Contact Lenses for the "Hard-to-Fit" Patient

Not everyone is an ideal candidate for contact lenses. If you have one or more of the following conditions, contact lens wear may be more difficult:

• astigmatism

• dry eyes

• presbyopia

• giant papillary conjunctivitis (GPC)

• keratoconus

• post-refractive surgery (such as LASIK)

 

 

But “difficult” doesn’t mean impossible. Often, people with these conditions can wear contacts quite successfully. Let’s take a closer look at each situation – and possible contact lens solutions.

 

Contact lenses for astigmatism

Astigmatism is a very common condition where the curvature of the front of the eye isn’t round, but is instead shaped more like a football or an egg. This means one curve is steeper or flatter than the curve 90 degrees away. Astigmatism won’t keep you from wearing contact lenses – it just means you need a different kind of lens. Lenses specially designed to correct astigmatism are called “toric” lenses. Most toric lenses are soft lenses. Toric soft lenses have different corrective powers in different lens meridians, and design elements to keep the lens from rotating on the eye (so the varying corrective powers are aligned properly in front of the different meridians of the cornea). In some cases, toric soft lenses may rotate too much on the eye, causing blur. If this happens, different brands that have different anti-rotation designs can be tried. If soft lens rotation continues to be a problem, gas permeable (GP) lenses (with or without a toric design) can also correct astigmatism.

 

Contact lenses for dry eyes

Dry eyes can make contact lens wear difficult and cause a number of symptoms, including:

• a gritty, dry feeling

• feeling as if something is in your eye

• a burning sensation

• eye redness (especially later in the day)

• blurred vision

If you have dry eyes, the first step is to treat the condition. This can be done a number of ways, including artificial tears, medicated eye drops, nutritional supplements, and a doctor-performed procedure called punctal occlusion to close ducts in your eyelids that drain tears away from your eyes. Once the dry eye condition is treated and symptoms are reduced or eliminated, contact lenses can be tried. Certain soft contact lens materials work better than others for dry eyes. Also, GP lenses are sometimes better than soft lenses if there’s a concern about dry eyes since these lenses don’t dry out the way soft lenses can. Replacing your contacts more frequently and reducing your wearing time each day (or removing them for specific tasks, such as computer work) can also reduce dry eye symptoms when wearing contacts.

 

Contact lenses for giant papillary conjunctivitis (GPC)

Giant papillary conjunctivitis (GPC) is an inflammatory reaction on the inner surface of the eyelids. One cause of GPC is protein deposits on soft contact lenses. (These deposits are from components of your tear film that stick to your lenses and become chemically altered.) Usually, changing to a one-day disposable soft lens will solve this problem, since you just throw these lenses away at the end of the day before protein deposits can accumulate on them. Gas permeable lenses are also often a good solution, as protein deposits don’t adhere as easily to GP lenses, and lens deposits on GP lenses are more easily removed with daily cleaning. In some cases of GPC, a medicated eye drop may be required to reduce the inflammation before you can resume wearing contact lenses.

 

Contact lenses for presbyopia

Presbyopia is the normal loss of focusing ability up close when you reach your 40s. Today, there are many designs of bifocal and multifocal contact lenses to correct presbyopia. Another option for presbyopia is monovision. This is wearing a contact lens in one eye for distance vision and a lens in the other eye that has a modified power for near vision. During your contact lens fitting we can help you decide whether bifocal/multifocal contact lenses or monovision is best for you.

 

Contact lenses for keratoconus

Keratoconus is a relatively uncommon eye condition where the cornea becomes thinner and bulges forward. The term “keratoconus” comes from the Greek terms for cornea (“kerato”) and cone-shaped (“conus”). The exact cause of keratoconus remains unknown, but it appears that oxidative damage from free radicals plays a role. Gas permeable contact lenses are the treatment option of choice for mild and moderate keratoconus. Because they are rigid, GP lenses can help contain the shape of the cornea to prevent further bulging of the cornea. They also can correct vision problems caused by keratoconus that cannot be corrected with eyeglasses or soft contacts. In some cases, a soft contact lens is worn under the GP lens for greater comfort. This technique is called “piggybacking.” Another option for some patients is a hybrid contact lens that has a GP center, surrounded by a soft “skirt”.

