The cornea is the clear outer layer of your eye that helps you focus light to see clearly. It has more nerve endings than even your skin, which is why it can feel so irritating to get even the smallest particle of dust or dirt stuck in your eye. Corneal sensory nerves play an important role in your eye health, regulating eyelid movements, such as blinking, as well as the preocular tear film, which keeps the eyes moist and healthy.
Corneal anesthesia is a rare condition that results in numbness of the cornea. The lack of sensation in your cornea can prevent you from feeling pain or recognizing injury or infection. If left untreated, the condition can worsen, leading to corneal ulcers, scarring, and vision loss. Corneal anesthesia can also lead to a clinical condition known as neurotrophic keratitis or neurotrophic keratopathy.
Understanding Corneal Anesthesia
What is Corneal Anesthesia?
Symptoms
Lack of sensation in the cornea is the hallmark symptom of corneal anesthesia. However, before you lose sensation in your cornea, you may experience preliminary symptoms, such as:
- Discomfort
- Extreme dryness
- Failure to produce tears
- Swelling or inability to comfortably close the eye
- Visible and constant redness
- Eye strain or pain
- Light sensitivity
- Blurred or decreased vision
Causes of Corneal Anesthesia
A wide range of issues and conditions may lead to corneal anesthesia and neurotrophic keratitis; however, the most prevalent is impairment of the ophthalmic branch of the trigeminal cranial nerve, otherwise known as the ophthalmic nerve. Other causes may include:
- Viral infections, such as herpes simplex and herpes zoster keratoconjunctivitis
- Neurosurgical procedures
- Eye surgeries for cataracts, orbital surgery, laser eye surgery to correct vision problems, and corneal transplants
- Chemical burns
- Toxicity from chronic use of eye medications
- Systemic diseases such as diabetes, multiple sclerosis, and leprosy
Risk Factors
Factors that may increase your risk of corneal anesthesia and neurotrophic keratitis include:
- Contact lenses: wearing contact lenses for long periods of time, sleeping in lenses, improperly disinfecting your lenses, and wearing lenses while swimming are all practices that can increase your risk of corneal damage or infection.
- Use of eye drops or medications: corneal toxicity can arise from the use of topical eye medications, including glaucoma eye drops, topical iodine, nonsteroidal anti-inflammatory eye drops, preservatives in eye drops, and others.
- Systemic diseases or viruses: diseases such as diabetes mellitus, herpes simplex virus (HSV), or ocular disease.
- Systemic therapies: neuroleptic, antipsychotic, and antihistamine drugs can cause trigeminal corneal innervation impairment.
Tests and Diagnosis
To begin, a medical professional will look at your history of systemic diseases or the use of medication or therapies (such as antihistamine, antipsychotic, or neuroleptic) known to cause impairment of the trigeminal corneal nerve. They will also inquire about past corneal surgeries or traumas, the use of eye medications or drops, potential chemical burns, or the use of contact lenses.
Next, your doctor will conduct a thorough eye exam, which may include a corneal sensitivity or corneal stain test. In some cases, a Schirmer test, which measures your ability to produce tears, may be helpful in diagnosing corneal sensitivity. During your eye exam, your professional may also conduct a microbiological examination to exclude the possibility of bacterial, fungal, or viral infections.
Treatments for Corneal Anesthesia
Treatment for corneal anesthesia and keratitis often depends on the stage of your condition and can range from eye drops to corneal neurotization surgery.
Artificial Tears
Artificial tears increase natural tear production and lubricate the ocular surface to provide temporary relief of dry eye symptoms. Your medical professional may recommend using artificial tears every 1 to 2 hours for corneal anesthesia.
Topical Antibiotic Eye Drops
Some corneal conditions can be treated with antibacterial eye drops, which may be prescribed along with steroid eye drops to reduce inflammation. However, the use of topical antibiotic drops can also slow corneal wound healing and cause residual corneal scarring or thinning, which can require surgery to correct and restore vision.
Cenegermin (also known as Oxervate)
Cenegermin (Oxervate) is an FDA-approved prescription eye drop for neurotrophic keratitis. The main ingredient is a human nerve growth factor that helps corneal epithelial cells and corneal nerves survive.
Corneal Neurotization
Corneal neurotization surgery is a type of nerve reconstruction surgery that helps promote the regrowth of nerves in the cornea. During this procedure, a surgeon will transplant a healthy nerve axon graft from a different area of the body, such as your leg, to the affected cornea. With corneal neurotization surgery, the average time to regain sensation in the cornea is 6 to 9 months, with full nerve regrowth after 12 months.
Not all patients are good candidates for corneal neurotization surgery. Your surgeon may recommend a non-surgical treatment plan for patients in certain cases, including:
- Extensive conjunctival scarring
- Poorly controlled diabetics
- Patients with poor systemic health
- Anticoagulation use
- Active or uncontrolled inflammatory or infectious ocular surface disease
- Donor nerve malignancy
- Absence of healthy donor nerves
- Ongoing external beam radiation
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Insurance Information
The Institute for Advanced Reconstruction participates in a wide range of insurance plans, including those listed below. However, each physician has their own accepted insurance and hospital affiliations. Before scheduling an appointment, please contact your insurance carrier to confirm that your provider is in-network.
If we are not an in-network provider, our friendly insurance specialists will help you find the most coverage available for your treatment.
- Horizon Blue Cross Blue Shield of New Jersey
- Medicare
- Railroad Medicare
- Aetna
- Cigna
- United Healthcare
- Oxford (Freedom, Liberty)
- MagnaCare
Patient Resources
Learn more about what to expect when it comes to surgical procedures and treatments at the Institute for Advanced Reconstruction by visiting our patient resource page.
Am I a Candidate for Treatment?
To find out if you’re a candidate for advanced treatments for corneal anesthesia. Schedule an eye exam with one of our specialists to rule out some of the possible causes of numbness of the cornea.