By Paul Barney, OD
PCLI—Anchorage, AK

Although uncommon, infectious endophthalmitis is one of the most feared complications of intraocular surgery. It can also occur after penetrating ocular trauma. This potentially devastating disease can result in permanent loss of vision—so recognizing early signs and symptoms is important.

Unfortunately, once the disease hits, chances of full visual recovery are poor. Damage to the ocular tissue occurs rapidly due to toxins from invading bacteria and enzymes produced by the body’s defense system. Also, aggressive surgical and medical treatment required to sterilize the infection can cause permanent damage.

Early recognition and prompt medical care is crucial. Any delay allows a bad situation to quickly become worse.

Be suspicious of infectious endophthalmitis in any patient experiencing abnormal pain and ocular inflammation after intraocular surgery or trauma. It is better to over diagnose and be safe than allow endophthalmitis to rapidly spread untreated.

Endophthalmitis with hypopyon

The hallmark subjective findings are:

• pain
• lid and ocular inflamamation
• decreased vision

Clinical findings can include the following. However, patients with early or atypical endophthalmitis may not demonstrate all of these:

• decreased vision
• photophobia
• lid edema
• conjunctival edema and hyperemia
• increased IOP
• corneal edema
• pronounced anterior chamber reaction with hypopyon
• vitritis

Infectious post-op endophthalmitis is caused by microbes invading the eye during surgery or soon after. Sources have been traced to:

• conjunctival flora
• contaminated irrigating solutions
• lens implants and sutures
• viscoelastics used during surgery
• surgical personnel

It is believed that bacteria bind better to the surface of some materials. For example, lens implants with polypropylene haptics and silk sutures have been shown to increase the risk of endophthalmitis. Wound dehiscence, wound abscesses, and infected glaucoma filtering blebs may result in microbial invasion and subsequent endophthalmitis.

The incidence and development of infectious endophthalmitis depends on how the infection enters the eye and how virulent the microbe is. The condition is more common after penetrating trauma than eye surgery. The incidence also varies by surgical procedure.

Precipitating Event	Incidence
Penetrating ocular trauma with retained intraocular foreign body	Up to 30%
Penetrating ocular trauma	3 - 7%
Glaucoma filtering surgery	0.5%
Penetrating keratoplasty	0.2%
Retinal and vitreous surgery	0.05%
Cataract surgery	0.05% - 0.5%
Principles and Practices in Ophthalmology (Albert & Jakobiec) Complications in Ophthalmic Surgery (Krupin, Kolker & Rosenberg)

The risk of endophthalmitis increases with some ocular and systemic conditions, and with intra-operative complications.

Increased Risk

• Wound leaks
• Clear cornea cataract incisions
• Abscessed sutures
• Broken posterior capsule
• Vitreous prolapse
• Contaminated IOLs and irrigating solutions
• Diabetes
• Immunosuppression
• Active systemic infections
• Bacterial blepharitis
• Nasolacrimal duct obstructions and infections

At Pacific Cataract and Laser Institute we utilize many systems to minimize the risk of this infection. Over the years we have seen approximately 1 case of infectious post-op endophthalmitis per 7000 intraocular surgical cases (0.0001%).

Virulent infections usually develop quickly while less virulent organisms are delayed. Acute post-op infectious endophthalmitis is the most common and develops within 6 weeks. Delayed infectious endophthalmitis occurs less commonly and develops more than six weeks after surgery.

Most Common Causative Organisms

88% Acute — within 6 weeks of surgery    Gram-positive bacteria—94%       - Coagulase-negative micrococci       - staphylococcus aureus       - Streptococcus species       - Enterococcus species    Gram-negative bacteria—6%

12% Delayed — 6+ weeks after surgery    Propionibacterium acnes    Coagulase-negative staphylococci    Fungi

Of reported cases, 88% occurred within 6 weeks of surgery—and the majority within 3 days. The classic presentation includes pain, reduced vision, lid edema, elevated IOP, severe anterior chamber reaction with hypopyon, and vitritis within 72 hours of surgery. This clinical scenario is more likely with virulent microbes such as Pseudomonas and Streptococcus species. With less virulent organisms such as staphylococcus aureus and staphylococcus epidermidis the infection may take days or weeks to manifest clinically.

Delayed-onset infectious endophthalmitis occurs months to years following surgery. It is the result of infection from low virulent organisms such as Propionibacterium acnes, or from bacteria that has become sequestered between the lens capsule and the IOL. Patients typically present with chronic, recurrent uveitis months or years after surgery. Although the uveitis usually responds to steroid therapy it recurs weeks or months later.

(Click here for an interesting case study.)

Patients with bacteria sequestered between the IOL and capsule frequently develop a white plaque on the posterior capsule or the posterior surface of the IOL. This is often misdiagnosed as posterior capsular opacification and treated with YAG laser capsulotomy. Unfortunately, laser treatment makes matters worse by dispersing the organisms and creating a more obvious infection.

Treatment of infectious post-op endophthalmitis depends on the presentation and severity. Acute cases are true ophthalmic emergencies and should be referred immediately to the operating surgeon or a vitreoretinal specialist. If vision is better than light perception, an anterior chamber and vitreous tap is usually taken, to obtain specimens for culture, and intravitreal antibiotics are injected. When vision is worse than light perception, an anterior chamber tap is taken, and a pars plana vitrectomy is performed with injection of intravitreal antibiotics. In both cases, topical antibiotics, cycloplegics, and topical steroids are used.

Delayed-onset cases require urgent treatment as well, but are not true emergencies unless they appear immediately following YAG laser posterior capsulotomy. Because the causative organism is less virulent, tissue damage is less severe and occurs at a much slower rate than in acute endophthalmitis.

Prognosis for visual recovery is directly related to:

• the pathogenicity of the offending organism
• the promptness of treatment

Cases involving highly virulent organisms have much less chance of full visual recovery than those with low virulent microbes. The more quickly the infection is diagnosed and treated the greater likelihood of visual recovery.

Infectious post-op endophthalmitis has potential for devastating vision loss and is a diagnosis most eye doctors hope they will never have to make. When it does occur, prompt diagnosis and treatment is of utmost importance. Hours can make a difference.

In closing, I encourage you to be suspicions of infectious endophthalmitis in any patient experiencing abnormal pain and ocular inflammation after intraocular surgery or trauma. It is better to over diagnose and be safe than hesitate and allow rapid infection to spread untreated.

What a mess! Click to read more.