• Contact Lens Problems and How To Avoid Them

    optometrist-eye-exam-250

    By John Dick ABO, FNAO

    Contact Lenses Are a Big Responsibility

    Contacts lenses are simply foreign bodies we are introducing to the eye to assist with correcting our vision. Since these medical devices are foreign to the surface of the cornea, improper care, maintenance and handling of contacts can result in very serious sometimes vision threatening complications. The body often reacts to objects it perceives as threats by engaging the immune system. The eye is no different than any other major organ or system. Planned replacement lenses which are often worn for a regimen of several weeks or months are especially prone to such problems.

    If not cleaned properly, the lens may collect debris, allergens, bacteria or proteins which will act as a blockade of the porous lens surface. To maintain a healthy cornea, it must receive moisture and nutrient rich oxygen. When wearing contacts, this oxygen is conducted through the material of the contact itself from the atmosphere to the surface. When deprived of oxygen the eye will attempt to address this problem by growing new blood vessels to the deprived area. This process is known as corneal neovascularization. This is the only mechanism the eye possesses to correct a perceived problem. In advanced stages, this problem can become extremely pronounced and begin to infringe on the pathway light travels to reach the retina; the visual axis. This can cause a loss of visual acuity or even scatter light as it enters the eye causing a distortion of one’s vision. Although presenting differently, proteins, bacteria and allergens may also present complications resulting in poor vision.

    Despite their appearance and association with emotions, tears serve a more vital purpose in the maintenance of healthy corneas than realized. The cornea is covered with a thin layer of lipids, aqueous and mucus known as the tear film. Having a healthy cornea tear film is one of the prerequisites for contact lens wear. It’s this protective and nourishing layer that allows contacts to remain moist and therefore optically clear and comfortable throughout the course of wear. There are two types of proteins found in tears: native and denatured. The denatured proteins will make your contacts appear hazy and possibly give them a milky appearance. Enzymatic cleaners typically work best to remove deposits effectively, but routine maintenance will prevent these problems all together. Overtime, denatured proteins will adhere to the surface of the contact if not properly removed. These deposits will build up as more denatured proteins are produced from lachrymation (tear production). If left to interact with the surface of the cornea, these deposits will cause the surface to eventually become misshapen. It’s this reshaping of the cornea that becomes problematic with respect to clear vision. As light strikes the refractive medium of the cornea, this irregular shape induces what is known as irregular astigmatism; causing light to scatter in different meridians not allowing it to focus properly on the retina. This will cause hazy vision and is very difficult for the eyecare professional to correct.

    Proper Care and Handling

    The proper care and handling of contacts is the first line of defense in preventing many complications associated with contact wear; the first and most important being that of proper contact lens hygiene. It’s important to remember all of the things our hands come into contact with during the day and all of the things we touch that others have touched. Do we really want any of these things going into our eyes? This is exactly what we are doing if we fail to wash our hands before insert our contacts. So, the most important step before doing anything with your contacts is to remember to wash your hands with antibacterial soap. Most liquid hand soaps today are antibacterial, but the importance of this cannot be underscored enough. Many eye infections would have easily been avoided if this simple task was done prior to handling contacts. Secondly, make sure you dry your hands with a lint-free cloth, because once again, anything you handle will easily be transmitted to the contact that will be going into your eye. Third, make sure to keep your contact lenses in their case with the lid closed when not using them. This is important because most patients keep their contacts in their bathroom and insert them as part of their morning ritual. If left exposed, your contacts will be susceptible to all sorts of environmental contaminants such as hairspray, deodorant, air fresheners or other air borne pollutants. All of these chemicals can easily settle on the surface of contact lens solutions and eventually make their way to the contact being absorbed into the lens.

    Before inserting your contacts, you will always need to “check for bowl.” What is meant by this? All contacts have a natural tendency to retain the shape that has the most amount of curvature used to correct refractive errors. Occasionally, the contact will flip inside out. The edges of the contact will take on a flared appeared rather than a curved one. Effectively, the contact is ready for insertion when the edges have a curved or “bowl” appearance. You can determine this by balancing the contact on your finger, holding it up to the light and checking the curvature to make sure the edges are taking on a bowl appearance. If not inserted properly, your contacts will not allow you to see as well as and may be uncomfortable.

