Keratoconus is a condition that affects the shape and clarity of your cornea, the transparent layer that covers the front of your eye. It causes your cornea to thin and bulge outwards into a cone-like shape, which can distort your vision and make you sensitive to light and glare. Keratoconus usually starts in adolescence or early adulthood and can progress for 10 years or more. It can affect one or both eyes, often differently. In this blog post, we will answer some of the most frequently asked questions about keratoconus. If you have keratoconus or know someone who does, this post may help you understand more about this condition and how to cope with it.
What is keratoconus and how does it affect your vision?
Keratoconus is a disorder of the eye that results in progressive thinning of the cornea, which is the clear, dome-shaped front surface of your eye. This causes your cornea to bulge outward into a cone shape, which distorts your vision and makes you more sensitive to light and glare. Keratoconus usually affects both eyes, though it often affects one eye more than the other. It generally begins to affect people between the ages of 10 and 25 and may progress slowly for 10 years or longer.
Keratoconus can affect your vision in various ways, such as causing blurry or double vision, nearsightedness, irregular astigmatism and poor quality-of-life. Depending on the severity of your condition and how quickly it is progressing, you may need different treatments to slow down the disease and improve your vision. Some possible treatments include eyeglasses or contact lenses, corneal collagen cross-linking (a procedure that strengthens the cornea), or cornea transplant surgery (a procedure that replaces your damaged cornea with a healthy donor cornea).
What are the symptoms and signs of keratoconus?
Some of the symptoms and signs of keratoconus are
- Blurred or distorted visio
- Double vision when looking with one eye
- Increased sensitivity to bright light and glare, which can cause problems with night driving
- Halos around bright lights
- Frequent changes in eyeglass prescriptions
- Sudden worsening or clouding of vision
These symptoms and signs may change as the disease progresses and may vary depending on the stage and severity of keratoconus.
What causes keratoconus and who is at risk?
The exact cause of keratoconus is not fully understood, but it may involve a combination of genetic and environmental factors. Some possible risk factors for developing keratoconus include:
- Family history. About 10 to 20 percent of people with keratoconus have a family history.
- Childhood eye-rubbing. Excessive childhood eye rubbing may contribute to the progression of keratoconus.
- Certain underlying disorders. Keratoconus may occur in association with some genetic or systemic conditions, such as Down syndrome, sleep apnea, asthma, Marfan syndrome, brittle cornea syndrome, and Leber congenital amaurosis.
- Irregular astigmatism. Keratoconus can cause irregular astigmatism (irregular curvature of the eye), which can also worsen vision quality.
How is keratoconus diagnosed and what tests are used?
Keratoconus can be diagnosed through a routine eye exam. Your eye doctor will review your medical and family history and conduct various tests to check for vision problems and changes in the shape of your cornea. Some common tests to diagnose keratoconus include:
- Eye refraction: This test measures your eyes to check for vision problems. You may be asked to look through a device that contains wheels of different lenses (phoropter) or a hand-held instrument (retinoscope) to help judge which combination gives you the sharpest vision.
- Slit-lamp examination: This test uses a vertical beam of light and a low-powered microscope to view your eye. Your doctor evaluates the shape of your cornea and looks for other potential problems in your eye.
- Keratometry: This test focuses a circle of light on your cornea and measures the reflection to determine the basic shape of your cornea.
- Computerized corneal mapping: This test uses special photographic tests, such as corneal tomography and corneal topography, to record images and create a detailed shape map of your cornea. Corneal tomography can also measure the thickness of your cornea. Corneal tomography can often detect early signs of keratoconus before the disease is visible by slit-lamp examination.
What are the treatment options for keratoconus and how effective are they?
There are different treatment options for keratoconus depending on the severity and progression of the disease. The effectiveness of these treatments varies depending on individual factors such as age, eye health, lifestyle, etc. Some of the treatment options are:
- Corneal collagen cross-linking: This is a procedure that involves applying a vitamin B solution to your eye and then exposing it to ultraviolet light for about 30 minutes or less. This strengthens the collagen fibers in your cornea and helps prevent it from bulging further. This treatment may slow or stop the progression of keratoconus and possibly prevent the need for a future cornea transplant.
- Eyeglasses or soft contact lenses: These can correct mild to moderate keratoconus by improving your vision. However, you may need to change your prescription often as your cornea changes shape.
- Specialized contact lenses: These include rigid gas permeable lenses, hybrid lenses, scleral lenses, and piggyback lenses. They are designed to fit over your irregularly shaped cornea and provide better vision than glasses or soft contacts. They may also help protect your cornea from rubbing and scarring.
- Corneal inserts: These are small plastic rings that are surgically implanted into your cornea to flatten it and improve your vision. They may also delay further deterioration of your cornea.
