Lubricants Add Comfort
To Contact Lens Wear
Yesterday's simple artificial tear products have given
way to scientifically formulated lubricating drops that offer maximum comfort to contact lens wearers.
By David W. Hansen, OD, FAAO
As contact lens practitioners, we have a straightforward goal: To achieve the best possible visual acuity and comfort while maintaining ocular health. To that end, we must select the appropriate lens material, design and care system for each individual.
The first critical step toward this goal is to investigate the patient's previous contact lens and medical history. The issues we must address often involve:
- Environmental factors
- Medical conditions
- Pharmacological requirements
- Ocular and systemic allergies.
Dryness and discomfort are common complaints associated with contact lens wear. Begley and coauthors (2001) reported that ocular discomfort comprised 79% and dryness 77% of symptoms in contact lens wearers.
Traditionally, we've selected lens care regimens to create a biocompatible environment that offers antimicrobial protection for the ocular surface. When a disinfecting system itself doesn't satisfy a patient's comfort needs, we usually prescribe an ocular lubricant. Together, the material, the care system, the lubricant and the ocular surface need to provide a barrier against contaminants while promoting comfort throughout the wearing schedule, even if it's for 30 days of continuous wear. When this synergy is lacking, we fall short of our goal and lose contact lens wearers.
THE COMFORT QUEST
Dropouts are the curse of the industry. When these formerly successful contact lens patients become dissatisfied, they revert to eyeglasses or pursue other refractive options. Again, one of their chief complaints is dryness.
Ocular rewetters offer only temporary relief of dryness symptoms. Most practitioners prescribe a lubricant only for patients who are dissatisfied with comfort. And many practitioners don't mention lubrication options during contact lens education. I've even heard some say, "It's only water. What can it do to help comfort?"
Research in the contact lens industry has advanced to address the dryness concern. Industry has looked at a combination of ingredients to protect the ocular surface, enhance the tear chemistry and balance electrolytes. The science behind these companion ingredients is modeled on the body's own tears, with emphasis on moisturizing and lubricating the contact lens and the corneal surface rather than just wetting the contact lens.
Manufacturers add preservatives to multi-dose products to prevent microbial contamination and thus protect patients from harmful pathogens. As we know, not all preservatives give our patients comfort with their antimicrobial action; and some even exacerbate dryness problems. Lubricating agents are added to prolong comfort.
Most comfort ingredients are demulcents containing high-molecular-weight polymers with water-binding properties and high viscosity. The term demulcent describes an agent, usually a water-soluble polymer, that's applied topically to the eye to soothe, protect and lubricate mucous membranes, hence, relieving dryness and irritation. Highly viscous lubricants increase resistance during the blink or rapid eye movements, resulting in blurred vision or discomfort.
NEXT GENERATION LUBRICANT
A new product -- Blink Contacts from Advanced Medical Optics Inc. -- is formulated with sodium hyaluronate, a naturally occurring biopolymer found in the vitreous and aqueous humor, joints, organs and extracellular matrices. Sodium hyaluronate has water-binding and viscoelastic properties and is an effective lubricant. It has a long history in the ophthalmic industry and is a proven agent in ophthalmic surgery. It's also been used in Japan as a prescription drop for dry eyes.
Contact lens practitioners have many choices when selecting lens care regimens. Products must be compatible with lens materials; and they must remain on the ocular surface long enough to enhance moisture and promote comfort. Sodium hyaluronate lubricating drops, such as Blink Contacts, are an important advance in contact lens care, offering both water-retention and lubrication for ocular health and comfort.
1. Begley CG, Chalmers RL, Mitchell GL, Nichols KK, Caffery B, Simpson T, DuToit R, Portello J, Davis L. Characterization of ocular surface symptoms from optometric practices in North America. Cornea. 2001 Aug;20(6):610-8.
Dr. Hansen is director of Professional Services for Advanced Medical Optics Inc.
Contact Lens Spectrum, Issue: September 2004