 

Contact lenses after corrective eye surgery

More than one million Americans each year have LASIK surgery to correct their eyesight. Sometimes, vision problems remain after surgery that can’t be corrected with eyeglasses or a second surgical procedure. In these cases, gas permeable contact lenses can often restore visual acuity and eliminate problems like glare and halos at night. GP lenses are also used to correct vision problems after corneal transplant surgery, including irregular astigmatism that cannot be corrected with eyeglasses. GP lenses prescribed after LASIK and corneal transplants sometimes have a special design called a “reverse geometry” design to better conform to the altered shape of the cornea. The back surface of these lenses is flatter in the center and steeper in the periphery. (This is the opposite of a normal GP lens design, which is steeper in the center and flattens in the periphery.)

 

Problem-solving contact lens fittings cost more

Fitting contact lenses to correct or treat any of the above conditions will generally take much more time than a regular contact lens fitting. These “hard-to-fit” cases usually require a series of office visits and multiple pairs of trial lenses before the final contact lens prescription can be determined. Also, the lenses required for these conditions are usually more costly than regular soft contact lenses. Therefore, fees for these fittings are higher than fees for regular contact lens fittings. Call our office for details.

 

Find out if you can wear contact lenses

If you are interested in wearing contact lenses, call our office to schedule a consultation. Even if you’ve been told you’re not a good candidate for contacts because you have one of the above conditions or for some other reason, we may be able to help you wear contact lenses safely and successfully.

Article ©2012 Access Media Group LLC.  All rights reserved.  Reproduction other than for one-time personal use is strictly prohibited.

Eye Exams for Contact Lenses

For many people, contact lenses provide greater convenience and more satisfying vision correction than eyeglasses. Here’s what’s involved in a typical contact lens exam and fitting:

 

A comprehensive eye exam comes first

Before being fit with contact lenses, a comprehensive eye exam is performed. In this exam, your eye doctor determines your prescription for corrective lenses (just a glasses prescription at this point) and checks for any eye health problems or other issues that may interfere with successful contact lens wear. If all looks good during your eye exam, the next step is a contact lens consultation and fitting.

 

What to expect during a contact lens fitting

The first step in a contact lens fitting is a consideration of your lifestyle and your preferences regarding contact lenses, such as whether you might want to change your eye color with color contact lenses or if you're interested in options such as daily disposables or overnight wear. Although most people choose soft contact lenses, the advantages and disadvantages of rigid gas permeable (GP) lenses will likely be discussed as well. If you are over age 40 and need bifocals, your eye doctor will discuss ways to deal with this need, including multifocal contact lenses and monovision (a prescribing technique where one contact lens corrects your distance vision and the other lens corrects your near vision).

 

Contact lens measurements

Just as one shoe size doesn't fit all feet, one contact lens size doesn't fit all eyes. If the curvature of a contact lens is too flat or too steep for your eye's shape, you may experience discomfort or even damage to your eye. Measurements that will be taken to determine the best contact lens size and design for your eyes include:

 

• Corneal curvature: An instrument called a keratometer is used to measure the curvature of your eye's clear front surface (cornea). This measurement helps your doctor select the best curve and diameter for your contact lenses. If your eye's surface is found to be somewhat irregular because of astigmatism, you may require a special lens design of lens known as a “toric” contact lens. At one time, only gas permeable contact lenses could correct for astigmatism. But there are now many brands of soft toric lenses, which are available in disposable, multifocal, extended wear and colored versions. In some cases, a detailed mapping of the surface of your cornea (called corneal topography) may be done. Corneal topography provides extremely precise details about surface characteristics of the cornea and creates a surface "map" of your eye, with different contours represented by varying colors.

 

• Pupil and iris size: The size of your pupil and iris (the colored part of your eye) can play an important role in determining the best contact lens design, especially if you are interested in GP contact lenses. These measurements may be taken with a lighted instrument called a biomicroscope (also called a slit lamp) or simply with a hand-held ruler or template card.

