If you’re faced with treating a corneal ulcer, you’ll need to do it quickly and with an understanding of how it heals and how to prevent recurrence. Here are some tips to managing keratitis.
Consider the differential diagnosis of corneal ulceration.
Not all corneal ulcers are bacterial. Particularly in people who don’t wear contact lenses without a preceding trauma, it’s important to consider alternative etiologies to a bacterial infection — or any infection, for that matter. Spontaneous breakdown of the corneal epithelium with underlying ulceration may occur in neurotrophic keratopathy, which is often associated with prior herpetic/viral processes. Pain out of proportion to corneal findings and subtle infiltrates may increase suspicion for an acanthamoeba infection.
Slit lamp examination of the eyelids and conjunctiva may reveal other causative factors such as lagophthalmos for exposure keratopathy, blepharitis for Staphylococcal marginal keratitis, limbal lesions for corneal dellen formation, as well as tarsal conjunctival lesions or foreign bodies causing mechanical ulceration of the underlying cornea.
Finally, consider rheumatologic causes, particularly in patients with marginal ulceration, corneal thinning and/or a past medical history that may point to this as the reason.
Recognize when corneal cultures are vital.
Although many infectious corneal ulcers will respond to empiric broad-spectrum topical antibiotic drops, atypical infections with resistant bacteria or nonbacterial microbes do occur. Cultures are therefore important for ulcers with features suggesting atypical infections, including multifocal ulcers, feathery infiltrates suggestive of fungal infection or ring infiltrates.
Ulcers that have not responded to empiric treatment may similarly benefit from cultures to rule out a resistant microbe. Corneal cultures are also indicated for ulcers greater than 1 mm in diameter, within 2 mm of the visual axis or associated with virulent features, such as significant corneal thinning or a hypopyon. In general, take corneal cultures for any ulcer with a potential for visually significant scarring, as well as those where corneal perforation or intraocular spread is a concern.
Watch out for non-healing epithelium.
In some cases, a persistent epithelial defect will remain deep into the treatment course. Particularly when an active stromal infiltrate is still present, persistent infection (potentially with an alternative microbial etiology to that which is being treated) must be considered and repeat cultures may be indicated.
For those with improvement or resolution of other infectious signs, but still with an epithelial defect, medication toxicity should be considered. Although very effective in halting the growth of bacteria, fortified antibiotic drops can also limit the division and healing of epithelial cells — especially after prolonged treatment. Topical antivirals may have a similar effect. A prolonged course of keratitis can also cause damage to corneal nerves, creating a comorbid neurotrophic keratopathy. Limiting surface toxicity and lubricating the ocular surface may help promote epithelial healing, though more aggressive measures such as a tarsorrhaphy, amniotic membrane placement or topical nerve growth factors may be indicated in refractory cases.
Take proactive steps to prevent recurrent ulceration.
After the keratitis is resolved and the epithelium is healed, attention should be directed toward preventing recurrence by addressing the underlying etiology. For many patients, this means a safe and slow reintroduction to contact lens wear with strict adherence to hygiene, and often refitting into daily disposable lenses.
Prophylactic medications may be indicated for those with herpes viral keratitis, and systemic medications may be necessary for those with inflammatory ulceration and underlying autoimmune disease with the help of a rheumatologist. Patients with exposure keratopathy should be managed in concert with eyelid specialists to optimize the protection of the ocular surface. In general, supporting ocular surface lubrication will help promote healthy and secure epithelium regardless of the initial etiology.
Optimize vision after the cornea has healed.
Corneal scarring after an ulceration may cause reduced vision simply due to corneal opacification. Equally, if not more important in many cases, however, is the astigmatic effect of corneal scarring. Local flattening, steepening or thinning in the area of corneal scars can create visually significant irregular astigmatism which is readily identifiable on topography.
In cases where spectacle refraction does not produce sufficient vision, rigid gas permeable or scleral lens fitting may be indicated to overcome this astigmatic effect. Corneal transplantation is reserved for eyes with poor vision despite spectacle or contact lens trials, though the risk of recurrent ulceration in the corneal graft must be considered depending on the underlying etiology.
The Academy’s YO Info Editorial Board is collaborating with YO leaders from our subspecialty society partners and thanks the American Society of Cataract and Refractive Surgery’s Young Eye Surgeons (YES) Committee Chair Zaina Al-Mohtaseb, MD and YES Committee Member Nandini Venkateswaram. MD for recommending Dr. Meeker as a contributing author for YO Info.
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About the author: Austin M. Meeker, MD, is a member of the cornea and comprehensive ophthalmology services department at Massachusetts Eye and Ear and a clinical instructor in ophthalmology at Harvard Medical School in Boston. |