- Cornea transplant surgery: This is an option for people who have advanced keratoconus with severe scarring or thinning of their cornea that cannot be corrected by other means. It involves replacing part or all of your damaged cornea with healthy donor tissue. The success rate of this surgery is high, but there are risks such as infection, rejection, glaucoma, cataract, etc.
How can glasses or contact lenses help with keratoconus?
Glasses or contact lenses can help with keratoconus by correcting your vision and reducing the effects of irregular astigmatism caused by your cornea’s shape. However, not all glasses or contact lenses are suitable for keratoconus. The best type of glasses or contact lenses for you depends on the severity of your condition and your personal preference. Some of the options are:
- Glasses: Glasses can correct blurry or distorted vision in early keratoconus. But people frequently need to change their prescription for eyeglasses as the shape of their corneas change. Glasses may also not be able to correct higher order aberrations (HOAs), which are visual distortions such as glare, halos, starbursts, etc., that occur in more advanced keratoconus.
- Soft contact lenses: Soft contact lenses can also correct mild to moderate keratoconus by improving your vision. However, they may not fit well over your irregularly shaped cornea and may cause rubbing and irritation. They may also not be able to correct HOAs as well as rigid surface contact lenses. There are some custom soft contact lenses designed for the correction of astigmatism from keratoconus.
- Rigid gas permeable (RGP) contact lenses: RGP contact lenses are hard contact lenses that have a smooth surface that conforms to your eye’s shape. They can provide better vision than glasses or soft contacts by reducing both lower order aberrations (LOAs), which are common refractive errors such as nearsightedness, farsightedness, and regular astigmatism; and HOAs. However, they may be uncomfortable to wear at first and may require frequent adjustments.
- Hybrid contact lenses: Hybrid contact lenses have a RGP central zone surrounded by an outer zone made of silicone hydrogel material. They can provide the clarity of RGP lenses with the comfort of soft lenses. They are another good option for mild to moderate keratoconus.
- Scleral contact lenses: Scleral contact lenses are large-diameter RGP lenses that vault over your entire cornea and rest on the white part of your eye (sclera). They create a tear-filled space between your eye and the lens that acts like a smooth optical surface. They can provide excellent vision correction for severe keratoconus with high levels of HOAs. They are also more stable and comfortable than smaller RGP lenses.
What is corneal collagen cross-linking and how does it work for keratoconus?
Corneal collagen cross-linking (CXL) is a procedure that strengthens and stabilizes the cornea by creating new links between collagen fibers within the cornea. The collagen fibers are the main structural component of the cornea that give it its shape and strength.
The CXL procedure involves two steps:
- First, liquid riboflavin (vitamin B2) is applied to the surface of your eye. This may require removing the thin outer layer of your cornea (epithelium) or using a special formulation that can penetrate through it.
- Second, your eye is exposed to ultraviolet (UV) light for about 30 minutes or less. The UV light activates the riboflavin in your cornea and causes it to form new bonds between the collagen fibers.
The new bonds increase the rigidity and stability of your cornea and help prevent it from bulging further. This may slow or stop the progression of keratoconus and possibly prevent the need for a future cornea transplant. However, this treatment does not reverse keratoconus or improve vision. You may still need glasses or contact lenses after CXL.
CXL is a relatively safe and minimally invasive procedure that can be done as an outpatient surgery. You may experience some side effects such as pain, sensitivity to light, dry eye, blurry vision, infection, or scarring. Your vision will be very blurry at first but should gradually improve within two to three weeks. You should follow your doctor’s instructions on how to care for your eye after CXL and when to resume your normal activities.
When is a corneal transplant necessary for keratoconus and what are the risks and benefits?
A corneal transplant is a surgical procedure that involves replacing part or all of your damaged cornea with healthy donor tissue. It is an option for people who have advanced keratoconus with severe scarring or thinning of their cornea that cannot be corrected by other means.
The benefits of a corneal transplant for keratoconus are:
- It can restore your vision and reduce your dependence on glasses or contact lenses.
- It can improve your quality of life and allow you to perform daily activities more easily.
- It has a high success rate, with about 90% of transplants lasting at least 10 years.
The risks of a corneal transplant for keratoconus are:
- It may require long-term use of eye drops to prevent rejection or inflammation of the donor tissue.
- It may not provide satisfactory vision or may fail over time, requiring another surgery.
A corneal transplant is usually done as a last resort when other treatments have failed or are not suitable.
How can I prevent or slow down the progression of keratoconus?