 

• Tear film evaluation: To be successful wearing contact lenses, you must have an adequate tear film to keep the lenses and your cornea sufficiently moist and hydrated. This test may be performed with a liquid dye placed on your eye so your tears can be seen with a slit lamp, or with a small paper strip placed under your lower lid to see how well your tears moisten the paper. If you have dry eyes, contact lenses may not be right for you. Also, the amount of tears you produce may determine which contact lens material will work best for you.

   

Trial lenses

In many cases, trial lenses will be used to verify the contact lens selection. Lenses will be placed on your eye and your doctor will use the slit lamp to evaluate the position and movement of the lenses as you blink and look in different directions. You will also be asked how the lenses feel. You'll typically need to wear these trial lenses at least 15 minutes so that any initial excess tearing of the eye stops and your tear film stabilizes. If all looks good, you will be given instructions on how to care for your lenses and how long to wear them. You will also receive training on how to handle, apply and remove the lenses.

 

Follow-up visits confirm the fit and safety

Your contact lens fitting may involve a number of follow-up visits so your doctor can confirm the lenses are fitting your eyes properly and that your eyes are able to tolerate contact lens wear. A dye (like the one used to evaluate your tear film) may be used to see if the lenses are causing damage to your cornea or making your eyes become too dry.

 

Often, your doctor will be able to see warning signs before you are aware a problem with your contact lens wear is developing. If such warning signs are evident in your follow-up visits, a number of things may be recommended, including trying a different lens or lens material, using a different lens care method, or adjusting your contact lens wearing time. In occasional cases, it may be necessary to discontinue contact lens wear altogether.

 

Your contact lens prescription  

After finding a contact lens that fits properly, is comfortable for you, and provides good vision, your doctor will then be able to write a contact lens prescription for you. This prescription will designate the contact lens power, the curvature of the lens (called the base curve), the lens diameter, and the lens name and manufacturer. In the case of GP contact lenses, additional specifications may also be included.

 

Routine contact lens exams

Regardless of how often or how long you wear your contact lenses, your eyes should be examined at least once a year to make sure your eyes are continuing to tolerate contact lens wear and show no signs of ill effects from the lenses.

Article ©2012 Access Media Group LLC.  All rights reserved.  Reproduction other than for one-time personal use is strictly prohibited.

Gas Permeable (GP) Contact Lenses

Gas permeable (GP) contact lenses, also known as rigid gas permeable (RGP) lenses, are hard contact lenses made of silicone-containing compounds that allow oxygen to pass through the lens material to the eye. Though not as popular as soft contact lenses, GP lenses offer a number of advantages over soft lenses.

 

Advantages of gas permeable lenses

 

1. GP lenses allow your eyes to “breathe” better.

 

GP lenses allow more oxygen to reach the front surface of the eye. This reduces the risk of eye problems caused by hypoxia (reduced oxygen supply). Gas permeable lenses provide a better oxygen supply than most soft lenses because:

• The silicone-containing lens materials of GP lenses are more permeable to oxygen than many soft lens materials (though new “silicone hydrogel” soft lenses are comparable to GPs in oxygen transmission).

• GP lenses are smaller in diameter than soft lenses, so they cover up less of the front surface of the eye (the cornea).

• Gas permeable lenses hold their shape and move on the eye with each blink. This movement pumps oxygen-containing tears under the lens. Soft lenses conform to the shape of the cornea and have only minimal movement with blinks, so little or no tears circulate under soft lenses.

 

2. GP lenses provide sharper vision.

 

Because they are custom-machined to a smooth surface and maintain their shape on the eye, GP lenses provide sharper vision than soft lenses, which can fluctuate in shape and clarity if they start to dry out. Gas permeable lenses also provide a more stable and accurate correction of astigmatism.

3. GP lenses last longer.

 

GP lenses are rigid, so there’s no worry about ripping or tearing them. They are also easier to keep clean and don’t need to be replaced frequently like soft lenses. With proper care, a single pair of GP lenses can last a year or longer. And since they're long-lasting, GP can be less expensive than soft lenses in the long run.

