Aging And Corneal Nerve Health: Mechanisms Of Degeneration And Emerging Therapies For The Cornea
Our eyes rely on a delicate network of nerves in the cornea, the clear front part of the eye, to maintain overall eye health. These corneal nerves are crucial for everything from sensing touch and pain to stimulating tear production and helping the eye heal. They play a vital role in maintaining a stable and healthy eye surface, a process known as ocular surface homeostasis. With age, however, these specialized nerves begin to deteriorate. This degeneration involves a reduction in nerve density and structural changes, driven by fundamental aging processes such as damage to genetic material (genomic instability), problems with how cells manage their proteins (impaired proteostasis), issues with the cell’s energy-producing components (mitochondrial dysfunction), and persistent, mild inflammation (chronic low-grade inflammation). This age-related decline leads to an imbalance in the nervous and immune systems (neuro-immune dysregulation), which reduces the essential nourishment and growth factors nerves need (trophic support). Consequently, wound healing slows down, and older adults become more prone to conditions like dry eye disease, a severe eye condition caused by nerve damage (neurotrophic keratopathy), and reduced sensation after eye surgeries (postsurgical hypoesthesia). Several factors can accelerate this age-related nerve damage, including diabetes, high cholesterol (dyslipidemia), certain brain disorders, chemicals in eye drops (topical preservatives), long-term contact lens wear, shingles affecting the eye (herpes zoster ophthalmicus), and insufficient oxygen to the eye surface (ocular-surface hypoxia). Given that corneal nerves have a limited ability to regenerate on their own, it is critical to find ways to slow down this degeneration and promote nerve repair. Promising new strategies are emerging, including regenerative medicine approaches, agents that protect nerves (neuroprotective agents), and lifestyle adjustments, all aimed at preserving and restoring corneal nerve health as we age.
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