Antibiotic Steroid Combos

What are the primary indications for stand‑alone topical ophthalmic antibiotics to treat active ocular surface infections?

Active bacterial infections of the ocular surface, including:

• Bacterial conjunctivitis

• Hyperacute conjunctivitis

• Microbial keratitis (MK)

  • aka bacterial corneal ulcer

What clinical findings suggest bacterial conjunctivitis that warrant topical antibiotic treatment?

• Mucopurulent discharge

• “Eyelids stuck shut” (especially on waking)

How does hyperacute conjunctivitis present, and why is it treated urgently with topical antibiotics?

• Rapid onset

• Copious purulent exudate

• Conjunctival chemosis

• Suggests highly virulent bacteria → requires prompt antibiotic therapy

When are topical ophthalmic antibiotics used for prophylaxis or bacterial overgrowth prevention?

• Prophylaxis:

  • Epithelial defects

  • Pre‑ or post‑surgical settings

• Bacterial overgrowth:

  • Anterior blepharitis (“Staph bleph”)

What is the FDA‑approved indication for topical antibiotic-steroid combination eye drops/ointments?

• “Ocular inflammation with a risk of superficial bacterial infection”

• Used when inflammation is present and bacterial infection or overgrowth is a concern

What is the role of each component in a topical antibiotic–steroid combination?

• Steroid:

  • Anti‑inflammatory (↓ redness, pain, swelling)

• Antibiotic:

  • Prophylaxis against bacterial infection

  • ↓ bacterial overgrowth, which often drives the inflammation

Why are antibiotic-steroid combinations preferred over steroids alone in certain ocular inflammatory conditions?

• Steroids suppress local immunity

• Antibiotic component:

  • Prevents secondary bacterial infection

  • Controls existing bacterial overgrowth contributing to inflammation

• Makes steroid use safer in at‑risk eyes

Which inflammatory corneal conditions commonly require a topical antibiotic-steroid combination?

• Infiltrative Keratitis (IK)

• Contact Lens Acute Red Eye (CLARE)

• Contact Lens–Associated Infiltrative Keratitis (CLAIK)

All are sterile inflammatory events with infection risk

What is the etiology and pathophysiology of Infiltrative Keratitis (IK)?

• Sterile inflammatory reaction of the cornea

• Triggered by bacterial biofilm/colonization on soft contact lenses

• Not a true infection, but inflammation secondary to bacterial antigens

What are the typical clinical findings of Infiltrative Keratitis (IK)?

• Usually unilateral

• Single or few small, round, hazy subepithelial infiltrates

• Location: central or mid‑peripheral cornea

• Often positive fluorescein staining

• Mild-moderate irritation, redness, ± discharge

How does Asymptomatic Infiltrative Keratitis (AIK) differ from symptomatic IK?

• Smaller infiltrates

• Typically mid‑peripheral

• No or minimal staining

• Patient largely asymptomatic

• Associated with mild limbal injection

What is Contact Lens Acute Red Eye (CLARE) and when does it occur?

• Acute inflammatory reaction of the cornea and conjunctiva

• Occurs after overnight (extended‑wear) soft contact lens use

• Symptoms classically present upon awakening

What are the major etiologic factors contributing to CLARE?

Inflammatory response to one or more of the following:

• Hypoxic stress from overnight lens wear

• Tight lens syndrome

• Possible gram‑negative bacterial colonization on soft CL

What are the typical corneal findings in CLARE?

• Usually unilateral

• Multiple small infiltrates or diffuse WBCs

• Location: just inside the limbus

• Usually no fluorescein staining (intact epithelium)

What are the classic symptoms and signs of CLARE?

• Moderate-severe pain

• Tearing and photophobia

• Marked redness with circumlimbal injection

• Acute onset on awakening

What is the etiology of Contact Lens-Associated Infiltrative Keratitis (CLAIK)?

• Sterile inflammatory reaction of the cornea and conjunctiva

• Triggered by certain multipurpose solutions (MPS)

• MPS is harbored within silicone hydrogel (SiHy) daily‑wear lenses

What are the typical corneal findings in CLAIK?

• Usually bilateral

• Multiple, small, coarse, granular intraepithelial infiltrates

• Positive fluorescein staining

• Location: central or paracentral cornea

What symptoms are associated with CLAIK, and how severe are they?

• Asymptomatic to mild symptoms, including:

  • Mild irritation

  • Tearing

  • Photophobia

• Conjunctival injection commonly present

• Less painful than CLARE or microbial keratitis

What exam pearls help differentiate CLAIK from other CL‑related inflammatory events?

• CLAIK: bilateral, central/paracentral, MPS‑related, mild symptoms

• IK: usually unilateral, subepithelial infiltrates, biofilm‑related

• CLARE: acute, painful, post‑overnight wear, peripheral infiltrates

Which ocular conditions are classic examples of staph‑mediated hypersensitivity requiring antibiotic-steroid combinations?

• Phlyctenular keratoconjunctivitis (phlyctenulosis)

• Marginal keratitis

  • aka staph ulcer

  • aka sterile peripheral ulcer

• Contact lens peripheral ulcer/infiltrate (CLPU/CLPI)

• Anterior blepharitis with staph hypersensitivity

Why are steroids alone insufficient in staph hypersensitivity ocular conditions?

• Steroids suppress inflammation but do not remove antigen source

• Persistent staph overgrowth → recurrent inflammation

• Antibiotics ↓ bacterial load → ↓ immune stimulation

What is the etiology and immunologic mechanism of a phlyctenule?

