Scott J. Fudemberg

BASICS

DESCRIPTION

• Presumed infection in or around filtering bleb.

• Filtering bleb is a subconjunctival pocket of fluid created intentionally in glaucoma surgery to drain aqueous humor or inadvertently after other types of eye surgery:

– Classification: Blebitis (no vitreous involvement) and bleb-associated endophthalmitis (BAE) (vitreous involvement)

– BAE: Early-onset (within 1 month of surgery) and late-onset (occurs more than 1 month after surgery)

EPIDEMIOLOGY

Incidence

• After superiorly located trabeculectomy with mitomycin c

• Blebitis: 5.7% (1)

• Early-onset BAE: 0.124%

• Late-onset BAE: 0.8–4%

RISK FACTORS

• Inferior bleb

• Thin bleb

• Bleb leak

• Antifibrotic agents (mitomycin c, 5-fluorouracil)

• Major complications in early postoperative period following trabeculectomy (flat anterior chamber, early wound leak, suprachoroidal hemorrhage)

• Prior conjunctivitis/upper respiratory infection

• Blepharitis

• History of prior bleb infection

• Chronic use of antibiotics

• Bleb manipulation

• Multiple filtration surgeries

Genetics

Many forms of glaucoma are hereditary, but predisposition to bleb-related infection is not known to be genetic.

GENERAL PREVENTION

• Surgical techniques that promote low diffuse blebs and minimize highly elevated, avascular, thin blebs

• Rapid diagnosis and management of bleb leaks

• Avoidance of eye rubbing in eyes with bleb

• Treatment of blepharitis in eyes with bleb

• Avoid chronic use of topical antibiotic drops

PATHOPHYSIOLOGY

• Early-onset BAE: Likely introduction of normal flora during surgery

• Late-onset BAE: Likely penetration of bleb by transiently present organisms through area of unhealthy tissue or bleb leak

ETIOLOGY

• Blebitis: Most studies report Staphylococcus epidermidis and S. aureus.

• Early-onset BAE: Most studies report S. epidermidis and S. aureus.

• Late-onset BAE: Strep species most commonly reported, followed by Haemophilus influenzae and gram negatives.

• Organisms that cause late-onset BAE are more virulent, produce exotoxins, may penetrate intact conjunctiva, may rapidly spread into anterior chamber and vitreous.

COMMONLY ASSOCIATED CONDITIONS

Conjunctivitis, uveitis, bleb leak, glaucoma

DIAGNOSIS

HISTORY

• Typically, late-onset BAE causes sudden onset red eye followed by photophobia, eye pain, discharge, and decreased vision:

– Prodrome in blebitis may be of several days or longer while in BAE may progress very rapidly over course of hours to devastating infection.

PHYSICAL EXAM

• Conjunctival injection localized to area of bleb (though may progress to diffuse injection)

• Milky, turbid appearance of bleb

• Frank purulent material in or leaking from bleb

• Bleb leak (may resolve during the course of infection as a result of scarring and/or blocking of leak with debris)

• Inflammatory cells in the anterior chamber (blebitis)

• Inflammatory cells in the vitreous (key differentiating feature between blebitis and BAE)

• Hypopyon in the presence of signs of external bleb infection is endophthalmitis until proven otherwise.

DIAGNOSTIC TESTS & INTERPRETATION

Lab

Initial lab tests

• Gonioscopy may be needed to identify microhypopyon.

• B-scan ultrasound of vitreous is needed if view is obscured by anterior segment inflammation.

• Utility of conjunctival cultures may be limited: If frank purulent material consider swab for gram stain, culture/sensitivities.

• Anterior chamber tap may be used to collect sample for gram stain and culture/sensitivity, but we generally favor low threshold for vitreous tap/inject.

Follow-up & special considerations

• Early diagnosis, prompt treatment, and very close follow-up are critical because progression of blebitis to BAE and BAE to devastating outcomes may be rapid.

• Follow-up of blebitis may be daily with low threshold for multiple exams per day.

• Follow-up of BAE may be multiple times per day with low threshold for hospital admission.

