you knowing the warning signs — increasing pain, worsening vision, new flashes or floaters, or a shadow across your vision. When in doubt, call. Surgeons would always rather hear from you about nothing than hear too late about something.
What your surgeon does to prevent all of this
It is easy to read a list like this and feel nervous. Remember what is happening on the other side of the drape: sterile technique refined over decades, antibiotic protocols, incisions engineered to seal themselves, microscopes that magnify every detail, and a follow-up schedule designed to catch problems early. Your surgery day is short, but the system around it is thorough.
And your part genuinely matters: use every drop as prescribed, show up to every post-op visit (even when the eye feels great), and follow the activity restrictions. Our week-by-week recovery timeline lays out exactly what to do and what to watch for at each stage.
Want the warning signs on your fridge? The 13-page Prep & Recovery Kit includes a one-page "when to call your surgeon" reference — the red-flag symptoms from this article, in large print, ready before surgery day. Plus the drop schedule, daily drop log, and recovery tracker.
Want this as a printable? The Cataract Surgery Handbook by Dr. Eye MD covers every complication in this article in more depth — with patient profiles, the questions that reveal how a surgeon handles problems, and a tear-out checklist for your appointments. 16 chapters, available on Kindle and in Kindle Unlimited.
Questions, Answered Honestly
What is the most serious risk of cataract surgery?
Infection inside the eye (endophthalmitis) — rare, well under one in a thousand cases with modern technique, but vision-threatening if it happens. Increasing pain, redness, or worsening vision in the first days after surgery warrant an immediate call.
Can cataract surgery cause retinal detachment?
It can slightly raise the risk, more so for very nearsighted patients. It remains uncommon. A sudden shower of floaters, flashes, or a dark curtain across your vision needs same-day evaluation.
What is cystoid macular edema after cataract surgery?
Swelling of the central retina, usually appearing weeks after surgery, that blurs central vision. It is one of the more common treatable complications and often responds to anti-inflammatory drops. Report blurry or wavy central vision at your follow-up.
Is a droopy eyelid after cataract surgery permanent?
Usually not. Mild droop after surgery is most often from the eyelid speculum or the bright microscope light and typically resolves over weeks to months. A persistent droop should be evaluated.
How do surgeons prevent complications?
Sterile technique, antibiotic drops, careful wound construction, and close follow-up. Your part: use every drop as prescribed, keep water and makeup away as instructed, never rub the eye, and show up to every post-op visit.
Medical disclaimer: This site provides educational information only and is not medical advice. Always consult your own eye surgeon about your care.