Patient Education Library
In order for the eye to work properly, light coming into the eye must be properly focused on the retina (or the back of the eye). When the image is not focused, there is an irregularity in the eye. This irregularity can be the overall shape of the eye or the curvature of the cornea (the clear outer covering of the eye), or both. The cornea should be curved equally in all directions. Astigmatism occurs when the cornea is curved more in one direction than another.
Astigmatism is quite common and, in the vast majority of cases, it is due simply to variations between people. Just as different people have different shaped feet or hands, people also have different shaped corneas. Rarely astigmatism is caused by lid swellings such as chalazia, and corneal scars, or by keratoconus (a rare condition in which the cornea becomes misshapen and pointed rather than smooth and rounded).
Astigmatism may cause blurred vision, eye strain or even headaches. It can also cause images to appear doubled, particularly at night. Small amounts of astigmatism can be ignored. But if any of its symptoms are present, astigmatism can be corrected by glasses or contact lenses. In most patients hard contact lenses do a better job of correcting for astigmatism than soft contact lenses.
Blepharitis is an infection of the eyelids. It is very common, and it is a permanent condition. Once it is present, it will always be present, but the severity may change over time. In some cases, the symptoms can disappear for long time periods, months or years, before returning.
Blepharitis can be controlled by careful cleaning of your eye lashes every day. This can be accomplished with warm water and mild shampoo (such as baby shampoo). Once the redness and soreness are under control, this cleaning may be decreased from daily to twice weekly. However, if the symptoms return, daily cleansing must be resumed immediately. Medication is of secondary importance in the treatment. In some cases eye drops or ointment will be prescribed to be used along with the daily cleansing.
However, medication alone is not sufficient; keeping the eyelids clean is essential. Warm, moist compresses can also help relieve the symptoms of blepharitis when used in conjunction with regular eyelid cleansing.
There are two main causes of blepharitis: staphylococcus bacteria and seborrhea. Staphylococcus bacteria commonly begins in childhood and continues throughout adulthood. Common symptoms include collar scales on lashes, crusting, and chronic redness at the lid margin. Dilated blood vessels, loss of lashes, sties, and chalazia also occur. Treatment is very important. In addition to eliminating the redness and soreness, treatment can prevent potential infection and scarring of the cornea and conjunctiva.
Seborrhea is secondary to overactive glands causing greasy, waxy scales to accumulate along the eyelid margins. Seborrhea may be a part of an overall skin disorder that affects other areas. Hormones, nutrition, general physical condition and stress are factors in seborrhea.
Cataracts occur as part of the normal aging process. Studies show that virtually everyone over age 65 has some cataract formation in their eyes! Cataracts can severely reduce your vision. At one time, cataracts were a leading cause of blindness in the world. But today, fortunately they can be treated. Modern surgical techniques, intraocular lens implantation and “same day surgery” make cataract surgery safe, fast and effective.
A cataract occurs when the normally clear lens of the eye becomes cloudy. As the cataract develops, the cloudiness no longer allows the lens to properly focus light on the back of the eye. This unfocused light causes the vision to look blurry or hazy. Development of cataracts has been associated with exposure to ultraviolet radiation. They are particularly prevalent in persons who spend a lot of time in the sun, such as fisherman. There is nothing you can do to prevent the formation of cataracts.
Treatment is indicated when decreased vision affects your everyday activities or hobbies. To determine how much your vision is decreased, your doctor should test you with a new test called contrast sensitivity. This test determines how much your everyday vision has been affected by the cataract.
Cataract surgery, in which the normal cloudy lens is removed, is now a very successful procedure. The most widely used technique is called phacoemulsification. A very small incision is made and a tiny ultrasonic probe is used to break up the cataract and gently suction it away. A clear membrane is left in your eye where an intraocular lens is placed (IOL). This IOL is necessary to replace the focusing power of the natural lens, which was removed. With insertion of an IOL, there is little need for thick cataract glasses and contact lenses that were used years ago.
Small incision surgery has several benefits. The procedure is very quick, sometimes taking less than 20 minutes. Also, recovery time is short. Patients are able to eat a light snack and drink immediately after the surgery. The results of the surgery are almost immediate. Most people notice an improvement in their vision soon after surgery. You will still need glasses to read after the surgery. Your new prescription is given several weeks after the procedure.
The human eye has receptors that are sensitive to three primary colors, red, green and blue. The brain is able to blend these three primary colors so that the eye is able to discriminate very slight differences. A person with normal color vision can see approximately 8,000 colors in nearly 8 million different shades and tints.
The retina is made up of 10 layers of different kinds of cells. These cells are connected to the brain by approximately 1 million tiny nerve fibers. When stimulated by light, these nerve fibers transmit electrical impulses from the eye to the brain, where the signals are interpreted to give vision. The retina is the focus of our “color receptors”.
The very back layer of cells in the retina is called the photoreceptors. There are two types of these cells; rod and cones. Rod function well in dimly lit situations and can perceive only black, white and shades of gray. Rods are located in the outer parts of the retina, away from central vision. Cones are the second type of receptor and they are located primarily in the central part of the retina. This type of receptor functions to provide daytime vision and the important central detail vision, such used for reading small print. There are three types of cones; red, green and blue cones. These three types of cones combine to provide for the wide range in color vision. There are only about 1/3 as many cones as rods.
Color vision testing can be used to identify color defects in your vision. There are many types of color vision tests, from the general screening methods that test your gross perception of color, to other more sensitive tests, which are much more time consuming. The most common type of color vision loss is inherited and occurs from birth. But several diseases are also known to cause color vision losses later in life.
