Definition
Ophthalmic anti-infectives are topical medications specifically formulated for administration to the eye to treat or prevent ocular infections. These infections may involve the conjunctiva, cornea, eyelids, lacrimal ducts, or deeper structures such as the anterior chamber. The agents may be antibacterial, antiviral, antifungal, or antiparasitic, depending on the causative pathogen. Ophthalmic anti-infectives are typically available as eye drops, ointments, gels, or inserts, and may also be used in combination with corticosteroids to address both infectious and inflammatory components.
1. Mechanism of Action (by subtype)
| Subtype | Mechanism |
|---|---|
| Antibiotics | Disrupt bacterial cell wall synthesis (e.g., fluoroquinolones, aminoglycosides), inhibit protein synthesis (e.g., macrolides, tetracyclines), or DNA replication |
| Antivirals | Inhibit viral DNA polymerase or interfere with viral replication (e.g., acyclovir, ganciclovir) |
| Antifungals | Disrupt fungal cell membrane by binding to ergosterol (e.g., natamycin, amphotericin B) |
| Antiparasitics | Impair parasite metabolic processes or nucleic acid synthesis (e.g., topical metronidazole in rare indications) |
2. Indications
Ophthalmic anti-infectives are used to treat:
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Bacterial conjunctivitis
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Bacterial keratitis or corneal ulcers
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Blepharitis
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Endophthalmitis (as adjunct to systemic or intravitreal therapy)
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Ocular herpes simplex infections
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Herpes zoster ophthalmicus (HZO)
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Fungal keratitis
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Trachoma (Chlamydia trachomatis)
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Prophylaxis in ocular surgery or trauma
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Gonococcal and neonatal conjunctivitis
3. Ophthalmic Antibiotics
A. Fluoroquinolones
Broad-spectrum, commonly used as first-line agents for moderate to severe infections.
| Generic | Brand Names | Generations |
|---|---|---|
| Ciprofloxacin | Ciloxan | 2nd |
| Ofloxacin | Ocuflox | 2nd |
| Levofloxacin | Quixin | 3rd |
| Moxifloxacin | Vigamox, Moxeza | 4th |
| Gatifloxacin | Zymar, Zymaxid | 4th |
| Besifloxacin | Besivance | 4th |
Advantages: Broad-spectrum, rapid bactericidal activity
Side effects: Burning, bitter taste, rare hypersensitivity
B. Aminoglycosides
| Generic | Brand | Activity |
|---|---|---|
| Tobramycin | Tobrex | Gram-negative > Gram-positive |
| Gentamicin | Genoptic | Similar to tobramycin |
Note: Often used in combination with steroids
Side effects: Local irritation, potential epithelial toxicity
C. Macrolides
| Generic | Brand | Notes |
|---|---|---|
| Erythromycin | Ilotycin | Ointment form, gentle on eyes |
| Azithromycin | AzaSite | Longer dosing interval |
Features: High ocular tissue penetration, safer in infants
D. Polymyxins (in combo formulations)
| Combination | Brand |
|---|---|
| Polymyxin B + Trimethoprim | Polytrim |
| Neomycin + Polymyxin B + Gramicidin | Neosporin Ophthalmic |
E. Sulfonamides
| Generic | Brand |
|---|---|
| Sulfacetamide | Bleph-10 |
F. Tetracyclines
| Generic | Form | Indication |
|---|---|---|
| Tetracycline | Ointment | Blepharitis, trachoma |
| Doxycycline | Oral | Meibomian gland dysfunction, rosacea-related keratitis |
4. Ophthalmic Antivirals
Primarily used for herpetic keratitis, herpes zoster ophthalmicus, and CMV retinitis (adjunctively).
| Generic | Brand | Indications |
|---|---|---|
| Ganciclovir | Zirgan | Herpes simplex keratitis |
| Trifluridine | Viroptic | Herpes simplex keratitis |
| Acyclovir (oral) | Zovirax | HSV keratitis, HZO |
| Valacyclovir (oral) | Valtrex | HZO |
| Foscarnet | (Off-label IV) | CMV retinitis (intravitreal) |
5. Ophthalmic Antifungals
Used in rare but serious conditions like fungal keratitis, endophthalmitis, or aspergillus ocular infections.
| Generic | Form | Indications |
|---|---|---|
| Natamycin | Natacyn (5% drop) | Filamentous fungi keratitis (e.g., Fusarium, Aspergillus) |
| Amphotericin B | Compounded solution | Yeast infections (e.g., Candida spp.) |
| Voriconazole | Compounded solution | Refractory fungal keratitis |
6. Ophthalmic Antiparasitic Agents
| Generic | Indication |
|---|---|
| Topical metronidazole (off-label) | Acanthamoeba keratitis (adjunct) |
| Chlorhexidine (0.02% solution) | Acanthamoeba keratitis |
| Polyhexamethylene biguanide (PHMB) | Acanthamoeba keratitis |
7. Formulations
| Formulation | Examples | Use Case |
|---|---|---|
| Drops | Most common (e.g., fluoroquinolones) | Acute infections, prophylaxis |
| Ointments | Erythromycin, Bacitracin | Lid margin disease, nighttime use |
| Gels | Ganciclovir | Longer contact time |
| Inserts | Rare (e.g., for CMV) | Controlled-release formulations |
8. Combination Products
Used when both anti-infective and anti-inflammatory therapy are needed (e.g., post-surgery).
| Brand | Contents | Indications |
|---|---|---|
| Tobradex | Tobramycin + Dexamethasone | Post-op inflammation, blepharitis |
| Zylet | Tobramycin + Loteprednol | Lid disease, keratitis |
| Maxitrol | Neomycin + Polymyxin B + Dexamethasone | Conjunctivitis, inflammation |
9. Precautions and Contraindications
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Avoid steroid-containing combinations in suspected viral (herpes) or fungal infections
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Contact lens wearers should avoid using drops with preservatives like BAK
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Avoid prolonged use to prevent:
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Superinfection
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Fungal overgrowth
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Resistance development
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Trifluridine is toxic to the corneal epithelium with prolonged use
10. Adverse Effects
| Agent | Common Side Effects |
|---|---|
| Fluoroquinolones | Bitter taste, eye irritation, white precipitate (ciprofloxacin) |
| Aminoglycosides | Corneal epithelial toxicity, allergic reactions |
| Antivirals | Stinging, punctate epithelial keratopathy |
| Antifungals | Burning, visual blur, corneal toxicity |
| Macrolides | Minimal; safe in neonates |
| Sulfacetamide | Hypersensitivity, Stevens-Johnson risk |
11. Resistance Considerations
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Fluoroquinolone resistance is increasing, especially in Staphylococcus aureus strains
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Always adjust treatment based on culture and sensitivity when infection is unresponsive
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Consider combination systemic + topical therapy in severe keratitis or endophthalmitis
12. Key Products by Region
| Generic | US Brands | UK Brands | International |
|---|---|---|---|
| Chloramphenicol | Chloroptic | Optrex Infected Eye | Minims, Albucid |
| Fusidic acid | (Not US available) | Fucithalmic | Fusithal |
| Azithromycin | AzaSite | (Not widely available) | Azyter (Europe) |
| Ganciclovir | Zirgan | Virgan | Ganciclovir Chauvin |
| Natamycin | Natacyn | (Limited) | Natamet (India) |
13. Patient Counseling Tips
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Do not touch the dropper tip to the eye to avoid contamination
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Use eye drops before ointments, with at least 5-minute spacing
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Complete full course even if symptoms improve
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Store refrigerated drops properly (e.g., chloramphenicol)
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Avoid contact lenses during active infection
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