The most telling signs of infection after cataract surgery are increasing eye pain, worsening vision, redness, and swelling that appear days after the procedure rather than improving steadily. The specific infection eye doctors worry about is called endophthalmitis, an infection inside the eye itself. It is rare, but when it happens, the window for effective treatment is narrow, and the signs can initially look like normal post-surgical inflammation. Knowing the difference matters.
The Warning Signs You Should Not Ignore
Normal recovery after cataract surgery involves some discomfort, mild redness, and blurry vision that gradually improves over the first few days. Infection flips that trajectory. Instead of getting better, the eye gets worse. The key red flags are a combination of symptoms, not usually a single one in isolation.
In a Brazilian surveillance study that tracked endophthalmitis cases over seven years, more than 60 percent of patients diagnosed with the infection had corneal swelling, a visible collection of white blood cells pooling in the front of the eye (called hypopyon), and significant inflammation in the front chamber of the eye at the time of diagnosis. Redness of the white part of the eye and haziness of the cornea were each present in close to half of confirmed cases, and cloudiness deeper in the eye was detected in about 40 percent of patients.1Rev. bras. oftalmol. Endophthalmitis after cataract surgery: results from seven years of epidemiological surveillance A large Chinese study spanning 12 years found that eye pain was the most common initial complaint among patients who developed post-cataract infection, with symptoms appearing on average around 10 to 11 days after surgery.2PubMed Central. Acute Infectious Endophthalmitis After Cataract Surgery: Epidemiological Characteristics, Risk Factors and Incidence Trends, 2008-2019
In practical terms, these are the signs that should prompt you to call your eye surgeon immediately:
- Increasing pain: Some achiness after surgery is expected, but pain that worsens after the first day or two, or new sharp pain appearing several days out, is a warning.
- Dropping vision: If your vision was getting clearer and then starts getting blurry or foggy again, that reversal is significant.
- Worsening redness: Redness that spreads or deepens after the initial postoperative period, rather than fading.
- Swollen or puffy eyelid: Beyond the first day or two, increasing lid swelling suggests something beyond routine healing.
- Sensitivity to light: Increasing light sensitivity days after surgery can signal inflammation from infection.
- A visible white or yellow layer in the eye: This is hypopyon, pus settling in the lower part of the front of the eye, and it is one of the most specific signs of serious infection.
None of these symptoms in isolation proves you have an infection. Some mild redness, light sensitivity, and even a bit of swelling can be part of a perfectly normal recovery. The pattern that matters is worsening symptoms after you’ve turned the corner, or new symptoms appearing days later. Infection tends to declare itself between roughly three and ten days after surgery, though it can show up earlier or considerably later.
How Common Is Post-Cataract Infection, Really?
The short answer is quite rare. In a large single-hospital study spanning five years and nearly 16,000 cataract surgeries, the rate of acute endophthalmitis was about 0.04 percent.3PubMed. Acute-onset endophthalmitis after cataract surgery (2000-2004): incidence, clinical settings, and visual acuity outcomes after treatment Other studies report slightly higher figures, around 0.076 percent in one 12-year dataset from China.2PubMed Central. Acute Infectious Endophthalmitis After Cataract Surgery: Epidemiological Characteristics, Risk Factors and Incidence Trends, 2008-2019 A more recent analysis from the Rotterdam Eye Hospital, covering over 56,000 procedures between 2016 and 2022 with routine antibiotic prophylaxis, found the incidence had dropped to about 0.03 percent. A literature review of 37 publications arrived at a similar overall rate.4JAMA Ophthalmology. Prophylactic Intracameral Antibiotics and Endophthalmitis After Cataract Surgery
So roughly 1 in 2,500 to 1 in 3,500 surgeries leads to an infection, depending on the era, technique, and whether antibiotics were used during the procedure. That is reassuringly low, but those numbers also mean that in a high-volume surgical center performing thousands of procedures per year, surgeons will encounter endophthalmitis regularly. The rarity should not make you complacent about symptoms.
Telling Infection Apart from a Non-Infectious Reaction
One of the trickiest aspects of post-cataract complications is that a condition called toxic anterior segment syndrome, or TASS, can look very similar to an infection in its early stages. Both cause redness, corneal swelling, blurry vision, and a reaction in the front of the eye. Telling them apart matters because the treatments are completely different: TASS responds to anti-inflammatory medication, while endophthalmitis requires antibiotics injected directly into the eye.