The conjunctiva is a clear membrane that is the tough, leathery outer coat of the eye. The white of the eye actually lies behind the conjunctiva. The conjuctiva has many small blood vessels and it serves to lubricate and protect the eye while the eye moves in its socket.
When the conjunctiva becomes inflamed, this is called CONJUNCTIVITIS. Conjunctivitis can have many causes, such as bacteria (as in “pink eye”), viruses, chemicals, allergies, and more. In many cases it is difficult to determine the primary cause for the inflammation. One of the most common is BACTERIAL CONJUNCTIVITIS.
BACTERIAL CONJUNCTIVITIS is associated with swelling of the lid and a yellowish discharge. Sometimes it causes the eye to itch and a mattering of the eyelids, particularly upon waking. The conjunctiva appears red and sometimes thickened. Often both eyes are involved.
The bacteria most commonly at fault are the Staphylococcus, the Streptococcus, and H. Influenza. This disease is very contagious, and can be easily transmitted by rubbing the eye and then infecting household items, such as towels or handkerchiefs. It is common that entire families become infected.
Conjunctivitis can be directly cured with treatment. Usually antibiotic drops and compresses ease the discomfort and clear up the infection in just a few days. In a few cases, the inflammation does not respond well to the initial treatment with eye drops. In those rare cases a second visit to the office should be made and other measures undertaken. In severe infection, oral antibiotics are necessary. Covering the eye is not a good idea because a cover provides protection for the germs causing the infection. If left untreated, conjunctivitis can create serious complications, such as infections in the cornea, lids, and tear ducts.
Certain precautions can to taken to avoid the disease and stop its spread. Careful washing of the hands, the use of clean handkerchiefs, and avoiding contagious individuals are all helpful. Little children frequently get conjunctivitis because of their poor hygiene.
A corneal abrasion occurs when the outer layer of the cornea, called the epithelium, is torn away. (The cornea is the clear outer coating of the front of the eye.)This can occur by a variety of means such as a finger in the eye, a tree limb, flying glass in an automobile accident, etc. It is one of the most common injuries to the eye.
The corneal has more nerve endings than virtually any other part of the body. Because of these many nerve endings, any damage to the cornea is very painful. Abrasions usually heal in a short time period, sometimes within hours. But while they are healing they can cause excessive tearing, redness, blurred vision and light sensitivity. In many cases, the cornea will heal overnight during sleep. If treatment is needed, it consists of a tight patch to keep the lids from moving and pain relievers as needed for comfort.
An antibiotic may be used following an abrasion because the open area of the epithelium invites infection. Small abrasions heal rapidly. However, if one covers more than one-third of the cornea, it may take an extra day or two for the epithelium to completely recover the front of the cornea.
Typically, an anesthetic is used in the eye doctor’s office to ease the pain and to aid in the examination. After the examination, the pain typically returns. But, repeated use of anesthetic can harm the eye and is therefore not used in the treatment of abrasions. It may take several weeks for all the blurriness to resolve. Permanent loss of vision is very rare with superficial abrasions.
DO NOT rub the eyes during the healing phase following an abrasion. New cells require time to re-connect to the non-damaged layers of the cornea. These new cells can be easily rubbed off. If the new cells get removed, the pain returns and repatching is necessary.
Occasionally, long after an abrasion has healed it recurs spontaneously, often upon awakening in the morning. This is called a recurrent erosion and represents an area of the epithelium that is not re-connected well to the deeper parts of the cornea.
The treatment is similar to that for the abrasion. Sometimes the surface of the cornea is treated with a special instrument in order to help form better connections between the corneal layers. Extended use of bedtime ointments or lubricants may also help in preventing recurrent erosions.
The retina lies in the back of the eye. It is a multi-layer tissue which is responsible for detecting visual images and transmitting these to the brain. The retina is similar to the film inside a camera. A retinal detachment occurs when it pulls away from the back of the eye.
Typically following a retinal detachment, different types of images appear. These include flashing lights, an apparent covering or curtain over part of the visual field or many floaters. Importantly, these symptoms can also be present without a retinal detachment. An immediate exam is necessary if you experience these symptoms.
Sometimes the retina does not fully detach, but only tears. In these cases, treatment is done with a laser or freezing technique (cryotherapy) that seals the tear. If the retina is fully detached, surgery is performed to place the retina back into position.
Diabetes is a disease which affects the blood vessels throughout the body, particularly vessels in the kidney and eye. When the blood vessels in the eye are affected, this is called diabetic retinopathy.
The retina lies in the back of the eye and is a multi-layered tissue which detects visual images and transmits these to the brain. There are major blood vessels which lie on the surface, or the front portion, of the retina. When these blood vessels are damaged due to diabetes, they may leak fluid or blood and grow scar tissue. This leakage affects the ability of the retina to detect and transmit images.
Diabetic Retinopathy is the leading cause of new blindness among adults in the United States. If untreated, there is a risk of becoming blind. The longer one has diabetes, the higher the incidence of developing diabetic retinopathy. Approximately 80% of people who have diabetes for 15 years have some damage to their retinal vessels. With today’s treatment only a small percentage of people have serious vision problems.
There are two types of diabetic retinopathy. Background retinopathy is considered the early stage. Reading vision is typically not affected, but it can advance and cause severe vision problems. There are usually no symptoms with background diabetic retinopathy. An exam is the only way to diagnose changes in the vessels of your eyes.
