Introduction: Contact Lens Related Problems

Contact lenses provide an excellent alternative to glasses for correction of refractive errors, and the technology of lenses continues to improve. However, contact lens use is not without risk, and the potential for vision threatening problems is present, especially in those who abuse the use of contacts. On this page can be found discussion about contact lenses in general and contact lens related problems.

Read this important information before proceeding further: These sections are not intended to replace the professional examination and diagnosis by a physician, and they are presented here purely for informational purposes. All possible diagnoses and treatment options are not covered, and the information discussed should not be taken as a recommendation to self-diagnose and self-treat a condition. A misdiagnosed or improperly treated eye condition can result in a permanent loss of vision, or a permanent loss of function of the eye or visual system. In the case of any eye problem, seek medical attention promptly. This can include emergency room treatment, as well as treatment by a medical physician or eyecare provider.

Conditions Discussed on this Page:

• Contact lens related problems

  • Lens comfort problems

  • Wearing time problems

  • Vision problems

  • Contact lens allergy

  • Lens deposits
     

• Contact lens complications

  • Tight lens syndrome

  • Corneal Ulcer (infection)

  • Corneal Warpage

  • Corneal swelling (edema)

  • Giant Papillary Conjunctivitis

  • Eye Redness
     

• Options for the bifocal user

• Reasons for Disposable Lens Use

• Should contact lenses be used extended wear?

For eye anatomy explanations, go to ANATOMY

Lens Comfort Problems

There are many reasons why a contact lens may be uncomfortable to wear, including underlying eye disease and other contact lens complications discussed on this page. In cases where the eyes are healthy and the contact lenses are new, there is always the possibility that a lens is defective. Generally, if a lens of a given brand and curvature has been worn successfully in the past without problem, a new and uncomfortable lens makes one strongly suspicious of an abnormally curved lens, or a lens with a scratch or other defect. Since most manufacturers (and online contact lens providers) offer a warrantee for defective lenses, it may be reasonable to return the lens for replacement or refund. Usually the lens must be returned in the bottle in which it was sent in order to get credit. In cases of new gas permeable or hard lenses, sometimes the lens can be smoothed or polished to improve the comfort.

If a new lens of a different brand than has been worn before is uncomfortable, the problem may be with the fit (tightness) of the lens, the thickness of the lens, and the edge design of the lens. Some soft contact lenses have a very high oxygen permeability (extended wear type lenses), and these may be more comfortable for some people. However, these lenses also demand more ocular lubrication to keep them hydrated and moist, so eyes which are somewhat dry may not be comfortable with this type of lens. If a lens is too tight, the cornea may become starved for oxygen, leading to discomfort (see Tight Lens Syndrome below). On the other hand, a lens that is too loose may irritate the eye due to excessive movement with blinking. Finally, certain characteristics of lenses (thickness and edge design) may be simply uncomfortable for some people. It may take a follow-up examination by the lens prescriber to distinguish between these problems.

An old lens that becomes uncomfortable may be developing deposits on the lens, scratches or nicks in the lens, or problems with the tears lubricating the surface of the lens. People are different with how long a given lens will remain comfortable, and good care of lenses will usually extend the life of a lens. Having to replace lenses frequently due to rapid protein deposit formation or other problems is a good reason to consider disposable lenses.

As mentioned above, the development of an underlying eye disorder not related to the contact lenses can make their use uncomfortable. Some conditions include eye allergy, dry eye, blepharitis, conjunctivitis, eyelid problems, iritis, phlyctenulosis, and pterygium. These conditions are discussed in other Ocular Symptoms and Diagnosis Sections. Pregnancy or hormonal changes are known to cause difficulty in contact lens use in women. Finally, other contact lens complications discussed below can cause discomfort with lens use.

People can develop problems with being unable to wear a lens as long as they would like. Sometimes this problem is simply related to external problems such as a high pollen count or being in an environment with poor air quality or low humidity. In cases where it becomes increasingly difficult to wear an older lens as long as previously, the lens may be developing protein deposits or other defects. Hard or gas-permeable lenses can often be polished, and will be comfortable to wear again, while soft lenses usually have to be replaced.

Some people are unable to wear any type of lens for the entire day, but can only wear the lens for a limited period of time. In cases where the eyes are somewhat dry, the use of rewetting drops (preferably preservative-free) can extend the time that the lenses can be used. Some people need to remove the lenses at some point during the day, such as lunchtime, and can then subsequently wear them longer during the afternoon. If one is having a problem with the wearing time of lenses, it is usually a good idea to have an eye examination to rule out any other potential problem such as infection or allergy. A lens case with solution should be carried if the lenses need to be removed during the day, since wearing a lens longer than it is comfortable can lead to disaster. One should never put a contact lens in tap water, or in solutions not designed for lens storage or disinfection.

