Neurotrophic keratitis (NK) is a rare degenerative corneal disease that can be misdiagnosed as other ocular conditions such as dry eye disease (DED), limbal stem cell deficiency (LSCD), recurrent corneal erosion (RCE), and others.
During a session at the American Society of Cataract and Refractive Surgery Annual Meeting, Sumit Garg, MD, of UCI Health, and Kendall Donaldson, MD, of Bascom Palmer Eye Institute, presented various patient cases and asked the audience to determine whether these were examples of NK or other diseases that may mimic NK.
A key hallmark of NK is “stain without pain.” Corneal sensitivity and staining are important indicators of NK.
The different stages of NK can be characterized as:
- Stage 1/mild NK: punctate epithelial keratopathy
- Stage 2/moderate NK: persistent epithelial defect without stromal involvement
- Stage 3/severe NK: involvement of the stroma that can progress to perforation
Multiple signs of stage 1 NK can overlap with DED, such as corneal punctate staining with fluorescein, narrow tear meniscus, and rapid tear break-up time. Decreased blinking is a key sign of NK that requires patient education and instruction to concentrate on blinking and closing their eyes.
Patients with NK rarely complain of symptoms, as corneal sensation is reduced or absent due to damage to the corneal nerves, thus corneal sensitivity testing can help distinguish DED from NK.
LSCD is characterized by conjunctival epithelial invasion of the cornea, and unlike NK, LSCD symptoms may include pain and/or ocular discomfort. Corneal sensitivity testing may help distinguish LSCD from NK.
RCE symptoms may include eye pain at night or upon awakening, while patients with NK rarely complain of symptoms. RCE is characterized by repeated episodes of eye pain with redness, photophobia, and tearing. Patients may also have a history of corneal trauma.
NK can be progressive, so early identification and treatment is important. It’s also key to educate patients on follow-up to avoid any permanent visual damage and/or surgery. The diagnosis of NK should be based on a detailed review of medical history with clinical exam, followed by corneal sensitivity testing.
Common comorbidities or etiologies of NK include:
- Ocular: herpes simplex virus, chronic DED, contact lens wear, ocular surgery (eg, LASIK), topical ophthalmic drug toxicity, etc.
- Central nervous system: stroke, neoplasm, degenerative disorders, etc.
- Systemic: diabetes, multiple sclerosis, etc.
- Genetic: Riley-Day syndrome, familial corneal hypoesthesia, etc.
The following conditions may worsen the prognosis of NK:
- Exposure keratitis
- Infectious keratitis
- DED
- Meibomian gland dysfunction
- LSCD
- Diabetes
In conclusion, NK should be suspected when there is a dissociation between clinical signs and reported symptoms—or lack of symptoms in this case.
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