When the retinopathy becomes advanced, new vessels grow, or proliferate, in the retina. These new vessels are the body’s attempt to overcome and replace the vessels which have been damaged by diabetes. But these new vessels are not normal. They may bleed, which causes vision to become hazy and sometimes causing a total loss of vision. These new vessels can also damage the retina by forming scar tissue and by pulling the retina away from its proper location. This stage, called proliferative retinopathy, requires immediate medical attention. Treatment is necessary to prevent severe loss of vision. Regular eye exams are crucial for all persons with diabetes. The progressing damage to the blood vessels in the eye can be slowed with treatment.
The eye has a tear film which coats the outer layer of the eye. This tear film is very important for the lubrication and comfort of the eye as well as for the clarity of vision. As we age, this protective tear film diminishes, and leaves the eye more exposed to the drying effects of the air, wind and dust. In many people the dryness is worse in the afternoon and evening.
Dry eye is not caused by a lack of tear production. In fact, during dry eye, the eye can still make so many tears that many patients complain of wet eyes and tearing with this malady. That’s because the dryness causes the eye to produce more tears in an effort to replace the tear film. Dry eye is probably the most common problem seen in the eye doctor’s office.
Dry eye symptoms include burning, stinging or a gritty sensation which may come and go depending on many factors. Itching, tearing and light sensitivity may also occur. Occasionally long strings of mucus can be stretched from a dry eye.
Blinking is very important for the maintenance of the tear film. When performing such activities as reading or working on a computer, we blink less frequently. This aggravates the symptoms of dry eyes. Sometimes environmental factors can also aggravate dry eye symptoms. Dry weather, either in hot or cold temperatures, robs the eye of needed lubricants. Cigarette smoke, fumes, dust and airborne particles are common irritants. In most patients, this condition is not associated with systemic disease.
Treatment helps in most patients. We cannot cure this condition, so treatment is an ongoing project. Usually artificial tears, available over-the-counter, soothe the eyes and give temporary relief. These artificial tears work for only an hour or two, at best, and must be repeated at frequent intervals. Ointments last longer, but they blur vision and are most effective at night.
Newer techniques to treat dry eye include plugs which block the tear duct. These plugs can be placed in the two tear ducts, top and bottom, in both eyes or in only the lower ducts. Some test plugs are also available which dissolve a few days after insertion. If the dry eye symptoms disappear when the temporary plugs are inserted, then permanent plugs should be considered as a treatment option.
Flashers and Floaters
The retina lies in the back of the eye and is a multi-layered tissue which detects visual images and transmits these to the brain. In front of the retina lies the vitreous humor. The vitreous is the jelly-like material that fills the large central cavity of the eye. It is composed primarily of water, but it is also made up of proteins and other substances which are more fibrous. The water and fibrous elements together give the vitreous the consistency of gelatin.
The vitreous is normally connected to the retina. During aging, the watery portion of the vitreous separates from the fibrous portions. As this occurs, the fibrous elements contract and can pull the vitreous away from the retina. This is called a Posterior Vitreous Detachment. This contraction on the retina is responsible for the characteristic “flashes” that often accompany the Posterior Vitreous Detachment. The “floaters” are frequently caused by the fibrous elements changing position during the Posterior Vitreous Detachment. They can also be caused by pieces of the retina being dislodged as the vitreous contracts. Besides aging, flashes and floaters are also associated with nearsightedness and injuries to the eye.
All patients who experience a recent onset of flashes and floaters should be examined immediately by their eye doctor. Most of the time nothing unusual is found, and simple reassurance is all that is needed. The flashes eventually go away, and the floaters diminish and become less bothersome with time.
However, in about 10% of the patients with a Posterior Vitreous Detachment, a tear of the retina is found. If left untreated, these tears may lead to a full retinal detachment. A full retinal detachment is a very serious sight threatening condition requiring a major surgical procedure to repair. When symptoms appear, it is important to examine the eye within a day of their onset. Changes can occur rapidly, and time can be of the essence if a retinal detachment is present.
Retinal tears are treated by sealing the tear with a laser or freezing technique (cryotherapy).
Glaucoma is the leading cause of blindness in the United States. It is a disease that typically affects older people, but it can occur at any age. Loss of vision is preventable if the disease is detected early and treatment is started.
The eye has about 1 million tiny nerve fibers which run from the back of the eye to the brain. These nerve fibers allow us to see. Glaucoma is a disease which causes the destruction of these fibers. It was once thought that the loss of these fibers was due to strictly to high pressure in the eye. But now it is known that even patients with normal eye pressure can have glaucoma and loss of these nerve fibers.
In many patients, the disease is not noticed in the early stages, because there is no pain and no noticeable change in vision. Early detection by an eye doctor is the key to the prevention of vision damage from glaucoma. Routine eye examinations are recommended.
Types of Glaucoma
The reason that eye pressure is high in many glaucoma patients is that the drainage system in the eye is not working properly. The fluid in the eye, called aqueous humor, does not flow out of the eye as quickly as it should. The drainage system lies in a part of the eye called the angle, which is between the outer layer and the iris of the eye. This angle can be open or closed.
There are several kinds of glaucoma. The most common form of glaucoma is called chronic open angle glaucoma. The drainage angle is open in these patients, but the eye fluid does not drain as quickly as it should. Closed-angle glaucoma occurs when the drainage angle closes, and almost no eye fluid can escape. During closed-angle glaucoma, eye pressure can get very high and there is pain. Angle closure glaucoma is an emergency and must be treated immediately. If the high pressure is allowed to continue for too long, blindness can result.
