Answers can be displayed by clicking once on the questions link.1: What is the healthiest type of contact lens?
Contact lenses are a very healthy and popular option for correcting vision with little risk of complications when the optometrist’s recommendations regarding lens-wearing schedule and care of the lenses are followed.1 When considering all lens types, an average of four per 10,000 contact lens wearers experience a severe eye infection, microbial keratitis or corneal ulcer, which may permanently affect vision.1 The lens types and wearing schedules that are least likely to result in microbial keratitis are rigid gas permeable (GP) lenses (1.2 per 10,000), soft lenses worn daily (1.9 per 10,000), and daily disposable soft lenses worn daily (2.0 per 10,000). The risk of microbial keratitis in any lens type increases over 5 times with overnight wear.2
GP lenses are typically smaller than soft lenses, and some initial awareness of the lens is experienced. However, total comfort is often achieved in one to two weeks of lens wear. GP lenses have advantages in both the quality of vision and eye health.(1,2,3)Conventional, older material, hard lenses (called polymethylmethacrylate or PMMA lenses) are no longer recommended as they do not provide any oxygen through the lens; therefore, swelling and even distortion of the front surface of the eye (the cornea) can result.4
Daily disposable soft contact lenses have been increasing in use in recent years (up to 23 percent of all soft lenses fit in the United States)5 because of their convenience and ability of the patient to put a new, fresh contact lens on their eye every day. Because daily disposable soft contact lenses are not worn overnight and are thrown away at the end of the day, there is little risk of complications due to overnight wear. There is little to no buildup of deposits, and solution-related problems, as well as case contamination problems, are essentially eliminated.1 This is important as lens6 and case contamination or infrequent replacement(7,8) are important factors in causing eye infection and inflammation. Because overnight wear of contact lenses increases the risk of eye infection by about five times(1,2,9,10,11) discarding the lenses every night greatly reduces the risk of this problem.
In recent years, conventional soft (or hydrogel) lenses are gradually being replaced by soft lenses containing silicone (also called silicone hydrogel lenses). This addition of silicone material to lenses can increase the amount of oxygen going through the lens to the eye by three to five times. As a result, the majority of soft lenses being fit today are made of these silicone hydrogel lens materials.12 Although silicone hydrogel lens materials have not reduced the risk of an eye infection, especially if worn overnight,1 the increased oxygen received by the eye results in less swelling (hypoxia) of the eye resulting in a healthy option for contact lens wear.13
While it is apparent that today's generation of rigid gas permeable (GP) lens materials, silicone-hydrogel soft lens materials, and daily disposable soft lenses are quite healthy, following your optometrist’s lens care and wearing schedule recommendations are key factors in long-term safe and comfortable contact lens wear. Your doctor will help determine what type of lens will be healthiest for your long-term contact lens needs.
No. Unfortunately, up to half of disposable and frequent replacement lens wearers wear their lenses longer than their recommended schedule.1 The analogy can be made about not going to the dentist until you have a toothache or having a family history of glaucoma (a potentially blinding eye condition) and not seeing the eye doctor until some loss of vision is noticed. It is important to follow your doctor’s recommended replacement schedule for your contact lenses. By the time the contact lenses feel uncomfortable, one of several problems could be present that could range from eyelid inflammation to a serious eye infection that, in rare cases, could potentially result in permanent loss of vision.2 The risk of an eye infection is about five times more common if the lens is worn overnight.(3,4,5)
It is important to resist the temptation to continue wearing the lenses past their prescribed period (often two or four weeks) even if they feel comfortable and the vision is good as this can result in complications that may result in temporary or permanent discontinuation of contact lens wear. Likewise, when you have only a one- or two-month supply remaining, that is an excellent time to order your next set of lenses. If the prescription is expiring, that is a great time to also schedule an eye examination. The most common noncompliance with lens replacement occurs in patients wearing two-week replacement soft contact lenses.1 An easy solution is to replace the lenses on the 1st and 15th of every month or to use an electronic reminder service or phone application to assist. Ask your optometrist for more information on these services, which are often available through contact lens manufacturers.
Why replace the lenses as prescribed by your optometrist? In short, it reduces your risk of potentially blinding complications and helps you remain a contact lens wearer for life. Because contact lenses are medical devices, the United States Food and Drug Administration (US FDA) has strongly advised that you follow the recommended lens-wearing and replacement schedules prescribed by your optometrist for safe and comfortable long-term wear.6
Regardless of the number of days a soft contact lens is worn, it should be replaced as recommended by an eye doctor. For example, if a patient is prescribed a contact lens that is to be replaced monthly, and he wears the lens every day, he should discard the lens one month after removing it from its original package. Similarly, if this patient wears this same monthly replacement lens once a week, he should still discard the lens one month after removing the lens from its original package (which may mean the lens is only worn four times in this scenario).
