Ocular Corticosteroids and NSAIDs: Powerful, and Not Without Cost
Inflammation is the eye's answer to almost every insult — a bruised iris after surgery, an allergic surface, a graft the body is trying to reject. Two drug families quiet it: corticosteroids, the broad and mighty suppressor of the whole inflammatory cascade, and NSAIDs, the narrower blocker of a single pathway. Steroids can rescue a sight-threatening uveitis in days. But left running, the same drops can silently raise the pressure until the optic nerve is gone, cloud the lens, and — most dangerously — turn a herpes ulcer into a corneal perforation. Knowing when to reach for which, and what each one costs, is the heart of ocular anti-inflammatory therapy.
A 58-year-old man comes to the eye clinic three weeks after routine cataract surgery. His vision, crisp on day one, has slipped again — hazy, with a dull ache. Two conditions could explain it, and they demand opposite drugs. Post-operative inflammation of the iris? That needs a corticosteroid to calm it. But when the nurse checks his intraocular pressure it reads 34 mmHg — the steroid drops he was sent home with have quietly driven it up. He is a "steroid responder," and had he stayed on them unmonitored, the first sign of trouble might have been permanent optic-nerve damage. In a single post-op patient you see the whole dilemma: the drug that treats the inflammation can also be the drug that blinds.
Why the eye needs its inflammation controlled
The eye is a small, closed, exquisitely transparent organ — and inflammation is opaque. In most of the body a little inflammation is a nuisance the tissue absorbs. In the eye it threatens sight directly: inflammatory cells clouding the clear aqueous, scar tissue gluing the iris to the lens, swelling of the macula that blurs central vision. So ophthalmology reaches for anti-inflammatory drugs constantly — after almost every intraocular operation, in uveitis (inflammation of the iris and inner coats), in allergic and immune surface disease, and to protect a corneal graft from rejection. The workhorses are two: corticosteroids and NSAIDs. They both dampen inflammation, but they act at very different points in the cascade, and that difference decides both their power and their price.
Corticosteroids: the broad suppressor
A corticosteroid molecule slips into the cell, binds the glucocorticoid receptor, and travels to the nucleus, where it turns the volume down on the whole inflammatory orchestra. It suppresses the enzyme phospholipase A2 at the top of the cascade — cutting off both prostaglandins and leukotrienes at their source — and switches off a wide programme of inflammatory genes and cytokines. Because it acts so high up and so broadly, a steroid is the most powerful anti-inflammatory the eye has. That breadth is exactly what makes it indispensable in serious disease: sight-threatening uveitis, stubborn post-operative inflammation, allergic and autoimmune surface disorders, and the prevention of graft rejection after a corneal transplant. The same broad mechanism is taught in full in the Inflammation & Joints chapter, where corticosteroid pharmacology is developed from first principles.
Not every steroid is equal — potency and "softness" vary by molecule. The strong, classic agents are prednisolone acetate (the workhorse for serious intraocular inflammation) and dexamethasone. At the gentler end sit the "soft" steroids — loteprednol etabonate and fluorometholone — designed or chosen to carry a lower risk of raising the eye pressure. Loteprednol is a clever "ester" steroid: it does its anti-inflammatory work and is then rapidly broken down to an inactive form, which limits how much pressure-raising trouble it can cause. Fluorometholone penetrates the eye less and so tends to raise pressure less. The trade-off is honest: softer steroids are safer on the pressure but generally less potent, so severe inflammation still calls for the strong agents under close monitoring.
A corticosteroid is a fire-department chief who cuts the power to the whole building the moment an alarm sounds. The fire goes out fast — but so do the lights, the lifts, the refrigerators and the security cameras. Shutting everything down stops the blaze, yet leave the power off for weeks and the building itself starts to fail: the pressure creeps up (glaucoma), the windows fog over (cataract), and with the alarms disabled a real intruder — a herpes virus, a fungus — can wander in unnoticed. An NSAID, by contrast, is a technician who trips only the single overheating circuit. Less dramatic, but it never plunges the whole building into the dark.