Contact lenses are better at correcting certain types of vision problems than others. Simple nearsightedness or farsightedness is usually easily corrected using contact lenses, but astigmatism can be more challenging to correct, especially with soft lenses. Contact lenses have varying success in correcting the need for reading glasses, with bifocal contact lenses being successful in only about 50% of people.

Toric soft lenses have an astigmatism correction built into the lens, but rotation of the lens can lead to a shifting of the astigmatism correction, and temporarily blurred vision. For people with severe or irregular astigmatism, gas-permeable lenses or hard lenses may offer better visual results. Irregular astigmatism is a situation where the cornea is distorted due to a scar or underlying disorder. Sometimes rigid contact lenses are the ONLY way to correct the vision in these cases, as even glasses will not help (as in keratoconus).

Many people who use contact lenses may experience halos around lights at night, and sometimes ghost images. This probably is a normal phenomenon in most people, and occurs when the pupil is larger (or more dilated) than the optical area of a soft lens, or of the lens itself in cases of rigid lenses. However, seeing a rainbow around lights indicates swelling of the cornea (corneal edema), and indicates that the lenses have been in too long and should be removed.

Blurred vision in one eye or the other with a contact lens that was previously clear could indicate a more serious eye problem, and should be checked by the lens prescriber. Of course, it is possible that lenses can become switched between the eyes, but usually this is fairly obvious. An older lens can develop deposits and other surface problems which can make the vision not only blurry, but also can make the lens uncomfortable to wear.

The fact that a contact lens is constantly touching the eye leads to the possibility of an allergy developing to the lens material, deposits on the lens, or to solutions used with the lens. The conjunctiva is a thin membrane which lines the white surface of the eye and the inside of the eyelids. Soft lenses usually extend somewhat onto the conjunctiva outside of the cornea. The inside of the eyelids are also in contact with lenses especially during blinking. The conjunctiva contains cells which can rapidly respond to allergens, leading to redness, itching, tearing or discharge, and a general inability to wear a contact lens.

A common source of allergy is a preservative found in the contact lens solutions. Thimerasol was used frequently as a preservative in the past, but severe allergic problems developed. Now, benzalkonium chloride and EDTA are common preservatives found in contact lens solutions. If one develops an allergy or sensitivity to these preservatives, symptoms of allergy (redness, itching, discharge) frequently develop especially when the lens is first inserted, or when rewetting drops containing these preservatives are used. Solutions marked as being for "sensitive eyes" usually contain no less preservatives than other solutions. If a lens solution allergy is suspected, switching to a preservative free lens disinfection system may help.

Developing an allergy to protein deposits on lenses is common, and this may lead to a condition called "giant papillary conjunctivitis". (see below) Regular enzyme cleaning may help prevent this complication, but often lenses with deposits need to be replaced. Rarely, one can develop an allergy to lens material itself, and trying a different brand, or switching to a rigid type of lens may help.

A more unusual but common allergy problem is the development of an allergy to bacteria present on the edge of the eyelid. These bacteria produce toxins which become trapped in the tears, especially beneath a contact lens. For more information on this condition, see Phlyctenulosis .

Protein deposits can frequently form on both soft and rigid types of lenses. With soft lenses, the regular use of enzyme cleaners as well as proper disinfection and daily cleaning of lenses can help prevent the protein deposition. Rigid lenses may develop deposits especially during seasons with high pollen counts, and polishing the lenses usually will buff off any deposits.

When a lens develops deposits, the eye can become irritated, itchy, and red. Wearing time may be decreased, and the vision may be somewhat blurred. Complications such as "giant papillary conjunctivitis (GPC)" may occur, which can limit the use of contact lenses for an extended period of time. Once deposits form on a soft lens, the lens usually has to be replaced. Rapid development of deposits on lenses is a valid reason to consider disposable lenses. Some contact lenses (Aquaflex and CSI) are resistant to deposit formation.
 

Tight Lens Syndrome

Normally a contact lens should move slightly on the surface of the eye with blinking or eye movement. Soft lenses usually move a few millimeters with a blink, while rigid lenses (gas-permeable or hard lenses) move more. This movement allows tears to circulate across the surface of the eye, helping to provide oxygen to the cornea. Of course, some oxygen can diffuse directly through a contact lens also (more so in soft lenses and disposable extended wear lenses). For different reasons, a contact lens during the course of the day may begin to fit more tightly onto the surface of the eye. This may be because the lens was too tight fitting to begin with, or it may be related to increasing drying of the lens and eye as the day proceeds. If the lens reaches a point where it stops moving on the eye, several things may happen. The oxygen transmission to the cornea will begin to drop, and the cornea may begin to swell (corneal edema). This leads to further tightening of the lens on the eye, with a further worsening of swelling. Symptoms during this period may include redness, eye irritation or burning, and a dry sensation. The vision may begin to blur, and halos or rainbows may be seen around sources of light.