If you only occasionally wear contact lenses, you should consider talking with your doctor about contact lenses that are discarded daily, which eliminates the need for contact lens solutions and is a convenient and healthy option for part-time lens wearers.
For a lens that is worn more than once before it is discarded (such as a monthly replacement or two-week replacement lens), the lens should be cleaned and disinfected using the recommended cleaning solution and care regimen upon removal. Rubbing and rinsing the contact lens prior to soaking the lens overnight will remove more deposits1 and decrease the microbial load2 which can help prevent infection or other complications. It is also important to be aware of the expiration date of the lens and dispose of it prior to or by that date.
For rigid gas permeable (GP) lenses, the procedure is different. These lenses are typically not replaced as frequently as soft contact lenses. Therefore, if the lens will not be worn for more than a few weeks, it should be stored clean and dry in a case. When it is desirable to wear the lens again, it should first be cleaned and disinfected according the GP solution manufacturer’s recommended guidelines. The exception would be if a spare lens or pair of lenses has been provided unopened—and therefore sterile—in solution from the manufacturer. Following the doctor’s recommendation for lens replacement of a GP is important as the replacement schedule can vary from several months to years. This is due to multiple factors including how well the lens is fitting on the eye, the condition of the lens, and the patient’s wearing history. Regardless of whether you think your GP lens needs replacement, it is still important to see your optometrist each year to check the status of your lens and the health of your eye.
It has been reported that between 12 to 52% of soft-contact lens patients replace their contact lenses less frequently than recommended by their doctor.1 This can be dangerous, as studies show there is a trend toward a higher rate of contact lens-related complications in those patients who are noncompliant with the recommended replacement frequency.(2,3) Patients who do not replace their lenses as recommended have also shown increased rates of signs and symptoms consistent with potential contact lens complications in those patients that self-reported a replacement frequency longer than that recommended by their doctors. Patients who follow the recommended replacement schedule report better vision and are at a reduced risk of contact lens-related complications.(2,4)
Washing hands before handling contact lenses is important for safe contact lens wear. The most serious risk associated with contact lens wear is a corneal infection due to dangerous organisms. Therefore, to prevent the transfer of germs from hands to lenses during the insertion and removal process, proper hand washing with an antimicrobial soap is advocated.
Antimicrobial soaps have been shown to be more effective than nonantimicrobial soaps in reducing levels of bacteria.1 Additionally, bacterial reductions with antimicrobial soaps are significantly improved by longer wash times and greater soap volumes. For example, washing hands for a total of 30 seconds using two pumps of foaming soap is more effective than a 15-second wash and one pump.1
Hands should then be thoroughly rinsed with water and dried with a lint-free towel prior to handling your contact lenses. Completely dry hands are important in order to avoid tap water contact with your lenses. Exposure of contact lenses and contact lens cases to water has been associated with Acanthamoeba keratitis, a severe corneal infection.(2, 3, 4) No other oils, lotions, hand creams or gels are recommended to be used on hands prior to handling lenses as these may coat or contaminate the lens surface. Additionally, smoking has been shown to increase the risk of corneal infections.5
It is also important to use the prescribed contact lens solutions properly. The tip of the solution bottle should not touch anything as this may cause contamination. Contact lenses should be rubbed and rinsed after removal prior to being soaked in solution overnight. Patients should never reuse contact lens solutions or use water on their lenses or in their cases as this can increase the risk of an eye infection. Contact lens cases should be replaced frequently (at least every 3 months).
Contact lenses should be replaced as prescribed by an eye doctor and only contact lenses prescribed by an eye doctor should be worn. Sleeping in contact lenses increases the risk of an eye infection, and, if patients experience symptoms (such as eye pain, redness, tearing, irritation, light sensitivity, or foreign body sensation) while wearing contact lenses, they should remove their lenses and call their eye doctor immediately for assistance.
The most serious complication of contact lens wear is a corneal infection, frequently called a microbial keratitis or an infectious corneal ulcer. The cornea is the clear tissue that covers the iris (colored portion of the eye). A properly fit soft contact lens rests primarily on this clear cornea and also on conjunctiva (white portion of the eye).
A severe corneal infection can occur if the eye gets irritated or scratched allowing bacteria or other microorganisms to gain access to and infect the cornea.5 However, some researchers believe that some organisms can cause a severe infection without a scratch or irritation on the cornea if they are exposed to the cornea for a prolonged period of time.5 Because contact lens wear increases the risk of an infection, it is important to follow a doctor’s recommendation regarding contact lens wear and lens replacement.
