Today I want to talk a bit about the children’s vision problem of a lazy eye. A lazy eye, technically referred to as amblyopia, means that one eye has not developed normally and always has blurred vision, even with the best correction of glasses or contact lenses.
Lazy eye is caused when the brain favours one eye and refuses to use the other because it cannot use the two eyes together. Because the vision is “turned off”, clear vision does not develop in the lazy eye.
How a Lazy Eye Develops
When we are born with normal vision, we learn to use both eyes together within the first few months of life. Our brains take the pictures from the two eyes and “fuse” it into one image. This is called binocularity.
When we have a lazy eye, our brains did not learn to use the two eyes together. At an early age, these children only use one eye, and their brains “turned off” the images coming in from the other eye. This is called suppression. Because the brain suppressed the lazy eye very early in life, normal vision did not have a chance to develop. So the child has lost the ability to see clearly out of that lazy eye, even with the best pair of prescription glasses or contact lenses. The amount of vision lost depends on how early the brain turned the eye off.
Causes of a Lazy Eye
Refractive Amblyopia This is when one eye is more nearsighted or farsighted than the other, making it difficult for the two eyes to focus together. It starts very early in life. An infant has no way of telling his parents that the one eye does not see as well as the other; so his visual system has to handle the problem by itself. Because it’s difficult to fuse the clear image with the blurry one, the brain suppresses the vision in the blurry eye that’s interfering and just uses the clear one. Long term suppression of the blurry eye causes vision to stop developing. Once discovered, treatment involves prescribing glasses, eye patching and vision therapy. This will establish binocularity and assist development of the poor visual skills that did not have a chance to develop on its own.
Strabismic Amblyopia Strabismus, often called crossed eye or squint, is a condition in which the brain is unable to properly align the two eyes. As a result, one eye may point in or out, up or down. When the two eyes are not pointing in the same place, two different images are being sent to the brain. The brain cannot fuse two different images into one and the result is double vision. The brain is then forced to turn off the vision coming from the misaligned eye to avoid seeing double. The child only uses the straight eye to see and vision in the turned eye does not have a chance to develop.
Treatment for a Lazy Eye
To correct amblyopia, the blurry eye must first be forced to work in order to allow the opportunity for clear vision to develop.
Patching does have some disadvantages. Because the good eye is covered, the child cannot see well and is often frustrated and uncooperative. It becomes difficult to keep the patch on the child. Also, there is a danger of loss of vision in the clear eye when it is covered most of the time for weeks on end.
The gains form patching is not always permanent. While it improves vision, it does not always improve the vision in the lazy eye to 20/20. And once patching is stopped, the improvement in vision can sometimes reverse itself.
In cases of strabismus (squint/crossed eye), surgery is sometimes recommended. Unfortunately, eye surgery does nothing to restore normal two-eyed vision, a learned process of the brain. Surgery simply makes the eyes appear straight, a cosmetic fix, and not a visual cure. The child will still suppress the lazy eye after surgery.
Vision therapy is highly successful in remediating a lazy eye. It not only corrects the poor vision in the lazy eye, but it also corrects the underlying problem of the brains inability to align and use both eyes together, so the gains are permanent. The patient’s brain is trained to stop suppressing the lazy eye and to fuse the images coming from both eyes for normal two eyed vision. This can be done at any age and is prescribed by a developmental/behavioral optometrist.
The “Critical Stage” for Treatment
Some parents are told that a lazy eye can only be corrected when the child is very young, usually age 6 or under. Some optometrists feel that if treatment is not undertaken during this “critical stage” of development, the amblyopia becomes fixed and untreatable. Parents of older children with lazy eyes are often told that it is too late to treat the problem. New research has found that a lazy eye can be corrected at any age when glasses and patching are combined with vision therapy.
A lazy eye is not easily recognized. A child may not even be aware that one of his eyes is not working with the other. If the eye misalignment is so slight, parents will not be able to tell something is wrong just by looking.
It is extremely important for children to develop equal vision in both eyes in order to succeed in school, sports, or any other activity that requires clear vision, good eye hand coordination, and strong depth perception. Children with untreated amblyopia may have a limited choice of career, and if there is an injury to the one good eye, they could be visually impaired or legally blind for life.
For these reasons, it is extremely important for parents to have their child’s eyes examined by an optometrist or ophthalmologist as early as possible so vision problems can be found and treated. Vision can be tested in infants and very young children, and it is recommended that a child be examined at least by the age of three.Leave a reply
If your optometrist or ophthalmologist has told you that you have glaucoma, you may be wondering what that means and how it can affect your sight. Glaucoma is a serious eye disease, but in most cases it can be controlled with correct treatment. Read on to find out glaucoma symptoms, types and treatment options. At the end we leave you with some tips to saving your sight with glaucoma.
What is Glaucoma?
Fluid is always flowing through the inside of your eye. If you have glaucoma, this fluid does not flow normally. Pressure inside your eye then rises and damages your sight. If the pressure remains high, it can cause blindness.
Your eye drains sort of like a sink. If the drain is clogged or blocked, the sink backs up. With glaucoma, the holes that fluid drain through get clogged or blocked. Pressure rises and it slowly destroys the delicate fibres of the optic nerve that send visual information to the brain and vision loss occurs starting with side vision.
Types of Glaucoma
The type of glaucoma you have depends on the size of the angle between the iris and the cornea, where the drainage holes lie.
Open Angle Glaucoma
This is the most common kind of glaucoma. Eye pressure rises slowly and destroys vision gradually, starting with side vision. There is no pain or other warning signs. In some cases vision may be lost, even though pressure stays within a normal range (low tension glaucoma).
The angle between the iris and cornea is normal, but the drainage holes get clogged from the inside.