Some persons are more likely to have glaucoma. These include persons who are older, have nearsightedness, have a family history of glaucoma, have had past eye injury, have diabetes or have a past history of vascular shock. Also, African-Americans are 6 times more likely to have the disease.
Glaucoma is treated with eye drops that lower the eye pressure. If the pressure does not fall to a low enough level with drops, then surgery may be necessary. Glaucoma surgery opens up the drainage system in the angle so that the eye fluid can flow more freely.
The cornea and the lens work together to focus images from the visual world on the back of the eye (the retina). If an image is out of focus, it is typically because the overall shape of the eye is incorrect or the cornea does not have the proper curvature. Farsightedness or hyperopia occurs when the eye is too small or the cornea is too flat. When this happens, visual images are focused behind the retina.
A person with hyperopia is able to see objects at a distance, but has trouble with objects up close, like books or newspapers. Many people are not diagnosed with hyperopia without a complete eye exam. School screenings typically do not discover this condition because they test only for distance vision.
Treatment includes contact lenses or glasses which correct for near vision. Corrective lenses should be worn for near tasks, such as reading, but do not need to be used for distance vision tasks, such as driving.
Nearsightedness is an extremely common condition where the curvature of an individual�s cornea is too steep to properly focus light onto the retina. Intacs (Intrastromal Corneal Ring Segments) are a safe, easy, non-laser alternative for correcting mild nearsightedness. Intacs are extremely thin, crescent-shaped plastic polymers that restore the cornea to its ideal curvature, resulting in clear, focused vision.
Who is a Good Candidate for Intacs
An initial consultation with a physician can determine whether or not a patient is a good candidate. Intacs are ideally suited for individuals with nearsightedness of 1.00 to 3.00 diopters and no more than 1.00 diopter of astigmatism. (A diopter is a measure of the power of eyeglasses or contact lenses). Patients also need to have stable vision and generally healthy eyes to qualify for Intacs.
The Procedure Explained
Prior to the insertion of Intacs, a small opening is made at the very edge of the cornea. Two crescent-shaped pockets or tunnels are made on the periphery of the cornea, outside the central optic zone (the area where the main ocular functions occur). These pockets are created between the layers of the cornea (known as the stroma) and the Intacs are fitted inside. The thickness of the Intacs depends on the amount of flattening needed (the thicker the Intac, the more flattening occurs). Once the Intacs have been fitted inside the eyes, the small opening is closed up.
Intacs essentially reshapes the cornea, allowing it to maintain its proper curvature. Anesthetic eye drops numb the eye to make the short procedure virtually pain-free. The procedure lasts 15 to 30 minutes and is performed on an outpatient basis.
Following the Procedure
Following surgery, many patients return home and rest for the remainder of the day. Improved vision typically begins to occur within the first 24 hours. Intacs are designed to remain in the eye permanently, although they can be surgically removed if the need arises. They are about as easy to detect as a pair of contact lenses. Best of all, because no corneal tissue is removed, Intacs do not weaken the strength or integrity of the eye.
IOLs for Refractive Surgery
When the eye is unable to properly focus, the result is blurry and unfocused vision. One option to correct for this is IOLs (Intra Ocular Lenses). IOLs have been used for many years to replace the natural lens during cataract surgery. IOLs for refractive surgery differ significantly from other refractive methods in that they do not involve changing the shape and/or structure of the cornea (the clear outer layer of the eye). IOLs replace the natural lens (phakic lens) of the eye and can correct for significant refractive errors, which can greatly enhance vision.
The Ideal Candidate
Phakic IOLs are ideally suited for individuals who are poor candidates for other refractive options, such as LASIK. This includes those with high refractive errors, including myopia greater than 10 diopters and hyperopia greater than +4 diopters. In addition, phakic IOLs are also an excellent choice for those with keratoconus, those who have thin corneas, or for those who are no longer able to tolerate contact lenses or eyeglasses.
The IOL Procedure
Inserting a phakic IOL is a nearly identical process to the lens implantation portion of a cataract procedure. Before surgery, an extensive set of eye tests are taken to determine the proper power of the lens to be inserted. The actual procedure is then performed through a small incision in the cornea. In some cases, tiny foldable IOLs can be inserted through a smaller incision (1/8 of an inch wide). Once inside the eye, these lenses unfold into a full-sized IOL. The advantage of the small incision approach is improved safety and faster recovery of vision after surgery.
The Intra Ocular Lens is implanted between the iris and the front surface of the human lens. IOLs are made of the same plastic as certain types of contact lenses. The procedure is typically performed with a general or topical anesthetic.
Health Issues Associated with Phakic IOLs
As with any surgery, complications are rare, but do exist. The main drawback to IOLs is that, unlike other refractive surgery options, the incision and procedure is performed inside the eye (as opposed to on the surface). The nature of this surgery carries heightened risks for internal eye infection or damage. A consultation with your physician can address potential health complications.
Because the IOLs for refractive surgery procedure is a reversible process, it offers a distinct advantage over some other procedures. If the results are less than optimal, the patient can choose to have the IOLs surgically removed. IOLs typically last forever. Best of all, unlike other refractive surgery options, IOLs do not weaken the strength or integrity of the eye.
LASIK & PRK
The cornea and lens combine to focus visual images on the back of the eye. When the overall shape of the eye is incorrect or when the curvature of the cornea is incorrect, the visual images are not in focus. The cornea accounts for approximately 2/3rds of the focusing power of the eye. By surgically changing the corneal curvature, most or all of the blur can be eliminated.
