A compromised lipid layer plays a key role in the development and perpetuation of dry eye disease because it allows increased aqueous evaporation and fails to protect against friction between the blinking lid and the ocular surface. A proprietary brand of emollient eye drops (Soothe XP. Bausch & Lomb) was created to re-establish the tear film lipid layer and restore moisture, and it is an effective choice for providing symptomatic relief in patients with dry eye disease, says one optometrist.
"There is a wide array of artificial tear products on the market, but many of them serve only to replenish the aqueous component of the tear film," said Dr. Bowling, director, Vision-America, Gadsden, AL. "However, a recent study evaluating the prevalence of dry eye subtypes among patients seen in a clinical optometry practice revealed that aqueous deficiency accounted for only about 16% of cases, whereas the largest proportion, 38%, were related to some type of lipid-related dysfunction.
"These data highlight the importance of choosing an artificial tear that will target tear film lipid abnormalities," he said. "However, patients with aqueous-deficient dry eye benefit as well from using [the drop] because there is substantial evidence to show that when the tear film is compromised, there is a marked increase in the rate of aqueous evaporative loss. Furthermore, a thick, intact lipid layer is critical for proper ocular surface lubrication and optimizing the optical quality of the tear film."
The benefits of treatment with these drops for improving tear film characteristics and other signs and symptoms of dry eye disease have been demonstrated in several clinical trials, Dr. Bowling said. In one study of 55 patients who met the enrollment criteria for the presence of both subjective symptoms and objective signs of dry eye, including a lipid-deficient tear layer, twice-daily treatment for 1 month improved the mean symptom score and was associated with a more than 100% increase in the mean thickness of the lipid layer. A similar increase in lipid layer thickness was recorded in another study that measured changes after instillation of a single drop of the solution in patients with an insufficient lipid layer.
Results of a study comparing the drop with a competitor emulsion-based artificial tear (Refresh Endura, Allergan) corroborated the benefit of the former drop for providing symptomatic relief, he said. At 8 hours post-instillation, 85% of patients who used that drop reported that they still were experiencing symptom relief, compared with only 25% of the control subjects.
"Achieving a durable subjective response is important with any product because it improves patient satisfaction and makes the treatment more convenient to use. In addition, in the patient with ocular surface disease, it's important to minimize exposure to preservatives," Dr. Bowling said.
"Any patient who needs to instill artificial tears more than four times a day should be using a preservative-free product. While non-preserved artificial tears are often needed in patients with severe dry eye, I've found most other patients can maintain good symptom control using the drops two to four times daily," he added.
Another study compared the emollient drops against prednisolone 1% (Pred Forte, Allergan) in patients with lid wiper epitheliopathy. This condition, which was named by Donald Korb, OD, describes the presence of upper lid tissue damage that can occur as a result of friction when the tear film does not provide sufficient lubrication during a blink. After 30 days of four-times-daily treatment, patients in both study groups had statistically significant improvements in both mean symptom scores and ocular surface staining scores.
"These are impressive results considering the comparator agent used in this study was prednisolone," Dr. Bowling said.
Because the drop is a lipid emulsion, patients should be counseled that some vision blurring can occur with instillation, but they can expect the effect to be transient, he said.
"[The solution] is formulated with a dual surfactant system so that after instillation, the drop spreads quickly and evenly over the ocular surface. I've found patients do well with this product and have not seen vision blur emerge as a significant problem," Dr. Bowling said.