Bandage Contact Lenses: The “Contact Lens” as a Drug Deliver System
A bandage lens, also called a therapeutic lens, is a special soft, very thin, high-water-content contact lens. In 1974 this hydrophilic lens was the first type to be used on an extended-wear basis, but without incorporating a prescription. It has a wide variety of uses before ocular surgery, after ocular surgery, and sometimes instead of surgery. It can also be therapeutic in conditions that do not respond to any other form of treatment.
The lens functions basically as a protective shield and prevents a damaged or ailing cornea from coming into contact with the eyelids and the air. Healing is thereby accelerated and pain is alleviated for as long as the lens is worn, which is on an extended basis (more than twenty-four hours). As such it can take the place of the tight eyepatch formerly used to immobilize the eye to facilitate the recovery process. It is usually needed only temporarily until the condition being treated has cleared up. The lens is placed on the cornea by the ophthalmologist and is removed by the doctor when the disorder being treated has been cured.
Uses of Bandage Lenses
The lens has been used for many years with varying degrees of success to treat a great number of conditions. The most frequent uses are for:
Dry Eyes. Although I have cautioned against the use of a soft lens when tear production is reduced, this lens plays an important role in severe cases of dry eyes. The dry-eye syndrome is a common by-product of the aging process and affects women more often than men. In postmenopausal women all the mucous membranes begin to dry because of the shift in hormone production. In these cases dryness of the eye can become quite severe. A dry eye may also be caused by drugs (birth control pills, antihistamines, and so on), injury to or infection of the lachrymal glands, autoimmune disorders (Stevens-Johnson syndrome), severe injuries or infections of the eye, and vitamin deficiencies.
Eyes with a marked reduction in tear production can lead to damaged corneas. For patients suffering from dry eyes a bandage lens in tandem with frequent instillation of artificial tears is an excellent treatment. The eye drops are absorbed by the highly hydrophilic (water-loving) lens, bathing the eye with them in a more constant fashion than if drops alone were used.
Bullous Keratopathy. As a result of the aging process or following injury to the eye, which may be accidental or occur after intraocular surgery such as cataract extraction, the cornea may swell with an abnormal amount of fluid. The inner surface of the cornea (endothelium) becomes damaged, vision becomes blurred, and there is marked pain. The bandage lens can reduce and sometimes completely alleviate both symptoms by protecting the eroded corneal surface and by acting as a barrier to prevent fluid from escaping from the cornea.
Corneal Ulcers and Abrasions. The bandage lens seems to accelerate the healing process in abrasions and ulcers that can result from viral, bacterial, and fungal infections. This form of treatment should only be used in conjunction with antibiotic, antiviral, or antifungal eye drops.
Trichiasis. As a result of an injury, infection, or aging, the eyelashes may turn inward and rub against the cornea. A bandage lens can act as a shield while (or until) the primary condition is treated.
Chemical and Thermal Burns. By eliminating the constant irritation of the eyelid coming into contact with the healing corneal tissue, a bandage lens allows the cornea to grow back normally and more rapidly. Using a bandage lens postoperatively after a burn increases the success rate of such surgery.
Penetrating Corneal Wounds. When the cornea becomes wounded, a bandage lens aids in forming a protective shield and can be employed to facilitate healing when surgery has to be delayed.
Bell’s Palsy. When the upper lid is unable to close completely, the cornea may become overly dry. The bandage lens protects the cornea, but frequent instillation of artificial tears is necessary as an adjunct.
The “Contact Lens” as a Drug Deliver System
There now exist tiny discs containing special medication that may be placed on the eye to provide a constant source of medication. The small oval-shaped flexible “lens” is worn over the sclera under the eyelid. Its sole purpose is to act as a reservoir for drugs in liquid form, allowing specific amounts to be released into the eye gradually over a prolonged period of time. It’s really a time-release capsule for the eyes. The drug in use is, therefore, more effective than when it is administered as intermittent drops, because constant, round-the-clock treatment is possible. Also lesser amounts of the drug may do the job with this method. This can in turn reduce the local and systemic side effects and allow the use of more potent drugs such as steroids and glaucoma medication. Once in place the “contact lens” is a convenient way of administering medication, particularly for patients who might not otherwise comply with the prescribed treatment. Ocusert, containing the glaucoma medication pilocarpine, and Lacrisert, containing lubricating medication, are the two special “lenses” now commercially available. They can be worn continuously (even while sleeping) and removed and replaced weekly for the duration of the treatment.
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