Daily-Wear Contact Lenses. Conventional hard lenses, gas- permeable lenses, and soft lenses can be worn to correct vision following a cataract removal. But the problem of daily insertion, removal, and cleaning is a real one, and discourages many a potential daily wearer. Fear of inserting a foreign object into the eye; diminished dexterity; reluctance to handle tiny, delicate, almost invisible objects—all can add up to a less-thansuccessful scenario. The replacement rate with soft lenses is particularly high: the average life span of a pair is two years because of loss, torn lenses, or lens deposits. Because of their advanced age aphakes often have dry eyes, and soft lenses require a more lavish tear supply than do hard lenses. Also, loose lids, usually found as a product of aging eye, can cause fitting and wearing problems.

Many aphakes do, however, adjust to life with daily-wear contact lenses. Sometimes a willing friend or relative helps with the lens care and handling. Aphakes also have some distinct advantages to mitigate their particular problems when it comes to contact lens wear. Since the cornea has been cut (and nerves severed) during the cataract extraction, the eyes are less sensitive and contact lenses feel more comfortable. (Unfortunately this desensitization may mean that the aphake is less aware of any injury and damage to the eyes; therefore these patients require careful monitoring.) For those who can’t cope, there are two more alternatives: extended-wear contact lenses, and intraocular lenses.

Extended-Wear Contact Lenses. As discussed previously this is a recent development, and many eye practitioners feel that these lenses are the safest alternative. As such they have become the single most frequently prescribed form of contact lenses for aphakes. And with good reason: extended-wear contact lenses are comfortable and provide good visual acuity. Primarily they solve the biggest drawback of aphakic contact lens wear by eliminating the daily insertion, removal, and cleaning required of all other types of contact lenses. In fact, extended wear for aphakes was FDA approved before extended wear for so-called “cosmetic” use because of the very real and greater need for this type of lens.

Extended-wear contact lenses are initially inserted at the doctor’s office and worn continuously for up to one month or more. During periodic eye examinations at the doctor’s office the lenses are usually removed and cleaned and then reinserted. As with daily-wear lenses, sometimes a neighbor or a relative is enlisted to help remove, clean, and insert the lenses between office visits.

Extended wear does have its drawbacks. The lenses currently available will not fit everyone, but they are successful in an estimated 75 percent of the aphakic population. Since they wear them for longer periods of time, aphakes tend to have even more of a problem with protein deposits than normally occurs with the daily-wear lenses. The useful life of the lens is thus shorter, necessitating frequent replacement, though the “saline eyewash” has been shown to be an effective preventive that can be used without removing the lens. Wearers should be hygiene conscious and be willing to go to the doctor for the needed follow-up visits.

Intraocular Lenses. Although they are not contact lenses, plastic intraocular lenses are quite similar and offer a viable and permanent solution for the aphake. Each year a larger percentage of those who undergo cataract removal will have a lens implant, usually at the time of cataract surgery. As a result they have a new substitute lens built right into the eye; quite often vision is restored to 20 / 20 without glasses. This is the most convenient form of cataract correction, since the lens is never removed unless complications ensue.

The intraocular lens is the brainchild of the English ophthalmologist Harold Ridley, who developed the idea during World War II. He saw wounded RAF pilots with fragments of Plexiglas windshields embedded in their eyes. The plastic remained inert, which led him to the conclusion that intraocular lenses could be made from the same material (polymethylmethacrylate, or PMMA, the same plastic from which conventional hard contact lenses are made) and safely placed into the eye.

Since ophthalmologists do not know the long-term effects of intraocular lens implants, the best candidates for ocular implants are the elderly. If they have dry eyes and eyelid abnormalities, which preclude wearing contact lenses, the lens implant will be the best type of vision correction. On the other hand those who are very nearsighted, have detached retinas, poorly controlled glaucoma, diabetes, or other eye diseases, are advised to seek the other vision-corrective devices mentioned earlier.

About 10 percent of the intraocular implants result in complications. Many of these can be corrected without removing the implant. They may include dislocation of the implant, changes in the cornea, inflammation of the iris, retinal detachment, and increased pressure in the eye that could lead to glaucoma. At times the intraocular lens will have to be removed. Tests are still being conducted to study the longterm effects of intraocular lenses.

Future developments in this field lie mainly in the improvement of the lenses themselves. Another method of vision correction involves grafting “live” contact lenses onto the aphake’s cornea. Donor corneas are frozen and ground to size, then sutured onto the living host cornea. To date several such operations have been successful.