4. GP lenses may slow the progression of nearsightedness.

 

In addition to their other advantages, some research suggests that wearing gas permeable lenses may slow the progression of myopia (nearsightedness) in some children. GPs are also used for orthokeratology, where specially designed contacts are worn during sleep to reshape the cornea and improve vision.

 

The Downside of GP Contact Lenses

So why doesn't everyone wear GP lenses? Potential disadvantages of GP lenses (compared to soft lenses) include:

 

1. Need for adaptation.

Unlike wearing soft lenses (which are comfortable right from the start), you may need few weeks before you can wear GP lenses comfortably all day. Initially, you may be able to wear the lenses only a few hours daily until your corneas adapt to them. But if you can tough it out for those first few days, you may be pleasantly surprised at how comfortable GP lenses become. Many people who switch from soft lenses to gas permeable lenses say GP lenses are more comfortable than soft lenses (after their eyes fully adapt) and their vision is noticeably clearer.

 

2. Inability to wear part-time.

To fully adapt to GP lenses and to stay comfortable wearing them, you have to wear them every day. If you stop wearing them for several days, you will be more aware of the lenses on your eyes and you’ll have to re-adapt to the lenses.

 

3. Increased possibility of dislodging.

Because they are smaller than soft lenses, gas permeable lenses can dislodge from your eyes during contact sports or if you rub your eyes aggressively.

 

4. Vulnerability to sand and dust.

GP lenses don’t conform to the shape of your eye like soft lenses do, so it’s possible sand or dust can get under your lenses at the beach or on a windy day. ( You can minimize this risk by wearing wrap-style sunglasses outdoors.)

 

5. Higher lens replacement costs.

Unlike soft lenses, which come in limited sizes, GP lenses are custom-made to the shape of your eye. This makes GP lenses more expensive to replace if you lose them. Also, it can take up to a week to get a GP lens replaced. So it’s a good idea to purchase a spare pair to avoid the inconvenience of being without your GP lenses if you lose or break one.

 

Best of Both Worlds?

Since comfort is the primary barrier to GP use, an interesting innovation is the hybrid contact lens. These lenses have a GP center, surrounded by a soft lens “skirt.” The goal of hybrid lenses is to provide the clarity of a gas permeable lens and wearing comfort that rivals that of a soft lens. Call for more information and a trial fitting to see if gas permeable lenses are right for you, call our office for more information and to schedule an appointment.

Article ©2012 Access Media Group LLC.  All rights reserved.  Reproduction other than for one-time personal use is strictly prohibited.

Orthokeratology

Orthokeratology, or “ortho-k,” is the process of reshaping the eye with specially-designed rigid gas permeable (GP) contact lenses. The goal of ortho-k is to flatten the front surface of the eye and thereby correct mild to moderate amounts of nearsightedness and astigmatism.

 

How ortho-k works

The GP lenses for ortho-k are applied at bedtime and worn overnight. While you sleep, the lenses gently reshape the front surface of your eye (the cornea) to correct your vision, so you can see clearly without glasses or contact lenses when you’re awake. The effect is temporary – generally enough to get you through a day or two – so you must wear the reshaping lenses each night to maintain good vision during the day. Currently, there are two brands of orthokeratology approved by the FDA:  Corneal Refractive Therapy (CRT) from Paragon Vision Sciences and Vision Shaping Treatment (VST) from Bausch & Lomb.

 

Who is a candidate for ortho-k?

Orthokeratology is frequently a good option for nearsighted individuals who are too young for LASIK surgery or for some other reason are not good candidates for vision correction surgery. Because it can be discontinued at any time without permanent change to the eye, people of any age can try the procedure, as long as their eyes are healthy.

Ortho-k is particularly appealing for people who participate in sports, or who work in dusty, dirty environments that can make contact lens wear difficult.

 

What results can you expect from ortho-k?

The goal for ortho-k is to correct your vision to 20/20 without eyeglasses or contact lenses during the day. In FDA trials of both CRT and VST lenses, more than 65% of patients were able to achieve 20/20 visual acuity after wearing the reshaping lenses overnight. More than 90% were able to see 20/40 or better (the legal vision requirement for driving without glasses in most states). Success rates for ortho-k tend to be higher for mild prescriptions. Call our office to find out if your prescription is within the range that can be successfully treated with ortho-k.