    Over-wearing your contacts can become problematic giving rise to complications which may put your vision in peril. This is why you should always remove your contacts unless advised it is okay to do  otherwise by your eyecare professional. Few contacts are approved by the FDA for continuous wear. After removing your contacts, you should instill artificial tears in each eye. This will allow the ocular tissues to hydrate if they become dry during the course of contact wear and will not only supply the patient with a soothing effect after a long day of wear, but may potentially remove any harmful debris on the corneal surface.

    Wearing Schedules

    Observing a proper wearing regimen is integral to preserving ocular health with respect to contact lens wear. Eyecare professionals know that patient’s today are busier than ever, especially their younger patients. The professional must balance what is in the best interest of the patient and preserving their eye health while taking into account the factor of convenience. This is one of the many factors considered when the eyecare professional decides what material and wearing regimen a patient should have before the doctor issues a prescription. If these guidelines are not taken seriously by the patient, they are putting their vision in peril.

    Most contacts are categorized by their replacement schedules. Certain brands of contacts may be used as daily disposable lenses while others are designed to be worn for an extended period of time (up to one year). Whatever the choice, your eyecare professional is familiar with your ocular needs and what will work best for your eyes. It’s also important to “build-up” wearing time when first beginning to wear contacts. This is to allow your eyes to become acclimated to the lenses without causing major discomfort. A good rule of thumb is to start the first day of wear by wearing your lenses no more than four hours. The next day extend this time by two hours and with each successive day extend this time by two hours. This should be done each day until your build up your wearing time to the hours you are active throughout the day. Most patients will wear their contacts anywhere from 14 to 18 hours depending on their particular schedule. It’s also important to note if you have to stop wearing your contacts for any reason you should cut your wearing time back when resuming wear. Once again, this allows the eyes to become acclimated to wearing contacts again.

    Your eyecare professional will also take into account any extenuating circumstances with respect to your wearing schedule. The doctor may ask him/herself several questions before considering a contact brand on this basis: Is the patient prone to dry eye complications, recurrent infections or an excessive amount of protein buildup? If the patient is currently wearing contacts, should the brand be switched for one that will provide the proper balance of protection and convenience? Is the patient mature enough to adhere to hygiene and wearing regimens? Will the patient take their contacts out at night (if they are not designed for continuous wear)? Does this patient have a greater need for oxygen to reach the corneal surface? In addition to how well the contact fits, all of the answers to these questions are major factors before a final determination is made regarding your prescription.

    Complications may vary greatly, but should always be taken seriously. On occasion, these complications may begin to threaten your vision and may even irrevocably harm your eyes to a point where correction is extremely difficult to affect the condition. The sad truth is that nearly all complications are preventable if some small measure of care is taken with respect to proper wearing and cleaning of contacts. Of all our five senses, vision has to be the one we rely on most and the one we would most hate to compromise.

    Common Complications from Contact Lens Wear

    Infections

    The most common infection associated with contact lens wear is called kertatitis which is simply an inflamed infection of the cornea. Keratitis may be caused by the herpes virus, bacteria, fungi or microbes (such as the acanthamoeba). Acanthamoeba is by far the most difficult infection to treat due to the prolific reproduction of the microbe and tenacity. All of the infections listed may result in sensitivity to light, blurred vision, foreign body sensation and excessive tearing and discharge. Understanding how each of these is transmitted will underscore the importance of observing good hygiene and proper care and handling of your contacts.

    The herpes virus exists in two forms: the herpes simplex virus which occurs in the form of cold sores and the sexually transmitted (known as Type I) and the sexually transmitted type affecting the genitals (known as Type II). The virus can be easily transmitted to the eye if you touch an open sore and then your eye. Treatment may be arduous and flare ups may occur several times after the initial infection. If left untreated, corneal scars may develop preventing light from efficiently reaching the retina and causing a loss of visual acuity. This problem can easily be prevented if the underlying cause is treated and if the patient observes excellent hygiene by thoroughly washing your hands with antibacterial soap before touching your face, eyes or handling your contacts or completely foregoing contact lens wear while being treated for the underlying virus.

