What is Keratoconus
Keratoconus is a progressive thinning of the cornea (the clear membrane at the front of the eye). The cornea and the intraocular lens are responsible for focusing light on the retina. Typically the cornea is a smooth consistent shape and helps the eye focus light on the retina. However, in patients with keratoconus, the cornea begins to become thin, usually in the late teens the to early twenties. This thinning causes the cornea to take on an irregular shape, protruding from the center or just below the center. The resulting shape is often characterized as the shape of a cone. This irregular surface causes blurry vision. The blurry vision is not correctable by normal glasses or contact lenses. Keratoconus usually involves both eyes, however one eye may be more advanced than the other.
The most effective way to improve a keratoconus patient’s vision is to correct the higher order aberrations and irregular astigmatism. Keratoconus experts now agree the most effective way to accomplish this is with scleral contact lenses.
What Causes Keratoconus?
Keratoconus is one of the most common corneal dystrophies in the U.S., affecting somewhere between 1 in every 400 to 1 in every 2000 Americans. Keratoconus is usually first diagnosed in the early teens the to early twenties.1, 2
It is thought that not a single event or condition causes keratoconus but rather a combination of genetic and/or environmental factors. Some of those factors linked to keratoconus are;
- An eye injury, i.e., excessive eye rubbing.
- About 7% have a family history of keratoconus.
- Systemic conditions, such as Leber’s congenital amaurosis, Down syndrome, osteogenesis imperfecta, and connective tissue disorders such as Ehlers-Danlos Syndrome and Marfan’s Syndrome.
- Ocular conditions, such as retinopathy of prematurity, retinitis pigmentosa, and vernal keratoconjunctivitis.
What are the Symptoms of Keratoconus?
Blurred vision that cannot be corrected with glasses is often the first symptom of keratoconus. Most patients with a keratoconic cornea will exhibit a high refractive error and irregular astigmatism. Distorted vision, even while wearing glasses is common. Distorted vision is usually the result of irregular astigmatism and other optical aberrations. Ordinary glasses will not correct irregular astigmatism or higher order optical aberrations. Seeing multiple images of the same object is another common symptom. Seeing 2, 3 or even 4 overlapping images is not uncommon.
The best way to diagnose keratoconus is with corneal topography. Corneal topography measures the peaks and valleys found on the cornea. Modern corneal topographers will collect as many as 6000 data points. A computer crunches the data to make a topographical map using different colors to show the variations in corneal curvature. Increased curvature or steepness is shown in red. The blue areas are relatively flat by comparison.
Corneal topography is one of the diagnostic tools doctors use to determine severity and degree of progression. Corneal topography is also used to differentiate different types of keratoconus. A corneal topographer is an essential, must have, tool in treating patients with keratoconus.
Testing the corneal thickness is called pachymetry. One of the hallmarks of keratoconus is the progressive thinning of the cornea. Corneal thickness is one of the markers we use to determine severity and progression. Corneal thickness can be calculated using a small ultrasonic probe designed specifically for this task. The accuracy and repeatability of this method; however, is somewhat user dependent. A more reliable and repeatable method is to use an optical coherence tomographer (OCT). The OCT is one of the most used devices in the modern eye doctor’s office. It is used for many things such as evaluating the fit of a contact lens, and the diagnosis and evaluation of many eye conditions.
Endothelial Cell Count
Measuring the endothelial cell count (ECC), while not critical to the diagnosis of keratoconus, is important in monitoring the ongoing progression and health of the cornea. The endothelial cells are found on the inside surface of the cornea and are responsible for maintaining corneal clarity. We continuously monitor the number of endothelial cells to help determine the cornea’s ability to support a contact lens.
Contact Lenses provide the Best Vision and Comfort
Keratoconus experts agree contact lenses are the treatment of choice for keratoconus. At Total Eye Care, our keratoconus experts find that over 90% of patients their patients are successfully treated with contact lenses. Scleral contact lenses give the most consistently reliable results with excellent vision and comfort. Glasses may be an option in the early stages of keratoconus; however, you should be closely monitored. As the corneal thinning worsens and irregular corneal astigmatism increases custom scleral contact lenses will reduce the distortion and provide better vision.
Contact Lens Treatment Options
Fortunately, we have numerous, effective treatment options for patients with keratoconus. Here are the most common and effective contact lens treatment options.
Scleral Contacts – The Treatment of Choice
Scleral contacts have made a resurgence in eye care and are now the treatment of choice amongst leading keratoconus specialists.3 With the modern lens materials and high tech manufacturing techniques scleral contacts are as comfortable as a soft contact lens. Scleral contacts are fully customizable. In addition to excellent comfort, scleral contacts also provide the best visual acuity of all of the keratoconus treatment options.
