Eye surgery can go wrong, but serious complications are uncommon. About 97% of cataract surgeries, the most frequently performed eye operation worldwide, proceed without any complications at all. For LASIK, the most popular elective vision correction, the risk of a truly devastating outcome like permanent vision loss is extremely low. That said, “going wrong” covers a wide range of outcomes, from annoying side effects that linger for months to rare but severe infections that threaten your sight. Understanding what can actually happen, and how likely each scenario is, puts you in a much better position before you agree to any procedure.
LASIK: What Can Go Wrong
LASIK is one of the safest elective surgeries in all of medicine, but it is not risk-free. The most common problem by far is persistent dry eye. Studies consistently find that somewhere between 20% and 55% of patients still report dry eye symptoms six months or more after the procedure. That is a wide range because it depends on how “dry eye” is defined. In one study, 43% of patients were still using eye drops at the six-month mark. In another following patients for two to five years, 55% reported ongoing symptoms. Most of these cases are mild and manageable, but for some people the dryness, burning, or sensitivity becomes a genuine quality-of-life issue.
Other LASIK complications include glare and halos around lights at night, under-correction or over-correction of your vision, and in rare cases a condition called corneal ectasia, where the cornea progressively thins and bulges after surgery. Ectasia is uncommon but serious, sometimes requiring a corneal transplant. The overall risk of needing a second “enhancement” procedure to fine-tune your results varies, but roughly 10% to 20% of patients may benefit from one depending on the complexity of their prescription.
Cataract Surgery Risks
Cataract surgery has an excellent safety profile, but with tens of millions of procedures performed globally each year, complications do occur. The total risk of permanent vision loss from the three most dangerous cataract complications combined is roughly 0.48%, or about 48 in every 10,000 surgeries. Here is how those break down:
- Infection (endophthalmitis): A severe infection inside the eye. Modern techniques, including placing antibiotics directly in the eye at the end of surgery, have driven the rate down to about 1 in 10,000 (0.01%). When it does happen, it requires urgent treatment and can cause significant vision loss.
- Retinal detachment: The retina peeling away from the back of the eye. In the first ten years after cataract surgery, the risk is about 0.4%, roughly four times higher than in an unoperated eye. Most retinal detachments can be repaired, but the visual outcome depends on how quickly it is caught.
- Severe bleeding (suprachoroidal hemorrhage): Bleeding behind the retina during or shortly after surgery. This is rare, about 0.07%, but when it happens it often causes severe or permanent vision loss.
A secondary film can also grow behind the new artificial lens months or years later, making vision cloudy again. This is not really a complication of surgery going wrong. It is treated with a quick, painless laser procedure in the office.
Glaucoma Surgery Complications
Glaucoma procedures like trabeculectomy work by creating a new drainage pathway to lower eye pressure. Because the surgery intentionally alters the eye’s plumbing, it carries a distinct set of risks. A study of 239 eyes found that within five years, about 18% developed a bleb leak (a leak at the surgical site), roughly 6% developed blebitis (inflammation of the drainage bleb), and 7.5% experienced endophthalmitis. Overall, about 23% of patients developed at least one of these complications within five years, with the risk continuing at a fairly steady rate over time rather than clustering right after surgery.
Hypotony, where the eye pressure drops too low after surgery, is another concern. Excessively low pressure can cause the retina to wrinkle, leading to distorted vision. Glaucoma surgery also carries a meaningful chance of not working well enough, requiring additional procedures or continued use of eye drops.
Retinal Surgery: Higher Stakes
Retinal surgery, particularly vitrectomy for a detached retina, operates in a higher-risk category because the retina is already damaged before the surgeon begins. The main worry after retinal detachment repair is a condition called proliferative vitreoretinopathy, where scar tissue forms on the retina and pulls it off again. This occurs in roughly 5% to 10% of all retinal detachment cases.
When PVR does develop, the path forward gets harder. Anatomic success rates for repairing a PVR-related re-detachment range from 45% to 85%, and even with repeated surgeries, 10% to 40% of these retinas fail to stay attached long term. One study using heavy silicone oil found only 39% of complicated retinal detachments remained attached after an average follow-up of two and a half years. These numbers illustrate that while routine retinal repairs succeed the vast majority of the time, complex cases can spiral into multiple surgeries with uncertain outcomes.
Health Conditions That Raise Your Risk
Your overall health plays a significant role in how likely you are to have a complication. The FDA lists several conditions as contraindications or warnings for refractive surgery like LASIK, and many of these apply to other eye procedures as well.
Diabetes is a relative contraindication for LASIK. One early study found a 47% complication rate in diabetic patients undergoing LASIK, compared to just 6.9% in non-diabetic controls. The most frequent problems were surface erosions and wounds that were slow to heal. For cataract surgery, diabetic patients who develop infections tend to have worse outcomes, with more aggressive organisms involved. Uncontrolled blood sugar in particular raises infection risk across all types of surgery.
Autoimmune and connective tissue diseases, including rheumatoid arthritis, lupus, and Sjögren’s syndrome, are considered contraindications for laser vision correction. These conditions can cause chronic dry eye and impair healing, making complications both more likely and harder to treat. The American Academy of Ophthalmology considers uncontrolled autoimmune disease an absolute contraindication for refractive surgery.
Other red flags include severe allergies (which increase the risk of inflammation under the LASIK flap), immunodeficiency conditions like HIV (especially with existing dry eye), and certain medications such as isotretinoin, which affects how the cornea heals. Pregnancy and breastfeeding also change the shape of your cornea temporarily, making accurate correction impossible.
How Surgical Errors Are Prevented
Wrong-site surgery, wrong-lens implantation, and patient mix-ups are known as “never events” because they should never happen. The World Health Organization’s Surgical Safety Checklist, used in operating rooms globally, requires the team to confirm the patient’s identity, the planned procedure, and the surgical site at three separate points: before anesthesia, before the incision, and before the patient leaves the operating room. In eye surgery specifically, the correct eye is marked beforehand, and the surgical team verbally confirms it together before proceeding.
These protocols have dramatically reduced wrong-site errors, but they have not eliminated them entirely. If you are having eye surgery, you will be asked to confirm which eye and what procedure multiple times. That repetition is not bureaucratic. It is the last line of defense against a preventable mistake.
Putting the Odds in Perspective
The vast majority of eye surgeries go exactly as planned. For cataract surgery, 97% of patients have zero complications, and the combined risk of permanent vision loss is under half a percent. LASIK rarely causes serious harm, though the chance of lingering dry eye is real and worth weighing. Glaucoma and retinal surgeries carry higher complication rates, but those procedures are typically done because the disease itself threatens your vision, and the risk of not operating is often worse than the risk of the surgery.
Your individual risk depends on several factors: the specific procedure, the health of your eye before surgery, any underlying medical conditions, and the experience of your surgeon. High-volume surgeons who perform hundreds or thousands of procedures per year tend to have lower complication rates than those who operate less frequently. Asking your surgeon about their personal complication rates, not just the national averages, gives you the most relevant picture of what to expect.