The three cardinal hazards of ocular steroids
Steroids buy their power with three signature complications the exam loves. First, steroid-induced glaucoma. In susceptible people — the "steroid responders," perhaps a third of the population and more among those with glaucoma or a family history — steroids reduce the outflow of aqueous fluid through the trabecular meshwork, and the intraocular pressure climbs. The danger is that it is painless and invisible: no red eye, no symptom, just a steadily rising pressure quietly killing optic-nerve fibres. This is why the rule is absolute — anyone on ocular corticosteroids, drops or otherwise, needs their intraocular pressure monitored. Second, posterior subcapsular cataract: prolonged steroid use clouds the lens in a characteristic pattern right at the back, degrading vision even after the inflammation is long gone. Third, and most acutely dangerous, potentiation of infection. By suppressing the immune response the steroid lets herpes simplex, fungi and bacteria run rampant across the cornea — turning a controllable infection into a sight-destroying ulcer.
The single most important reflex in ocular pharmacology: never start a corticosteroid in a red eye without first excluding herpes simplex keratitis. A dendritic (branching) corneal ulcer that stains with fluorescein is the red flag — put a steroid on that eye and the virus, unopposed, can melt straight through the cornea to perforation. "No steroid on an undiagnosed red eye, and never on a dendritic ulcer" is the rule that saves eyes. When steroids are genuinely needed in herpetic disease (for stromal inflammation), they are used only under specialist supervision, always with antiviral cover.
- Corticosteroids bind the glucocorticoid receptor and suppress the whole inflammatory cascade (via phospholipase A2) — the most powerful ocular anti-inflammatory.
- Uses: uveitis, post-op inflammation, allergic/immune surface disease, and preventing corneal-graft rejection.
- Three cardinal hazards: steroid glaucoma (raised IOP), posterior subcapsular cataract, and potentiated infection.
- Steroid glaucoma is silent — anyone on ocular steroids needs IOP monitoring.
- "Soft" steroids (loteprednol, fluorometholone) raise pressure less but are less potent.
- Prednisolone acetate and dexamethasone are the strong agents for serious disease.
From drops to implants: escalating delivery
How a steroid is delivered depends on how deep the inflammation sits. Surface and anterior-segment disease responds to eye drops. But drops barely reach the back of the eye, so posterior disease — sight-threatening uveitis at the macula, or macular oedema — demands the drug be placed nearer its target: periocular injection (around the eye), intravitreal injection (directly into the vitreous gel), and slow-release intravitreal implants that steadily elute steroid over months. Dexamethasone and fluocinolone implants can control chronic posterior inflammation and diabetic macular oedema for long stretches from a single insertion. The same cardinal hazards still apply, only concentrated at the back: intravitreal and implanted steroids very commonly raise the pressure and accelerate cataract. These posterior-delivery devices are explored further in the Retina chapter alongside the anti-VEGF and steroid options for macular disease.
NSAIDs: the narrow, steroid-sparing blocker
Where the steroid cuts the whole cascade, the NSAID snips a single branch. A topical NSAID inhibits cyclo-oxygenase (COX), the enzyme that makes prostaglandins. Prostaglandins are the messengers behind much ocular pain, surgically induced miosis (the pupil clamping down during an operation) and, crucially, the macular swelling that can follow cataract surgery. Blocking only that one pathway is far more selective than a steroid — and, decisively, it carries none of the steroid's pressure-raising or cataract-forming risk. That is the whole appeal: NSAIDs are steroid-sparing. The named agents are ketorolac, diclofenac, bromfenac and nepafenac (nepafenac is a prodrug that penetrates well and converts to its active form inside the eye). Their principal jobs are controlling pain — after cataract and refractive surgery, and in a corneal abrasion — holding the pupil open during surgery, and, most importantly, preventing and treating cystoid macular oedema (fluid cysts at the macula) after cataract surgery. The underlying COX and prostaglandin pharmacology is the same one built up in the Inflammation & Joints chapter.