Mini-scleral lenses are about the size of a small, soft contact lens making it a comfortable lens to wear. Their comfort is significantly better than what is experienced with traditional gas permeable lenses but not as good as a normal scleral lens. Mini-scleral lenses are rarely used since they don’t offer any real advantage over the larger scleral lenses. Scleral contacts are typically more comfortable since the weight of the lens is moved further a way from the highly sensitive limbal area. The limbus is the area where the colored part of the eye meets the sclera.
The SynergEyes contact lenses bring together the visual acuity of a gas permeable lens and the comfort of a soft lens. They use a small gas permeable lens surrounded by a soft lens skirt. Synergeyes lenses can actually be used for any contact lens patient. We have found Synergeyes lenses to be especially helpful not only for patients with keratoconus but also irregular astigmatism. Synergeyes lenses are best reserved for patients with early keratoconus. The biggest disadvantage to Synergeyes lenses is their cost, lack of durability, and limited customization. Most patients with keratoconus tell us the comfort and vision from their scleral contacts is superior to what the experienced with the Synergeyes lenses.
Traditional Keratoconic Gas Permeable Lenses
Traditional gas permeable lenses such as the Rose K lens have been the mainstay of keratoconus treatment for decades. These lenses are typically 8.5mm to 10 mm in diameter. They are designed so the entire lens moves over the cornea a couple millimeters with each blink. Small diameter gas permeable lenses have slowly gone out of favor due to lens technology advancements made in the past 5 to 10 years.
Soft Contact Lenses
A few soft contact lens manufacturers do make soft lenses for patients with keratoconus. They offer limited customization and the poorest visual acuity of any of the contact lens options. Their comfort is better than a traditional gas permeable lens but generally inferior to that found with a scleral contact lens. These lenses are very rarely used.
Successfully Treating Keratoconus With Contact Lenses
At Total Eye Care, our keratoconus specialists have a great deal of experience in fitting patients with advanced contact lens designs. If you have questions you can schedule a free consultation with Dr. Driscoll, the keratoconus specialist at Total Eye Care, by calling 817.416.0333. You can also schedule your free consult online. The keratoconus lens fitting involves making a topographical map of your cornea. After the eye exam, we will make a topographical map of your eye. Corneal topography allows us to see the exact size and position of your “cone”.
Fitting Keratoconus Lenses
Next, we will select a diagnostic lens and place it on your eye. You will know what your new lenses will feel like and what kind of vision you can expect before you leave the office. After the diagnostic lens settles on your eye we will calculate what adjustments are needed to optimize a lens for you. It takes a few weeks to have these custom lenses designed and made. When we receive the lenses we will call you to schedule a time to teach you how to care for your new lenses. A few additional visits may be needed to see how you adapt to your new lenses and if any further modifications will improve the fit or vision.
Surgery is Rarely Needed
In most cases, the cornea will stabilize by the mid 30’s. The vast majority of patients are best treated with the scleral contact lenses. Some patients; however, may benefit from corneal cross-linking followed by scleral contact lenses. We are regularly asked by patients to give second opinions on whether they will benefit from surgical intervention.
The newest development in the surgical treatment of keratoconus is corneal cross-linking (CXL). Corneal cross-linking involves bathing the cornea with riboflavin and then activating its collagen cross-linking properties with exposure to ultraviolet light. The strength and stability of the cornea are increased with cross-linking. By increasing the linking between the collagen fibers the corneal strength increases. Some corneal flattening may also occur.
After cross-linking patients are then fit with scleral contact lenses to further improve their visual acuity and quality of life. Cross linking increases with age; therefore, younger patients are typically better corneal cross linking candidates.
Approximately 5% of patients with will eventually need a corneal transplant (penetrating keratoplasty). The most common reason for a corneal transplant is reduced vision due to corneal scarring. Frequent episodes of corneal hydrops is another reason why a corneal transplant may be required. In most cases, further treatment with a contact lens is necessary to achieve the best visual acuity following a corneal transplant.
Medically Necessary Contact Lenses
Some vision plans have a benefit for contact lenses used to treat keratoconus called Medically Necessary Contact Lenses. Vision plans are typically the only source for this kind of coverage. The criteria required to meet the medically necessary contact lenses threshold varies between vision plans. Most patients with keratoconus qualify for medically necessary contact lens coverage.
Keratoconus is not the only condition where medically necessary contact lens benefits may apply. Some other examples of other conditions that may qualify are high refractive error (including high astigmatism), pellucid marginal degeneration, dry eye syndrome, and keratitis. If you are not sure if you qualify, please feel free to call us at 817.416.0333. In some cases, we may be better able to answer these questions in person during our Free Consult which you can also schedule online.