Cleaning with a surfactant cleansing solution and disinfecting may not remove all the deposits that cling stubbornly to the lens surface. To remove these deposits a special enzyme solution is used; this “digests” and dissolves lens proteins much the same way the enzymes in your body help break down protein.

You should use the enzyme cleaner once a week to help prevent buildup of protein deposits. (To help you remember, perform this procedure on the same day every week—the first or the last day, or every Wednesday, etc.) Once deposits are established, they will increase and can pit the lens surface, leaving it damaged even after it’s purged of the accumulations. Enzyming is especially important for those who tend to produce tears heavily laden with protein. Factors such as air pollution, makeup, and eye irritation increase production of this protein.

The enzyme tablets come in a starter kit, which also contains two vials for mixing and soaking (one for each lens) and a “lens retriever” to help remove the lenses from the solution. After using up the starter tablets you can buy the tablets from your doctor or pharmacy and keep using the original vials and retriever.

To use the enzymatic cleaner follow the informative circular that the manufacturer provides with the package. Though the instructions suggest simply rinsing the lenses with saline before submerging the lenses in the enzyme solution, I would recommend that you use cleaning solution and rinse off the lenses thoroughly with saline. Also, instead of dissolving the enzyme tablet in distilled water, you may use premixed saline solution if you don’t have distilled water on hand.

If you are allergic to the chemicals in preserved saline, I still recommend enzyming the lenses once a week and using the heat method of disinfection. If the chemicals in the enzyme cleaner affect your eyes, you can leach the lenses by soaking them in pure, unpreserved saline for several hours after enzyming.

Soft Contact Lens Lubricating Solutions

Soft lenses are generally more comfortable than hard lenses. But an eye that’s even slightly dry can cause soft-lens discomfort. To restore adequate moisture you can instill a drop or two of saline solution while wearing the lenses. Or you can use one of the special lubricating solutions formulated for contact lenses. These will clean, lubricate, and cushion the lenses while they’re still in your eye, and may be used as often as needed. Decongestants, which are not formulated for contact lens use, contain chemicals that may be absorbed by the lenses and are definitely to be avoided. Never use any eye drops not recommended by your doctor while you are wearing soft contact lenses.

Soft Contact Lens Mechanical Cleaning

Mechanical cleaning (massaging the lens with saline) is very important to maintain the integrity of the lens. If this procedure is omitted, a light filmy deposit will form on the lens, especially if it is heat disinfected. The lens will eventually become less comfortable, less transparent, and allow less oxygen to pass through it. In just a few weeks the lens will have to be replaced. Mechanical cleaning, therefore, is integral to every soft-lens wearer’s regimen. For some wearers, however, it is the only method recommended for cleansing their lenses.

The surfactant cleaners, chemical disinfecting solutions, and preserved saline solutions all contain chemicals that the soft plastic lenses can absorb and then release into the eye. About 20 percent of soft-lens wearers are allergic to preservatives and therefore should not use the solutions that contain them. Usually switching to nonpreserved saline solution and thermal disinfection will solve the problem.

Such was the case with one of my patients. She had been using the cold disinfection method for a few months with no problems. One day she walked into my office with red, itchy, irritated eyes and a whitish ocular discharge. After purging her lenses of the chemicals, I placed her on a strict, no-preservative regimen that utilized a mechanical cleaning method, an unpreserved saline solution that she mixed herself, thermal sterilization, and once-a-week enzyming. Every day she removed her lenses, placed them one at a time in the palm of her hand, and placed several drops of the saline on the lens. She then massaged the lens with the index finger of her other hand for at least one minute to remove the accumulated dirt. After rinsing the lens with nonpreserved saline, it was ready for heat sterilization. This procedure has proved so successful, I now prescribe it for most of my allergic patients.

Like the lenses themselves, the products used in conjunction with them must be tested before they are approved by the FDA for the general market. The contact lens manufacturer and your practitioner may recommend a specific system based upon the chemical composition of the lenses and the way they react with your own physiological makeup. Particular brands do have their die-hard fans who swear by their products and complain of problems when they switch to another brand. Should you develop an allergic reaction or sensitivity to one of the ingredients in a particular solution, you’ll need to switch to a brand that omits the offending agent. The preservatives most often implicated as causing such reactions are thimerosal, a mercuric compound, and chlorhexidine, an active ingredient in certain surgical soaps.

