Treating dry eye with lipid-based eye drops

Treating dry eye has become a significant part of practicing optometry, and many of us are seeing a growth in this part of our practices. Patient complaints of eyes that are dry, irritated, and uncomfortable will increase as the Baby Boomer population grows older and digital device use increases with associated reduced blink rate. It is estimated that 40 million people in the United States suffer from dry eye.¹

The prevalence of dry eye varies based on parameters used to gather data and ranges from 14 percent for patients over age 48 in the U.S., to 25 percent in Canada, and 33 percent in Taiwan and Japan.²

Related: 5 things you don't know about punctal plugs

Many aspects of dry eye are still not well understood, and its management can be challenging. Most, or perhaps nearly all, symptomatic forms of dry eye have an evaporative component,³ which likely contributes to aqueous tear loss through a defective lipid layer. This, in turn, can lead to increased osmolarity, ocular surface inflammation, and damage.

The meibomian glands in the eyelids secrete meibum, a lipid complex that forms the protective lipid layer of the tear film. The lipid layer prevents evaporation of aqueous tears and prevents drying.  Lipid deficiency due to meibomian gland dysfunction (MGD) is the most common cause of symptoms associated with dry eye disease.³

 

Importance of the lipid layer

The function of the lipid layer has been studied extensively in recent years. While some believe that is merely a protective layer to prevent the aqueous tears from evaporating, recent studies show that the lipid layer is even more complicated; keeping the tear film intact, allowing it to spread across the ocular surface instead of collapsing.

This also keeps the tears flowing across the eye and into the puncta. Without this layer, the tear film cannot spread properly and worse yet, is then prone to evaporation.⁴

Treatment of meibomian gland dysfunction has traditionally been with the use of warm compresses, lid scrubs, and artificial tears. Adding a liquid to tears almost always provides initial relief of dry eye discomfort, but patients often complain that the relief is short lived. There are a number of lipid-containing eye drops on the market that are underutilized.

Related: Using warm compresses to treat MGD

Using a lipid-containing artificial tear to help reform the protective layer of the tear film could give patients more relief from the collapse of the overall tear film and the evaporation of aqueous tears. One study shows that lipid-based tears are as safe, effective, and acceptable as aqueous-based artificial tears.⁵

As we gain a greater understanding of the layers of the tears, it makes sense that adding lipid eye drops to tears helps to recreate the protective and spreading function of the tears that the lipid layer provides. This may be more helpful than simply increasing the aqueous layer with artificial tears

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