Contact Lenses
- Bifocal and Multifocal Contact Lenses
- Contact Lens Basics
- Contact Lenses for the 'Hard-to-Fit' Patient
- astigmatism
- dry eyes
- presbyopia
- giant papillary conjunctivitis (GPC)
- keratoconus
- post-refractive surgery (such as LASIK)
- Eye Exams for Contact Lenses
- 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 known as a "toric" contact lens. At one time, only gas permeable contact lenses could correct for astigmatism. But now, there are many brands of soft toric lenses, which are available in disposable, multifocal, extended wear and colored versions.
- 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 by placing a liquid dye 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.
- Gas Permeable (GP) Contact Lenses
- Orthokeratology
- Toric Contact Lenses for Astigmatism
Bifocal and Multifocal Contact Lenses
Bifocal and multifocal contact lenses are designed to give you good vision when you reach your 40s. Beginning at this age, you may need to hold reading material - like a menu or newspaper - farther from your eyes to see it clearly. This condition is called "presbyopia."
Bifocal and multifocal contact lenses are available in both soft and rigid gas permeable (GP) materials.
Bifocals, Multifocals - What's the Difference?
Bifocal contacts lenses (like bifocal eyeglass lenses) have two powers - one for seeing clearly far away and one for seeing clearly up close. Multifocal contact lenses, like progressive eyeglass lenses, have a range of powers for seeing clearly far away, up close and everywhere in between. ("Multifocal" is also used as a catch-all term for all lenses with more than one power, including bifocals.)
Types of Multifocal Contact Lenses
Based on design, there are basically two types of multifocal contact lenses:
Simultaneous vision lenses. With these lenses, both distance and near zones of the lens are in front of your pupil at the same time. Although this might sound unworkable, after a short period of time your visual system learns to use the power you need and ignore the other lens power(s), depending on what you are looking at. Simultaneous vision lenses are the most popular type of multifocal contact lens. They are nearly always soft lenses and are available in two designs:
Concentric ring designs - These are bifocal lenses with either the distance or near power in the center of the lens, with alternating rings of distance and near powers surrounding it.
Aspheric designs - These are progressive-style multifocal lenses, with many powers blended across the lens surface. Some aspheric lenses have the distance power in the center of the lens; others have the near power in the center.
Alternating vision (or translating) lenses. These are GP multifocal lenses that are designed like bifocal eyeglass lenses. The top part of the lens has the distance power, and the bottom part of the lens contains the near power. When you look straight ahead, your eye is looking through the distance part of the lens. When you look down, your lower lid holds the lens in place while your pupil moves (translates) into the near zone of the lens for reading.
Will Multifocal Contact Lenses Work for Me?
Most people who try multifocal contact lenses are happy with them. But some compromises may be necessary when you wear these lenses. For example, your distance vision with multifocal contact lenses may not seem clear enough, or you may have trouble with glare at night or not being able to see small print.
In some cases, a person with presbyopia may prefer monovision or modified monovision. Both of these fitting strategies use single vision lenses - that is, lenses that each have only one power - instead of multifocals.
In monovision, you wear a single vision contact lens on one eye for your distance vision and a single vision contact lens on the other eye that has a prescription for your near vision. In modified monovision, you wear a single vision "distance lens" on one eye and a multifocal contact lens on the other eye to help you see better up close.
To determine the best contact lenses for your vision needs when you reach "bifocal age," call our office for a consultation.
Article ©2015 Access Media Group LLC. All rights reserved. Reproduction other than for one-time personal use is strictly prohibited
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Contact Lenses for the "Hard-to-Fit" Patient
Not everyone is well suited to the most common types of contact lenses. If you have one or more of the following conditions, contact lens wear may be more challenging:
But "challenging" 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 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 in several 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 for dry eye sufferers, 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 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 have historically been 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.
The last few years have produced quite a bit of innovation in contact lenses for keratoconus. There are now several soft lenses for keratoconus, as well as many scleral lenses. These are large lenses made of GP material that remain completely above the cornea, with the outer edge of the lens resting on the white of the eye (sclera).
Another option is called "piggybacking," where soft and GP lenses are worn together on the eye for greater comfort than a GP alone would provide. Hybrid contact lenses that have a GP center surrounded by a soft "skirt" can produce the same effect.
Contact Lenses After Corrective Eye Surgery
Hundreds of thousands of people 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 - including large GP scleral 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.
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 ©2015 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 is what's involved in a typical contact lens exam and fitting:
A Comprehensive Eye Exam Comes First
Before you are fitted 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 or contact lens specialist 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:
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 your cornea and creates a surface "map" of your eye, with different contours represented by varying colors.
Trial Lenses
In many cases, trial lenses will be used to verify the contact lens selection. Lenses will be placed on your eyes 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. Typically you'll 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 will 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 too dry.
