Neurotrophic Keratitis

Neurotrophic keratitis is a progressive eye condition that arises due to damage to the trigeminal nerve. This nerve plays a crucial role in corneal health, and its impairment can be caused by various factors, including eye diseases, viral infections, chemical burns, or extended use of contact lenses. For treatment, eye drops are often employed to support the healing of the cornea.

Causes

Neurotrophic keratitis can be triggered by multiple factors, primarily revolving around nerve damage:

• Corneal Nerve Damage: Damage to the trigeminal nerve is fundamental, as it is vital for maintaining corneal health.

• Viral Infections: Infections such as herpes simplex and herpes zoster can directly damage nerve tissues.

• Surgical Procedures: Eye surgeries like LASIK or corneal transplants may alter nerve function.

• Long-term Use of Eye Medications: Certain medications, particularly those containing preservatives, may compromise corneal sensitivity and contribute to nerve damage.

• Systemic Conditions: Diseases that affect nerve function, including diabetes, multiple sclerosis, and some genetic disorders, increase the likelihood of developing neurotrophic keratitis.

Symptoms

Neurotrophic keratitis is a rare eye disorder marked by:

• Reduced Corneal Sensation: Due to nerve damage, corneal sensitivity is decreased, making early symptoms hard to detect.

• Blurred Vision: A common symptom that might be mistaken for other eye conditions.

• Redness and Dry Eyes: Often misattributed to less severe eye issues.

In more advanced stages, severe symptoms may emerge:

• Corneal Scarring and Ulcers: These can significantly impair vision and lead to more serious problems.

• Visual Impairment: Without treatment, the condition can cause a substantial loss of vision.

Early identification of initial, subtle symptoms is crucial to ensuring timely diagnosis and intervention to prevent severe complications.

Diagnosis

Diagnosing neurotrophic keratitis involves a comprehensive clinical assessment that combines medical history review with specific diagnostic tests. Key steps include:

• Examination of patient’s history focusing on conditions affecting the trigeminal nerve.

• Use of a Cochet-Bonnet esthesiometer to evaluate corneal sensitivity.

• Slit-lamp examination to identify any corneal surface irregularities.

• In advanced cases, in vivo confocal microscopy may be used for detailed imaging of corneal nerves to assess nerve density and structure.

The condition is classified into three stages, which is essential for devising an appropriate treatment plan. Early stages show subtle changes, while advanced stages present with significant corneal damage.

Treatments

Treatment approaches for neurotrophic keratitis vary based on severity:

• Mild Cases: Focus on maintaining eye moisture using preservative-free artificial tears or gel substitutes and autologous serum drops to assist healing.

• Severe Cases: May require advanced interventions, such as amniotic membrane transplantation, therapeutic contact lenses, or Cenegermin, which promotes corneal nerve regeneration and epithelial repair.

• Surgical Interventions: In extreme cases, procedures like partial tarsorrhaphy or corneal neurotization may be necessary to restore eye functionality and address nerve dysfunction.

Medications

Cenegermin (Oxervate), a cornerstone medication for neurotrophic keratitis, is a genetically engineered human nerve growth factor. It plays a pivotal role in:

• Aiding corneal nerve regeneration and promoting epithelial growth.

• Administered as eye drops, typically six times a day for eight weeks.

• While effective, it has challenges such as high costs, complex protocols, and potential side effects like ocular pain.

• Despite this, Cenegermin remains a critical treatment for restoring corneal sensation and healing persistent defects.

Prevention

Proactive measures can significantly reduce the risk of developing neurotrophic keratitis:

• Regular Eye Examinations: Essential for early detection, especially for individuals with risk factors like diabetes or prior eye surgeries.

• Eye Protection: Vital to prevent injury-related damage.

• Managing Ocular Surface Diseases: Ensures overall eye health.

• Avoiding Prolonged Contact Lens and Specific Medications Use: Unless recommended by a healthcare professional.

• Healthy Lifestyle Choices: A balanced diet and diligent management of systemic conditions, like diabetes, are crucial for eye health.