Neurotrophic Keratitis More Common Than Reported, Study Finds

Neurotrophic Keratitis More Common Than Reported, Study Finds

By reviewing several years worth of patient records, researchers have found that neurotrophic keratitis (NK) may be more common that previously reported.

Early diagnosis and treatment also led to better patient outcomes, and the researchers called for greater awareness of NK among ophthalmologists and for the prompt use of NK-specific treatments.

Researchers at Paris’s Bichat–Claude-Bernard Hospital and the Fondation Ophtalmologique Adolphe de Rothschild reviewed over 300,000 electronic records related to NK from November 2009 through October 2017. Specifically, they wanted to know the disease’s frequency, main causes, and factors influencing prognosis. The records also allowed them to see how various treatments affected patient outcomes.

“To our knowledge, this is the largest observational study on NK epidemiology, etiologies, treatments and outcome,” the researchers write in their study “Neurotrophic keratitis: Frequency, etiologies, clinical management and outcomes,” published in The Ocular Surface.

NK is a rare eye disorder affecting the cornea. The cornea is the clear, outer layer of the eye, which acts like a window to focus light into the eye. NK occurs when the nerves serving the cornea cannot function properly. Many things can cause this, including herpes viruses, dystrophies, and overuse of topical eye medication.

A total of 335 patients with NK were included in the study, with 34.2% diagnosed with multifactorial (several causes) NK and 8.2% with idiopathic (of unknown cause) NK.

Neurotrophic keratitis can have many origins. The most common found in this study were herpes infection (32.2%), irritation from medical treatment (31.9%), underlying neurologic causes (central nervous system diseases, 27.7%, and intracerebral tumors and/or surgeries, 17.5%) and diabetes (10.5%). They note that because their hospital is also a referral center for neurologic diseases, their rate of neurologic causes may be higher than its true average.

The team found a rate of 11 cases of NK per 10,000 patients, in contrast to the previous recorded rate of only 1.6 per 10,000. Because of this, the authors recommend setting a lower threshold for diagnosis, so patients don’t miss vital treatment. Doctors should check for NK, they say, in cases of corneal ulcers, epithelial defects, or irregular epithelia.

According to its researchers, this is the first study to measure NK frequency directly. Previous estimates of NK frequency were based on conditions associated with NK.

In light of their results, they recommend that doctors examine eyes for dryness, signs of disease and the inability to close one’s eyelids (lagophthalmos). When NK is suspected, treatment should begin promptly and patients should be monitored closely.

The authors found that medical treatment worked for almost 70% of the patients in their study. Because dryness aggravates NK, lubricants such as hyaluronic acid, should be prescribed to all patients. When disease was present on the eye’s surface, they found matrix-metalloprotease inhibitor therapy to be helpful. They cautioned, however, that physicians should limit treatment with topical antibiotics.

Where medical treatment alone was not enough, patients benefitted from combined medical and surgical treatments. Surgical procedures specific to NK include use of autologous serum and RGTA with overlay and/or inlay amniotic membrane transplantation (AMT).

A key clinical measurement of vision in NK cases is corrected distance visual acuity, or CDVA. The authors found that prompt treatment, even when an initial diagnosis had been missed, had the best effect on final CDVA — that measured at the end of treatment.

NK can be classified according to the severity of corneal damage: stage 1 corresponds to epithelial alterations, stage 2 to persistent epithelial defects, and stage 3 to corneal ulcers. The best treatments for NK seemed to vary by disease stage. AMT and RGTA, for instance, proved useful in cases of stage 2 and 3 NK. RGTA, however, did little for stage 1 cases.

This study shows that NK may be more common than previously thought and that patient outcomes benefit most from prompt treatment. Although unable to evaluate the use of newer therapies, such as topical nerve-growth factor, the researchers note that more data, especially concerning long-term outcomes, are needed to fully evaluate the risks and benefits of all available treatment options.

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