Often, your doctor will be able to see warning signs even before you begin to notice them. If such warning signs are evident in your follow-up visits, your doctor may recommend trying a different lens or lens material, using a different lens care and cleaning method, or adjusting your contact lens wearing time. Occasionally, it may be necessary to discontinue contact lens wear altogether.
Your Contact Lens Prescription
Once you find a contact lens that fits properly, is comfortable for you, and provides good vision, your doctor will 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 remain healthy and tolerant of contact lens wear.
Article ©2015 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 rigid contacts 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.
Advantages of Gas Permeable Lenses
GP lenses allow your eyes to "breathe." Getting oxygen to the eye reduces the risk of problems caused by hypoxia (reduced oxygen supply). Because GP lenses are made with oxygen-permeable silicone, they allow more oxygen to reach the front surface of the eye than traditional hydrogel soft contact lenses. (However, many of the new silicone hydrogel soft contact lenses are comparable to GPs for oxygen delivery.)
GP lenses provide sharper vision. Because they maintain their shape on the eye, GP lenses provide sharper vision than soft lenses, which can fluctuate in shape. And gas permeable lenses don't contain water, so they are not prone to drying out. Many soft lenses contain a large percentage of water and will compromise vision if they start to dry out.
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. Since they're long-lasting, GP lenses can be less expensive than soft lenses in the long run.
GP lenses can slow the progression of nearsightedness. GPs used for overnight orthokeratology - also called corneal reshaping, or ortho-k - have been shown to reduce the progression of myopia (nearsightedness) in some children. Overnight ortho-k also enables clear daytime vision without the use of glasses or contacts.
GPs are great for multifocal designs and problem corneas. Many wearers feel that GP multifocals offer superior vision to soft bifocals. GPs are also the most common choice for eyes that have been compromised by corneal diseases, or for people who still need vision correction after refractive surgery such as LASIK.
The Downside of GP Contact Lenses
So why doesn't everyone wear GP lenses? Potential disadvantages of GP lenses (compared with soft lenses) include:
Need for adaptation. Unlike wearing soft lenses, which are immediately comfortable, you may need a 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.
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.
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.
Vulnerability to sand and dust. GP lenses don't conform to the shape of your eye like soft lenses do, so it's possible for sand or dust to get under your lenses at the beach or on a windy day. (You can minimize this risk by wearing wrap-style sunglasses outdoors.)
Higher initial and replacement costs. Unlike soft lenses, which come in off-the-shelf sizes, GP lenses are always custom-made to the shape of your eye. This makes GP lenses more expensive to purchase, and 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.
Hybrid Contact Lenses
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 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 a trail fitting.
Article ©2015 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. This process is also known as corneal reshaping, and by brand names such as CRT (Corneal Refractive Therapy) and Bausch & Lomb's Vision Shaping Treatment (VST).
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.
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.
Ortho-k Can Slow the Progression of Nearsightedness
Several clinical studies have indicated that corneal reshaping lenses can reduce the rate of myopia progression in nearsighted children. When worn only at night, these lenses can slow down eye growth - the source of progressing myopia - by more than 50% compared with glasses and soft contacts, according to multiple studies. In another study, published in 2014, participants used a daytime-wear GP in one eye and an ortho-k lens in the other, and no eye growth was found over a one-year period in the ortho-k eye.
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 corneas, 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 ©2015 Access Media Group LLC. All rights reserved. Reproduction other than for one-time personal use is strictly prohibited.
Toric Contact Lenses for Astigmatism
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 specially designed contact lenses to achieve clear vision.
You have several options: "Toric" soft contact lenses are the most common choice, but there are also gas permeable (RGP or GP) lenses and hybrid 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 variations in the eye's shape. 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. Getting a good toric fit might mean trying a few brands of lenses.
Many Options in Soft Toric Lenses
Soft toric lenses are available 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.
And if soft toric lenses don't adequately correct your astigmatism, gas permeable lenses will often do the trick.
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 GP lenses are rigid and maintain their shape on the eye, a toric 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 you have a stronger prescription, or if regular gas permeable lenses fail to correct your astigmatism adequately, toric GP lens designs are also available.
Hybrid Contact Lenses
Hybrid lenses have a rigid GP center surrounded by a "skirt" of soft lens material. The idea of hybrids is to combine the excellent optics of a GP lens with the comfort of a soft lens. And unlike soft lenses, the vision provided by hybrids does not depend on position, so lens rotation is not an issue.
Cost of Contacts for Astigmatism
Properly fitting a soft toric contact lens takes more time and requires more expertise than fitting regular soft contacts. Fitting GPs and hybrids can take more time and expertise as well, and lens material cost is higher than with spherical contact lenses. Consequently, our fees for patients with astigmatism are higher than our regular contact lens fees.
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 ©2015 Access Media Group LLC. All rights reserved. Reproduction other than for one-time personal use is strictly prohibited.
