Artificial Tears & Lubricants
Artificial tears and lubricants have been the mainstay in dry eye treatment since the beginning. Artificial tear technology has progressed dramatically in the last decade, seeing the introduction of several new types of tear replacements that aim to target specific tear components. Your tears are made of three main components, the inner mucous layer, the middle aqueous layer and the outer oil layer. The inner mucosal layer helps the tear stick to the eye. The middle aqueous layer provides moisture and antimicrobial enzymes. Finally, the outer oil layer is comprised of lipids that slows evaporation. Dysfunction in any of these layers can begin the inflammatory cycle that is dry eye. To combat these tear film dysfunctions, researchers have developed multiple artificial tear types aimed at the varying components of the tear. Our favorite lubricants currently include Oasis Tears and Oasis Tears Plus (PF), Retaine MGD (PF), Theratears Xtra (P), Refresh Repair (TP), Refresh Mega-3 (PF), Celluvisc (PF) and Tears Again Liposome Spray.
Lipid based emulsions are used to combat dysfunctions of the oil layer, often caused by meibomian gland dysfunction and blepharitis. These tears tend to be milky and may cause smoky vision after instillation. These are one of the main categories used in our office as evaporative dry eye disease is highly exacerbated by our dry climate in Nevada. Examples include Retaine MGD (PF), Systane Balance (P) and Optive Advanced (PF and TP).
The majority of artificial tears focus on enhancing the aqueous layer of the tears and increasing lubricity. Most of these tears use molecules like carboxymethylcellulose, propylene glycol, glycerin, hydroxypropyl methylcellulose, polyethylene glycol and dextran as the active ingredient. There are too many options in this category to list, so we will focus on the few that have special features.
One of our favorite inactive ingredients is sodium hyaluronate, which has been shown to have protective effects on the corneal epithelium aiding healing and some versions actually release water molecules when you blink. Oasis Tears (PF), the thicker Oasis Tears Plus (PF) and Blink (TP and PF) all contain sodium hyaluronate.
Another great inactive ingredient is hydroxypropyl guar. This gel forming molecule increases retention time of the tear and forms an anchoring bandage over damaged corneal epithelial cells. HP-Guar is found in Systane (P and PF), Systane Ultra (P and PF), Systane Balance (P), Systane Complete (P) and Systane Gel Drops (P).
Hypo-osmotic tears are designed to counteract the hyperosmolarity often found in dry eye patients. Examples include TheraTears (P and PF), Theratears Xtra (P) and Hypotears (P and PF).
FreshKote (P) is a prescription artificial tear that features a high oncotic pressure that aids the cornea by reducing microcystic edema. It also contains components to supplement all three layers of the tear and restore proper osmolarity.
Gels can greatly increase the time the lubricants stays in the eye. Many of these products are just thicker versions of the counterparts listed above. These tend to cause blurred vision, so their use is often limited to before bedtime or for those with nocturnal lagophthalmos (incomplete eyelid closure). Refresh Optive Gel (TP), Systane Gel Drops (P) and Genteal Gel (P), Theratears Nighttime Gel (PF) and Blink Gel (P) are examples. Though not gels, thicker formulations like Celluvisc (PF) and Oasis Tears Plus (PF) are often also recommended, especially for nocturnal lagophthalmos in conjunction with moisture chamber masks.
Ointments for nighttime use are generally not recommended as there is some thought that they may exacerbate meibomian gland dysfunction and trap inflammatory component against the eye. Retaine PM (PF) and Refresh PM (PF) are examples.
Lacrisert (PF) is an one of kind prescription product for moderate to severe dry eye patients. It consists of a small hydroxypropyl cellulose rod that is inserted into the inferior cul-de-sac of the eye. The idea behind this product is to provide a constant supply of lubricant to the eye without regular drop instillation. Some patients note a foreign body sensation with this option when used during waking hours. A great use of Lacrisert is for patients that suffer from overnight dryness as the foreign body sensation is generally not noted during sleep.
A special note about preservatives. Listed above you will note that products are listed with a P, PF or TP. These stand for preserved, preservative free and transient preservative. Some patients can be sensitive to preservatives in the products they use for treatment, so much so that some preservative reactions can exacerbate the dryness issues. For those patients using dry eye products on a consistent basis they should use the preservative free versions when available to avoid this complication.