A corneal infection can become a serious and blinding eye condition if left untreated. Bacterial infections are more common than fungal or amoebae infections.(3, 4) Some bacterial infections progress extremely quickly and can cause blindness—sometimes within as little as 24 hours if not diagnosed and treated promptly. Symptoms of infection often include severe pain, redness, discharge, light sensitivity, and blurred vision. These symptoms are most common in one eye only.5 The best way to determine whether your symptoms are due to an infection or a less severe problem is to remove your lenses and consult your optometrist as soon as possible after the onset of symptoms. There are approximately one million visits to a doctor’s office or emergency room as a result of corneal inflammation or infection annually.6
In some circumstances, once the infection has been treated, a dense corneal scar can remain, which limits vision. Some patients need to wear different contact lenses after these episodes or may not be able to wear contact lenses at all. Patients with severe vision loss after an infection could also require a corneal transplant to restore their vision.
Fortunately, the risk of having a contact lens-related corneal infection (microbial keratitis) is low. The risk of infection varies by the type of contact lens worn (1.2 to 25.4 per 10,000 lens wearers). The lowest rate of microbial keratitis among lens wearers, 1.2 out of 10,000, occurs with rigid gas permeable (GP) contact lenses worn daily (not overnight).1 Some cases of corneal infections are extremely severe and can permanently affect vision. GP and daily disposable lenses are the least likely to be associated with these severe infections. The lenses most commonly associated with these severe infections are soft contact lenses worn overnight.1 These lenses worn overnight are also associated with the highest risk of any form of microbial keratitis with a rate of approximately 20 out of 10,000 lens wearers. The rate of infection for soft contact lenses is five times greater with overnight wear than for those who do not wear their lenses overnight.(1,2,3,4)
In summary, patients who wear rigid gas permeable contact lenses have the lowest rate of corneal infections compared to those who wear soft contact lenses overnight, which have the highest rate of corneal infections.
One study evaluated factors commonly found in individuals who wore contact lenses and had corneal infections. The following types of patients have been shown to have a greater risk for infection: those who wear their contact lenses overnight (occasionally or frequently), those with poor hygiene (such as neglecting to wash/dry hands before handling lenses), those who do not replace their lens cases frequently (every 1 to 3 months) and those who are smokers.5
Yes. It has long been documented that overnight use (extended wear) of contact lenses increases the risk of corneal infection, which can permanently affect vision.(1,2,3,4) A study published in 2008 reported the rate of corneal infections for those who regularly wore their lenses overnight was 19.5 to 25.5 in 10,000 wearers compared to a rate of 1.9 to 11.9 in 10,000 wears for those who did not wear their lenses overnight.2 Another study concluded the risk of a corneal infection was 5.4 times higher in those who wore their lenses overnight compared to those who didn’t wear lenses overnight.1
Additional publications have continually reported an increased risk of corneal infection (also called microbial keratitis) during extended wear compared to daily wear even though newer lens types and replacement modalities have been introduced.(3,4) More recent evaluation of modern lens types has shown a risk of infection about five times higher for overnight wear of contact lenses when compared to daily wear.1
There are some contact lenses approved for overnight wear (nights of wear and replacement schedules can vary with different lenses). However, the risks of a corneal infection are still higher when wearing these lenses overnight compared to removing the lenses nightly. It is important to follow your doctor’s recommendation for overnight wear, so let your doctor know if you are sleeping in your lenses so that you can discuss the risks and potential complications, choose the best lens options, and arrange for the appropriate follow-up care.
Despite an increase in oxygen delivery to the eye, newer silicone hydrogel lens materials have not significantly decreased the rates of corneal infection (microbial keratitis), compared to traditional hydrogel lenses.(1,2,3) While studies have shown that the rate of microbial keratitis with silicone hydrogel lenses worn overnight is no different than that of extended-wear hydrogel lenses, silicone hydrogel lenses can be worn for a much longer period of time for the same level of risk (30 days of continuous use with certain silicone hydrogel lenses versus seven days of overnight use for certain hydrogel lenses).2
If you are interested in overnight wear or daily replacement of your contact lenses, discuss your lens type and options, including associated risks, with your optometrist.
