Endophthalmitis – A Complete Medical Guide

Overview

Endophthalmitis is a severe, sight‑threatening inflammation of the interior of the eye (the vitreous and/or aqueous chambers) caused by infection with bacteria, fungi, or, rarely, parasites. The condition can develop rapidly, often within hours to days after an inciting event, and requires prompt medical attention.

Who it affects: While anyone can develop endophthalmitis, the highest‑risk groups are:

• Post‑operative patients – especially after cataract surgery, intravitreal injections, or vitrectomy.
• Individuals with ocular trauma (penetrating injuries, foreign bodies).
• Patients with systemic infections that spread to the eye (hematogenous endophthalmitis).
• Immunocompromised persons (diabetes, HIV, chemotherapy).

Prevalence: Endophthalmitis is rare but serious. In the United States, the incidence after cataract surgery is approximately 0.04%–0.07% (4–7 cases per 10,000 surgeries) [1]. Post‑intravitreal injection rates are slightly higher, ranging from 0.05% to 0.1% [2]. Traumatic endophthalmitis accounts for about 10%–15% of all cases [3].

Symptoms

The onset can be abrupt. Common symptoms include:

• Pain – deep, aching eye discomfort that may worsen with eye movement.
• Redness – conjunctival injection (bloodshot eye).
• Visual loss – blurred vision, floaters, or sudden loss of vision.
• Photophobia – heightened sensitivity to light.
• Decreased visual acuity – inability to read normal print.
• Eye discharge – watery or purulent (pus‑like) secretion.
• Swelling of eyelids – ptosis or edema.
• Eye “floaters” – dark specks or cobweb‑like shadows drifting across the visual field.
• Anterior chamber reaction – visible “flare” or cells when examined with a slit lamp.
• Fever or systemic signs – may be present with hematogenous spread.

Because symptoms can mimic less serious conditions (e.g., conjunctivitis), any sudden eye pain or vision change after surgery or injury warrants urgent evaluation.

Causes and Risk Factors

Infectious Agents

• Gram‑positive bacteria – Staphylococcus epidermidis, Staphylococcus aureus, Streptococcus species (most common).
• Gram‑negative bacteria – Pseudomonas aeruginosa, Haemophilus influenzae.
• Fungi – Candida spp., Aspergillus spp. (more common in immunosuppressed or after trauma with plant material).
• Parasites – Rare (e.g., Toxoplasma gondii).

Primary Categories

• Exogenous endophthalmitis – Direct inoculation from surgery, intravitreal injection, or trauma.
• Endogenous (hematogenous) endophthalmitis – Spread from a distant infection (e.g., bacterial endocarditis, urinary tract infection).

Risk Factors

• Recent intra‑ocular surgery (especially cataract extraction).
• Repeated intravitreal injections for age‑related macular degeneration (AMD) or diabetic retinopathy.
• Penetrating ocular trauma, especially with contaminated objects.
• Systemic conditions: diabetes mellitus, immunosuppression, chronic steroid use.
• Pre‑existing ocular surface disease (dry eye, blepharitis) that increases bacterial load.
• Inadequate sterile technique in the operating room or clinic.
• Use of silicone oil tamponade after retinal surgery (can be a nidus for infection).

Diagnosis

Diagnosis is primarily clinical, supported by laboratory testing.

Clinical Examination

• Visual acuity testing – determines baseline and loss.
• Slit‑lamp biomicroscopy – evaluates cornea, anterior chamber cells/flare, hypopyon (pus layer).
• Fundus examination – by indirect ophthalmoscopy; may show vitritis (inflammatory debris in vitreous), retinal lesions, or necrosis.
• Intra‑ocular pressure (IOP) – often low initially, may rise later.

Laboratory & Imaging

• Vitreous tap – a needle is used to aspirate a small volume of vitreous fluid for Gram stain, culture, and polymerase chain reaction (PCR) testing.
• Aqueous tap – if vitreous access is difficult.
• Ultrasound B‑scan – useful when media opacity prevents direct view; shows dense vitreous opacities.
• Optical coherence tomography (OCT) – provides high‑resolution images of retinal layers, helpful for assessing macular involvement.
• Blood cultures – especially in suspected endogenous cases.

Prompt sampling before antibiotics are started improves culture yield, which guides targeted therapy.

Treatment Options

Treatment must be initiated within hours of suspicion. Management combines antimicrobial therapy, possible surgical intervention, and supportive measures.

Intravitreal Antibiotics

Direct injection of high‑dose antibiotics into the vitreous cavity is the cornerstone.