• Type III hypersensitivity reaction

• Triggered by excess exotoxins from Staphylococcal overgrowth in normal flora

• Lesion is sterile (immune‑mediated, not infectious)

How does a phlyctenule typically present clinically?

• Unilateral red eye

• Focal accumulation of conjunctival WBCs

• Located at or near the limbus

• Coincides with lid crossing points:

  • 10:00, 2:00, 4:00, 8:00

What eyelid condition is commonly associated with phlyctenular keratoconjunctivitis?

Anterior blepharitis

What is the etiology and immunologic mechanism of marginal keratitis?

• Type III hypersensitivity reaction

• Triggered by excess exotoxins from Staphylococcal overgrowth in normal lid flora

• Lesion is sterile (immune‑mediated, not infectious)

What are the typical corneal findings in marginal keratitis?

• Unilateral red eye

• Single or multiple peripheral (marginal) corneal infiltrates

• Positive fluorescein staining

• Lesions correspond to lid crossing points:

  • 10:00, 2:00, 4:00, 8:00

What symptoms are associated with marginal keratitis, and how severe are they?

• Variable severity

• May range from asymptomatic to:

  • Tearing

  • Pain

  • Photophobia

What eyelid condition is commonly associated with marginal keratitis, and why is this important?

• Anterior blepharitis (Staph bleph)

• Acts as the source of staph exotoxins

• Underlies recurrence if lid disease is untreated

What is the etiology and pathophysiology of CLPI/CLPU?

• Type III hypersensitivity reaction

• Triggered by excessive Staphylococcal colonization on soft contact lenses

• Essentially marginal keratitis in a contact lens wearer

• Sterile inflammatory process, not a primary infection

What are the typical corneal findings in CLPI/CLPU?

• Usually unilateral

• Single, circular, well‑defined focal infiltrate

• Size: ≤ 2 mm

• Location: peripheral cornea just inside the limbus

• CLPI: no fluorescein staining

• CLPU: positive staining (epithelial defect)

What symptoms are associated with CLPI/CLPU, and how severe are they?

• Wide spectrum: asymptomatic → severe pain & photophobia

• Common symptoms:

  • Foreign body sensation

  • Tearing

• Signs:

  • Bulbar and limbal injection

What are the components and formulation options of Tobradex?

• 0.3% Tobramycin + 0.1% Dexamethasone

• Available as:

  • Suspension (generic available)

  • Ointment (trade name only)

What is the typical dosing regimen for Tobradex?

• q2h for 2 days, then

• QID for 5 days

Why is dexamethasone used instead of other steroids?

Dexamethasone is the only one that does not degrade when mixed with antibiotics.

How does Tobradex ST differ from standard Tobradex?

• 0.3% Tobramycin + 0.05% Dexamethasone

• No generic available

• Lower steroid concentration with enhanced delivery technology using Xanthan gum

What does the “ST” in Tobradex ST stand for, and why is it important?

• ST = Suspension Technology

• Uses a xanthan gum vehicle

• ↑ contact time on ocular surface

• Allows bioequivalent steroid effect despite lower dexamethasone concentration

What is the typical dosing regimen for Tobradex ST?

• q2h for 2 days, then

• QID for 5 days

• Same dosing as Tobradex, despite lower steroid %

What are the components and formulation of Zylet?

• 0.3% Tobramycin + 0.5% Loteprednol

• Suspension only

• Generic available

How does loteprednol in Zylet differ from dexamethasone in other combo agents?

Loteprednol has better penetration to target tissue and has lower risk of IOP elevation.

What is the typical dosing regimen for Zylet?

• q2h for 2 days, then

• QID for 5 days

Which antibiotic-steroid combinations are considered less desirable, and why?

• Older formulations with:

  • Weaker antibiotics

  • Higher allergy risk (e.g., neomycin)

  • Inferior steroid choices (e.g., hydrocortisone)

• Still used, but not first‑line compared to Tobradex or Zylet

What did the SCUT (Steroids for Cornela Ulcers Trail) study find?

• Tested outcomes of adding 1% prednisolone acetate as adjunctive therapy 48 hours after treatment with moxifloxacin to culture positive bacterial corneal ulcers.

• Results:

  • No overall difference in time to re-epithelialization, corneal perforation, or 3mos BCVA

    • No safety concerns with addition of steriods

  • No overall difference in scar size, except for:

    • Subgroup of pts who had finger counting entering VA had 0.17 logMAR better endoint acuity

    • Subgroup of pts with completely central ulcers had 0.20 logMAR better endpoint acuity.

What was the main take‑home message of the Steroids for Corneal Ulcers Trial (SCUT) regarding steroid use in microbial keratitis?

Steroids may be considered ONLY in select cases of bacterial keratitis, not routinely. They should be added cautiously and only after initial antibiotic response is demonstrated.

Under what specific conditions should a topical steroid be added to treatment for microbial (bacterial) keratitis per SCUT and AAO guidance?

Consider steroids only if ALL are met:

• Risk of visually significant scarring (within the pupillary zone)

• Treated on antibiotics alone for 24-48 hours first (48 h per 2023 AAO PPP)

• Clear slit‑lamp improvement (↓ staining size, evidence of re‑epithelialization)

• Preferably culture‑positive for bacteria to rule out fungal or protozoal keratitis