• There is no formally established protocol for follow-up of these conditions.

Pathological Findings

• Thin (1–2 layer) conjunctival epithelium (4)[B]

• Goblet cell depletion resulting in decreased production of mucin, which is a crucial biological/physical barrier of the cornea and conjunctiva (4)[B]

• Presence of hyalin in bleb (4)[B]

DIFFERENTIAL DIAGNOSIS

• Endophthalmitis (not bleb-associated)

• Uveitis

• Scleritis

• Episcleritis

• Sterile inflammatory response (intraocular foreign body, surgical manipulation, intraocular injection)

TREATMENT

MEDICATION

First Line

• Blebitis: Fortified vancomycin (25–50 mg/mL) and tobramycin (14 mg/mL) or cefazolin (50 mg/mL); apply alternating topical drops every half hour post loading dose (1 drop every 5 min for a total of 4 drops) (2)[A] (5)[A].

• BAE: Intravitreal administration of vancomycin (1 mg/0.1 mL) and ceftazidime (2.25 mg/0.1 mL) (2)[A] (5)[A].

• BAE (if intolerant to ceftazidime): Intravitreal administration of vancomycin (1 mg/0.1 mL) and amikacin (0.4 mg/0.1 mL) (keep in mind the use of an aminoglycoside such as amikacin that can cause macular infarction and should be used cautiously) (2)[A] (5)[A].

• Intravitreal antibiotics may be repeated every 48–72 h.

• Use of steroids may be needed to control inflammation, but should be used with great caution (1)[C] (2)[A].

Second Line

For mild blebitis only: Fourth-generation fluoroquinolones (gatifloxacin 0.3% or moxifloxacin 0.5%) apply topical drops every hour post loading dose (2)[A] (5)[A]

ADDITIONAL TREATMENT

General Measures

• Oral concentrations of fluoroquinolones (moxifloxacin 400 mg per day) reach significantly higher intravitreal concentrations than the topical counterpart; therefore, these drugs can be used as an adjunct to current therapy and as a prophylaxis for vitreous involvement (3)[B].

• With bleb leak or low intraocular pressure: No eye rubbing, shield when sleeping (or at all times except when taking eyedrops in those that cannot avoid physical contact with the eye), no bending, no straining.

• Worsening signs/symptoms should prompt immediate re-evaluation (redness, blurred vision, discomfort, tearing).

Issues for Referral

If blebitis is suspected immediately refer patient to an ophthalmologist.

SURGERY/OTHER PROCEDURES

• Vitreous tap/inject and vitrectomy should be strongly considered in all patients with BAE.

• Results of the Endophthalmitis Vitrectomy Study may not be extrapolated to included patients with BAE, which may progress more rapidly than late-onset postcataract endophthalmitis.

• Additional glaucoma surgery to control intraocular pressure may be needed following blebitis/BAE because subsequent filtration failure is common.

IN-PATIENT CONSIDERATIONS

Admission Criteria

Low threshold for admission in patients who progress rapidly and in those patients who are noncompliant or likely unable to follow intense regimen of medication administration

ONGOING CARE

FOLLOW-UP RECOMMENDATIONS

• No firmly established and generalizable guidelines

• Close follow-up guided by circumstances of infection and recovery

PATIENT EDUCATION

• Signs and symptoms of infection including redness, discomfort, and blurred vision should be detailed with patient.

• Patient should be instructed to return immediately for development or worsening of these symptoms.

PROGNOSIS

• Blebitis due to Staphylococcus species has a good prognosis with full resolution and decreasing chances of evolution into endophthalmitis.

• BAE has poor prognosis despite aggressive medical intervention and final visual acuity is often 20/200 or less.

COMPLICATIONS

• Bleb failure

• Pain

• Vision loss

• Blurred vision

• Loss of eye

• Elevated intraocular pressure

• Growth of more virulent/resistant infecting organisms

• Conjunctival scarring

• Intraocular scarring (such as posterior synechiae, peripheral anterior synechiae)

• Cataract

• Retinal detachment

Stay updated, free articles. Join our Telegram channel

Join