The use of rewetting drops may help prevent this cycle of lens tightening onto the eye, and may help to prevent complications. The fit of the lens may need to be checked as well, and sometimes a new lens is needed. Once the lens has tightened onto the eye enough to cause symptoms, the lens should be carefully removed. Lubricating drops should be placed several times to help loosen the lens before removal. Sometimes removal of a tight lens can lead to a painful corneal abrasion, which would require further treatment by an ophthalmologist. Another risk of the tight contact lens syndrome is of infection (corneal ulcer).

The development of a corneal ulcer (an infection of the cornea) unfortunately is a common complication of contact lens use. Soft contact lenses have a higher risk of corneal ulcer than rigid lenses, but all lenses have some risk. Disposable contact lenses worn extended wear were found to have a much higher risk of corneal ulcer than any other type of lens, for reasons that are not fully understood. A corneal ulcer starts when a bacteria (or rarely a fungus or parasite) infects an area of breakdown in the corneal surface. The surface may break down, forming a small corneal abrasion, due to routine lens use. Overwear of lenses, improper cleaning of lenses, extended wear use of lenses, and overly tight lenses may increase the risk of developing this surface breakdown. Normally, a corneal abrasion, even if tiny, is uncomfortable. However, a contact lens can act as a bandage on the eye masking symptoms, and some contact users develop a lack of sensitivity of the cornea.

Once an infection begins, most people experience severe symptoms. The eye typically becomes red and painful. There may be tearing or discharge and sensitivity to light. The vision may be variably blurred. There are other disorders which can cause these symptoms, but the risk of corneal ulcer in contact lens users is such that the most important thing to do initially is to remove the contact lens. An appointment should be arranged immediately with an ophthalmologist to determine if an infection is present. A corneal ulcer needs to be treated intensively with antibiotic eyedrops, and often a culture of the infected cornea, or of the lens or lens case is performed. Frequent follow-up appointments will help the ophthalmologist determine if the infection is being adequately treated with the antibiotics. Usually a week or two of antibiotic eyedrops is needed, and contact lenses cannot be worn during this time.

A successfully treated corneal ulcer may still leave a scar which could affect the vision. It is important to avoid situations which can lead to corneal ulcer, such as overwear of lenses, poor disinfection techniques, swimming with contact lenses in, and ignoring symptoms of pain or redness.

"Warpage" of the cornea refers to a distortion in the shape of the cornea, usually due to the use of rigid contact lenses, and especially poorly fitting rigid lenses. The type of lens most notorious for this is the "hard" type of lens, which is a non-gas-permeable lens made of a plastic called PMMA. This type of lens is still used today successfully by many people. However, the lens is known to flatten out the cornea, often reducing or eliminating astigmatism. When lens use is discontinued, the cornea will try to spring back to its original shape. Thus, it may be impossible to find a glasses prescription that will consistently give clear vision for times when the contact lens is not in. Often only the contact lens itself can give clear vision. A condition known as "irregular astigmatism" refers to an irregular curvature of the cornea, usually caused by poorly fitting rigid lenses.

It may take several weeks of not using a contact lens for the cornea to return to its normal curvature. At this time, the proper fitting measurements can be made to determine the shape of a contact lens needed which will not distort the shape of the cornea.

Corneal edema, or swelling, occurs when there is an inadequate supply of oxygen reaching the cornea due to contact lens wear. Essentially, the cornea becomes smothered by the lens. Sleeping in contact lenses, as with extended wear lenses, greatly increases the risk of corneal edema. In this situation, even less oxygen reaches the cornea because the eyelid is closed over it. Also, the normal blinking of the eye is not present, which helps tears and oxygen to circulate under the lens.

Symptoms of corneal edema included blurred or foggy vision, seeing rainbows around lights, redness, and possibly irritation or pain. Complications of corneal edema include corneal abrasion, a tight lens syndrome (see above), and corneal ulcer or infection. Generally, a lens should not be worn if symptoms of corneal edema are occurring.

Giant Papillary Conjunctivitis (GPC) is a type of allergic reaction, usually to protein deposits on contact lenses. Since these deposits are more common with soft contact lens use, GPC is more common with soft lenses also. Sometimes GPC can occur as a reaction to the presence of a lens itself, or in reaction to lens solutions used. GPC is visible as large lumps beneath the upper eyelid (usually). These lumps can interfere with lens use, as they may "grab" the lens when the upper eyelid blinks over the lens. Other symptoms include itching, discharge, and redness.

Regular enzyme treatments and proper contact lens cleaning techniques may reduce the chance of GPC. The use of preservative-free solutions can help as well. However, once GPC develops, the use of contact lenses often must be temporarily discontinued while the condition resolves. Anti-inflammatory and anti-allergy eye medications may help to speed resolution and to ease symptoms. Frequent cases of GPC due to protein deposits on lenses may be prevented by using disposable lenses, since these do not have a chance to build up the deposits.