Above all, though, never use the solutions formulated for hard contact lenses since those hard-lens chemicals will be absorbed by the soft lens and will permanently ruin them. Don’t be tempted to experiment on your own. Make sure you read the label carefully before buying and listen to the advice of your contact lens specialist. Even if you have the correct soaking, cleaning, and rinsing solutions, there’s the possibility of mistaking one for another. For instance, you might inadvertently rinse the lens with cleaning or soaking solution. On a short-term basis this will not cause permanent damage to the lenses or to the eye. However, over a prolonged period of time the lenses will deteriorate and the eyes can become irritated.

Saline Solutions

Saline solution (0.9 percent sodium chloride) is the common thread that runs through the soft-lens maintenance routine. After using any of the other solutions—cleaning, chemical disinfecting, or enzyme—soft lenses should be thoroughly rinsed with saline to flush away all traces of dust, dirt, deposits, and the solutions themselves, which contain chemicals that could prove very irritating to the eyes. If you use the thermal disinfection (”heat”) system, after cleaning, the lenses should be immersed in saline to keep them hydrated during the process. (Saline solution is, by the way, the basic component of many other contact lens solutions to which special agents are added.) Saline is also the last thing that should come into contact with soft lenses before insertion, and may be compared with the wetting solutions used in hard lenses, which make the lenses compatible with the eye. Saline solution can even be used alone to clean the lenses in some cases.

Today there is an array of forms and brands of saline solutions that can easily confuse the consumer. Basically they’re all designed to mimic the salt composition of the tears in your eyes. Ideally they should be pure and devoid of harmful chemicals that can be absorbed by the indiscriminate soft-lens plastic. They should also be sterile to avoid introducing harmful microorganisms to the eye. It’s these last two criteria that are the most difficult to meet.

There exists a controversy among physicians as to which type of saline solution to use. Each type has its advantages and disadvantages, as you will see. The main point to remember is that whatever solution you use, make certain that you follow the instructions of your physician to the letter.

Salt Tablets. In the beginning, there was the salt tablet. With one 250 mm sodium chloride tablet mixed with one ounce of distilled water, contact lens wearers could make their own small batches of saline as needed, and at a minimal cost. The result was salt and water, pure and simple. However, the FDA voiced its concern that the homemade solution posed a hazard to consumers because of a number of factors: poor patient compliance, the potential for faulty mixing and measuring, and possible microbial contamination. I had one patient, for example, who thought that if one salt tablet was good, two were better. At the other end of the spectrum there were those patients who used only half a tablet in an attempt to stretch the solution. Still others refrigerated their saline solutions so they’d keep longer; they intended to save money and reduce the frequency of making the saline solution each day by this cumbersome method. As a result salt tablets (made at the time by Bausch & Lomb and Blairex) were taken off the market, leaving available only the sterile, premixed preserved saline solution that had received FDA approval.

Several manufacturers eventually entered the preserved saline market. However, a small percentage of patients became allergic to the preservatives used in the saline. Therefore the pendulum has swung back to a preference for unpreserved saline, available in either the reinstated, FDA- approved salt tablets or the premixed, sterile unit packs discussed below.

Few people may realize that salt tablets are now back on the market, especially the newcomers to soft contact lens wear. Because of the possible dangers of misuse and contamination, it is recommended that if you use salt tablets, you take the following precautions: Always mix a fresh batch of saline every day; avoid using yesterday’s solution for rinsing and disinfecting the lenses or for rehydrating them while in your eyes. Use only U.S.P. salt tablets (others, such as those for heat prostration, contain added chemicals). Mix them with distilled or purified water that is also labeled U.S.P. (United States Pharmacopeia), purchased in drugstores. Steam-distilled water is best; chemically distilled water and other bottled waters (such as spring water) contain substances that could be absorbed by the lenses. (I recommend keeping the bottle of water in the refrigerator to reduce the chance of bacterial contamination.) Use the approved plastic bottle that comes with the salt-tablet kit to mix the saline, and be sure to add the correct amount of distilled water as indicated by the fill line on the bottle. The tablet takes about fifteen minutes when left to dissolve on its own. If you’re in a hurry (as you probably will be if you mix it up fresh every morning), shaking the bottle speeds up the process considerably. Once dissolved, the saline is ready to use for cleaning, rinsing, or sterilization purposes, within the next twenty-four hours. Once a day clean the plastic mixing bottle very well by flushing it out with hot tap water.

