By Shirley Ha, HBSc., O.D., FCOVD
Not all dry eye problems, including those related to wearing contact lenses, are the same. Typically, dry eye patients, both contact lens wearers and non-wearers, report symptoms of dryness and have signs of inadequate tear volume, decreased tear breakup time (TBUT) and corneal staining that support the dry eye diagnosis. However, there are some dry eye patients and contact lens wearers without dry eye who have normal, objective test results but continue to complain of discomfort that mimics the symptoms of dryness and grittiness. Notwithstanding the routine assessment and management of aqueous dry eye and Meibomian gland dysfunction (MGD) that disrupts tear film support, lid wiper epitheliopathy (LWE) is often an overlooked condition, one that is characterized by worldrenowned dry eye researcher Dr. Donald Korb of Boston, MA as the distinctive feature for symptoms of dry eye1.
The lid wiper area lies behind the row of Meibomian glands on the upper lid margin. Akin to a windshield wiper blade, it moves up and down across the bulbar conjunctiva onto the corneal surface about 12,000 times a day to clear the eye of debris and replenish the pre-corneal tear film layer that protects the ocular surface from mechanical stresses during a blink.
In patients with symptoms of dry eye, decreased lubricity or increased coefficient of friction between the lid wipers and the lens surface occurs and the lid wiper surface becomes compromised. The constant friction causes a change to the epithelium of the inner-upper lid margin. Instead of a wiper blade that glides smoothly without leaving “streaks” in the tear film, clinically shown as decreased TBUT, the irregular lid wiper area now has uneven pressure over the contact lens surface, increasing its sensitivity and patient discomfort.
The causes of LWE are many and can include pre-existing dry eye conditions, secondary, but not limited to exposure keratopathy, age, cosmetic lid surgery, lagophthalmos, incomplete blinking and environmental factors. With any new contact lens fits or refits, the lid wiper area should be scrutinized for evidence of LWE, in addition to other screening tests. This should be repeated at all regular follow-ups thereafter.
Clinically, LWE is detectable with topically applied fluorescein or lissamine green or rose bengal dyes. By gently lifting and everting the upper lid, the lid wiper area can be assessed and classified for width, length and shape of the staining.
The increase in epithelial permeability in this region must be differentiated from the same dye uptake that occurs in the Line of Marx (LOM). While LWE is caused by repeated irritation between the lid wiper surface and the front surface of the lens, the LOM is a “normal” thin band of accumulated, superficial, conjunctival epithelial staining that lies directly behind the mucocutaneous junction.
LWE patients demand lubricious contact lenses that can reduce the insult to, and protect the lid wiper area and the ocular surface. Sometimes it is best to discontinue wear for a while if there has been chronic irritation of the lid wiper area. Lenses with higher surface wettability, such as the Alcon’s DAILIES TOTAL1® water-gradient contact lenses, with better oxygen permeability (SiHy material) and lower modulus may help reduce the LWE mechanical friction, as can Type I, II – lower ionicity lenses that minimize protein buildup. Also, patient compliance in the cleaning and lens replacement regime, with emphasis on rubbing and rinsing immediately after CL removal and timely replacement, is necessary to ensure that the lenses are clean and fresh for everyday wear.
Recommend contact lens solutions that remove lipids and proteins effectively while providing a more wettable lens surface to protect it from lipid and protein deposition. Sometimes the additional soak prior to lens insertion can offer improved comfort by further enhancing the beginning wettability of the lens. For incomplete blinkers, blinking exercises can be prescribed several times a day. The lids should “kiss” each other on each blink in order to modify and develop better blink habits and to forcibly express the Meibomian gland for better tear film stability. Blink training also has a very important biofeedback mechanism to prevent forced blinking, which may be very negative. By placing the index fingers on the lid margin during a blink, there should be no pulling sensation if blinking correctly.
The posterior margin of the eyelid is an important but under-assessed structure when it comes to ocular surface diseases and non-specific contact lens dropouts. LWE with staining may be an early indicator of dry eye disease and should be considered and evaluated, even when contact lens patients are asymptomatic and/or if diagnostic dry eye testing is normal. For contact lens providers, restoring the lid surface to some normalcy can increase contact lens performance and comfort for patients and decrease idiopathic contact lens dropout.
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1. KORB DR, HERMAN JP, BLACKIE CA, et al. “Prevalence of Lid Wiper Epitheliopathy in Subjects with Dry Eye Signs and Symptoms”, Cornea, vol. 29, April 2010, p. 377-83.