NSAIDs have their own caution, and it is a serious one: corneal "melt" (keratolysis). Rarely, a topical NSAID can trigger breakdown of the corneal surface, thinning and even perforating it — a mirror image of the steroid's herpes danger but by a different route. The risk concentrates in eyes that are already vulnerable: a dry, poorly wetted, or otherwise compromised ocular surface (severe dry eye, neurotrophic corneas, diabetes). So an NSAID is not a free pass to sprinkle on any painful eye; on a fragile cornea it must be used cautiously and briefly, with the surface watched.
Reach for a corticosteroid when you need to suppress genuine, established inflammation of the inside of the eye — uveitis, brisk post-operative iritis, graft rejection — accepting the need to watch the pressure. Reach for an NSAID when the goal is pain control, keeping the pupil dilated in surgery, or preventing and treating macular oedema after cataract surgery, and you want to avoid loading the eye with steroid. In routine cataract surgery the two are often combined: a steroid to settle the anterior-chamber inflammation and an NSAID to protect the macula from cystoid oedema. In a steroid responder whose pressure has already climbed, switching some of the anti-inflammatory load onto an NSAID is a way to keep inflammation controlled without feeding the glaucoma.
- NSAIDs inhibit COX, blocking prostaglandin-mediated pain, surgical miosis and macular oedema.
- Named agents: ketorolac, diclofenac, bromfenac, nepafenac (a prodrug).
- Key uses: post-op and refractive pain, maintaining intra-operative mydriasis, preventing/treating cystoid macular oedema.
- The big advantage: steroid-sparing — no IOP rise, no cataract.
- The signature caution: rare corneal melt (keratolysis), especially on a dry or compromised surface.
- Steroid and NSAID are frequently combined after cataract surgery — one for inflammation, one for the macula.
- Starting a corticosteroid on a red eye before excluding herpes simplex — a dendritic ulcer plus a steroid risks corneal melt and perforation.
- Prescribing ocular steroids without ever checking the pressure — steroid glaucoma is silent and can blind before any symptom appears.
- Treating an NSAID as harmless on any painful eye — on a dry or compromised cornea it can trigger a sight-threatening melt.
A 30-year-old contact-lens wearer has a painful red eye. Fluorescein staining reveals a branching (dendritic) corneal ulcer. Which treatment is contraindicated as first-line therapy?
- Corticosteroids (prednisolone acetate, dexamethasone, loteprednol, fluorometholone) bind the glucocorticoid receptor and broadly suppress inflammation — the eye's most powerful anti-inflammatory, used for uveitis, post-op inflammation, immune surface disease and graft protection.
- Steroids' three cardinal hazards: steroid-induced glaucoma (silent, needs IOP monitoring), posterior subcapsular cataract, and potentiated infection — never start a steroid in an undiagnosed red eye or on a dendritic ulcer.
- Delivery escalates with depth: drops for the front, periocular/intravitreal injections and slow-release implants for posterior disease.
- NSAIDs (ketorolac, diclofenac, bromfenac, nepafenac) inhibit COX — steroid-sparing for pain, surgical mydriasis and cystoid macular oedema, with no IOP/cataract risk but a rare danger of corneal melt.
- Kanski's Clinical Ophthalmology: A Systematic Approach — Ocular therapeutics; uveitis; corneal disease.
- Bartlett JD, Jaanus SD. Clinical Ocular Pharmacology — Corticosteroids and non-steroidal anti-inflammatory drugs.
- American Academy of Ophthalmology, Basic and Clinical Science Course (BCSC) — Fundamentals and Principles of Ophthalmology; Glaucoma.
- Rang & Dale's Pharmacology — Anti-inflammatory and immunosuppressant drugs.
- British National Formulary (BNF) — Eye: anti-inflammatory preparations.
- Royal College of Ophthalmologists / NICE guidance — Management of uveitis and post-operative inflammation.