Laser In Situ Keratomileusis (LASIK) and Photo-Refractive Keratectomy (PRK) are two surgical techniques which utilize lasers to reshape or change the curvature of the cornea.
LASIK had its origins about thirty years ago and was originally developed to treat patients who had very poor vision due to corneal disease. It has now evolved into a successful technique for correcting refractive errors. The current procedure, done on an outpatient basis, involves both the use of conventional and laser surgery to correct nearsightedness, farsightedness and astigmatism. LASIK can correct a much higher degree of nearsightedness with or without astigmatism than any other refractive procedure, with excellent results (95% of patients achieve 20/40 vision or better).
In performing LASIK, eye drop anesthetic is used to numb the eye. The surgeon then uses a special instrument to cut into and behind a layer of the cornea. A portion of the cornea is peeled back to create a flap and expose the inner portions of corneal tissue. The eye is then positioned under the excimer laser which has been computer programmed to remove microscopic amounts of the internal corneal tissue. Removal of the tissue changes the curvature of the cornea. If the patient is nearsighted, tissue closer to the central part of the cornea is removed to decrease the curvature or flatten the cornea. If a patient is farsighted, tissue in the peripheral part of the cornea is removed to increase the curvature of the cornea. To correct for astigmatism, selected tissue at certain angles is removed to insure that the cornea curves equally in all directions. After the laser has been used, the flap is returned to its original position. The corneal tissue has extraordinary natural bonding qualities that allow effective healing without the use of stitches.
Since only local anesthetic is used, patients remain awake during the procedure. The entire procedure takes only a few minutes. Improved vision is often possible on the day following the surgery. Eye drops and night protection are necessary for designated periods of time.
Advantages of LASIK include:Faster healing time
Rapid visual recovery
Less risk of scarring
Less risk of corneal haze
Less post-op discomfort
The second eye can be done within a week
Treatment of a wider range of nearsightedness
Photo-Refractive Keratectomy, PRK is another method of surgically reshaping the cornea using the excimer laser. The difference between LASIK and PRK is that for PRK, the corneal flap is not created. That is, the outer layer of the cornea remains in place and the laser removes tissue directly from this outer layer. During LASIK , a part of the cornea is peeled back so that the laser removes tissue from the inner corneal layers. PRK is used for low to moderate amounts of nearsightedness.
Just as in LASIK, the laser treatment requires less than a minute. But unlike LASIK, the healing period time is longer. The correction for nearsightedness, farsightedness and astigmatism is the same as in LASIK. The corneal curvature is changed so that the visual images are properly focused on the back of the eye.
The macula is the tiny central part of the retina which is responsible for fine detail vision and for color perception. Macular degeneration is a disease of this very important portion of the retina. It usually affects both eyes, but often begins in one eye.
In many cases, patients are not aware of macular degeneration in one eye, because the other eye compensates for the weaker one. The most common symptoms include difficulty reading, seeing up close or distorted lines. It occurs most often in people over fifty years of age. If you notice a dimness of vision in one or both eyes or if straight lines appear distorted, you should see an eye doctor immediately. There is no cure for macular degeneration, but recent research suggests that certain vitamins and nutrients may slow the progress of the disease in certain patients. If the disease is advancing, laser surgery can be also be used to slow the disease.
If you are over fifty, have your eyes examined regularly. If you have symptoms, report them to your eye doctor immediately before the disease progresses too far.
The cornea and lens of the eye work together to properly focus visual images on the retina. If an image is out of focus, it is because the overall shape of the eye is incorrect or because the cornea does not have the proper curvature. When the eye is too big or the cornea is too steep, visual images are focused in front of the retina. This condition is called nearsightedness or myopia.
Myopia normally starts to appear between the ages of eight and twelve years old, and almost always before the age of twenty. Once myopia starts, as the body grows, the myopia often increases. It typically stabilizes in adulthood. Changes in glasses or contact lens prescriptions are necessary during growth periods.
Someone with myopia has an inability to see objects at the distance, such as street signs, chalk boards and television. Many times, myopia is diagnosed during school screenings.
The treatment for nearsightedness includes lenses which allow visual images to be focused on the retina. These lenses can be in the form of contact lenses or glasses. Once the eye has stabilized and myopia is no longer progressing, laser vision correction is an option for many.
The classic migraine is a severe headache, which in some instances may be accompanied by nausea. Ocular migraines are visual disturbances in which visual images look gray or have a wavy appearance. They almost always occur in only one eye. Other common symptoms are loss of vision, particularly in one eye, and increased sensitivity to bright lights. The visual distortion, when it occurs, normally starts in central vision and then moves off to one side.
The ocular migraine can occur either in conjunction with the common migraine or without the corresponding headache. Generally, when it accompanies the common migraine, the visual disturbances happen before the onset of headache symptoms. In younger people with common migraine, it is typical for the ocular migraines to also occur. As people age, it becomes more common to experience ocular migraines without headache symptoms.
In general there is no serious complications caused by ocular migraine. Treatment, in most instances, is not necessary unless the ocular migraine is linked to the common migraine.
The retina lies in the back of the eye and is a multi-layered tissue which detects visual images. These images are transmitted to the brain through approximately 1 million tiny nerve fibers. These nerve fibers converge in the back of the eye, before going to the brain, into a bundle called the optic nerve. If some or all of the nerve fibers are damaged, visual capability deteriorates.
When the optic nerve becomes inflamed, this condition is called optic neuritis. The nerve tissue becomes swollen and red, and the nerve fibers do not work properly. If many of the nerve fibers are involved, the vision may be dramatically affected, but if the optic neuritis is mild, vision is nearly normal. Optic neuritis can be caused by many diseases and conditions and may affect the optic nerve of one or both eyes.
