Why Are Steroids Contraindicated in Keratitis? Understanding the Risks

October 9, 2025 •

5 min read

Prior use of topical steroids has been reported as an important risk factor for infectious keratitis, sometimes leading to worse clinical outcomes. This highlights the critical nature of understanding why steroids are contraindicated in keratitis, particularly when the infection's cause has not been identified.

Quick Summary

Steroids are largely contraindicated in infectious keratitis due to immunosuppression, which can exacerbate infections like fungal and amoebic keratitis. They also delay corneal healing and carry risks of complications like corneal melting and secondary glaucoma.

Key Points

Immune Suppression: Corticosteroids suppress the body's natural inflammatory and immune responses, which are vital for eliminating infectious agents in the cornea.
Exacerbated Infection: By weakening the local immune defense, steroids can allow bacteria, fungi, and parasites like Acanthamoeba to multiply and cause a more severe infection.
Delayed Healing: Steroids inhibit corneal epithelial cell regeneration and collagen synthesis, leading to delayed wound healing, and increasing the risk of corneal thinning, melting, and perforation.
Increased Ocular Pressure: Long-term or potent topical steroid use can cause a dangerous rise in intraocular pressure, potentially leading to irreversible steroid-induced glaucoma.
Masking Symptoms: The anti-inflammatory effect of steroids can reduce pain and redness, masking the progression of the underlying infection and leading to a delayed or incorrect diagnosis.
Pathogen-Specific Risk: The severity of the risk depends on the pathogen; steroids are absolutely contraindicated in fungal keratitis, highly risky in amoebic and most bacterial cases, but may be used cautiously for viral stromal keratitis under expert supervision with antivirals.

What is Keratitis?

Keratitis is an inflammation of the cornea, the transparent, dome-shaped front part of the eye that covers the iris and pupil. While inflammation is a natural response to injury or infection, it can also lead to painful symptoms and scarring that impairs vision. Corticosteroids, a class of potent anti-inflammatory drugs, might seem like a logical treatment to reduce this inflammation and prevent scarring. However, in cases of infectious keratitis, where a pathogen like bacteria, fungi, or a virus is the cause, the use of steroids presents significant risks and is often contraindicated. The core issue lies in the immunosuppressive effects of steroids, which, while reducing inflammation, can also hinder the body's ability to fight off the underlying infection, turning a manageable condition into a sight-threatening one.

The Core Contradiction: Suppression vs. Protection

The body's immune response is a double-edged sword during an infection. It attacks the invading microorganisms, but the associated inflammation can also cause collateral damage to delicate corneal tissues, leading to haze and scarring. Corticosteroids act by broadly suppressing this inflammatory response. For non-infectious or allergic keratitis, this is beneficial. However, in infectious cases, this suppression can be disastrous. The inflammatory response, mediated by immune cells like neutrophils, is crucial for eliminating the infectious agent. By inhibiting this process, steroids can tip the balance in favor of the pathogen, allowing it to multiply and invade deeper into the cornea.

The Increased Risk of Infection and Exacerbation

One of the primary reasons why steroids are contraindicated in keratitis is their ability to promote the proliferation and worsening of certain infections. For example, animal studies have shown that steroids can promote the growth of specific pathogens, especially when used without effective antimicrobial coverage. This can cause the infection to progress and spread more aggressively than it would otherwise.

Fungal Keratitis: An Absolute Contraindication

For fungal keratitis, topical steroid use is considered an absolute contraindication.

Promotes Fungal Growth: Steroids can enhance fungal replication and allow microorganisms to penetrate deeper into the cornea.
Worse Outcomes: Observational studies have linked prior steroid use with worse outcomes and a higher likelihood of requiring surgical intervention, such as a corneal transplant.
Masked Symptoms: The anti-inflammatory effect can mask the severity of the infection, delaying correct diagnosis and treatment.

Acanthamoeba Keratitis: A High-Risk Scenario

Acanthamoeba keratitis, a parasitic infection often linked to contact lens wear, is another condition where steroids are generally avoided. The parasite has a resistant cyst form and a replicating trophozoite form. Studies have shown that steroids can induce the cysts to transform into the active, more virulent trophozoite stage, leading to a more severe and prolonged infection. Retrospective analyses confirm that prior steroid use is associated with poorer outcomes and treatment failure in amoebic keratitis.

Bacterial Keratitis: A Complex Calculus

The role of steroids in bacterial keratitis is highly controversial and requires careful consideration and expert management. While a large study (SCUT) found no overall benefit for adjunctive steroid use, it did suggest potential benefits for specific, severe cases when administered early and in conjunction with intensive antibiotics. However, this is not a recommendation for general use. The risks remain high, especially if the pathogen is not identified or if antibiotic treatment is inadequate. Steroid use is also particularly harmful in cases involving Nocardia keratitis. Indiscriminate use is a significant risk factor for poor visual prognosis.

