23.4 Anti-Infectives, Corticosteroids, NSAIDs, Allergy Agents, Lubricants, Supplements & Anti-VEGF
Key Takeaways
- Topical corticosteroids raise intraocular pressure in steroid responders and accelerate posterior subcapsular cataract.
- Steroid monotherapy is contraindicated in herpes simplex epithelial keratitis and in untreated fungal keratitis.
- Fluoroquinolones are the usual empirical choice for bacterial keratitis; fortified antibiotics are used for severe ulcers.
- Preservative-free artificial tears are preferred when drops are used more than four to six times daily.
- AREDS2 supplementation is indicated for intermediate or advanced age-related macular degeneration, not for prevention in healthy eyes.
Anti-infective agents
Anti-bacterial.
| Group | Examples | Typical use |
|---|---|---|
| Fluoroquinolones | Moxifloxacin, gatifloxacin, ciprofloxacin, ofloxacin, levofloxacin | Broad spectrum; first-line empirical treatment for bacterial keratitis and post-operative prophylaxis |
| Aminoglycosides | Tobramycin, gentamicin | Gram-negative cover; epithelial toxicity with prolonged use |
| Macrolides | Erythromycin ointment, azithromycin drops | Gram-positive; blepharitis; neonatal prophylaxis |
| Polymyxin combinations | Polymyxin B with trimethoprim or bacitracin | Broad-spectrum conjunctivitis cover |
| Fortified antibiotics | Fortified cefazolin or vancomycin plus fortified tobramycin or an aminoglycoside | Severe or sight-threatening ulcers; compounded, refrigerated, short shelf life, often hourly dosing including overnight |
Patient instruction for a corneal ulcer regimen is a technologist task with real consequences: hourly drops including through the night, a five-minute gap between different agents, no contact lens wear, and daily review. A patient who does not understand the overnight dosing will under-treat a sight-threatening infection.
Anti-viral. Ganciclovir 0.15% gel and trifluridine 1% drops for herpes simplex epithelial keratitis; oral aciclovir, valaciclovir and famciclovir for herpes zoster ophthalmicus and for prophylaxis in recurrent herpes simplex. The key teaching point: corticosteroid monotherapy in herpes simplex epithelial keratitis is contraindicated — it promotes viral replication and can turn a dendrite into a geographic ulcer.
Anti-fungal. Natamycin 5% suspension is first-line for filamentous fungal keratitis; voriconazole and amphotericin are used topically, and oral or intravenous agents for deep or severe disease. Fungal keratitis is slow to treat, often taking many weeks, and steroids are avoided.
Anti-parasitic. Acanthamoeba keratitis is treated with biguanides (polyhexamethylene biguanide, chlorhexidine) with or without a diamidine, often for months. Prevention is the practical message: contact lenses must never be rinsed or stored in tap water, and should not be worn while swimming or showering.
Corticosteroids
| Agent | Relative potency | Typical use |
|---|---|---|
| Prednisolone acetate 1% | High | Post-operative, uveitis; a suspension — shake well |
| Dexamethasone 0.1% | High | Post-operative, inflammation |
| Difluprednate 0.05% | Very high | Severe inflammation; higher pressure-rise risk |
| Loteprednol 0.2–0.5% | Moderate, ester steroid | Lower pressure-rise risk; chronic surface inflammation |
| Fluorometholone 0.1% | Lower penetration | Surface inflammation, allergy |
The three complications to know:
- Steroid-induced ocular hypertension. About a third of the population are steroid responders and a small percentage are high responders. Pressure must be checked at intervals in anyone on a topical steroid beyond a couple of weeks.
- Posterior subcapsular cataract — dose and duration related, and irreversible.
- Potentiation of infection — herpes simplex, fungal and bacterial keratitis all worsen, and epithelial healing is delayed.
Taper rather than stop abruptly after prolonged use, to avoid rebound inflammation.
Non-steroidal anti-inflammatory drugs
Examples: ketorolac, diclofenac, nepafenac, bromfenac, flurbiprofen.
Mechanism: inhibit cyclo-oxygenase and therefore prostaglandin synthesis.
Uses: post-operative inflammation and pain, prevention and treatment of cystoid macular oedema, maintaining intraoperative mydriasis (flurbiprofen), allergic conjunctivitis itch, and post-refractive-surgery discomfort.
