A dry eye is a condition in which a person doesn’t have enough quality tears to lubricate and nourish the eye. Tears are necessary for maintaining the health of the front surface of the eye and for providing clear vision.
Dry eye is a common and often chronic problem, particularly in older adults. With each blink of the eyelids, tears spread across the front surface of the eye, known as the cornea.
Tears provide lubrication, reduce the risk of eye infection, wash away foreign matter in the eye and keep the surface of the eyes smooth and clear.
Excess tears in the eyes flow into small drainage ducts in the inner corners of the eyelids, which drain into the back of the nose. Dry eyes can occur when tear production and drainage is not in balance.
Due to its multifactorial nature involving interrelated underlying pathologies, DED can rapidly become a chronic refractory condition.
Since the onset of the COVID-19 pandemic, the prevalence of DED has steadily increased. Current treatments for DED might not work for everyone, and the increasing prevalence has accelerated the development of novel therapies.
Here are 3 things you should know about DED and emerging strategies to treat it. The new definition of DED provides practitioners a practical tool to diagnose DED in the clinic. In the United States, more than 16 million patients have been diagnosed with DED, and an estimated 6 million adults have symptoms but have not yet been diagnosed.
DED, clinically referred to as keratoconjunctivitis sicca, is defined by the Tear Film and Ocular Surface Society’s Dry Eye Workshop II (TFOS DEWS II) panel as a multifactorial disease of the ocular surface characterized by a loss of homeostasis of the tear film and accompanied by ocular symptoms, such as discomfort and visual disturbance.
It involves tear film instability and hyperosmolarity, ocular surface inflammation and damage, and neurosensory abnormalities.
DED is often classified into 2 primary subtypes: aqueous tear-deficient dry eye, characterized by an inefficiency or inability of the lacrimal glands to produce tears, and evaporative dry eye, typically attributed to excessive evaporation of the tear fluid.
The newer definition can help clinicians to determine the specific DED subtype to guide and individualize treatment. The symptoms of DED are heterogeneous and often include dryness, red eyes, blurred vision, photophobia, ocular discomfort or pain, foreign body sensation, fluctuating vision, irritation, and burning.
These symptoms can have a substantial effect on daily activities and can lead to a reduction in work productivity with a consequently high impact on quality of life.
The COVID-19 pandemic has led to a higher prevalence of DED. Risk factors and exacerbating causes of DED include advanced age, female gender, medications (eg, antihistamines, estrogens, selective serotonin antagonists), low humidity environments, extended screen viewing, systemic diseases (eg, Sjögren syndrome, diabetes mellitus), and prior ophthalmic surgery.
The COVID-19 pandemic has led to an increase in the prevalence of DED, especially among the younger population. The increase in remote schooling and working has exposed individuals to greater use of visual display terminals.
Increased screen time leads to excessive evaporation of tear fluid because of prolonged blinking intervals, and gazing is thought to be the main causative factor. Several studies have shown that 1 hour of tablet or smartphone use increases eye strain and blur in young adults by as much as 5 times.
Furthermore, the widespread use of face masks adds a potential second component to the DED epidemic. The displacement of a mask or its incorrect fitting could disperse air around the eyes, and the air leakage could cause a rapid evaporation of tears leading to mask-associated DED.
Emerging treatments for DED include a nasal spray Treatment for DED is aimed at improving symptoms by increasing or supplementing tear production, slowing tear evaporation, reducing tear resorption, or reducing ocular surface inflammation.
The TFOS DEWS II management and treatment recommendations include a 4-step process. First-line treatment for most patients with mild or preclinical DED includes artificial tears and lifestyle modifications, including taking frequent screen breaks by looking at a distant object and blinking at regular intervals.
For moderate to severe cases, additional disease-modifying prescription drugs may be needed. Surgical intervention is considered only if these recommendations fail to yield positive results.
Owing to the inflammatory nature of DED, topical corticosteroids are an effective treatment option, particularly for moderate to severe DED when first-line treatments such as ocular lubricants are insufficient.
Loteprednol etabonate (LE) is a corticosteroid with a low risk of corticosteroid-related adverse effects such as elevated intraocular pressure. The LE ophthalmic suspension 0.25% was recently approved by the United States Food and Drug Administration (FDA) following the completion of the STRIDE 3 trial.
LE is the first agent indicated for the short-term treatment of the signs and symptoms of DED. In STRIDE 3, ocular discomfort severity was significantly improved by day 15 in both the intent-to-treat group and in a predefined subgroup with more severe ocular discomfort at baseline, compared with the vehicle group.
LE was well tolerated and had a favorable safety profile. Varenicline, a nicotinic acetylcholine receptor agonist, is an emerging agent for DED with a novel mechanism of action; this preservative-free nasal spray stimulates the trigeminal parasympathetic pathway to increase tear production.
The parasympathetic nervous system controls tear film homeostasis partially via the trigeminal nerve, which is accessible within the nasal cavity.
Results from the MYSTIC, ONSET-1, and ONSET-2 trials have demonstrated statistically significant improvements in the Schirmer score (a measure of natural tear film production) among individuals treated with varenicline compared with controls, which was the primary end point in these trials.
Key secondary end points of ONSET-1 and ONSET-2 included change from baseline in symptoms as assessed by the eye dryness score.
Both trials showed statistically or nominally statistically significant improvement in symptom scores at day 28, and in ONSET-2, as early as day 14, among patients treated with varenicline nasal spray compared with controls.
All doses under study were well tolerated with no serious drug-related adverse events. The FDA accepted the new drug application (NDA) for varenicline nasal spray for the treatment of DED in March 2021.