Acute Corneal Hydrops
Corneal hydrops is characterized by localized swelling of the cornea. Reduced visual acuity and pain are the most prominent symptoms. Episodes of corneal hydrops will often result in some degree of scarring. Corneal hydrops is relatively rare. Only 1 out of 1000 patients with keratoconus experience acute corneal hydrops. If you have keratoconus and are experiencing pain it is important for you to call us.
What Can I do to Prevent My Keratoconus From Getting Worse?
See Your Keratoconus Specialist Yearly
Seeking regular eye care at intervals recommended by your keratoconus specialist is the most important thing you can do. With regular eye exams, we can monitor potential progression and alter your care as needed to optimize your vision and health. For optimal ocular health and vision, we recommend a yearly eye exam and evaluation of your contact lenses. We usually monitor patients with keratoconus every 6 to 12 months. A poorly fitting contact lens may cause additional scarring, discomfort, and decreased vision. Because of this, your contact lenses should be evaluated at least yearly.
Have a Pair of Backup Glasses
Having a pair of glasses to wear when you can’t wear your contact lenses is also extremely important. Like most keratoconus patients, you probably see better with your contacts than your glasses; however, there are times when your eyes need a break. Having a backup pair of glasses allows you to give your eyes that much-needed break.
It is also a good idea to avoid vigorous eye rubbing. Studies link vigorous eye rubbing to contributing to the cause and progression of keratoconus.
What Can I Expect Over the Coming Years?
The good news is having keratoconus will not have a negative affect on your day to day life. Having keratoconus means you will need regular eye care. It also means that the best vision you can attain with your glasses will likely not be as good as that vision you achieve with your contacts. Over the coming years, your vision will fluctuate just like everyone else. Keratoconus is a condition that must be managed and when done so, patients do very well.4
How Do I Learn More?
Total Eye Care is conveniently located in the middle of the Dallas Fort Worth Metroplex in Colleyville, Texas. Keratoconus is a complicated condition with many treatment options. We are here to help guide our patients through the process.
We offer complimentary keratoconus treatment consults to help patients decide which treatment option is best for them. You can schedule your free consultation online with Dr. Driscoll at either our Colleyville or Keller/Southlake Location. We can also schedule your appointment by calling 817.416.0333.
kare-uh-tuh-koh-nus or kare-uh-toh-koh-nus
Keratoconus is one of the most common corneal dystrophies. In the U.S. keratoconus affects somewhere between 1 in 400 to 1 in 2000 Americans.
Blurry vision is the primary symptom of keratoconus; however, the vision very rarely decreases to the point of blindness. If a scleral contact lens does not provide sufficiently improve visual acuity a corneal transplant may be required.
Yes, scleral contact lenses are the most effective and most common treatment for keratoconus. They are highly effective in improving visual acuity and visual function.
Keratoconus stabilizes over time. Younger patients, typically late teens to mid-twenties, will experience the fastest progression. It is important to see a keratoconus specialist, at least yearly, to ensure your current treatment is still appropriate.
LASIK does not cause keratoconus; however, if the cornea is left too thin after LASIK the cornea will begin to protrude and become even thinner. This is called post-surgical corneal ectasia. It has a very similar clinical appearance to keratoconus but with a different cause. Post-surgical corneal ectasia is treated similarly to keratoconus.
Yes, Ehlers-Danlos Syndrome is more common in patients with keratoconus. EDS does not cause keratoconus but it is a risk factor.
In general, pellucid marginal degeneration is characterized by a thinning and protruding of the cornea that extends to the inferior peripheral cornea. In keratoconus, the thinning and steepening of the cornea is central or inferior central and does not extend to the periphery.
A keratoconic cornea is thin and weak. It changes shape in an irregular fashion causing the corneal surface to become distorted. When light passes through the distorted cornea your vision becomes blurry. A rigid lens or scleral lens will smooth out the optical surface of the eye improving vision.
Yes, most patients can safely drive with keratoconus. Having keratoconus does not have to cause any limitations in how you live your life. Most patients live normal lives just like patients without keratoconus.
About Dr. Richard Driscoll
Dr. Driscoll is a therapeutic optometrist and keratoconus specialist at Total Eye Care in Colleyville, Texas. A 1988 Graduate of the Illinois College, Dr. Driscoll has been treating patients with keratoconus for over 30 years. Following Dr. Driscoll’s Graduation from the Illinois College of Optometry, he joined the residency program at the Tuscaloosa VA Medical Center in Tuscaloosa, Alabama. Dr. Driscoll likes to write. He wrote An Eye Doctor Answers: Explanations To Hundreds Of The Most Common Questions Patients Wish They Had Asked, available on Amazon.com, and The Patient’s Guide to Keratoconus which you can download here.
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