Some people, especially children, develop optic neuritis following a virus illness such as mumps, measles, or a cold. In others, optic neuritis may occur as a sign of a neurologic disease affecting nerves in various parts of the body, such as multiple sclerosis. In a rare condition called Leber’s optic neuropathy, which often runs in families, a special kind of optic neuritis may appear in both eyes within a short span of time. Most of the time, however, the cause for optic neuritis is unknown. In those cases, the eye disorder is called neuritis idiopathic, meaning that no particular cause can be found.
Optic neuritis usually comes on suddenly, and the patient notices vision is blurred in one or both eyes. The vision is dim, like somebody turned down the lights, and colors may appear to be washed out. There may be pain in the area of the eye socket, especially when moving the eyes. The vision may continue to get worse over a week or two, and may seem worse after exercising or a hot bath.
A careful description of these symptoms is important to your doctor for the diagnosis of optic neuritis. The optic nerve enters the back of the eye where it appears as a small disc. Your eye doctor can examine the optic nerve inside the eye by using a special instrument called an ophthalmoscope. Swelling of the optic nerve may or may not be visible. If the optic nerve inflammation occurs inside the eye, it can be readily detected. If swelling of the nerve occurs behind the eye, the doctor may not be able to see the swollen nerve tissue.
Since optic neuritis can be confused with many other causes of poor vision, an accurate medical diagnosis is important. Ultrasound, CT scans or visual brain wave recordings might be ordered. Other tests which may be performed include color vision, side vision, and pupil reactions to light.
Unfortunately, there is no good treatment for optic neuritis. Cortisone-like medications (steroids) can be prescribed, but in most cases they are not effective. In many cases, patients with optic neuritis improve without treatment. The vision may return to normal or, in some cases, good but incomplete improvement occurs. A few patients fail to recover normal vision, especially those with special conditions.
Ptosis occurs when the upper eyelid droops to an abnormal level and covers part of the eye. It can have many causes including age, injury or nerve malfunction. It can also occur at birth.
Age is the most common cause of ptosis. The muscles that elevate the eyelid stretch and become thinned, resulting in a loss of muscle tone and the inability to hold the upper lid in the proper position above the eye.
Injury is another common cause of ptosis. Trauma to the eye, such as during an automobile accident, can damage the delicate structures around and in the eye.
Sometimes ptosis can be noticed at birth. In these cases it is due to an abnormality in the development of the muscles that elevate the upper lid. Three-quarters of the time it affects only one eye.
Ptosis can also be caused by a malfunction of the nerves which control and activate the eyelid muscles. These cases are rare and proper diagnosis is important in order to avoid unnecessary surgery. When a neurological disorder is present, symptoms typically include visual complaints independent of the droopy eyelid. Difficulty reading and driving are common complaints. Raising the entire brow with the muscles of the forehead and scalp may cause headaches and eyestrain as well. In newborns, this problem must be addressed and treated properly to insure normal maturation of the visual system and the avoidance of amblyopia (lazy eye).
The most common treatment for ptosis is surgical, and there are a number of possible approaches. The goal is to tighten the muscles so that the lid is elevated to match the lid on the other side, but with a minimum of scars and side effects. One possible complication is that the muscles can be over tightened. This results in the inability to close the eye completely after surgery. Such a situation creates a dry eye condition that may be difficult to manage.
In the age-related form, both eyelids may be drooping, but only one is low enough to require surgery. Almost invariably in these cases, the unoperated eyelid will appear lower after a successful repair of the first eye. The second eye also may eventually require surgery.
What is the Capsule?
The natural lens of the eye is held in place by a thin clear membrane called the lens capsule. The capsule completely surrounds the lens and separates it from the thick fluid in the back of the eye, called the vitreous, and the thinner fluid in the front of the eye, called the aqueous.
Cataract Surgery Effects the Capsule
Cataract surgery is necessary when the natural lens become cloudy and must be removed. When cataract surgery was originally performed, surgical techniques were not as refined as today, and both the natural lens and the capsule were removed during surgery. Newer techniques allow the capsule to remain in the eye and hold the implanted lens (or intraocular lens, IOL) in place. Leaving the capsule in place during surgery is a great advancement because it allows the vision after surgery to be more stable and provides for less surgical complications.
Sometimes the posterior, or back, portion of the capsule becomes cloudy after cataract surgery. The reasons for this cloudiness are unknown. If the posterior capsule becomes so cloudy that it detrimentally effects vision, then a capsulotomy is performed.
What is a Capsulotomy?
A capsulotomy is a procedure in which an opening is created in the center of the cloudy capsule. The opening allows clear passage of the light rays and eliminates the cloudiness that was interfering with the vision. A laser beam is used to create this opening. This procedure is painless, very safe and typically the results can be seen immediately. For capsulotomy, as with any surgery, rare complications can occur, such as swelling or retinal detachment. These complications can cause loss of vision.
A cloudy capsule will may times appear the same way as the original cataract. The vision is cloudy or hazy and the patient is heavily bothered by glare. In fact, vision is so similar that some patients think that the cataract has come back or regrown. This is impossible, cataracts cannot return once the natural lens has been removed.
If your vision is getting worse after cataract surgery, it could be that your capsule is becoming cloudy. Your eye doctor should give you a thorough eye examination to determine the cause of your vision loss. If your capsule is becoming cloudy, your eye doctor can then determine whether a capsulotomy is necessary to improve your vision.
