Bacterial Keratitis and Treatment Quiz

Allergic Eye Disease

• Affects up to 30% of the population
• Seasonal and perennial
• Bilateral
• Conjunctival injection and chemosis, tearing, itching, eyelid swelling
• Papillary reaction
• Many patients self-medicate
• Allergic shiners are caused by blood pooling
• Atopy (eczema, hayfever, and asthma starting early in life)
• Chronic with seasonal exacerbations and remissions
• Improves around puberty
• Itching, photophobia, blurred vision, copious mucoid discharge, ptosis, shield ulcer
• Two main subtypes: palpebral, limbal, and mixed
• Vernal Keratoconjunctivitis (VKC)
  • Younger
  • Males > females
  • Limited duration; resolves at puberty
  • Spring
  • Upper tarsus
  • Rare conjunctival cicatrization
  • Shield ulcer, corneal scar, and rare corneal vascularization
• Atopic Keratoconjunctivitis (AKC)
  • Older
  • No predilection
  • Chronic
  • Perennial
  • Lower tarsus
  • Common conjunctival cicatrization
  • Persistent epithelial defects, common corneal scar, common corneal vascularization

Treatment Algorithm for Allergic Conjunctivitis

• Mild: Symptoms without photophobia; Occasional topical antiallergic drop
• Moderate: Symptoms with photophobia; Daily topical antiallergic drop + cold compress
• Severe: Diffuse SPK and/or shield ulcer; Pulsed high-dose steroids
  • Oral steroids 1 mg/kg/day x 3 days if severe
• First-line:
  • Oral antihistamine
  • Nasal steroid
  • Immunotherapy
  • Other immunomodulator
  • Topical ophthalmic steroids
  • Topical ophthalmic dual-activity agents
• Topical cyclosporine
• Topical calcineurin inhibitor (tacrolimus)
• Consider allergen avoidance and supportive measures.

Allergic Conjunctivitis Management

• Avoid/eliminate allergens
• Shower and change clothes after exposure
• Identify contributing factors: contact lenses, dry eye, blepharitis
• Supportive measures:
  • Cold compresses
  • Artificial tears
  • Topical vasoconstrictors
  • Topical antihistamines and mast-cell stabilizers
  • NSAIDs
  • Judicious use of corticosteroids

Clinical Grading of Vernal and Atopic Keratoconjunctivitis and Treatment

• Grade 1 to 4: Signs/Symptoms range from mild to severe
• Grade 1: Mild symptoms
• Grade 2: Moderate symptoms
• Grade 3: Severe, diffuse symptoms
• Grade 4: Severe symptoms with complications
• Treatment: depends on grade

  • Mild to moderate: daily topical antiallergic drop, cold compress, cromolyn sodium QID, olopatadine QD-BID ,Tx1 +FML0.1% QD-BID

  • Severe: pulsed high-dose steroids, oral corticosteroids

Vitamin A Deficiency

• Partial night blindness is the 1st symptom
• Xerophthalmia: corneal and conjunctival dryness
• Can progress to corneal ulceration, perforation, and keratomalacia (severe wrinkling/opacification esp in children)
• Vitamin A is required for goblet cell development
• Deficiency leads to a thick mucin layer, keratin buildup (Bitot's spots), usually in temporal area

Infectious Conjunctivitis

• Viral

  • Adenovirus: most common cause of acute viral conjunctivitis (90%). Very contagious (respiratory and ocular secretions). Symptoms include: watery discharge, conjunctival hyperemia, irritation, itching, mild photophobia, contralateral involvement. 10-minute rapid test for Adeno hexon protein.
  • Pharyngo-Conjunctival Fever: Adenovirus (serotypes 3, 4, & 7). Symptoms include: pharyngitis (sore throat, difficulty swallowing), follicular conjunctivitis, fever, mild epithelial keratitis (rarely subepithelial infiltrates), and preauricular lymphadenopathy (+PAN sometimes).
  • Epidemic Keratoconjunctivitis (EKC): Adenovirus (serotypes 8, 19, and 37). Symptoms include: tearing, may be preceded by URI, FB sensation, bilateral follicular conjunctivitis, and punctate epithelial keratitis. Long-term complications are possible
  • Acute Hemorrhagic Conjunctivitis: Picornavirus (enterovirus type 70, coxsackievirus A24). Common in densely populated tropical areas and in younger patients. Symptoms include sudden-onset pain, tearing, FB sensation, conjunctival injection, subconjunctival hemorrhage (SCH) which may be petechial.