There are many potential complications associated with contact lens wear, which can include both inflammatory and infectious events. There is some evidence that daily disposable lenses decrease the overall rate of a corneal inflammatory response (termed corneal infiltrates), compared to reusable lenses.4 However, daily disposable lenses have not been shown to decrease the rate of infection (microbial keratitis) compared to reusable lenses. Although the rate of microbial keratitis is not reduced, daily disposable lenses reduce the risk of severe microbial keratitis (which results in vision loss) compared to reusable lenses.1
In contact lens-related corneal infections, the organism most commonly found is pseudomonas aeruginosa, a type of bacteria. In fact, this bacteria is overwhelmingly associated with contact lens-related corneal infections when compared with all other organisms. Studies report that up to 73% of corneal infections are associated with Pseudomonas aeruginosa.(1,2,3,4,5) Not every ocular medication or other prescribed treatment is effective against every organism. Thus, it is important to understand the organism associated with the infection so that the most appropriate medication(s) and/or other treatments can be prescribed.
If you have a suspected corneal infection, it is important to bring your lenses, solutions and lens case to your doctor’s appointment. These items may undergo a bacterial culture (a laboratory test used to grow and identify the bacteria causing your infection) to assist in your treatment.
According to the 2014 Morbidity and Mortality Weekly Report (MMWR) published by the Centers for Disease Control and Prevention (CDC), there are nearly one million office visits annually for keratitis and contact lens disorders.1 While contact lenses are generally safe when worn and cared for properly, they are also the No. 1 risk factor for microbial keratitis.2 Multiple pathogens may be harmful to the eye; however, there are two particularly dangerous microorganisms for contact lens wearers to be aware of.
The first is the gram-negative bacterium, Pseudomonas aeruginosa, typically found in soil and water. Pseudomonas is one of the microorganisms most commonly isolated from corneal ulcers and contaminated lens cases.(3,4) If left untreated, this highly opportunistic bacteria can rapidly invade the cornea and cause perforation.5
Another highly virulent microorganism is the free-living, waterborne amoeba known as Acanthamoeba. Although the incidence of Acanthamoeba keratitis is rare, up to 85% of cases involve contact lens wearers.6 Acanthamoeba keratitis can be particularly troublesome, because co-infection with other microorganisms is common, and there is often resistance to treatment. On average, mean duration of treatment is 4 to 5 months, and may still result in the need for corneal transplantation.6
Despite both of these microorganisms being ubiquitous in nature, they are almost entirely preventable with proper compliance with lens hygiene and care. This includes avoiding contact with all forms of water including tap water, proper cleaning and replacement of lenses and cases, and not topping off lens solutions.
According to the Center for Disease Control (CDC),1 United States Food and Drug Administration (FDA),2 American Optometric Association (AOA),3 and the American Academy of Ophthalmology (AAO),4 if you experience any eye irritation or potential symptoms of an infection while wearing contact lenses, it is important to remove your lenses immediately and contact your optometrist right away. These symptoms may include:
- Excess tearing or discharge
- Unusual sensitivity to light
- Itching, burning or gritty sensations
- Blurred vision
- Swelling or pain
If left untreated, an infectious ulcer can cause rapid destruction of the cornea, sometimes within 24 hours. This can lead to permanent vision loss from scarring, which may result in the need for corneal transplantation.
There are multiple causes for irritation in contact lens wearers, ranging from low-grade inflammation to severe eye infections. Potential problems may include:1
- Allergies (environmental, solution toxicity, lens deposits)
- Dry eye
- Mechanical problems (corneal abrasion, poor fitting lenses)
- Inflammation (most often from sleeping in lenses)
- Viral infections
- Bacterial infections
- Fungal infections
The management and treatment of each condition may vary, thus it is important to determine the cause for irritation. In some cases, prescribing the wrong medication can worsen the problem. If you are experiencing a problem with your eyes or contact lenses, it is best to immediately remove your lenses and schedule an examination with your optometrist.
If your contact lenses feel dry, filmy or uncomfortable it is recommended that you discuss this with your eye care provider. These may be signs that you are having a contact lens complication; alternatively, you may need a prescription for a different brand of contact lenses or a different replacement schedule. There are a variety of reasons these types of symptoms may occur:
- Dry eye: Dry eye affects close to one-third of the general population.1 Symptoms often vary, but may include fluctuating vision, mild discomfort, burning, itching, watering and pain.2 Contact lens wear may make these symptoms worse. In many cases, signs and symptoms do not always correlate. In one study, 25% of symptomatic contact lens wearers did not show any classic signs of dryness.3 In addition to treating the underlying dry eye, changes to lens materials or care products may reduce your symptoms.