The timing is the biggest clue. TASS usually shows up within the first 12 to 48 hours after surgery, while bacterial infection typically appears between days three and ten.5PubMed Central. Unusual Inflammatory Clinical Presentation After Cataract Surgery and that Thought-provoking Question: Is this Infection or Toxic Anterior Segment Syndrome? TASS also tends to cause a distinctive pattern of corneal swelling that extends evenly from edge to edge of the cornea, and it does not involve the deeper parts of the eye.6ScienceDirect. Toxic Anterior Segment Syndrome Infection is more likely to produce haziness or cloudiness deeper inside the eye, and it tends to come with more severe pain. However, both conditions can cause poor visual acuity and significant front-of-the-eye inflammation, and in some cases, the clinical overlap is enough that doctors have to treat for infection while awaiting lab results, just to be safe.
For you as a patient, the practical takeaway is simple: any dramatic worsening of your eye within the first two weeks after surgery warrants an urgent call to your surgeon, regardless of whether the cause turns out to be infection, TASS, or something else. Your surgeon will sort out the diagnosis.
What Causes These Infections
Most post-cataract infections are caused by bacteria that normally live on the surface of your own eye and skin. The surgery creates a temporary opening, and in rare cases, bacteria slip inside. The most common culprits are staphylococcus species (particularly coagulase-negative staphylococci, the relatively mild bacteria that colonize everyone’s skin), along with streptococcus species and various gram-negative organisms.7PubMed Central. Endophthalmitis After Cataract Surgery: A Postoperative Complication
In outbreak settings, where multiple patients at the same facility develop infections around the same time, gram-negative bacteria are more common. One review of endophthalmitis outbreaks found that gram-negative organisms accounted for about 65 percent of outbreak-related cases, with Pseudomonas aeruginosa being the single most common species in those clusters.8PubMed. Endophthalmitis outbreaks following cataract surgery: causative organisms, etiologies, and visual acuity outcomes This is a very different pattern from the individual cases that pop up sporadically, where gram-positive skin bacteria dominate. Outbreak cases often trace back to contaminated equipment or solutions rather than the patient’s own bacteria.
Fungal infections are rarer but tend to be more difficult to treat. A large outbreak in South Korea in 2020 was traced to contaminated surgical gel products. The species responsible was predominantly Fusarium oxysporum, and the risk associated with the contaminated product lot was enormously elevated compared to products from other manufacturers.9PubMed Central. Fungal Endophthalmitis Outbreak after Cataract Surgery, South Korea, 2020 That outbreak affected hundreds of eyes. The initial clinical picture included inflammation in the front of the eye in about 90 percent of cases, visible cloudiness in the vitreous in about three-quarters of eyes, and a characteristic feathery or fluffy infiltration around the lens in roughly half the affected eyes.10JAMA Ophthalmology. An Outbreak of Fungal Endophthalmitis After Cataract Surgery in South Korea The fluffy appearance is actually a useful diagnostic clue that distinguishes fungal infection from the more typical bacterial kind.
Late-Onset Infections
Not all infections show up within the first couple of weeks. Some low-grade organisms can quietly establish themselves inside the eye and cause symptoms months or even years later. These delayed infections are often caused by slow-growing bacteria like Cutibacterium acnes (formerly known as Propionibacterium acnes), which is the same species associated with acne on the skin. One documented case involved a patient who developed signs of infection 11 years after cataract surgery, eventually traced to Cutibacterium acnes and Staphylococcus warneri hiding behind the implanted lens. The clinical signs were subtle: discrete white granules on the iris, on the inner lining of the cornea, and within the capsular bag around the lens implant.11PubMed Central. Delayed Bacterial Endotheliitis and Endophthalmitis 11 Years after Cataract Surgery
Late-onset infections often do not cause the dramatic pain and redness associated with acute endophthalmitis. Instead, they tend to produce chronic, low-level inflammation that waxes and wanes, sometimes temporarily improving with steroid eye drops (which suppress inflammation without treating the infection). If you had cataract surgery months or years ago and develop persistent or recurring fogginess, mild redness, or floaters in the operated eye, it is worth mentioning your surgical history to your eye doctor. These infections are harder to diagnose because they can mimic non-infectious causes of inflammation, and the organisms may not grow easily in standard lab cultures.