• Vancomycin (1 mg/0.1 mL) – covers Gram‑positive organisms, especially MRSA.
• Ceftazidime (2.25 mg/0.1 mL) or Amikacin – for Gram‑negative coverage.
• For fungal cases: Amphotericin B (5–10 µg/0.1 mL) or Voriconazole (100 µg/0.1 mL).

Because of rising antibiotic resistance, culture‑directed therapy is ideal when results return.

Systemic Antibiotics

• Used especially in endogenous disease or when there is a systemic source.
• Typical regimens: intravenous vancomycin plus ceftazidime or cefepime, adjusted per culture.

Surgical Management

• Pars plana vitrectomy (PPV) – removal of infected vitreous; improves visual outcomes, especially when presenting visual acuity is ≤ hand motions (the Endophthalmitis Vitrectomy Study supports early PPV) [4].
• Combined PPV with intravitreal antibiotics is common practice.
• In severe cases, silicone oil may be used as a tamponade after vitrectomy.

Adjunctive Therapies

• Topical antibiotics – e.g., moxifloxacin drops, to treat any concurrent surface infection.
• Corticosteroid eye drops or systemic steroids – used cautiously after adequate antimicrobial coverage to reduce inflammatory damage.
• Pain control – oral NSAIDs or acetaminophen; avoid topical NSAIDs that may delay healing.

Follow‑up Care

• Daily to weekly examinations in the first month, then taper based on response.
• Repeat intravitreal injections may be needed if infection persists.

Living with Endophthalmitis

Even with successful treatment, patients may experience lasting visual changes. Practical tips help manage daily life:

• Protect the eye – wear an eye shield or sunglasses, especially when outdoors.
• Adhere to medication schedule – set alarms or use pill organizers for intravitreal and systemic drugs.
• Monitor vision – keep a simple log of visual acuity changes; report any new drops in vision immediately.
• Limit strenuous activities – avoid heavy lifting, vigorous exercise, or activities that raise intra‑ocular pressure for at least 2 weeks post‑surgery.
• Control systemic diseases – maintain optimal blood glucose, blood pressure, and treat any ongoing infections.
• Supportive devices – magnifiers, high‑contrast reading glasses, or screen‑reading software can help if vision remains reduced.
• Emotional health – sudden vision loss can cause anxiety; consider counseling or support groups.

Prevention

Because most cases are iatrogenic, strict aseptic technique is essential.

• Pre‑operative antisepsis – use povidone‑iodine 5% solution on the conjunctiva for at least 30 seconds before intra‑ocular procedures (CDC recommendation) [5].
• Use of sterile drapes, gloves, and instruments – ensure proper operating‑room protocols.
• Prophylactic antibiotics – intracameral cefuroxime or moxifloxacin at the end of cataract surgery has reduced infection rates to <0.01% in large studies [6].
• Proper intravitreal injection technique – use a sterile lid speculum, apply povidone‑iodine, and wear a mask.
• Post‑procedure care – educate patients to report pain, redness, or vision changes within 24‑48 hours.
• Trauma prevention – wear protective eyewear during high‑risk activities (sports, woodworking, metalwork).
• Systemic health – control diabetes, treat skin infections, and avoid unnecessary immunosuppression when possible.

Complications

If not promptly treated, endophthalmitis can lead to irreversible damage.

• Permanent vision loss – ranging from mild reduction to total blindness.
• Retinal detachment – inflammatory traction can separate the retina.
• Glaucoma – secondary to inflammation, scarring, or steroid use.
• Sympathetic ophthalmia – a rare bilateral granulomatous uveitis triggered by ocular injury.
• Phthisis bulbi – shrinkage of the globe due to chronic inflammation.
• Systemic spread – especially with fungal organisms, leading to meningitis or sepsis.

When to Seek Emergency Care

References

1. Mayo Clinic. "Endophthalmitis after cataract surgery." 2023. mayoclinic.org
2. Cleveland Clinic. "Intravitreal injection complications." 2022. clevelandclinic.org
3. American Academy of Ophthalmology. "Traumatic endophthalmitis." 2021. aao.org
4. Endophthalmitis Vitrectomy Study Group. *A Randomized Trial of Vitrectomy for Post‑operative Endophthalmitis.* Archives of Ophthalmology. 1995;113(12):1479‑1485.
5. CDC. "Guidelines for infection control in ophthalmic surgery." 2020. cdc.gov
6. European Society of Cataract & Refractive Surgeons. "Intracameral antibiotics to prevent endophthalmitis." 2022. escrs.org