Delayed Healing and Corneal Complications

Another critical risk is that steroids impede the natural healing process of the cornea. The healing of a corneal epithelial defect relies on cell migration and the orderly deposition of collagen. Steroids interfere with both of these processes:

Delayed Re-epithelialization: Steroids can significantly delay the healing of the corneal surface, which is vital for protecting the eye from further infection.
Risk of Corneal Melting: By activating enzymes like collagenase and suppressing collagen synthesis, steroids can contribute to progressive corneal thinning, a process known as corneal melting. This can lead to corneal perforation, a medical emergency requiring surgery.

Systemic Side Effects

Beyond the immediate impact on the infection, long-term or potent topical steroid use can cause other serious ocular side effects.

Steroid-Induced Glaucoma: Corticosteroids can cause a significant rise in intraocular pressure (IOP) in some individuals, which can lead to permanent optic nerve damage and vision loss if not detected and managed promptly.
Cataract Formation: Prolonged steroid use, especially potent topical versions, is a known risk factor for developing cataracts, which can cloud vision and require surgery.

Steroid Use in Context: An Important Caveat

It is important to note that steroids are not universally contraindicated in all corneal inflammation. For specific non-infectious or post-infectious inflammatory conditions, like herpetic stromal keratitis (inflammation deeper in the cornea), they are used carefully. In these cases, the inflammation itself is the main threat to vision. However, steroids are always used alongside adequate antiviral therapy and under close ophthalmologist supervision to manage the risk of reactivating the underlying infection. This highlights that context is key, and an expert diagnosis is non-negotiable.

Comparison of Steroid Impact by Keratitis Type


Feature	Bacterial Keratitis	Fungal Keratitis	Herpetic Keratitis	Acanthamoeba Keratitis
Effect of Steroids	Complex, controversial. May be used in severe, confirmed cases with antibiotics, but risks persist.	Highly detrimental. Promotes fungal replication and leads to worse outcomes.	Used for stromal disease, but only with concurrent antiviral therapy.	Highly detrimental. Triggers active amoebic replication and worsens disease.
Inflammatory Response	Suppressed, allowing bacteria to proliferate if not controlled by antibiotics.	Suppressed, hindering the body's ability to contain fungal growth.	Controlled to minimize immune-mediated stromal scarring, while antivirals suppress the virus.	Suppressed, leading to uncontrolled parasitic proliferation and poor outcomes.
Corneal Healing	Delayed re-epithelialization observed in studies.	Delayed and worsened, increasing risk of perforation.	Can be delayed, but the benefit in controlling stromal inflammation is balanced against this risk.	Delayed healing and risk of corneal melting are significant.
Contraindication Level	High risk, needs expert judgment and confirmed pathogen.	Absolute contraindication.	Contraindicated for active epithelial disease; managed carefully for stromal cases.	Strong contraindication, especially early in treatment.

Conclusion

While corticosteroids are potent tools for controlling inflammation, their use in keratitis requires extreme caution due to the significant risk of exacerbating infectious processes and delaying corneal healing. For fungal and Acanthamoeba infections, they are strongly contraindicated. In bacterial cases, their use is reserved for highly specific, severe, and culture-confirmed infections under close expert supervision. The immunosuppressive nature of steroids, along with the risks of corneal melting, perforation, and steroid-induced glaucoma, underscores the importance of a precise diagnosis before any consideration of steroid therapy. Patients with a suspected corneal infection should always be managed by an eye care specialist to ensure the safest and most effective treatment strategy. For further information, visit the official American Academy of Ophthalmology website for Preferred Practice Patterns regarding infectious keratitis: AAO Guidelines.

Frequently Asked Questions

Yes, but in very specific and limited circumstances. For example, in certain non-infectious inflammatory keratitis or herpetic stromal keratitis, an eye specialist may prescribe topical steroids alongside appropriate antiviral medications to reduce inflammation and scarring. This must be done under strict medical supervision.

Corneal melting is the progressive thinning and ulceration of the cornea. Steroids can contribute to this by activating enzymes (collagenases) that break down corneal tissue and inhibiting the synthesis of new collagen, disrupting the eye's healing process.

For fungal keratitis, steroids can be particularly dangerous. They promote fungal replication and worsen the infection, leading to a higher risk of complications like perforation and an increased need for surgical intervention.

Yes, prolonged or potent topical steroid use can induce a type of glaucoma by increasing intraocular pressure. This can damage the optic nerve and cause permanent vision loss. Regular monitoring of eye pressure is necessary when using ocular steroids.

If an infection was misdiagnosed and steroids were started inappropriately, they can suppress the immune system and allow the pathogen to flourish. This can cause the infection to worsen rapidly after an initial, deceptive reduction in inflammation.

Ophthalmologists first attempt to identify the cause of the keratitis, often through a corneal culture. They only consider adding a steroid once the infection is under control with specific antimicrobial therapy and the underlying pathogen is known. Indiscriminate use is avoided.

Yes. Beyond worsening the infection and delaying healing, long-term use can increase the risk of cataract formation. Steroids can also mask the true severity of an infection, leading to delayed diagnosis and treatment.