Who Is at Higher Risk
Certain factors raise the odds that a post-cataract infection will develop, and they fall into two broad categories: things about your health and things about the surgery itself.
On the surgical side, a case-control study found that wound abnormalities during the procedure and the use of certain types of lens implants were significantly associated with endophthalmitis, as was being on immunosuppressive treatment at the time of surgery.12PubMed. Endophthalmitis after cataract surgery: risk factors relating to technique and events of the operation and patient history
Diabetes is the systemic condition most studied in relation to post-cataract infection risk. A meta-analysis found that people with diabetes had a modestly but consistently higher rate of endophthalmitis compared to those without it. The risk was particularly elevated when diabetes was combined with high blood pressure, and men with diabetes faced a higher risk than women with diabetes.13PubMed Central. Do people with diabetes have a higher risk of developing postoperative endophthalmitis after cataract surgery? A systematic review and meta-analysis Among diabetic patients specifically, those on insulin therapy had roughly four times the odds of developing endophthalmitis compared to diabetic patients not on insulin, even after adjusting for blood sugar levels.14PubMed Central. Risk factors for endophthalmitis after cataract surgery in diabetic patients: a case control study
If you have diabetes or take immunosuppressive medications, this does not mean you should avoid cataract surgery. It means your surgeon may take extra precautions and you should be especially attentive to the warning signs during recovery.
How Doctors Confirm an Infection
When a surgeon suspects endophthalmitis based on your symptoms and the clinical exam, they will usually sample the fluid inside your eye for testing. The goal is to identify the specific organism causing the infection, which helps guide antibiotic selection. Traditionally, this relies on culturing the sample, essentially trying to grow the bacteria in a lab dish, but culture results can take days and sometimes come back negative even when infection is present.
Molecular testing using PCR has significantly improved diagnostic accuracy. In the European Society of Cataract and Refractive Surgeons multicenter study, PCR testing boosted the rate of identifying a pathogen by about 20 percent compared to standard culture methods alone. Six patients in that study were positive by PCR but negative on both culture and stain, meaning the infection would have gone unidentified without molecular testing.15PubMed. Laboratory diagnosis of endophthalmitis: comparison of microbiology and molecular methods in the European Society of Cataract & Refractive Surgeons multicenter study and susceptibility testing A separate study showed that real-time PCR picked up bacterial infection in about 91 percent of clinically diagnosed endophthalmitis cases from eye fluid samples, and the technique could also help distinguish between true infection and sample contamination based on how strongly the test reacted.16Journal of Cataract & Refractive Surgery. Real-time polymerase chain reaction test to discriminate between contamination and intraocular infection after cataract surgery
In practice, treatment usually starts before the lab results come back. Waiting for a culture result while bacteria multiply inside the eye risks permanent vision loss, so surgeons inject broad-spectrum antibiotics into the eye first and adjust the treatment once they know what organism they are dealing with.
Treatment and What to Expect
The cornerstone of treating post-cataract infection is injecting antibiotics directly into the vitreous cavity of the eye. This delivers a much higher concentration of medication to the site of infection than oral or intravenous antibiotics could achieve. In severe cases, or when the initial injection does not work, repeated injections or surgical removal of the vitreous gel (vitrectomy) may be necessary.17PubMed Central. Endophthalmitis
The question of when to escalate from injection alone to vitrectomy has evolved. A landmark randomized trial of 420 patients found no clear advantage to early vitrectomy over a simpler “tap and inject” approach for most patients, though the evidence was not strong.18PubMed Central. Early vitrectomy for exogenous endophthalmitis following surgery More recent work has argued for moving to vitrectomy sooner, particularly when the infection is severe enough to obscure the view of the retina. One study found that complete early vitrectomy, combined with systemic antibiotics and retreatment when needed, improved the chances of recovering good vision (20/40 or better) by roughly 50 percent compared to a predominantly injection-based approach.19PubMed Central. Complete and Early Vitrectomy for Endophthalmitis After Cataract Surgery: An Alternative Treatment Paradigm
Visual outcomes depend heavily on how quickly treatment starts and how aggressive the infecting organism is. In a series of 62 eyes treated with an aggressive early-vitrectomy approach, about 79 percent ultimately recovered vision of 20/40 or better, while roughly 10 percent ended up with very poor vision despite treatment.19PubMed Central. Complete and Early Vitrectomy for Endophthalmitis After Cataract Surgery: An Alternative Treatment Paradigm A smaller study of 21 eyes treated with vitrectomy found that two-thirds achieved functional vision afterward, a dramatic improvement from the baseline where only about 10 percent had usable vision at the time of diagnosis.20PubMed. Clinical analysis of 23-gauge vitrectomy for the treatment of acute endophthalmitis after cataract surgery The message is cautiously optimistic: most people who develop endophthalmitis after cataract surgery and receive prompt treatment recover useful vision, but a minority do not, and delays make the odds worse.
