What is Neurotrophic Keratitis?
Neurotrophic keratitis is a problem with the surface of the eye resulting from a decrease in corneal sensitivity due to damage to the corneal nerves caused by chronic inflammation and irritation.
Why are the corneal nerves important? What do they do? What happens when they are impaired?
First, the corneal nerves play an important sensory role in reflex tearing which protects the surface of your eyes. An example of this would be if a gust of wind blows a particle (debris) into your eye, the sensory nerves on the surface of your eye will feel it and reflexively you will start tearing in an effort to wash out the foreign body. This is your eye’s way of protecting itself.
Second, we all have transparent skin on the surface of our eyes called epithelium. The corneal nerves play an integral role in supporting the health, growth and repair of this skin.
When your corneal nerves are damaged, as in neurotrophic keratitis, the overall health of the surface of your eye declines due to the impairment of the ability of the skin on the front of your eye to heal properly. This can result in the skin breaking down.
As the surface of your eye breaks down and begins to develop irregularities, including cracks and breaks, you may experience blurry, or fluctuating vision.
The cracks and breaks (open wounds) on the surface of your eye can range from small openings, known as superficial punctate keratopathy (SPK), to recurrent and/or persistent epithelial defects. These open wounds can lead to thinning of your cornea, scarring and even corneal perforation. The open wounds can also become infected (known as ulcers).
Prognostic indicators in neurotrophic keratitis include the degree of sensory loss, the duration of the condition, and the presence of other ocular surface issues (i.e. dry eye, environmental allergic keratoconjunctivitis, meibomian gland dysfunction, blepharitis, ocular rosacea, demodex, contact lens related ocular irritation, other).
People with reduced corneal sensitivity must be educated and instructed to seek proper medical evaluation immediately if their eye(s) become red, irritated, or they experience any changes in their vision. People with damage to their nerves may not feel as much pain or irritation as someone who doesn’t have this reduced sensitivity; they therefore must be cognizant of lowering the threshold for which they seek medical attention.
What causes Neurotrophic Keratitis?
Neurotrophic keratitis is more common than previously thought; it can be caused or exacerbated by:
- Chronic contact lens wear
- Chronic use of eyedrops which contain ingredients that are not healthy for the surface of your eye (i.e. preservatives)
- Long term use of some topical medications (i.e. Timolol, Sulfacetamide, Betaxolol, Diclofenac sodium, Ketorolac, etc.)
- Chronic inflammation associated with dry eye, environmental allergies ocular rosacea, blepharitis, demodex and/or meibomian gland dysfunction (MGD)
- Herpetic infections of the cornea (simplex or zoster)
- Prior surgery which has damaged the nerves in this area (i.e. for trigeminal neuralgia, acoustic neuroma, other)
- Systemic diseases that can cause neurotrophic keratitis include diabetes, multiple sclerosis, and vitamin A deficiency
- Previous eye surgery (i.e. laser, cataract and/or glaucoma surgery)
- The normal aging process
- Other less common causes
Symptoms of Neurotrophic Keratitis
Because of the damage to your nerve endings you may have mild, or no symptoms at all. Alternatively, you can experience any of the following:
- A stinging, burning or irritation of your eyes.
- Decreased, blurry or fluctuating vision.
- Mucus discharge from your eyes.
- Sensitivity to light.
- A “foreign body sensation”, as if you have an eyelash or a grain of sand in your eye(s).
- Discomfort wearing contact lenses.
How is Neurotrophic Keratitis Diagnosed?
The diagnosis of neurotrophic keratitis is made by taking a careful ocular, medical and surgical history, performing a thorough examination of the surface of your eyes using a biomicroscope with various medical dyes, and formally assessing your corneal sensitivity.
The treatment of neurotrophic keratitis is based upon the severity of your condition and is aimed at promoting the healing and health of the surface of your eye. Concomitant ocular issues should also be treated (i.e. dry eye, environmental allergic keratoconjunctivitis, ocular rosacea, blepharitis, meibomian gland dysfunction, herpes infection, blepharitis, contact lens associated irritation and inflammation, etc).
Treatment of Neurotrophic Keratitis often consists of:
- Topical lubrication with preservative-free artificial tears, gels, and ointments
- Punctal occlusion (i.e. punctum plugs)
- Low dose oral doxycycline or tetracycline (which have shown anti-inflammatory and anti-collagenolytic activity)
- Topical autologous serum
- Amniotic membrane placement
- Oxervate (Cenegermin) is an FDA approved topical recombinant nerve growth factor. It is an eye drop which is instilled in the affected eye(s) 6 times each day at 2-hour intervals for 8 weeks.
- Scleral contact lenses
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