• Oct 2014
    AAO Cornea/External Disease PPP Panel, Hoskins Center for Quality Eye Care


    These are summary benchmarks for the Academy’s Preferred Practice Patterns® (PPP) guidelines. The Preferred Practice Patterns series of guidelines has been written on the basis of three principles.

    • Each Preferred Practice Pattern should be clinically relevant and specific enough to provide useful information to practitioners.
    • Each recommendation that is made should be given an explicit rating that shows its importance to the care process.
    • Each recommendation should also be given an explicit rating that shows the strength of evidence that supports the recommendation and reflects the best evidence available.

    Preferred Practice Patterns provide guidance for the pattern of practice, not for the care of a particular individual. While they should generally meet the needs of most patients, they cannot possibly best meet the needs of all patients. Adherence to these Preferred Practice Patterns will not ensure a successful outcome in every situation. These practice patterns should not be deemed inclusive of all proper methods of care or exclusive of other methods of care reasonably directed at obtaining the best results. It may be necessary to approach different patients' needs in different ways. They physician must make the ultimate judgment about the propriety of the care of a particular patient in light of all of the circumstances presented by that patient. The American Academy of Ophthalmology is available to assist members in resolving ethical dilemmas that arise in the course of ophthalmic practice.

    The Preferred Practice Pattern® guidelines are not medical standards to be adhered to in all individual situations. The Academy specifically disclaims any and all liability for injury or other damages of any kind, from negligence or otherwise, for any and all claims that may arise out of the use of any recommendations or other information contained herein.

    For each major disease condition, recommendations for the process of care, including the history, physical exam and ancillary tests, are summarized, along with major recommendations for the care management, follow-up, and education of the patient. For each PPP, a detailed literature search of PubMed and the Cochrane Library for articles in the English language is conducted. The results are reviewed by an expert panel and used to prepare the recommendations, which they rated in two ways.

    The panel first rated each recommendation according to its importance to the care process. This “importance to the care process” rating represents care that the panel thought would improve the quality of the patient’s care in a meaningful way. The ratings of importance are divided into three levels.

    • Level A, defined as most important
    • Level B, defined as moderately important
    • Level C, defined as relevant but not critical

    The panel also rated each recommendation on the strength of evidence in the available literature to support the recommendation made. The “ratings of strength of evidence” also are divided into three levels.

    • Level I includes evidence obtained from at least one properly conducted, well-designed randomized controlled trial. It could include meta-analyses of randomized controlled trials.
    • Level II includes evidence obtained from the following:
      • Well-designed controlled trials without randomization
      • Well-designed cohort or case-control analytic studies, preferably from more than one center
      • Multiple-time series with or without the intervention
    • Level III includes evidence obtained from one of the following:
      • Descriptive studies
      • Case reports
      • Reports of expert committees/organizations (e.g., PPP panel consensus with external peer review) 

    PPPs are intended to serve as guides in patient care, with greatest emphasis on technical aspects. In applying this knowledge, it is essential to recognize that true medical excellence is achieved only when skills are applied in a such a manner that the patients’ needs are the foremost consideration. The AAO is available to assist members in resolving ethical dilemmas that arise in the course of practice. (AAO Code of Ethics)

    Initial Evaluation

    Initial Exam History

    • Ocular symptoms (e.g., degree of pain, redness, discharge, blurred vision, photophobia, duration of symptoms, circumstances surrounding the onset of symptoms)
    • Contact lens history(e.g., wearing schedule, overnight wear, type of contact lenses, contact lens solution, contact lens hygiene protocol, tap-water rinse of contact lenses, swimming, using a hot tub, or showering while wearing contact lenses)
    • Review of other ocular history, including risk factors such as herpes simplex virus keratitis, varicella zoster virus keratitis, previous bacterial keratitis, trauma, dry eye, and previous ocular surgery, including refractive surgery
    • Review of other medical problems
    • Current and recently used ocular medications
    • Medication allergies

    Initial Physical Exam

    • Visual acuity
    • General appearance of patient including skin conditions
    • Facial examination
    • Globe position
    • Eyelids and eyelid closure
    • Conjunctiva
    • Nasolacrimal apparatus
    • Corneal sensation
    • Slit-lamp biomicroscopy
      • Eyelid margins
      • Conjunctiva
      • Sclera
      • Cornea
      • Anterior chamber for depth and the presence of inflammation, including cell and flare, hypopyon, fibrin, hyphema
      • Anterior vitreous
    • Contralateral eye for clues to etiology as well as possible similar underlying pathology