• Bacterial

  • Causes: often infectious (duration < 3 weeks), immunologic, traumatic, or toxic
  • Discharge subtypes: watery, mucoid, purulent/mucopurulent, hyperpurulent
  • Papillae: allergies, topicals, irritation, bacteria
  • Follicles: viruses, chlamydia, drugs, lymphoid disease

• Chlamydial Conjunctivitis (Adult)

  • Transmission: Auto-inoculation from genital secretions or eye-eye spread
  • Can cause systemic complications like urethritis and dysuria, especially in females.
  • Symptoms include watery mucopurulent discharge, preauricular lymphadenopathy, large follicles, perilimbal subepithelial K infiltrates, and pannus

• Neonatal Conjunctivitis -Causes: bacterial, reflecting maternal vaginal flora. Gram-positive and gram-negative bacteria are common. -Risk factors: Maternal STIs, ruptured membranes, prolonged labor, prematurity

• Gonococcal Conjunctivitis (Neonatal) -Transmission: sexual contact or vertical transmission -Symptoms are acute. Common symptoms include: thick, purulent discharge (often serosanguineous initially), lid edema, conjunctival chemosis, and small conjunctival hemorrhages -Gonococcal keratoconjunctivitis= Can lead to significant corneal involvement

• Corynebacterium Conjunctivitis

  • Bacteria, rare in developed countries -Causes systemic symptoms such as pseudomembranes (throat, nose) -May cause other systemic issues like cardiac arrhythmias and myocarditis -Treatment: Frequently resistant to FQs and emycin, so sensitivity testing is imperative. Possible treatment is cephalosporins or aminoglycosides.

• Other

  • Viral (mumps, herpes simplex): rare in the neonatal population; typically manifests within 1 or 2 weeks of birth.
  • Bacterial (staphylococcal, streptococcal): rare in newborns but can develop with poor hygiene or if there are breaks in skin or mucus membranes
  • Viral: (measles, haemorrhagic conjunctivitis)

Phlyctenulosis

• Focal elevated nodule
• Accompanied by engorged blood vessels
• Type IV hypersensitivity reaction to microbial antigens (e.g., staphylococcal cell wall components)
• Associated with tuberculosis
• Primarily occurs in the perilimbal conjunctiva (near the limbus). It's mostly seen in children, but can appear elsewhere.
• Initial appearance: small, subepithelial, often asymptomatic. Central portion can turn yellow or ulcerate.
• Treatment: Topical steroids, often starting with low concentrations and gradually tapering down to a daily application. TB testing is important if TB is suspected. Maintenance therapy may involve topical cyclosporine or tacrolimus.

Pediatric Blepharokeratoconjunctivitis (BKC)

• Average onset age: approximately 6 years old
• More severe in Asian/Middle Eastern populations
• Typically recurrent episodes of blepharitis, hordeola (styes), or chalazia (granulomas).
• Usually unilateral or bilateral, involving one or more localized peripheral stromal infiltrates, separated from the limbus.
• Conjunctival changes: phlyctens (small, elevated lesions), follicles or papillary hyperplasia
• Corneal involvement: phlyctenulosis, punctate epithelial erosions/superficial punctate keratitis, and pannus.
• Treatment: Topical steroids (short-term), cyclosporine, tacrolimus (compounded for use). Important to assess and treat any associated blepharitis with lid hygiene including warm compresses and cleaning as needed.