    Bacteria keratitis can develop as a result from exposure to staph or other forms of bacteria. These infections can develop very quickly and result in blindness if not treated aggressively and soon after the initial infection. Fungal infections may result as direct contact with organic material getting into the eye, i.e., mowing your yard and weed eating.  If some of this grass were to get into the eye it may possess a form of fungi that proliferates once it comes into contact with the cornea. Microbes such as acanthamoeba, are commonly found in soil, fresh water and nature and can even be found in tap water, well water, hot tubs and sewage systems.

    This is why using and following the directions from the manufacturer and eyecare professional regarding cleaning, use of solutions and hygienic protocols are extremely important. Any of these infections, if not responsive to treatment, may force a patient to require a corneal transplant (which is an extremely difficult procedure) or in worst case scenarios require total enucleation of the eye (removal of the eye itself). The stakes couldn’t be higher. A few simple steps such as washing of your hands, using fresh contact lens solutions, not sleeping in your contacts, vigorously cleaning your lenses, keeping the cornea moist with artificial tears/soft lens rewetting drops, and limiting exposure to environmental hazards will all work together to prevent these infections from occurring in the first place. Wearing safety glasses while doing outdoor activities such as mowing will also work to prevent not only a traumatic injury, but also the risk of infection.

    Corneal Neovascularization

    There are two main factors that contribute positively to the overall health of the cornea: maintaining a fluid environment and supplying an adequate supply of oxygen to the corneal tissue. The cornea is a clear, transparent tissue covering the pupil.  It is a refractive medium responsible for one-third of the refractive ability of the eye. The cornea is much like the aperture of a camera. It must remain clear in order for light to effectively make its way along the visual axis (the pathway light uses to allow the process of vision to occur).

    Oxygen is required to maintain the integrity of tissue and physiological processes throughout the human body. Human cells require oxygen to allow the process of cellular metabolism to occur, to provide energy and to repair itself. The eye is no different from any other tissue in this respect. However, the way oxygen is transmitted to the eye does differ. The cornea is the only tissue in the human body completely devoid of blood vessels which carry nutrient rich oxygen to the corneal surface. This is known as anoxia (a lack of blood vessels to carry oxygen). The cornea is supplied by oxygen through the corneal tear film (a protective layer of tears covering the cornea) on the front and from the aqueous humor (which is nutrient and oxygen rich fluid) circulating through the anterior chamber on the backside of the cornea and directly in from of the iris.

    If a patient fails to remove their contacts at night (if not approved for continuous wear) or does not practice good contact lens hygiene, lenses may deprive the surface of the cornea of oxygen. To combat this problem, the eye will initiate an autoimmune response in the form of growing new blood vessels. This ingrowth of new vessels is known as corneal neovascularization. These new blood vessels will crop up along the peripheral edges of the contact lens as they grow to reach the affected area. Blood vessels carry oxygen. The growth of new vessels is the attempt by the body to correct what it perceives as oxygen deprivation.

    The cornea needs to remain a clear, transparent tissue to serve its function of directing light to the retina. A problem with corneal neovascularization occurs when the vessels begin to encroach on the visual axis. This pathway must remain unhindered to allow light to travel on its way to the retina where it will be received and transmitted to the brain via the optic nerve. This is where the process of perception occurs. If the vessels reach this region of the cornea, light will have to filter through them much as sunlight filters through the branches of a tree. This becomes problematic because the light rays necessary for vision will be scattered and not precisely focused at one focal point on the retina. This gives rise to a condition known as irregular astigmatism and it can be nearly impossible for your eyecare practitioner to correct. As with any contact lens complication, corneal neovascularization can be easily prevented through observing the wearing regimen decided upon by your doctor and proper cleaning of your lenses.

    Giant Papillary Conjunctivitis

    Giant Papillary Conjunctivitis or “GPC”, for short, is a condition mainly affecting the upper eyelids. The conjunctiva is a protective tissue covering that lines the eyelids and covers the sclera (the white part of the eye). It functions by providing moisture to the eye as well as acting as a barrier against microbes, bacteria, allergens and other debris which would otherwise cause infection. Any inflammation of the conjunctiva is known as conjunctivitis. When we think of conjunctivitis, most patients usually think about the “angry” red and inflamed eye you can see, hence the name “pink eye.” However, this inflammation can also affect the areas you cannot see. As stated earlier, the conjunctiva covers more than just the sclera.