The development of eye redness with contact lens use is always a warning sign. At the least, it may mean that the lenses have been in too long, and should be removed. Many conditions can cause eye redness (see the Eye Redness section), but contact lens use makes certain problems more likely. Often, a red eye with contact lens use is treated like a case of conjunctivitis (pink eye), when actually the redness may be due to a contact lens related allergy or infection. Some common causes of a red eye with contact lens use include:

• Lens allergy, lens solution allergy, or allergy to protein build-up on lenses.

• Lens overwear with corneal edema, with corneal drying or a tight contact lens syndrome.

• Interaction of bacterial toxins (from the eyelids) trapped beneath the contact lens leading to corneal irritation (phlyctenulosis).

• Corneal ulcer.

• Giant papillary conjunctivitis.

• Poorly fitting or defective contact lenses.

Eye redness associated with contact lens use should not be ignored, and the eye should be examined by an ophthalmologist to determine the cause.

Other Contact Lens Considerations:

Options for the Bifocal User

Contact lenses are generally designed to correct the distance vision, leaving the eye itself to focus additionally for near vision. However, as people age, the focusing ability of the eye gradually declines. Usually in the early forties, this becomes noticeable, and reading material has to be held further away to be able to focus on it. Eyestrain symptoms and headache can occur. In people who do not use contact lenses, a bifocal prescribed in glasses can eliminate any problems with reading. However, what options are available for contact lens users?

• Reading Glasses -

  This is the simplest option for reading with contact lenses in: using reading glasses over top of the lenses. However, most contact lens users prefer to avoid glasses use, and it may be difficult to keep up with a pair of reading glasses when the distance vision is clear with contact lenses.

• Monovision -

  This refers to using one eye for distance vision, and one eye for near vision. Usually the non-dominant eye is set for reading (usually the left eye). Advantages of this system include the ability to read and see at distance without glasses using relatively inexpensive contact lenses. Disadvantages include a loss of depth perception and the possibility of eyestrain symptoms. Some people are simply not comfortable with this arrangement.

• Bifocal Contact Lenses -

  A bifocal contact lens can be used in one or both eyes to maximize both near and distance vision. Unfortunately, sometimes clear reading vision comes with some sacrifice of clear distance vision. Probably on 50% of people successfully use bifocal contact lenses, and they are among the most expensive of contact lenses.

Disposable contact lenses can be a useful option for some contact lens users, and there seems to be a trend toward increased use of this type of lens. Even disposable lenses that are discarded on a daily basis are available, although most people use the type of lens that is discarded after 2 weeks. Some reasons and situations for which disposable lenses may be useful include:

• Rapid deposit formation on lenses, with or without the development of giant papillary conjunctivitis.

• Having to replace contact lenses frequently, whether it be because of lens deterioration, damage, or the losing of lenses.

• Sensitivity to solutions used to clean or disinfect lenses.

• Difficulty in finding another type of lens that is equally comfortable for an individual.

Some problems associated with disposable lenses include:

• A higher risk of infection (corneal ulcer), whether or not the lenses are used extended wear.

• A higher cost than most lenses. At wholesale cost, the 8 six-pack boxes needed to replace a lens every two weeks costs about $150 a year. One may be able to buy 4 sets of daily wear lenses at this cost.

• A tendency to abuse the use of the lenses, such as wearing a lens for more than two weeks, an absence of lens disinfection, and wearing the lenses in situations not usually recommended, such as swimming. (These factors may lead to the increased risk of infection).

• Poorer vision with disposable lenses. These lenses are very thin, and correct very little astigmatism. If an eye has borderline astigmatism, a more substantial lens may correct the vision better.

• Problems using the lens with dry eye. Disposable lenses require more eye fluid to keep them hydrated.

There are definite situations where disposable lenses are appropriate, and some situations where they should be avoided. Exercising caution with the use of any contact lens helps to prevent complications.

Many people are able to wear lenses continuously for many days with no apparent problem or complication. However, sleeping in contact lenses, while convenient, substantially increases the risk for infection and other complications. The oxygen supply to the cornea drops overnight while wearing a contact lens. This can lead to swelling of the cornea (giving blurred vision or the visualization of rainbows around lights), breakdown of the corneal surface, and ultimately infection of the cornea (ulcer). This risk is high enough that many eyecare providers discourage against the use of contact lenses on an extended wear basis. If the lenses are used this way, extreme caution should be taken, and the lenses should be removed with any sign of trouble (eye redness, pain, blurred vision, sensitivity to light, etc.) In fact, it may be reasonable to consider refractive surgery as an alternative to extended wear contact lens use.

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