Advantage over steroids: they do not raise intraocular pressure and do not cause cataract.
Risks: stinging, and — importantly — corneal melting with prolonged use, particularly in dry eye, diabetes, rheumatoid arthritis, neurotrophic corneas and after surgery. Any patient on a topical NSAID with a persistent epithelial defect must be reviewed.
Allergy medications
| Class | Examples | Onset / role |
|---|---|---|
| Antihistamine / mast cell stabiliser combinations | Olopatadine, ketotifen, azelastine, bepotastine, alcaftadine | Rapid itch relief and prophylaxis; the usual first choice |
| Mast cell stabilisers | Cromolyn, lodoxamide, nedocromil | Prophylactic; need days to weeks to work, so they must be started before the season |
| Topical antihistamines | Emedastine | Rapid, short-acting |
| Topical NSAIDs | Ketorolac | Itch relief |
| Topical steroids | Loteprednol, fluorometholone | Severe or vernal disease, short courses under supervision |
| Decongestants | Naphazoline, tetrahydrozoline | Whitening only; rebound hyperaemia with regular use — discourage |
Non-pharmacological measures matter and should be taught: cool compresses, allergen avoidance, preservative-free lubricants to dilute allergen, refrigerating the drops, and not rubbing the eyes — rubbing degranulates mast cells and is also associated with keratoconus progression.
Ocular lubricants
| Form | Notes |
|---|---|
| Preserved drops | Acceptable up to about four times daily |
| Preservative-free drops | Required when used more than four to six times daily, and in surface disease, because benzalkonium chloride is directly toxic to the epithelium with frequent use |
| Gels | Longer contact, transient blur; often evening use |
| Ointments | Longest contact, marked blur; usually bedtime only |
| Lipid-containing emulsions | Target evaporative dry eye and meibomian dysfunction |
Also relevant: cyclosporine 0.05% and lifitegrast 5% for aqueous-deficient and inflammatory dry eye — both take weeks to months to show benefit, and patients must be told so or they will abandon treatment.
Nutritional supplements
AREDS2 formulation: vitamin C 500 mg, vitamin E 400 IU, zinc 80 mg (or a lower zinc dose), copper 2 mg, lutein 10 mg and zeaxanthin 2 mg.
Indication: intermediate or advanced age-related macular degeneration — it slows progression in those eyes. It is not indicated for prevention in healthy eyes or in early macular degeneration.
The beta-carotene point: the original AREDS formula contained beta-carotene, which increased lung cancer risk in smokers and former smokers. AREDS2 replaced it with lutein and zeaxanthin. Never recommend a beta-carotene-containing formula to a smoker.
Omega-3 supplementation is widely used for dry eye, with mixed trial evidence.
Anti-neovascular (anti-VEGF) agents
Examples: ranibizumab, aflibercept, bevacizumab (used off-label), brolucizumab, faricimab.
Mechanism: bind vascular endothelial growth factor, reducing neovascularisation and vascular leakage.
Indications: neovascular age-related macular degeneration, diabetic macular oedema, proliferative diabetic retinopathy, macular oedema from retinal vein occlusion, myopic choroidal neovascularisation and retinopathy of prematurity.
Administration: intravitreal injection under strict aseptic technique, initially monthly then on a treat-and-extend or as-needed schedule.
Risks to counsel: endophthalmitis (rare but devastating), retinal detachment, intraocular inflammation, transient pressure rise, subconjunctival haemorrhage (common, alarming, benign) and a theoretical systemic thromboembolic risk.
Post-injection instruction the technologist usually delivers: expect floaters and a red patch on the white of the eye; do not rub the eye; and return immediately for increasing pain, worsening vision, increasing redness or discharge, because those are the warning signs of endophthalmitis. Give the instruction in writing as well as verbally.
Why is corticosteroid monotherapy contraindicated in herpes simplex epithelial keratitis?
Which complication is associated with topical NSAIDs but not with topical corticosteroids?
Why was beta-carotene replaced with lutein and zeaxanthin in the AREDS2 formulation?
A patient is started on a mast cell stabiliser for seasonal allergic conjunctivitis and reports after two days that it is not working. What is the correct explanation?
What is the most important warning to give a patient after an intravitreal anti-VEGF injection?