    When considering the extent of the conjunctiva it’s important to remember it also refers to the lining of the eyelids. When the doctor examines a patient with an inflamed conjunctiva, he/she will typically do what is called a lid eversion. This is a simple procedure in which the doctor flips the eyelid back to examine the papillae on the underside. Papilla, or the plural form papillae, is an anatomical reference to any nipple-like protrusion or structure. For example, we have several papillae on our tongues which serve the function of taste buds. Giant papillary conjunctivitis is an extreme inflammation of these papillae resulting in the inability to wear your contacts and discomfort for the patient.

    There are two theories about how giant papillary conjunctivitis develops. Both theories involve chronic irritation of the papillae. “Mechanical microtrauma” is one such theory in which it is believed the papillae are irritated from either an ill-fitting contact lens interacting with the eyelid as the process of blinking occurs or the interaction of a defect on the contact surface and the eyelid. The generally accepted theory among most practitioners is the involvement of denatured proteins. If contacts are not cleaned properly, worn for longer than recommended, or not replaced when recommended, denatured proteins will begin to build on the contact surface. As this build-up reaches a critical point, it will begin to interfere with contact lens wear. Just as with mechanical microtrauma, this protein build-up will chronically agitate the underside of the eyelid as the blinking process occurs. The resulting affect is inflammation. The earliest symptoms of giant papillary conjunctivitis will be itching, a gritty feeling, foreign body sensation after contact lens removal, an increase in mucous production and not wanting to wear your contacts for the full extent of your wearing time.

    Once again, observation of hygienic contact lens protocols will go a long way in preventing this complication. Although giant papillary conjunctivitis is not as serious as many other complications listed here, it can be extremely frustrating to the patient as you work with your eyecare professional to resolve it. This condition can last several months or in extreme cases years. It will necessitate the need for shortened wearing times, possibly a regimen of daily eye drops to reduce inflammation, and shorter replacement intervals of planned replacement lenses. As with many complications, prevention is key element. Using fresh solutions, cleaning your contacts vigorously, removing them at the end of the day and paying attention to the early onset of symptoms will prevent small problems from becoming huge issues.

    Protein Deposits

    The eye is covered by a thin layer of tears known as the corneal or precorneal tear film. This film serves several different functions. It provides lubrication to the eye, provides it with nutrients and constituents necessary for cellular repair, and acts as an outside barrier to potentially harmful debris, bacteria and microbes. The tear film also possesses proteins and electrolytes secreted by the lacrimal gland. Although there are only four proteins existing in large concentrations, it is estimated there are nearly 500 different types of proteins found in a human tear! These proteins are classified into two different categories: native and denatured.

    It’s important to make a distinction between these two categories. Native proteins are ones that provide nutrients and help the eye to maintain biological processes. Denatured proteins are ones that have been altered by temperature, pH, radiation (exposure to UV), and other chemicals. The closest analogy that can be made to denatured proteins is that of a fried egg. When cracking the egg the “white” is transparent. It is still serving a biological function. Once the white is exposed to heat, however, it becomes opaque. It will no longer carry on its biological function. This is exactly what happens to denatured proteins. They are basically protein chains in which the bonds that hold them together have been reorganized and no longer serve the biological function for which they were intended.

    It is these denatured proteins responsible for the hazy appearance of contacts when they have not been cleaned properly and take on a milky appearance. Strings of denatured proteins will be attracted from the corneal tear film to the buildup of proteins on the lens surface. If not cleaned properly, these deposits will continue to build over time eventually causing the patient’s vision to become distorted, or allowing an infection to occur. If left untreated, these deposits will even warp the shape of the cornea inducing what is known as irregular astigmatism. Basically, an irregular scattering of light, this condition will not allow the light required for the process of vision to travel the visual axis of the eye uninterrupted. The result is a decrease in visual acuity which may be extremely difficult for the eyecare professional to correct.

    Eyecare professionals will often place teenagers or those at high risk in a daily disposable lens to prevent this and other complications from arising. If the patient is a high risk of not exercising cleaning regimens, this makes perfect sense. However, if the patient’s prescription and fitting requirements do not allow for daily disposable lenses to be prescribed, cleaning your lenses vigorously after use, soaking them in clean solutions and not over extending wearing times will all work together to prevent protein deposits and other complications from occurring.


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