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Aging and Dry Eye: Age-Related Changes in the Function of the Ocular Sensory Apparatus Likely Underlie Dry Eye Symptoms

Anat Galor, Elizabeth R. Felix, Constantine D. Sarantopoulos, Eden R. Martin5 and Roy C. Levitt*

Dry eye is a multifactorial disease impacting the ocular surface that results in symptoms of discomfort, visual disturbance, and tear film instability associated with potential damage to the ocular sensory apparatus. Dry eye is diagnosed in approximately 3.2 million U.S. women and 1.7 million U.S. men older than 50 years of age. While the natural history of dry eye remains to be determined, dry eye rates increase with age, reaching the highest among women 75-79 years of age and men 80-84 years of age. Many patients with dry eye describe features of neuropathic pain, including spontaneous pain, hyperalgesia and allodynia, suggesting dysfunction of the ocular sensory apparatus, which likely impacts the lacrimal functional unit altering basal and reflex tear secretion. Co- morbid conditions such as depression and post-traumatic stress disorder commonly associated with other chronic pain conditions provide further evidence that dry eye may be associated with central processing abnormalities. In fact, recent data show dry eye represents a chronic overlapping pain condition that is significantly impacted by environment and shared genetic factors. In the following sections we review how aging may impact the anatomical structures associated with dry eye. Among other factors, sensitization of the ocular sensory apparatus occurs which occurs with aging is likely influenced by multiple environmental and genetic factors common to other chronic pain conditions and an important driver of ocular pain and dry eye symptoms with aging.