There is no way to prevent keratoconus, but you can try to reduce your risk and slow down its progression by:
- Getting regular eye exams
- Avoiding eye rubbing or doing it gently
- Treating any conditions that affect your eyes or cause inflammation
- Wearing sunglasses to protect your eyes from UV rays
- Following your doctor’s instructions on glasses or contact lenses
- Considering corneal collagen cross-linking (CXL), a procedure that strengthens the cornea and may prevent the need for a cornea transplant in some cases
How does pregnancy affect keratoconus or its treatment?
Pregnancy may affect keratoconus or its treatment in several ways:
- Pregnancy may cause hormonal changes that can reduce the stiffness of your cornea and make it more prone to bulging or thinning.
- Pregnancy may trigger or worsen keratoconus in some women who have a genetic predisposition or unrecognized keratoconus before pregnancy.
- Pregnancy may require you to change your glasses or contact lenses prescription more often as your vision changes.
- Pregnancy may limit your options for keratoconus treatment, such as corneal collagen cross-linking (CXL) or surgery, which are not recommended during pregnancy or breastfeeding.
Where can I find support groups or online communities for people with keratoconus?
There are several support groups or online communities for people with keratoconus where you can find information, advice, and emotional support from others who share your condition. Some of them are:
- Keratoconus Group on Facebook: This is a support community for keratoconus patients, their family and friends, and eye care professionals. You can join the private Facebook group at Facebook.com/groups/KeratoconusGroup to chat with over 28,000 members from around the world.
- r/Keratoconus on Reddit: This is a subreddit for people with keratoconus where you can post questions, share experiences, and get advice from other redditors. You can visit this subreddit at Reddit.com/r/Keratoconus to join the discussion.
- National Keratoconus Foundation: This is an outreach program of Gavin Herbert Eye Institute at UC-Irvine that provides resources and education to individuals with keratoconus. You can visit their website at www.nkcf.org to access newsletters, webinars, and podcasts.
How do I choose a qualified eye doctor who specializes in treating keratoconus?
To find a keratoconus specialist, you can:
- Ask your regular eye doctor for a referral
- Ask for recommendation in r/Keratoconus community on Reddit
- >Ask for recommendation in Keratoconus Group's private Facebook group
- Check online directories or databases of keratoconus specialists
- Research the credentials and reputation of potential keratoconus specialists
- Schedule a consultation with one or more keratoconus specialists and ask them questions
What questions should I ask my eye doctor about keratoconus and its treatments?
Asking your eye doctor about your condition or treatment can help you understand your eye health better and make informed decisions. Some questions you can ask your eye doctor about keratoconus or its treatment are:
- What is the cause of my keratoconus?
- How severe is my keratoconus and how fast is it progressing?
- What are the best options to correct my vision?
- Is corneal collagen cross-linking a suitable treatment for me? How does it work and what are the risks and benefits?
- Do I have a higher risk of developing complications such as corneal scarring or hydrops?
- Is keratoconus genetic? Should I have my family members tested?
These are just some examples of questions you can ask your eye doctor. You may have other questions that are specific to your situation. The important thing is to be curious and proactive about your eye health.
How common is keratoconus and how does it vary by age, gender, ethnicity, etc.?
Keratoconus is a relatively rare condition, but its exact prevalence varies depending on the source and method of diagnosis. One study from the Netherlands estimated that the annual incidence of keratoconus in people aged 10-40 years was 1:7500 (13.3 cases per 100 000) and the prevalence in the general population was 1:375 (265 cases per 100 000). Another systematic review and meta-analysis reported that the global prevalence of keratoconus ranged from 3.3 to 2300 cases per 100 000.
Keratoconus may also vary by age, gender, ethnicity and other factors. Some studies have found that keratoconus is more common and severe in people of Asian origin compared to white people, and that Asians tend to present at a younger age. Keratoconus also seems to affect males more than females, although this may depend on the diagnostic criteria used. Other possible risk factors for keratoconus include genetic factors, eye rubbing, atopy, sun exposure and hormonal changes.
Is keratoconus genetic or inherited and can it be passed on to my children?
Keratoconus is a complex condition of multifactorial etiology. Both genetic and environmental factors are associated with keratoconus. Evidence of genetic etiology includes familial inheritance, discordance between dizygotic twins, and association with other known genetic disorders. Around 1 in 10 people with keratoconus also have a parent with the condition. However, not everyone who inherits genes for keratoconus will develop it. Certain environmental and behavioral factors also play a role. These are called epigenetic factors. Some examples of epigenetic factors are rubbing your eyes vigorously, having certain conditions such as retinitis pigmentosa or Down syndrome, or wearing contact lenses for a long time.
Therefore, keratoconus can be passed on to your children if they inherit genes for it from you or your partner. However, this does not mean that they will definitely develop it. The risk may depend on other factors as well. If you have keratoconus or a family history of it, you may want to consult an eye doctor (ophthalmologist or optometrist) for more information and advice on how to monitor your children’s eye health.