How Modern Prevention Has Changed the Odds
The single biggest advance in preventing post-cataract infection has been the use of antibiotics injected directly into the eye at the end of the surgical procedure. A review of the evidence found that this practice reduced the incidence of endophthalmitis roughly three and a half times over, with an odds ratio between 0.14 and 0.19, and that adding antibiotic eye drops afterward did not provide meaningful additional benefit beyond the injection.21PubMed. Intracameral antibiotics during cataract surgery: efficacy, safety, and cost-benefit considerations A meta-analysis looking specifically at which antibiotics work best for this purpose found that moxifloxacin and vancomycin showed the strongest protective effects.22AJO International. Effectiveness of intracameral antibiotics in reducing postoperative endophthalmitis risk after cataract surgery: A meta-analysis
This practice is now standard in many countries, but not universally adopted everywhere. If you are preparing for cataract surgery, it is reasonable to ask your surgeon whether they use intraoperative antibiotics and which kind. The evidence strongly supports it.
The Antibiotic Resistance Question
A growing concern across all of medicine is whether the bacteria causing infections are becoming resistant to the antibiotics used to treat them. In post-cataract endophthalmitis specifically, the picture is mixed. One study of over 200 culture results from endophthalmitis cases found that resistance to at least one antibiotic was present in about 43 percent of samples, and about 11 percent showed multidrug resistance. Encouragingly, no trend toward increasing resistance over time was observed in that dataset.23PubMed Central. Role of Antimicrobial Resistance in Outcomes of Acute Endophthalmitis
That said, the resistance landscape varies by region. A systematic review noted that coagulase-negative staphylococci, the most common cause of post-cataract infection globally, frequently show resistance to methicillin and fluoroquinolones. In parts of India, multidrug-resistant Pseudomonas strains with near-total resistance to several common antibiotic classes have been reported. Vancomycin has remained reliably effective against gram-positive organisms, though early signs of emerging resistance have appeared in the United Kingdom.24International Ophthalmology. Antimicrobial resistance in post-cataract endophthalmitis: a systematic review on resistance pattern and treatment outcomes This is why surgeons often inject a combination of antibiotics targeting different types of organisms when treating a suspected infection, rather than relying on a single drug.
Telehealth Follow-Up and Catching Problems Early
One development that has reshaped postoperative monitoring is the use of telehealth for follow-up visits. A comparative study examining teleconsultation versus in-person hospital visits after uncomplicated cataract surgery found that common early complications like lid swelling, pain, redness, and watering were detected in both groups at the day-one follow-up, and complication rates were comparable by the one-month mark.25PubMed Central. A comparative clinical study of postoperative care by teleophthalmology and in-person consultation at hospital outpatient department after an uncomplicated cataract surgery Patients in the hospital-visit group actually reported more complications on day one, likely reflecting the more detailed examination possible in person rather than a true difference in outcomes.
Telehealth can work well for routine post-cataract check-ins, but it has real limits when it comes to catching endophthalmitis. A video call might reveal that you are in pain and your eye looks red, but it cannot visualize hypopyon, measure anterior chamber inflammation, or examine the vitreous for cloudiness. If anything about your recovery feels wrong, particularly worsening pain or declining vision between days two and fourteen, telehealth should be a bridge to an in-person exam, not a substitute for one. The organisms that cause post-cataract endophthalmitis can permanently damage the retina within hours to days, and the physical exam findings that distinguish routine inflammation from true infection require a slit lamp and a trained eye.