Contact Lens-Induced Dry Eye

Contact Lens-Induced Dry Eye

Contact Lens-Induced Dry Eye

By Gary N. Foulks, MD, FACS

We have known since the mid-1980s that contact lens wear can aggravate, or even produce, dry eye, findings that have been corroborated by more recent research.^1,2 Two mechanisms have been proposed to explain this effect. First, the contact lens itself may increase tear evaporation, rendering the tear film unable to provide adequate lubrication during blink. Second, wearing contact lenses decreases corneal sensation—this natural desensitization response is what allows wearers to adapt to contact lenses—thereby decreasing the stimulus to create tears and producing a relative aqueous deficiency on the surface of the eye.

End-of-Day Discomfort

Discomfort in contact lens wearers is particularly problematic in the afternoon and evening due to the continuous tear film evaporation over the course of the day. If, in addition, the aqueous compensation mechanism is compromised due to dry eye disease, the volume of tears produced may be further reduced, rendering the eye unable to fully replenish the evaporating tear film. Diminished tear volume can produce discomfort due to reduced lubrication; however, both increased evaporation and diminished aqueous production also serve to increase tear film osmolarity, which further irritates the eye.
  
 When the eye is dry, loss of water from the lens matrix combined with the osmolarity of the tear film can affect the contact lens’ configuration, leading to an altered fit and potentially adding to the patient’s discomfort.
   
A good artificial tear can ease discomfort by restoring stability to the tear film and rehydrating the contact lens. The challenge is to select a drop that is compatible with the patient’s contact lens. Hard contact lenses can accommodate most drops, even viscous polymers. Using thick polymer drops with soft contact lenses, however, can interfere with clarity of vision. Additionally, lipid containing drops may leave deposits on soft contact lenses, especially silicone hydrogel lenses. Because of these potential interactions, aqueous electrolyte solutions or simple rewetting drops may be the best choice for soft lens wearers.

Keeping Patients in Contact Lenses

Meibomian gland disease (MGD) is the most common cause of contact lens intolerance. While contact lens wear does not typically produce MGD, wearing contact lenses can aggravate MGD by combining two factors that are known to produce tear evaporation (underlying lid disease and contact lens wear). Treating MGD is the best way to restore overall eye health and, hopefully, return the patient to comfortable contact lens wear.
   
To treat MGD, I recommend warm compresses and mechanical massage of the glands in the lid. If there is a significant amount of inflammation present, oral doxycycline or topical azithromycin are good options. It should be noted that this is an off-label use; however, both drugs are now widely used in the treatment of MGD.
   
In addition to addressing lid disease, test tear production to determine whether aqueous deficiency is contributing to contact lens intolerance. If so, punctal plugs will sometimes solve the problem. However, if the patient has true dry eye disease, using punctal plugs can exacerbate symptoms by retaining high concentrations of inflammatory mediators on the eye. For these patients, ophthalmic cyclosporine helps to control inflammation associated with dry eye and often allows patients to stay in contact lenses.
   
It’s also prudent to assess the fit of contact lenses. Is there appropriate lid interaction with the contact lens and is the tear exchange appropriate for the type of lens being used? Make necessary adjustments to fit and tear exchange in order to maximize the chance of contact lens tolerance. Additionally, consider the contact lens material. Soft contact lens wearers may benefit from a low-water content lens like silicone hydrogel or lenses made from the biocompatible omafilcon A material.
   
Finally, look for surface damage to the eye. Patients without surface damage have a better chance of returning to contact lens wear. But if dry eye is severe and damage is present, therapeutic scleral contact lenses may be needed.

Gary N. Foulks, MD, FACS, is the Arthur and Virginia Keeney professor of ophthalmology, University of Louisville, Louisville, KY, and is editor-in-chief of The Ocular Surface.

REFERENCES
1. Farris RL. The dry eye: its mechanisms and therapy, with evidence that contact lens is a cause. CLAO J. 1986 Oct-Dec;12(4):234-46.
2. Guillon M, Maissa C. lens wear affects tear film evaporation. Eye Contact Lens. 2008 Nov;34(6):326-30.