Phlyctenular Conjunctivitis (and Tuberculosis)

• Recurrent fever and cough every 2 weeks for 3 months, possibly associated with abdominal TB; (+) PPD skin test (22 mm after 48 hrs)
• Confirmation of active or latent TB necessary: sputum test for acid-fast bacilli (-) and chest radiograph (-).
• Treatment: Rifampin, isoniazid, ethambutol, pyrazinamide for 2+ months and subsequently rifampin + isoniazid for another 4 months or until disease is resolved.

Infectious Infiltrates (Sterile vs. Infectious)

• Infiltrates: large, central >2mm, and/or associated with stromal involvement/melting suggest infection.
• Signs suggesting infection: pain, anterior chamber reaction (AC), mucopurulent discharge, epithelial defect.
• Hypopyon: whitish-yellowish layer of WBCs, often associated with corneal ulceration and iritis. May be helpful for judging severity/effectiveness of therapy.

Corneal Ulcer (Culture & Collection)

• When to Culture: central, large, or deep stromal involvement, chronic or unresponsive infection, history of corneal surgery, atypical features
• Culture Techniques: Kimura spatula, blade, culturette swab, calcium alginate swab. Sterilize scraping tools.
• Culture media: blood agar, chocolate agar, Sabouraud dextrose agar (for fungi), thioglycollate broth
• Microscopy stains: Gram stain, Giemsa stain, Calcofluor white, acid-fast stain, Grocott-Gömöri methenamine silver, Periodic acid-Schiff (PAS)

Bacterial Keratitis (Subtypes & Treatment)

• Common organisms: Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus pneumoniae

• Gram negative bacilli

  • Pseudomonas aeruginosa—most common cause of contact-lens related corneal infections, with a tendency to form biofilms. Can create a “ground glass” appearance to the surrounding stroma. Antibiotic resistance common.

• Gram positive cocci: Staphylococcus aureus, Streptococcus pneumoniae and Streptococcus viridians

• Treatment: -4th gen FQs, topical antibiotics -If unresponsive, systemic agents such as oral antibiotics (doses vary per agent) and fortified antibiotic combos (Cefazolin 50 mg/mL + [Gentamycin OR Tobramcyin 14 mg/mL] q1h each, alternate every 30 minutes)

Atypical Mycobacterium (Non-TB)

• Often slower to develop, may present as a lack of response to conventional antibiotic therapies
• Diagnosis: acid-fast stain, culture on Löwenstein-Jensen medium
• Treatment: empiric, broad-spectrum topical antibiotics (frequently using FQs, or aminoglycosides)

Fungal Keratitis

• Clinical presentation: nonspecific to specific. Specific signs suggest fungal infection: feathery or filamentous margins, gray/white non-suppurative infiltrate, elevated infiltrate, multifocal or satellite lesions, or hypopyon.
• Diagnosis: KOH wet mount; in vivo confocal microscopy (IVCM)
• Common risk factors: CL wear, chronic ocular surface disease, chronic keratitis (HSV, HZ), corneal trauma, immunosuppression, topical corticosteroid use.
• Treatment: early use of topical and systemic antifungals. (Amphotericin B 0.15%, Natamycin 5%, Topical Voriconazole 1%, Ketoconazole, Fluconazole or Itraconazole) Systemic antifungal agents for severe/recalcitrant infections: Voriconazole (200-400 mg/day), Posaconazole (800 mg/day)

Anterior Chamber Tap (Paracentesis)

• Procedure: document VA & IOP first, administer anesthetic and antiseptic, insert 1/2 inch, 30-guage needle to the anterior chamber. Aspirate 0.1-0.2 mL. Allow culture time.
• Used for endophthalmitis diagnosis.

Acanthamoeba Keratitis

• Risk factors: soft contact lens wear, contaminated water or soil, trauma, immunosuppression.

• Pathophysiology: Trophozoite form feeds on corneal cells.

• Clinical findings: varies depending on stage: epithelial, subepithelial/anterior stromal, radial keratoneuritis, or hypopyon.

• Treatment:

• Biguanides (polyhexamethylene biguanide 0.02% and chlorhexidine 0.02%) every 1 to 2 hours for milder forms or when drug is available.