 

How long does ortho-k take?

Though you may see some improvement in your vision after a day or two of overnight ortho-k, it can take several weeks for the full effect to be apparent. During this time, your vision will not be as clear as it was with glasses or contacts, and you are likely to notice some glare and halos around lights. It’s possible you may need a temporary pair of eyeglasses for certain tasks, like driving at night, until your vision is fully corrected by the ortho-k lenses.

 

Is ortho-k comfortable?

Some people have comfort issues when attempting to wear gas permeable contact lenses during the day. But since ortho-k GP lenses are worn during sleep, comfort and lens awareness are generally not a problem.

 

Cost of orthokeratology

Ortho-k is a significantly longer process than a regular contact lens fitting. It requires a series of office visits and potentially multiple pairs of lenses. Also, GP lenses used for ortho-k are more costly than most regular contact lenses. Therefore, fees for orthokeratology are higher than fees for regular contact lens fittings.

 

Can I have LASIK after ortho-k?

Yes, it’s possible to have LASIK surgery after orthokeratology. But because ortho-k lenses reshape your cornea, you must stop wearing the lenses for a period of time (usually several months) so your eyes can return to their original shape and stabilize. Be sure to tell your LASIK surgeon that you’ve worn ortho-k lenses, so they can advise you how long you should wait before having the surgery.

Article ©2012 Access Media Group LLC.  All rights reserved.  Reproduction other than for one-time personal use is strictly prohibited.

Toric Contact Lenses for Astigmatism

If you have astigmatism – a common condition where the eye isn’t perfectly round, but more football- or egg-shaped – then you’ll need a special design of contact lenses called “toric” lenses for clear vision. Toric contact lenses are available in both soft and rigid gas permeable (RGP or GP) lens materials. Most contact lens wearers who need toric contacts choose soft toric lenses.

 

How do toric lenses work?

When you have astigmatism, different meridians of your eye need different amounts of correction for nearsightedness or farsightedness. Imagine the front of your eye is like the face of a clock: A line drawn from the 12 to the 6 is one meridian, a line from the 1 to the 7 is another, and so on. Soft toric contact lenses have different powers in different meridians of the lens to correct the eye’s astigmatism. They also have design elements to keep the lens from rotating on your eye, so the meridians of the lens stay aligned with the meridians of your eye. Today, you can choose from many brands and styles of soft toric lenses.  So if Brand A doesn’t fit properly or rotates too much, Brand B may perform better. And if soft toric lenses don’t adequately correct your astigmatism, gas permeable lenses will often do the trick.

 

Toric contact lens cost

Properly fitting a toric contact lens takes more time and requires more expertise than fitting regular soft contacts. Several office visits are required, and sometimes several different lenses must be evaluated. Consequently, our professional fee for fitting toric lenses is higher than our fee for a regular contact lens fitting. The lenses themselves also cost more than regular soft lenses. Call our office for details.

 

Gas permeable lenses for astigmatism

If you have a mild to moderate amount of astigmatism, you may want to consider gas permeable contact lenses. GP lenses usually provide sharper vision than soft toric lenses. And because gas permeable lenses are rigid and maintain their shape on the eye, a toric GP design usually isn’t needed. The astigmatism due to unequal curves on the front surface of your eye is corrected by a layer of tears that forms between your eye and the spherical back surface of the GP lens. If regular gas permeable lenses fail to adequately correct the astigmatism, customized toric GP lens designs are also available.

 

Many options in soft toric lenses

Today, many brands of soft toric lenses are available and you have a choice of lenses approved for daily wear (lenses you remove before sleep) and extended wear (lenses approved for overnight wear). There are also soft toric lenses to enhance or change your eye color and multifocal toric lenses if you have presbyopia.

 

Call for more information

Call our office today to learn more about contact lens options for astigmatism and to schedule a contact lens consultation to find out which lenses are the best solution for you.

Article ©2012 Access Media Group LLC.  All rights reserved.  Reproduction other than for one-time personal use is strictly prohibited.