Neurotrophic Keratitis is a rare eye condition that effects the clear surface of the eye, the cornea. Normally, the cornea is very sensitive due to an abundance of nerves running through the surface. When an injury occurs, the eyelids close and tears are produced to try to "flush" the invading substance out of the eye. When the nerves are desensitized or damaged, the protective processes can no longer be initiated which can lead to further damage. To further complicate the condition, the patient is typically unaware of the severity of their injuries being that they cannot necessarily FEEL any associated.
What Causes Neurotrophic Keratitis?
Anything that can potentially damage the corneal nerves can lead to Neurotrophic Keratitis. This can include different corneal dystrophies that cause degeneration of the corneal integrity. The most common cause is from damage to the Trigeminal Nerve, a nerve that runs through different portions of the face and branches to the ophthalmic nerve, which directly innervated the cornea.
Herpes Zoster and Herpes Simplex are two common causes of Neurotrophic Keratitis. Other causes include Surgery involving the cornea or that occurs near or around the eye. This can include cataract surgery, orbital surgery, laser eye surgery to correct vision problems, and corneal transplants.
When the Trigeminal Nerve is damaged, this can lead to significant pain flare-ups, called Trigeminal Neuralgia. Surgery to repair this nerve can also lead to nerve damage and resultant Neurotrophic Keratitis.
Other causes of corneal sensation loss include the overuse of certain eye drops that desensitize the eye surface. Such medications can include timolol and betaxolol, which are used to treat glaucoma; sulfacetamide, which is a topical antibiotic; as well as diclofenac sodium and ketorolac, which are topical nonsteroidal anti-inflammatories drugs or NSAIDS.
How is it Treated?
Treatment of Neurotrophic Keratitis is based around protecting the corneal surface. When the surface does not respond to first line medications and topical treatments, alternative methods may be used.
Scleral Lenses: these are a large gas-permeable lens that vaults the surface of the eye and acts as a fluid reservoir for the eye surface. These lenses form a protective barrier from the eye lid and allows the cornea to be constantly bathed in a tear reservoir.
Amniotic Membranes: Amniotic Membranes are full of stem cells, which help restore damaged elements of the corneal surface in a short amount of time. They can be applied in a dehydrated state underneath a bandage soft contact lens, or as a cryopreserved lens. These can be applied in office by an optometrist and are typically left on the eye for 5-7 days to allow the membrane to fully dissolve.
Oxervate is a new ophthalmic drop that is formulated to treat the underlying cause of Neurotrophic Keratitis. It is comprised of a protein that is structurally identical to the naturally occurring nerve growth factor (NGF) produced by the human body. The eye drop stimulates regenerative properties to maintain the eye's anatomical integrity.
Ask your optometrist about the different options available to you if you have eye pain resulting from nerve damage!
Neurotrophic Keratitis is caused by loss of corneal nerve sensation with
resultant dryness, blurred vision and other potential complications.