• Diamidines (propamidine-isethionate) 0.1% every 1 to 2 hours. Taper down to every 4 hours as inflammation resolves.

• Miltefosine (50 mg twice to three times per day), Voriconazole (systemic and 1% topical), systemic and topical antifungal agents (Natamycin, Miconazole, Ketoconazole, Itraconazole)

• Mechanical debridement (for epithelial level) is sometimes needed.

Corneal Dystrophies

• Overview: group of disorders that affect the cornea, often resulting in corneal opacity or visual problems. (EBMD):

  • Symptoms: mild irritation to acute pain; on awakening, epiphora and redness occur. Can cause irregular astigmatism.
  • Treatment: symptomatic relief, epithelial debridement, and diamond burr polish, or PTK.

• Other dystrophies:

  • Spheroidal degeneration
  • Salzmann's nodular degeneration
  • Crocodile shagreen
  • White Limbal Girdle of Vogt

• Treatment is variable, and dependent on individual needs. This may include topical lubrication in earlier stages. Consider topical steroids in inflammatory episodes, but avoid in cases of risk of recurrence.

Keratoplasty (General)

• Indications: vision improvement, restoration of corneal integrity, therapeutic treatment of infection, or cosmetic needs
• Donor tissue: evaluated and screened for potential viability.
• Recipient factors: should be evaluated to assess health of ocular surface (eyelid, conjunctiva, tear film), inflammation, glaucoma, and other systemic factors.

Keratoplasty (Specific Subtypes)

• Penetrating keratoplasty (PK): comprehensive replacement of the corneal tissue
• Partial-thickness keratoplasty: anterior lamellar keratoplasty (ALK), deep anterior lamellar keratoplasty (DALK), Descemet stripping endothelial keratoplasty (DSEK), Descemet membrane endothelial keratoplasty (DMEK)

Neurotrophic Keratitis/Keratopathy

• Reduced corneal sensation — associated with reduced or absent corneal innervation, commonly seen with HSV keratitis, HZ keratitis, or other neurological diseases or surgical ablation.
• Treatment: taping of lids (nighttime), lubricative eye drops, amniotic membrane patching, or in some cases, tarsorraphies (suturing the eyelids).

Mooren's Ulcer

• Progressive stromal ulceration and thinning of the peripheral cornea associated with significant inflammation (benign type vs. aggressive type).
• Treatment: Topical steroids, topical antibiotics, and/or systemic immunosuppressants as indicated

Peripheral Ulcerative Keratitis (PUK)

• Progressive stromal ulceration and thinning of the peripheral cornea linked to systemic autoimmune conditions like Rheumatoid Arthritis, Granulomatosis with polyangiitis, or Systemic lupus erythematosus
• Treatment: Topical and sometimes systemic steroids and/or immunosuppressants.

Corneal Verticillata (and Fabry Disease)

• Golden-brown, whorled epithelial opacities.
• Can be associated with Fabry disease, a systemic disorder.
• Treat by discontinuing potentially causative pharmaceutical agents (e.g., quinolones, amiodarone).

Miscellaneous Conditions of the Cornea

• Arcus senilis: bilateral, white ring in peripheral cornea due to lipid deposition in elderly individuals. No treatment necessary unless cholesterol or other lipid issues need managing.

• Band keratopathy: chalky or band-like, calcified deposits in the anterior stroma associated with diverse systemic disorders or ocular conditions. Treatment is dependent on underlying cause

• Cornea verticillata: fine, golden-brown, irregular, horizontal lines/opacities in the inferior and paracentral cornea Treatment required only if attributed to systemic medications/diseases. If corneal verticillata is secondary to Fabry disease, a multidisciplinary approach including genetic testing, cardiac evaluation, and kidney function evaluation is required.

Test your knowledge on the types of bacteria linked to contact lens-related keratitis, the recommended dosage of Azithromycin for treatment, and the mechanisms that enhance bacterial resistance. This quiz will challenge your understanding of bacterial infections and their management.