Dry eye syndrome (keratoconjunctivitis sicca) is a common condition where the eye’s tear film is insufficient or unstable, leading to irritation and discomfort. This lack of lubrication frequently results in a temporary decrease in vision quality, which is intensified for contact lens wearers. The lens rests directly on the eye’s surface, disrupting the delicate tear layer.
How Dryness Affects Vision Clarity
The tear film functions as the eye’s primary refractive surface, focusing light onto the retina. This film must be perfectly smooth to bend light accurately and provide sharp vision. The tear film consists of three layers: an inner mucous layer, a middle watery layer, and an outer lipid (oil) layer that prevents rapid evaporation.
When dry eye occurs, the stability of this film is compromised, often due to a deficiency in the oily layer or insufficient tear production. This instability causes the tear film to break up prematurely, exposing patches of the corneal surface and the contact lens. The resulting surface irregularity scatters incoming light, which the brain perceives as temporary or fluctuating blurriness.
Vision is blurriest right before a blink because the tear film has had the longest time to evaporate. A blink temporarily restores the smooth surface by spreading fresh tears over the lens, which clears the blurriness immediately. Reduced blinking frequency, common during sustained activities like reading or using a computer, accelerates this evaporation, making the blurriness more persistent.
Contact Lens Characteristics That Increase Symptoms
The physical presence and material composition of a contact lens inherently interact with the tear film, exacerbating dry eye symptoms. Contact lenses function like a sponge, drawing moisture from the eye’s natural tears to maintain their own hydration. This process, known as lens dehydration, significantly contributes to end-of-day discomfort and blurry vision.
Older generation hydrogel lenses, which often have high water content, are prone to dehydrating in dry environments, pulling substantial moisture from the eye. While newer silicone hydrogel materials permit greater oxygen flow, they can still contribute to dryness because silicone components may resist wetting and increase the speed of tear evaporation from the lens surface.
A lens that does not fit correctly can interfere with the natural circulation of tears underneath it. A tight-fitting lens impedes the exchange of fresh tears, leading to debris buildup and a less stable tear film. Over time, the lens accumulates deposits of protein and lipids, which roughen the surface and directly cause vision to become cloudy.
Practical Steps for Clearer Vision
Managing dry eye while wearing contact lenses involves product changes, environmental modifications, and conscious habits. Switching to daily disposable lenses is effective, as it prevents the buildup of deposits that occurs on lenses worn for multiple days. For those with significant dryness, specialty lenses, such as scleral lenses, may be recommended because they vault over the cornea and hold a reservoir of fluid to keep the eye hydrated.
Specific types of eye drops provide immediate relief. Preservative-free artificial tears are preferable because standard preservatives can irritate an already compromised eye surface. These lubricating drops can be used throughout the day to rewet the lens surface and stabilize the tear film. Always confirm that the chosen drops are approved for use with contact lenses to avoid damaging the material.
Modifying daily habits reduces the frequency of blurriness, especially during prolonged screen use where the blink rate decreases. The 20-20-20 rule involves looking at something 20 feet away for 20 seconds every 20 minutes to encourage conscious blinking and rest the eyes. Environmental factors can be addressed by using a humidifier in dry indoor spaces and ensuring adequate hydration. Persistent or painful blurriness that does not resolve warrants consultation with an eye care professional.