Keratoconus is a rare, progressive disease that affects the cornea, which is the clear, transparent layer at the front of the eye. The cornea is responsible for focusing the light that comes into your eye onto the retina for clear, sharp vision. Keratoconus causes the corneal tissue to thin out and bulge into a cone-like shape which deflects the light entering the eye and distorts vision.
The exact cause of keratoconus is not known. The disease usually starts to appear in the late teens or twenties and can affect one or both eyes, usually progressing at a slow pace and slowing or stabilizing after around 10-20 years. It is believed that there is a genetic component as often it runs in families.
New research suggests that there may be a link between keratoconus and oxidative damage which weakens the cornea. There is also an association with overexposure to ultraviolet (UV) radiation from the sun and chronic eye irritation.
With the gradual change in the shape of the cornea, vision becomes progressively worse. The patient may experience nearsightedness, astigmatism, distorted vision (straight lines look wavy), blurry vision, light sensitivity and glare, and eye redness or swelling. Typically, patient’s eyeglass prescription will change often as the vision becomes worse and contact lenses will be difficult to wear due to discomfort and improper fit.
When keratoconus become more severe (which usually takes a long time however on occasion can happen rather quickly), the cornea can begin to swell and form scar tissue. This scar tissue can result in even further visual distortion and blurred vision.
In the early stages of the disease, standard eyeglasses and soft contact lenses will usually correct the nearsightedness and astigmatism experienced by the patient. As the disease progresses however, glasses and soft contact lenses may no longer correct vision and soft lenses may become uncomfortable. This is when other forms of vision correction will be recommended.
Gas Permeable and Scleral Contact Lenses
At the more advanced stage of keratoconus rigid gas permeable (RGP) contact lenses, scleral or semi-scleral lenses may be used for increased comfort and visual acuity. Since they are more rigid, RGP and scleral lenses are able to create a smooth, round shape around the cornea, creating a smoother surface for better vision. Scleral or semi-scleral lenses have a larger diameter which covers the entire cornea and reaches over into the white part of the eye, which is known as the sclera. Many patients find these more comfortable than regular RGPs and find that they move around less when the eyes move. The main disadvantage of these rigid lenses is that for some, they are somewhat less comfortable than soft lenses and they must be continually refit as the shape of the eye changes.
Whether it is glasses or contact lenses being used to correct vision, patients will likely have to undergo many tests and prescription changes as their vision needs change.
Intacs are small, surgically implanted plastic inserts which are placed on the cornea to flatten it back to shape. Usually they are able to restore clear vision, with the continued use of glasses. Intacs are often recommended when contact lenses and eyeglasses are no longer able to correct vision adequately. Intacs take about 10 minutes to insert and can delay the need for corneal transplant.
Corneal Crosslinking (CXL)
In corneal crosslinking, a UV light and eye drops are used to strengthen and stiffen the cornea which helps to reduce bulging and restore the cornea to its natural shape.
When corneal scarring occurs and eyeglasses and contact lenses no longer help, doctors may suggest a corneal transplant to replace the corneal with healthy donor tissue to restore vision. Most patients will still require eyeglasses or contact lenses for clear vision following the transplant.
Keratoconus is a condition that requires ongoing treatment by a qualified eye doctor. If you or a loved one suffers from this disease make sure that you find an eye doctor that you like and trust to accompany you on this journey.
Symptoms of Keratoconus
Keratoconus typically first appears in individuals who are in their late teens or early twenties, and may progress for 10-20 years, and then slow or stabilize. Each eye may be affected differently. In the early stages of keratoconus, people might experience:
- Slight blurring of vision
- Distortion of vision
- Increased sensitivity to light
The cornea is responsible for focusing most of the light that comes into the eye. Therefore, abnormalities of the cornea, such as keratoconus, can have a major impact on how an individual sees the world, making simple tasks such as driving a car or reading a book very difficult.
Astigmatism Diagnosis & Treatment
Astigmatism is a very common eye condition that’s easily corrected with eyeglasses or contact lenses and on some occasions, surgery.
Astigmatism is caused when your eye is not completely round. Because our bodies are not perfect, astigmatism occurs in nearly everybody to some degree but for some, not to the degree that it causes blurring. Your eye is naturally shaped like a sphere. Under normal circumstances, when light enters the eye, it bends evenly, creating a clear picture on the back of your eye. In a person with astigmatism, their eye is shaped more like a football and light entering the eye is bent more in one direction than the other. This causes only part of the picture to be in focus at any given time. Objects at any distance can appear blurry and wavy. For vision problems due to astigmatism, glasses or contact lenses, and sometimes even vision correction surgery are all possible treatments.
People with undetected astigmatism often have blurred vision which can be associated with fatigue and eyestrain. While these symptoms may not necessarily be the result of astigmatism, you should schedule an eye exam if you are experiencing one or more symptoms.
Our eye doctor in Sarasota can diagnose astigmatism with a thorough eye exam. Astigmatism may occur in combination with other vision problems such as nearsightedness and farsightedness. Because astigmatism gets worse over times, visit Dr. Soto whenever you notice changes in your vision.
Many people have never heard of astigmatism, although it is an extremely common eye condition.
Astigmatism is one type of refractive error. Nearsightedness and farsightedness are other types of refractive error. Refractive errors are not eye diseases. Refractive error is a result of and imperfection of the size and shape of the eye, which results in blurry or double vision.
If left untreated, astigmatism may cause eyestrain, headaches, and blurry vision. If you have astigmatism you may not see objects in the distance or near without some form of distortion.
Small amounts of astigmatism can go unnoticed, however, you may be suffering from eye fatigue, eyestrain, and headaches.
Astigmatism is a condition that usually can develops early in childhood. According to a study from The Ohio State University School of Optometry, 28% of school age children suffer from astigmatism. Parents should be aware that their children might not notice that their vision is blurry, not understanding that this is not normal. Nevertheless, astigmatism should be treated because vision problems can lead to learning problems and in extracurricular activities. Make sure to have your child’s eyes examined at an eye doctor’s office at least once a year.
Astigmatism is generally caused by a cornea with an irregular shape. The cornea is the front, clear layer of the eye. With astigmatism, the cornea is not round and spherical and is instead irregular having two curves instead of one curve. Astigmatism in some cases could also be caused by the lens located inside the eye that is irregular in shape.
Eyes with astigmatism distort the light that comes into the eyes because the cornea is irregularly shaped. This causes the light rays entering the eye to create two images in the back of the eye (because of the two curves), instead of one image. This is what causes the distortion in sight.
For most people, their astigmatism is fully corrected using prescription glasses or contact lenses. If you select contact lenses to correct your vision, soft contact lenses are the most common option. If for whatever reason soft contact lenses are not an option, rigid gas permeable (RGP or GP) are also a great choice. Rigid gas permeable lenses usually give the clearest vision but the adaptation process will be significantly longer. Another option are hybrid contact lenses. These contacts have a center made from a rigid gas permeable (RGP) lens and an outer ring made of soft contact lens material. This type of lens provides both excellent clarity and comfort. LASIK could be another option to correct astigmatism. LASIK usually only corrects low levels of astigmatism and some patients with higher levels of astigmatism might not be candidates.
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