During the early and middle years of life, the lens of the eye provides for the capability to focus both near and distant images. To accomplish this feat, the lens changes shape, getting thicker for near objects and thinner for distant objects.
Presbyopia occurs when the lens of the eye is no longer able to change shape. This typically takes place around age forty. Some persons may be older, closer to fifty, and some younger, less than thirty-five, when the lens loses its flexibility. For people who have presbyopia, vision is blurred when looking at near objects, such as during reading. Also, it may become difficult adjusting focus when switching from near to distance vision.
The amount of power that is needed in glasses to correct for presbyopia is dependent on the strength of the glasses needed for distance vision. For persons who are nearsighted, removal of the glasses may make it easier to read up close. For those not nearsighted, glasses or bifocals are needed to see well up close. A complete eye examination will determine the strength of lenses needed to see well at all distances.
The retina lies in the back of the eye and is a multi-layered tissue which detects visual images and transmits them to the brain. Retinitis pigmentosa (RP) refers to a group of related diseases which tend to run in families and cause slow but progressive loss of vision. In retinitis pigmentosa, there is gradual destruction of some of the nervous sensors in the retina.
The first symptoms usually occur in youth or young adulthood, although it may be first seen at any age. Retinitis pigmentosa causes night blindness and loss of side vision. In normal persons, the visual system adjusts to darkness after a short period of time. People with night blindness adjust to darkness very slowly, or not at all. Due to the loss of side vision (peripheral vision) in patients with retinitis pigmentosa, mobility becomes more difficult.
Most forms of retinitis pigmentosa are inherited. Different patterns of heredity are associated with different degrees of progression. An attempt to know more about how severely the disease has affected other family members may help predict how a specific person might ultimately be afflicted, though variability exists within each family. Such knowledge is also helpful in making decisions about such things as marriage, family and occupation.
In general, there is no specific treatment. Recent research suggests that some patients may benefit from certain kinds of vitamin therapy. But these studies are not conclusive. Much research is directed toward solving this problem. Periodic examinations by an eye doctor are advised.
It is important to keep in mind that patients with retinitis pigmentosa may develop other treatable disease, such as glaucoman or cataracts. Low vision aids may be prescribed. In some cases, retinitis pigmentosa may be associated with other disease processes which might need evaluation by other medical specialists.
Despite visual impairment, the many rehabilitative services that are available today allow patients with retinitis pigmentosa to live meaningful and rewarding lives.
RK & AK
The cornea and lens combine to focus visual images on the back of the eye. When the overall shape of the eye is incorrect or when the curvature of the cornea is incorrect, the visual images are not in focus. The cornea accounts for approximately 2/3rds of the focusing power of the eye. By surgically changing the corneal curvature, most or all of the blur can be overcome.
Radial Keratotomy (RK) is a surgical procedure that can help people with mild to moderate myopia. The technique has been in existence for more than thirty years. During RK, tiny spoke-like incisions are made in a “radial” pattern around the cornea. These cuts in the cornea serve to change the corneal curvature. To correct for nearsightedness, the cuts are used to flatten the cornea.
As with laser vision correction, the vast majority of patients have had their vision corrected to 20/40 or better. It is most effective when treating low to moderate levels of nearsightedness.
Astigmatic Keratotomy (AK) is used to help people with astigmatism. Astigmatism is an uneven curvature of the cornea. It is curved more in one direction than the other, causing a distortion in vision. During AK, one or more surgical incisions are made in the cornea. These incisions help eliminate the uneven curvature and “round out” the cornea. A rounder cornea means objects no longer appear blurred or distorted. AK is sometimes performed at the time of cataract surgery, in order to reduce or eliminate the patient’s preexisting astigmatism.
Strabismus - Crossed Eyes
What is strabismus?
Strabismus is a visual defect in which the eyes are misaligned and point in different directions. One eye may look straight ahead, while the other eye turns inward, outward, upward or downward.
You may always notice the misalignment, or it may come and go. The turned eye may straighten at times and the straight eye may turn.
Strabismus is a common condition among children. About 4% of all children in the United States have strabismus. It can also occur later in life.
It occurs equally in males and females. Strabismus may run in families. How ever, many people with strabismus have no relatives with the problem.
How do the eyes work together?
With normal vision, both eyes aim at the same spot. The brain then fuses the two pictures into a single three-dimensional image. This three – dimensional image gives us depth perception.
When one eye turns, two different pictures are sent to the brain. In a young child, the brain learns to ignore the image of the misaligned eye and sees only the image from the straight or better-seeing eye. The child then loses depth perception.
Adults who develop strabismus often have double vision because the brain is already trained to receive images from both eyes and cannot ignore the image from the turned eye.
Good vision develops during childhood when both eyes have normal alignment. Strabismus may cause reduced vision, or amblyopia, in the weaker eye.
The brain will recognize the image of the better-seeing eye and ignore the image of the weaker or amblyopic eye. This occurs in approximately half the children who have strabismus.
Amblyopia can be treated by patching the “good” eye to strengthen and improve vision in the weaker eye. If amblyopia is detected in the first few years of life, treatment is usually successful.
If treatment is delayed until later, amblyopia usually becomes permanent. As a rule, the earlier amblyopia is treated, the better the visual result.
What causes strabismus?
The exact cause of strabismus is not fully understood.
Six eye muscles, controlling eye move ment, are attached to the outside of each eye. In each eye, two muscles move the eye right or left. The other four muscles move it up or down and at an angle.