- Allergies: Allergic disorders of the eye can cause swelling, itching, watering and redness in response to both acute and chronic exposure to allergens. One common condition that causes these symptoms is known as allergic conjunctivitis—a swelling of the eye tissues in response to environmental allergens. This condition is easily treated, once identified, with topical eyedrops that can be instilled about 10 to 15 minutes prior to contact lens wear. Another possibility is giant papillary conjunctivitis (GPC). Although not a true allergy, GPC is an inflammatory response to the interaction between the inner eyelid and deposits on the contact lens surface. It often presents about 18 to 20 months after beginning lens wear and can cause itching, foreign body sensation, and excessive mucous secretion.4
- Solution incompatibility or toxicity: There are a wide variety of contact lens solutions on the market. Not all solutions are compatible with every brand or type of contact lenses. In some cases you can develop a sensitivity or toxicity to the preservatives or other ingredients in a lens solution. If this occurs, it can lead to contact lens discomfort and increase your risk of corneal ulcer or infection.5
- Improper cleaning: There are a few common mistakes often made in regards to contact lens hygiene so we will review the best practices here. Always rub and rinse your contact lenses to clean them after removing from your eye. Rubbing and rinsing the contact lens removes deposits and also dramatically reduces the microbial load on the lens surface.6 Always use fresh solution when filling the case to disinfect your lenses (i.e., avoid “topping off” old solution with fresh solution). Once your lenses are clean and disinfected (typically overnight), you will apply them for the day and discard the used solution. Next, rinse the contact lens case with contact lens solution, dry it with a tissue, and allow it to air dry.7 No water should contact the case or lenses in this cleaning process.8 The contact lens case itself should be replaced regularly (every 1 to 3 months) to avoid the buildup of biofilm, bacteria and debris.
- Overwear: Following the wear and replacement schedule set by your eye care provider decreases the risk of both infection and inflammation. It is important to remember that once the blister pack is opened, the contact lens is being “used” even if it is not worn. For example, a monthly replacement lens should be replaced after 30 days, whether it is worn one time or 30 times. For patients who sleep in their contact lenses, symptoms of discomfort and irritation are common upon awakening.9 Although certain contact lenses are approved for extended wear, not everyone can tolerate this modality.
If you think any of the above scenarios apply to you, be sure to speak to your optometrist. It does not necessarily mean you must discontinue contact lens wear—simply finding a more appropriate lens option, such as a daily disposable contact lens, might relieve your symptoms.
There are no definitive contraindications to contact lens wear when taking prescription medication; however, certain types of medications may contribute to dry eye syndrome, a condition that can be worsened by contact lens wear. These medications include anti-histamines, decongestants, antidepressants, antipsychotics, anti-anxiety medications, blood pressure medications, diuretics, overactive bladder medications, heartburn medications, and oral contraceptives, just to name a few.1 These drugs can alter your tear film by reducing the amount of tears produced. This may impact the comfort level of your contact lenses. Be sure to notify your optometrist of any medications, both over-the-counter and prescription, that you are taking.
If you are taking topical eyedrops, it is recommended they be instilled when the contact lenses are not on the eye. The medication or preservatives may be absorbed by the lens, which can cause prolonged exposure and toxicity.2 The general consensus is to wait 10 to 15 minutes between instillation of eyedrops and the insertion of a contact lens since most of the instilled drug will leave the ocular surface and enter the drainage system of the eye within minutes.3 Consult with your optometrist regarding any eyedrops you are taking or want to take to ensure they are compatible.
Glasses are strongly recommended for all contact lens wearers, regardless of your wear or replacement schedule. Glasses not only provide the opportunity to give your eyes a break from contact lens wear, but they may be required should you be unable to wear your contact lenses for any reason (such as a lost contact lens, an eye infection, etc). At minimum, your glasses should allow you to see 20/40 or better, which is the legal requirement to drive in most states.1
Overwearing contact lenses can increase your risk for complications from inflammation and/or infection. This is especially true for patients who sleep in their lenses—even those lenses approved for extended or overnight wear.2 Remember, if your eyes are irritated for any reason, it is recommended that you remove your contact lenses immediately and contact your optometrist for your next steps.3
Contact lens wearers should see their optometrist at least once per year. More frequent visits may be recommended for those patients who have experienced complications from contact lens wear, who require specialty lens designs or who have other eye disease. Additionally, according to federal law, contact lens prescriptions expire after one year, unless otherwise specified by your individual state.1
A complete annual eye examination with a contact lens evaluation ensures not only the accuracy of your contact lens prescription, but also examines the health of the entire eye, the fit of the lens on the eye, and allows for early detection of any potential for contact lens related complications including negative impacts the lens could be having on the eye or visual system.