Chemical (Cold) Disinfection. There are several disinfection solutions on the market. Disinfection solutions contain chemicals such as thimerosal and chlorhexidine in sufficient concentration to kill the most common microorganisms. Since the lenses remain in the solution for long periods of time, they are kept wet and free of deposits.

The cold disinfection process is simple, and only slightly more inconvenient than storing hard contact lenses. After cleaning and rinsing the contact lenses with saline, they are placed in a special storage/ disinfection case, covered with the disinfection solution and left for at least four hours, usually overnight. Make certain that the storage case is rinsed daily with hot tap water and that it is free of any impurities before use. The lenses are then rinsed again with saline before insertion. Because of its relative convenience and simplicity, many contact lens wearers prefer this method over thermal sterilization, especially those who travel frequently. Unfortunately, the soft-lens plastic absorbs a certain amount of the preservatives contained in the solution, and after a while the wearer may develop an allergy to the chemicals. Approximately one fifth of those who start out with chemical disinfection will eventually change to heat disinfection because of this allergic reaction.

On the horizon are different disinfecting systems that don’t contain the two preservatives named above. One utilizes hydrogen peroxide, a system that has been used by doctors in this country, and outside the U.S. by consumers for years. Another utilizes sorbate, or sorbic acid, and is now available in the U.S.

Thermal (Heat) Disinfection. A safe, effective alternative to cold disinfection is heat, which will also destroy harmful bacteria. After lenses are cleaned and rinsed with saline, they are placed in a special case containing saline solution. The case is placed in the thermal unit, which heats up after you switch it on. In older units there is a well into which you pour distilled water. When this water has boiled away, the lenses are sterile. Newer units utilize dry heat. The unit shuts off automatically, and most people sterilize their lenses before going to bed and let them stay in the unit overnight.

The process actually takes less than an hour, including the time required for the lenses to cool before they can be reinserted. The problem with heat sterilization is that many wearers find it a nuisance. In addition, incomplete cleansing and rinsing of the lenses before sterilization may cause deposits to be baked into the lens surface. This method is also tougher on the plastic and may shorten the life of the lenses. There are certain lenses (such as the extended-wear lenses, Perma-Lens, Hydrocurve, and Sauflon) that hold up particularly badly under high heat sterilization. You should consider investing in a newer “dry,” “low” heat thermal unit if you’ve been using an older model. The newer models are smaller, function with a lower but equally effective temperature, and are easier on the lenses. Also, you needn’t put distilled water into the lower chamber, thus adding to the convenience.

Occasionally a heating unit will malfunction by failing to turn off, turning off soo soon, or not turning on at all. Though a nuisance, this is no cause for panic. As an alternative you can place the lenses in their carrying case in a pan of boiling water for thirty minutes. Remove the case from the pan and let the saline and lenses cool to complete the process. This method may also be used when traveling if you forget or decide not to bring your heating unit with you.

Always wash and dry your hands before handling the lenses. Prepare your work area, be it sink or tabletop. Establish your routine and then stick to it to avoid mixing up the lenses. It’s advised that you always start with the right lens. I place a tiny dot on the rim of the right lens of my patients to allow them to distinguish it from the left lens and to banish the right-or-left problem forever. Whenever you rinse your lenses with water, be certain the water is cool. Never use hot water.

Hard contact lens solutions

Proper contact lens care includes using the proper solutions. These all play different roles in making contact lenses more comfortable and safer to wear. Essential solutions are wetting, cleaning, and soaking solutions, though you may find you occasionally need to use a lubricating solution while the lenses are in place. As is the case with the lenses themselves, the standards for hard-lens solutions are set by the American National Standards Institute. These standards apply to the solutions‘ functions, labeling and packaging, sterility, and the tolerance of the eye to the solutions.

Wetting Solution. Essentially, this turns a hydrophobic lens surface into a hydrophilic one that’s readily kept wet by the tears. It coats the lens surface and helps prevent any bacteria and dirt on your fingertip from being transferred onto the lens during insertion. It also provides a liquid cushion between the lens and the eyelid, and the lens and the cornea, making the lens more comfortable.

Cleaning Solution. This solution removes the dirt, oil, protein, and any other residues that have built up on the lenses during normal wear. If you don’t remove these particles regularly, they will collect in the micropores of the plastic, making your lenses less comfortable and less optically clear. Always rinse off the cleaning solution thoroughly with cool water and use a wetting solution before inserting a lens, because it may irritate the eye. I find that the cleaning solutions that have a gellike consistency tend to do a slightly better job than the more liquid ones; perhaps this is because they require more rubbing, an essential factor in mechanical cleaning.