Closed/Narrow Angle Glaucoma
This is less common. The condition is either acute (closed angle) or chronic (narrow angle). With the acute form eye pressure rises suddenly and vision can be lost within a few hours and must be lowered right away to prevent blindness. Severe pain, nausea, vomiting and blurred vision can occur with an acute attack. With the chronic form of closed angle glaucoma, pressure rises more slowly and often without any symptoms.
The angle is narrower than normal. If fluid can’t get through the angle, the iris pushes forward and blocks the drainage holes.
Other forms of glaucoma can be linked to an injury or inflammation of the eye, a cataract, an eye tumor, or advanced diabetes.
Who Does Glaucoma Affect?
The major risk factor for glaucoma is age. Glaucoma most often affects people over 50, but everyone over 35 should be tested at least every 2 years. African people are more likely to develop open angle glaucoma at a younger age, than if you are Caucasian. Asians are more likely to develop closed angle glaucoma. You also have a higher risk of developing glaucoma if a close family member has had the disease or if you have high blood pressure or high blood sugar. If you are at risk for glaucoma, you should have your eyes checked at least once a year.
How Is Glaucoma Diagnosed?
Most people learn they have glaucoma during an eye exam. Simple tests that measure your eye pressure and examining the inside of your eye usually alert your eye doctor to a problem. Other tests reveal loss of vision and damage to the delicate structures of your eye.
Taking Your Medical History
Because glaucoma is often hereditary, your eye doctor needs to know if other members of your family have the disease. You also need to tell your eye doctor about any medical conditions you have, such as high blood sugar, high blood pressure, irregular heart beat or lung disease that could affect your eye pressure.
Measuring Your Eye Pressure
An instrument called a tonometer measures the pressure inside your eyes. Your eye doctor lightly touches a plastic prism to your eyeball. Your eye is numbed with drops, so this should be painless. Sometimes your pressure may be measured by a tonometer that sends a puff of air onto the cornea.
Examining Your Optic Nerve
Your eye doctor examines the inside of your eyes for changes in your optic disc. Changes indicate damage from pressure. Your eye doctor looks through each pupil with a hand held instrument called an ophthalmoscope. Your pupils may also be dilated and pictures taken to record changes in your optic disc.
Checking Your Drainage Angle
Your eye doctor examines the angle between the iris and the cornea, where the drainage holes lie. A special lens called a gonioscope is used which tells the eye doctor whether the drainage angle is open or closed. This helps determine the kind of glaucoma you have.
Testing Your Field of Vision
A visual field test, called perimetry, tells your eye doctor whether you have lost any side vision. A printout is then made to show your field of vision.
How is Vision Loss Stopped?
Your eye doctor cannot restore vision that has already been lost, but in most cases eye pressure can be lowered to prevent further loss of sight. Your treatment depends on the type of glaucoma you have and how it responds to medication. Some cases may require laser treatment or surgery.
Treating Open Angle Glaucoma
In most cases of open angle glaucoma, pressure inside the eyes rises and damages the optic nerve. The only ways to control pressure and prevent loss of vision are to decrease fluid production or increase drainage. To decrease fluid production, your eye doctor may prescribe eye drops. To increase drainage your eye doctor may recommend eye drops or laser treatment or surgery to open the drainage holes.
Depending on your condition, you may use one or more kinds of eye drops. Drops that decrease production of fluid are used one or two times a day. Drops that increase drainage are used two to four times a day. Most people can use eye drops without any side effects, but they can cause headaches, eye irritation, blurred vision and other symptoms.
When eye pressure can’t be controlled with eye drops, laser treatment is used in a procedure called trabeculoplasty. The laser is a beam of energy that can be focused to a tiny point. The laser is aimed at precise spots around the edge of the iris (coloured part). Each burst of laser stretches the tissue to open the clogged holes and allow fluid to drain freely.
When laser treatment can’t control your eye pressure, the eye doctor may suggest a procedure called trabeculectomy. A new drain is made in your eye so that fluid can bypass the clogged drainage holes. The doctor makes a flap in the sclera (white part), and a tiny hole is made under this flap. This new opening allows fluid to drain freely. This is usually done as outpatient surgery. You’re awake, but your eye is numbed so you shouldn’t feel any pain.
Treating Closed Angle Glaucoma
This is a medical emergency so urgent treatment is needed to lower pressure as fast as possible to prevent damage to the optic nerve and save your sight. Eye drops are needed every 15 – 30 minutes to decrease production of fluid and pull the iris away from the drainage holes. Your doctor may also use diuretic pills and medication given through an IV line to decrease production of fluid.
Once the pressure is lowered, a laser is used to make a new opening in your iris. This is called an iridotomy. This takes a few minutes and you can go home afterwards and resume your normal routine. Your doctor may check your pressure again the next day.
Tips for Saving Your Sight
Untreated, glaucoma can quietly steal your sight. Always stick to your treatment plan and save your vision. Because glaucoma can run in families, encourage other members of your family to have their eyes checked regularly too.
- Use your medication as directed- even after your pressure is under control.
- Make and keep regular appointments with your eye doctor.
- Tell your eye doctor if you have any side effects, notice any changes to your vision, or forget to take your medication.
- Make sure you understand exactly how and when to take your medication. Learn the name and dosage of each drop and what it does.
- If you forget to take your medication, take it as soon as you remember. Don’t wait until the next regular time.
- Wherever you go, always carry your medication with you. Take an extra supply when you travel.
- Tell all your doctors that you have glaucoma and give them a list of your medications. This can help prevent interactions with other medications you take.
- When you buy over the counter drugs, read the label. Check with your eye doctor if the label says that anyone with glaucoma shouldn’t take this medication.