Contact Lenses Care

Compared with conventional soft lenses, the extended-wear lenses offer almost all the same liabilities , as well as a few more. They are the most expensive contact lenses (about six hundred dollars), in part because of the cost of the special lenses but mainly because of the extensive professional follow-up examinations required.

The visual acuity provided by the extended-wear lenses is similar to that of conventional daily-wear soft lenses. So far these lenses are available only for those who are nearsighted and for those who have undergone cataract extraction. They cannot correct significant amounts of astigmatism. However, research is going on in this field.

Extended-wear contacts will absorb impurities from the environment and are even more prone than conventional soft lenses to accumulate deposits of lipid, protein, calcium, and mucus from the tears and eyelids. In some cases these deposits simply cannot be removed, and the lenses must be replaced.

Extended-wear lenses are less durable than other lenses and may have to be replaced as often as twice a year. Though they are inserted and removed infrequently, a delicate touch is required. Many people have difficulty in handling the lenses since the extended-wear lenses have the feel and consistency of Saran Wrap. It is also extremely difficult to tell whether these lenses are inside out. Usually the best candidates for extended-wear lenses are those who have previously worn lenses—particularly soft lenses—on a daily basis. These wearers are familiar with the normal sensations that conventional soft lenses produce and are thus in a better position to detect and report abnormal symptoms to their eye doctor. In fact, when I fit an individual with extended-wear lenses, I make certain that he has gone through at least one week of daily insertion and removal.

Though for the most part wearers can forget about their lenses while they’re wearing them, extended-wear lenses may become uncomfortable under certain conditions. Dry air can do it; so can the accumulation of the aforementioned deposits. A reduction in oxygen supply can result from extended wear, producing irritation and edema, since some eyes simply need more oxygen than others—especially when the contact lens is worn for long periods of time.

In some cases round-the-clock contact lens wear may temporarily thicken and distort the cornea, resulting in spectacle blur whenever the contacts are removed and glasses are worn. In rare instances extended wear may increase the chance of infection. In the first place wearers are sometimes lulled into a false sense of security because the lenses stay on for so long. They may forget that they are, in fact, contact lens wearers, and become cavalier in their attitude toward caring for their lenses and their eyes. If an infection should occur, it happens under the lens “bandage” and may not be as evident as in daily-wear lenses. Reduced tear flow and oxygen supply may cause the surface of the cornea to become swollen and even abraded, providing a welcome mat for microbes and bacteria that will multiply even more readily when there’s less air in their environment. On the other hand, in daily wear a slight infection that’s taken hold can be halted at an early stage when the lens is removed, the cornea is exposed to the air, and the normal supply of bacteria-fighting tears is present.

When I was chosen to be a research investigator for one of the extended-wear contact lens companies, I have had the opportunity to fit many patients with these lenses. Despite rigid written and oral instructions as to the care and handling of the lenses, the need for frequent eye examinations, and the attention to abnormal symptoms, there was a small percentage of patients with poor compliance—and therefore poor lens performance. Such was the case of one patient who, even after suffering for several days, thought that a red, irritated eye was not important enough to bring to my attention. When she did finally arrive at my office, she had a severe corneal ulcer. The lens was immediately removed and she was placed on antibiotic drops and oral medication. The healing process took two weeks, and she was fortunate that the infection cleared fully, leaving no permanent scar.

Keratitis, characterized by tiny areas of abrasion or inflammation on the surface of the cornea, can occur in any type of contact lens wear, but is more common in extended wear. A decrease in oxygen supply may be the cause, or the cornea may become irritated by the contact lens solutions used, or by the lens itself when the tear layer is too thin. The condition may also be the result of infection.

Another potential hazard with extended wear is neovascularization, a growth of new blood vessels on the normally avascular (without blood vessels) cornea. This results because a reduction in oxygen stimulates the formation of new blood vessels as the body attempts to restore the supply of this vital gas. By reducing the oxygen supply sufficiently over a significant period of time, extended-wear contact lenses are the lens type most likely to create this condition. Neovascularization will cause eye irritation and reduce visual acuity. However, the blood vessels will disappear after the lenses have been removed.

Wearers must bear in mind that these are extended wear (days, weeks, months) contact lenses, not continuous wear. Though they have been approved by the FDA for up to two weeks for cosmetic wear, and three months or more for aphakes, the schedule will vary from person to person. How long you go between cleanings depends upon the health of your eyes, the amount of lens deposits you tend to accumulate, the type of lens, the way you work and relax, your individual ocular physiology and tear chemistry, and even the environment in which you live and work. (City air is not a particular problem, but confined areas of fumes, gases, and sprays are a contraindication for wearing any type of contact lens.) Naturally, specific instructions will be given to you by your doctor. In some patients the lenses simply become too dirty too rapidly to make extended wear feasible.

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