Soaking Solution. In addition to further removing the oil and protein deposits, a soaking solution is a disinfectant. It protects the eye from bacterial and fungous infections. Soaking solutions also keep your lenses moist; though essentially hydrophobic, PMMA does absorb a slight amount of water. Tap water is not a suitable substitute, since the minerals it contains irritate the mucous membranes in the eye. It may also cause insoluble calcium deposits to form on the lenses, and it isn’t sterile. Make certain that you change the soaking solution each day and clean the storage case with hot water once a day.

Some practitioners prefer to store the lenses in a dry state. No microorganisms except for fungus spores can survive under dry conditions.

Although both these procedures are acceptable, I prefer the soaking method and feel that the lenses are cleaner and more comfortable when kept moist continuously.

All-in-One Solutions. A few companies produce an all-purpose solution to be used for wetting, cleaning, and soaking. Although this may be a convenience, I prefer the use of separate solutions because each contains different ingredients for its specific function. Anything else represents a compromise, because the various ingredients would negate each other’s effectiveness. For instance, substances that are contained in good soaking solutions negate the wetting effect; also the cleaner in a cleansing solution would be an irritant when it came into contact with the eye.

Comfort and Lubricating Solutions. These are instilled into the eye while the contact lenses are in place. They rewet, lubricate, clean, and cushion the lenses, and act as a kind of “artificial tears” that aid the spread of the normal tears. They are particularly useful for “dry eyes” that result from hormonal disturbances (such as the dryness of the mucous membranes that occurs after menopause, allergies, antihistamines, and birth control pills). They may be used as often as needed. Although the lubricating solutions are essentially the same, some patients may prefer one to another. These solutions are specially formulated to be used with contact lenses, and should not be confused with ocular decongestants, which whiten the eye and are not recommended.

• Must have the sharpest visual acuity possible.
• Have a high amount of astigmatism.
• Have moderately “dry eyes.”
• Are concerned about the cost.
• Use topical eye medications.
• Prefer an easy lens care system.
• Desire a durable lens.

NEW DEVELOPMENTS IN COMFORT

One of the reasons for rigid-lens failures is due to the fact that PMMA allows neither oxygen-rich air nor oxygen-rich tears to pass through it. Your cornea needs oxygen to remain healthy; in hard lenses it relies mainly on the tears that flow under the lens and are replenished with each blink. If the tears‘ supply of oxygen isn’t sufficient, the lens is uncomfortable and can’t be worn for very long. (Gas-permeable contact lenses, which are not made of PMMA, are a big threat to the future of conventional hard contact lenses because they retain most of the hard lens’s advantages and few of their disadvantages. Another cause of discomfort in hard lens wear is the constant rubbing of the upper lid as it crosses the inflexible lens edge during each blink. Standard lenses are being made more comfortable in several ways to overcome these discomforts.

SIZE AND THICKNESS

The modern conventional rigid lens is usually between 8 and 10 mm in diameter and doesn’t cover the cornea completely. Earlier hard lenses were much larger and covered not only the cornea, but the sclera (white part of the eye) as well. Over the decades improved fitting and manufacturing techniques have allowed the lenses to gradually shrink in diameter and thickness. Now we even have “ultra-thin mini-lenses” with a center thickness of .035 mm and less than 8 mm in diameter. These contacts are very comfortable for a hard lens but difficult to fit, since they have to be centered perfectly over the pupil. Unlike the larger lenses, which have a large tolerance of movement without adversely affecting vision, these small thin lenses should move only slightly with each blink; otherwise blurred vision will occur. If a cornea is too steep or too flat or has too much astigmatism, the mini-lens should not be prescribed. For people who can wear them, however, small, thin lenses are more comfortable for several reasons. Well-fitted ones are more likely to float on a layer of tears and less likely to touch the cornea, so there’s less sensation. They also touch the lids less, further increasing comfort. In addition, small lenses that are thin enough to flex during the blink help tear circulation, thereby reducing the possibility of overwear syndrome. (The larger the lens, the greater the distance tears have to travel once they’ve entered under the lens edge. By the time they reach the center of the cornea, much of the oxygen has been depleted.) Contacts must, however, remain large enough to cover a fully dilated pupil so that night vision isn’t adversely affected. Thin mini-lenses must also be handled more carefully to avoid loss and warpage.