As the diversity of drop products expands and knowledge of the nuances of various ocular surface maladies increases, consider how the differences between drop products might make one drop a better choice for a given patient.
In recent years, the incidence and impact of dry eye disease has come to dominate the artificial tear market as more stakeholders-including eye-care professionals, general medical personnel, and patients-have recognized the need for better treatments for this condition.
What is increasingly lost in this conversation is the tremendous scope of artificial tear applications, important uses that go beyond the traditional diagnosis of dry eye disease. While many of these may fall loosely under the rubric of dry eye, the diversity in etiology, symptomology, and presentation create a diagnostic jigsaw puzzle that is often solved by a recursive trial of one drop or another.
Some clinicians may resort to simplifying this problem by choosing a single product to recommend-a one-size-fits-all approach.
However, as the diversity of drop products expands and the understanding of the nuances of various ocular surface maladies increases, it seems worthwhile to consider the differences between drop products and how these might make one drop a better choice for a given patient.
A classic example of fitting the artificial tear product to the patient is symptomatic dry eye following corneal surgical procedures.
Some patients experience a temporary, partial loss of corneal sensation that can impact normal blink reflexes. This can lead to an incomplete lid closure during sleep, corneal surface exposure, and a significant burning or foreign object sensation upon awakening. In these patients, an ointment or gel formulation at bedtime can provide the overnight ocular surface protection that a traditional drop cannot match.
Other situations may not be so clear-cut. One area where the use of artificial tears is exploding is in relief of the chronic “tired eyes” complaint that often accompanies workers who spend all day in front of a computer screen.
In contrast to traditional dry eye, this situation is at least in part due to a tiredness that goes beyond the eyes. Many relieve the condition with a cup of coffee, a trip to the water fountain, or any temporary activity that breaks the monotony of the computer monitor.
A number of artificial tears products are designed to do this as well, acting as a variation to the “splash of water in the face.” Such products-including Visine Tired Dry Eyes, Clear Eyes Cooling Comfort, or Rohto Cooling Drops-are promoted as addressing this phenomenon of tired eyes. All of these products, as well as others designed to treat tired eyes, report a long duration of action. For these patients, it is probably less important to have a drop that is long-lasting, and more important to achieve a rapid, rejuvenating feeling.
Some patients are more concerned about how their eyes look and depend on products that include some form of redness relief. Many drops are available that include an adrenergic agent (typically naphazoline HCl) that provides a fast, effective means to reduce conjunctival hyperemia. The caveat to these products is that they can be overused, and this can result in an ocular irritation (most likely due to repeated exposure to drop preservative) that can include both redness and dry eye.
An underappreciated cause of ocular surface irritation and subsequent artificial tear use is systemic prescription medication. Anti-depressants and anxiolytics are particularly notorious for an association with dry eye, and some of these may also have long-term ocular side effects.1
Ocular drying is also associated with any drug that possesses anti-cholinergic effects, such as anti-histamines or drugs used to treat Parkinson’s disease. The anti-cholinergic effect implies a negative impact on lacrimation, so these patients are likely candidates for traditional aqueous artificial tear preparations, especially those designed for a long duration of action.
The explosion of drop formulations has paralleled an increase in the understanding of dry causes. This raises the question of whether clinicians can now begin to ask if specific formulations can be designated for different types of dry eye. One way to dissect different formulations is by their compliment of lubricants.2 These include carboxymethyl cellulose (CMC), hydroxypropyl methylcellulose (HPMC), polyethylene glycol (PEG), propylene glycol (PG), and hyaluronic acid (HA).
Some of these are not technically designated as active drop components, but all function as lubricants. It is likely that different combinations will have different performance characteristics from patient to patient.
Most clinicians have a preferred brand. It is worth keeping in mind that even in head-to-head studies where one brand may be superior to another, another study will yield an equally convincing opposite result.
For example, in a recent study,3 Rohto Dry Aid was shown to be comparable to Systane Balance for most metrics, yet it was significantly better in the subjective, quality-of-life measures. In another study, it was Systane that was judged superior to Refresh Tears.2
It is probably more accurate to think in terms of a handful of first-line therapies (Systane, Refresh, GenTeal, Soothe, Dry-Aid, for example). It is likely that each of these products is superior for some part of the dry eye population. When it comes to finding the right artificial tear, there is no better approach than empirical trial and error.
Gail L. Torkildsen, MD
Dr. Torkildsen is in private practice in Andover, MA, and also does consulting in ophthalmic clinical research. She did not indicate any proprietary interest in the subject matter.
1. Wong J, Lan W, Ong LM, Tong L. Non-hormonal systemic medications and dry eye. Ocul Surf. 2011;9:212-226.
2. Moshirfar M, Pierson K, et al. Artificial tears potpourri: a literature review. Clin Ophthalmol. 2014;8:1419-1433.
3. Torkildsen G, Brujic M, Cooper MS, et al. Evaluation of a new artificial tear formulation for the management of tear film stability and visual function in patients with dry eye. Clin Ophthalmol. 2017;11:1883–1889.