To line up and focus both eyes on a single target, all of the muscles in each eye must be balanced and working together. In order for the eyes to move together, the muscles in both eyes must be coordinated.
The brain controls the eye muscles. Strabismus is especially common among children with disorders that affect the brain, such as:
A cataract or eye injury that affects vision can also cause strabismus.
What are the symptoms of strabismus?
The main symptom of strabismus is an eye that is not straight. Sometimes children will squint one eye in bright sunlight or tilt their head to use their eyes together.
How is strabismus diagnosed?
Strabismus can be diagnosed during an eye exam. It is recommended that all children have their vision checked by their pediatrician, family doctor or ophthalmologist (medical eye doctor) at or before their fourth birthday. If there is a family history of strabismus or amblyopia, an ophthalmologist can check vision even earlier than age three.
The eyes of infants often seem to be crossed. Young children often have a wide, flat nose and a fold of skin at the inner eyelid that can make the eyes appear crossed.
This appearance of strabismus may improve as the child grows. A child will not outgrow true strabismus.
An ophthalmologist can usually tell the difference between true and false strabismus.
How is strabismus treated?
Treatment for strabismus works to:
Straighten the eyes
Restore binocular (two-eyed) vision
After a complete eye examination, an ophthalmologist can recommend appropriate treatment.
In some cases, eyeglasses can be prescribed for your child. Other treatments may involve surgery to correct the unbalanced eye muscles or to remove a cataract. Covering or patching the strong eye to improve amblyopia is often necessary.
How is strabismus surgery done?
The eyeball is never removed from the socket during any kind of eye surgery. The ophthalmologist makes a small incision in the tissue covering the eye to reach the eye muscles.
Certain muscles are repositioned during the surgery, depending on which direction the eye is turning. It may be necessary to perform surgery on one or both eyes. When strabismus surgery is performed on children, a general anesthetic is required. Local anesthesia is an option for adults.
Recovery time is rapid. People are usually able to resume their normal activities within a few days. After surgery, glasses or prisms may be useful. In many cases, further surgery may be needed at a later stage to keep the eyes straight. For children with constant strabismus, early surgery offers the best chance for the eyes to work well together. In general, it is easier for children to under go surgery before school age.
As with any surgery, eye muscle surgery has certain risks. These include infection, bleeding, excessive scarring and other rare complications that can lead to loss of vision. Strabismus surgery is usually a safe and effective treatment for eye misalignment.
It is not, however, a substitute for glasses or amblyopia therapy.
Strabismus in Adults
What is adult strabismus?
Strabismus is a condition in which the eyes are misaligned and point in differ ent directions. Most strabismus in adults has been present since childhood.
Strabismus which occurs in adults with out a history of childhood eye misalign ment should be carefully evaluated for medical or neurological causes such as:
Other neurological disorders..
In this form of strabismus, called Esotropia, the eye turns inward.
What are the symptoms of adult strabismus?
If the strabismus has been present since early childhood, the symptoms are usually minimal. If it develops later, the most common symptom is double vision. Some adults with strabismus will have:
Discomfort when reading
Abnormal head positions to use their eyes together.
In this form of strabismus, called Exotropia, the eye turns outward.
What causes double vision?
When your eyes are not aligned prop erly, each eye sees a different image. Infants and children can learn to suppress or ignore the image from one eye in order to avoid seeing a double image. Adults are unable to suppress one of the images, and therefore have double vision. This can be relieved by closing one eye, wearing a patch or aligning the eyes.
How is adult strabismus treated?
There is a common misconception that strabismus in adults is difficult or impossible to treat. Actually, adults with strabismus have many different treatment options including:
Glasses with prisms
Eye muscle surgery, with or without adjustable sutures
Eye muscle exercises may be helpful in treating special problems such as convergence insufficiency, a condition in which the eyes are misaligned only for close work or reading.
Glasses with prisms are most useful for correcting small deviations. The images are realigned by prisms to compensate for the misalignment of the eyes, and the double vision may be relieved.
How does surgery work?
The most common treatment for strabismus at any age is surgery on the eye muscles. A tight muscle is surgically weakened by moving the muscle back on the eye. A weak muscle is tightened by removing a small segment of the muscle to shorten it. Surgery may involve the straight eye, the misaligned eye, or both.
What anesthetic is used in strabismus surgery?
Usually strabismus surgery is performed under general anesthesia. Sometimes surgery can be performed while the individual is awake or slightly sedated. In this situation, an injectable local anesthetic or anesthetic eyedrops are used.
What are adjustable sutures?
Adjustable sutures are a surgical technique that allows for some “fine tuning” of the alignment after surgery. The operation is performed in two stages.
In the first stage, one or more muscles are repositioned with “slip knot” sutures. In the second phase, usually performed within the next 24 hours, the muscle (s) may be repositioned by untying and retying the knots under eyedrop anesthesia. In many cases, no adjustment is needed and the slip knot is converted to a standard knot. Adjustable sutures require good cooperation from the patient and may not be suitable for everyone.
What are the risks of strabismus surgery?
The risks of strabismus surgery are extremely low, but as with all surgery there are potential problems. These may include:
An unfavorable reaction to anesthesia
Reduced or double vision
Inadequate eye alignment
An adult does not need to live with misaligned eyes. Glasses, prisms, exercises, and other treatments can sometimes help. Surgery can be done to:
Align the eyes for cosmetic reasons
Eliminate double vision
Improve the use of the eyes together
Advances in surgical techniques allow an excellent chance of successful alignment and improved appearance for most individuals.