    Diagnostic Tests

    • Manage majority of community-acquired cases with empiric therapy and without smears or cultures
    • Indications for smears and cultures:
      • Sight-threatening or severe keratitis of suspected microbial origin prior to initiating therapy
      • A large central corneal infiltrate that extends to the middle to deep stroma
      • Chronic in nature
      • Unresponsive to broad spectrum antibiotic therapy
      • Clinical features suggestive of fungal, amoebic, or mycobacterial keratitis
    • The hypopyon that occurs in eyes with bacterial keratitis is usually sterile, and aqueous or vitreous taps should not be performed unless there is a high suspicion of microbial endophthalmitis
    • Corneal scrapings for culture and smears should be inoculated directly onto appropriate culture media and slides in order to maximize culture yield. If this is not feasible, place specimens in transport media. In either case, immediately incubate cultures or take promptly to the laboratory.

    Care Management

    • Topical antibiotic eye drops are preferred method in most cases
    • Use topical broad-spectrum antibiotics initially in the empiric treatment of presumed bacterial keratitis
    • For central or severe keratitis (e.g., deep stromal involvement or an infiltrate larger than 2 mm with extensive suppuration), use a loading dose (e.g., every 5 to 15 minutes for the first 30 to 60 minutes), followed by frequent applications (e.g., every 30 minutes to 1 hour around the clock). For less severe keratitis, a regimen with less frequent dosing is appropriate.
    • Use systemic therapy for gonococcal keratitis
    • For patients treated with ocular topical corticosteroids at time of suspected bacterial keratitis, reduce or eliminate corticosteroids until infection has been controlled
    • When the corneal infiltrate compromises the visual axis, may add topical corticosteroid therapy following at least 2 to 3 days of progressive improvement with treatment with topical antibiotics. Continue topical antibiotics at high levels with gradual tapering.
    • Examine patients within 1 to 2 days after initiation of topical corticosteroid therapy

    Management Recommendations

    Patient Education

    • Inform patients with risk factors predisposing them to bacterial keratitis of their relative risk, the signs and symptoms of infection, and to consult an ophthalmologist promptly if they experience such warning signs or symptoms
    • Educate about the destructive nature of bacterial keratitis and need for strict compliance with therapy
    • Discuss possibility of permanent visual loss and need for future visual rehabilitation
    • Educate patients with contact lenses about increased risk of infection associated with contact lens, overnight wear, and importance of adherence to techniques to promote contact lens hygiene
    • Refer patients with significant visual impairment or blindness for vision rehabilitation if they are not surgical candidates (see www.aao.org/smartsight)

    Antibiotic Therapy of Bacterial Keratitis

    Organism Antibiotic Topical
    No organism
    identified or
    multiple types
    of organisms


    50 mg/ml

    9–14 mg/ml


    100 mg in 0.5 ml

    20 mg in 0.5 ml



    50 mg/ml
    15–50 mg/ml
    10,000 IU

    100 mg in 0.5 ml
    25 mg in 0.5 ml



    9–14 mg/ml
    50 mg/ml 
    20 mg in 0.5 ml
    100 mg in 0.5 ml
    50 mg/ml
    50 mg/ml 
    100 mg in 0.5 ml
    100 mg in 0.5 ml
    20–40 mg/ml
    10 mg/ml
    10 mg/ml

    20 mg in 0.5 ml

    Nocardia Sulfacetamide
    100 mg/ml
    20–40 mg/ml

    16 mg/ml

    20 mg in 0.5 ml

    * Fewer gram-positive cocci are resistant to gatifloxacin and moxifloxacin than other fluoroquinolones.
    † Besifloxacin 6 mg/ml; ciprofloxacin 3 mg/ml; gatifloxacin 3 mg/ml; levofloxacin 15 mg/ml; moxifloxacin 5 mg/ml; ofloxacin 3 mg/ml, all commercially available at these concentrations.
    ‡ For resistant Enterococcus and Staphylococcus species and penicillin allergy. Vancomycin and bacitracin have no gram-negative activity and should not be used as a single agent empirically in treating bacterial keratitis. 
    § Systemic therapy is necessary for suspected gonococcal infection. 
    ¦ Data from Chandra NS, Torres MF, Winthrop KL. Cluster of Mycobacterium chelonae keratitis cases following laser in-situ keratomileusis. Am J Ophthalmol 2001;132:819-30.