Educational Eye CareTerms
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, eyestrain 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, glasses or contact lenses can correct astigmatism. 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.
Careful cleaning of your eyelashes every day can control blepharitis. 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.
Cataract Surgery and Lens Implantation
The eye is a marvelous optical instrument, which takes the images from the real world and focuses them on a tiny spot in the back of the eye. The ability to focus these images comes from two parts of the eye, the lens of the eye and the front cover of the eye, or the cornea. The lens accounts for about 1/3 of the focusing power.
The Natural Lens is Removed During Cataract Surgery
A cataract occurs when the lens of the eye becomes cloudy so that it can no longer focus the real-world images. Patients with cataracts see the world as very hazy, because light cannot pass freely through the lens to be focused on the back of the eye. The only way to remove a cataract is to remove the lens itself.
Cataract Surgery Procedure
Cataract surgery is a procedure that removes the cloudy lens from the eye. Today, this procedure can be accomplished very quickly and no stitches are needed. A local anesthetic is used and the surgeon makes a small incision in the outer covering of the eye. Then a technique is used, called phacoemulsification, which removes the lens through the small incision.
At least 95% of the patients receive an artificial lens implant after the cataract is removed. This lens is called an intraocular lens or IOL and is made from the same plastic as certain types of contact lenses. In some cases, a special tiny foldable IOL is used for implantation. This type of lens is inserted into the eye through a very small opening, only 1/8th inch. Once in the eye, the lens unfolds to its full size.
The IOL replaces the 1/3 of the eye’s focusing power of the natural lens. Without this lens, the eye cannot focus. In a small number of cases, an IOL is not used and the patients must wear glasses or contact lenses to help them see. IOLs are beneficial because they are permanent in the eye. They do not get lost, like glasses, or have to be replaced, like contact lenses. Also, many times the focusing power of the IOL can be determined so that it closely matches your eye. With an IOL, glasses for distance vision may not be needed.
This cataract surgery technique has many benefits. No hospital stay is needed, there is no pain, no injections are required, there is quick recovery and the vision after surgery is typically very good.
Are There Any Risks?
Cataract surgery and IOL implantation is quite safe. The IOLs must pass through a very stringent approval process before they can be used. The benefits of the implant greatly outweigh the small-added risk of implantation.
As with any surgery, complications can occur. There is a possibility of hemorrhage or infection. Your eye doctor will discuss potential complications of cataract surgery and IOP implantation with you.
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.
Color blind test
The Chart was developed to provide a less complicated, more economical, screening test to detect the major color deficit seen in male children. The test was validated by J. Chen, M.D. of the Department of Family Medicine, University of Maryland School of Medicine in a paper titled “Rapid Detection of Red-Green Color Vision Deficit– The Creamer Test”. The Chart was awarded third prize for scientific merit at a meeting of The Southern Medical Association.
About 5% of all male children and many females have some degree of inherited red-green color confusion. This problem can cause the child difficulty with daily activities and is an important factor in the choice of careers. Although color blindness cannot be cured, early detection in children is advisable to inform parents and teachers that there is a problem and counseling can be provided. This chart has proven to be valuable by teachers, physicians, eye care professionals and others interested in the care of children.
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 conjunctiva 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.
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 that 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 that 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 that 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.
The LipiFlow Thermal Pulsation System is a revolutionary way to treat Evaporative Dry Eye caused by Meibomian Gland Dysfunction (MGD). Opening and clearing blocked glands allows the body to resume the natural production of lipids (oils) needed for the tear film.
In controlled clinical studies of patients who received a single LipiFlow treatment, the average meibomian gland score at 4 weeks increased by two to three times over the baseline condition, which reflects improvement in the number of glands secreting improved quantity and quality of lipid oil. Additionally, at four weeks after the LipiFlow treatment, 79% of patients reported improvement in dry eye symptoms with continued relief that can take weeks to months depending on the degree of severity of their disease and other contributing factors.
Floaters and Flashers
The retina lies in the back of the eye and is a multi-layered tissue that 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 that 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 that run from the back of the eye to the brain. These nerve fibers allow us to see. Glaucoma is a disease that 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.
Hyperopia (Far sightedness)
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.
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, chalkboards and television. Many times, myopia is diagnosed during school screenings.
The treatment for nearsightedness includes lenses that 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 that 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 neurological 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 that 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.
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.
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 that 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.
The retina lies in the back of the eye. It is a multi-layer tissue that 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.
The retina lies in the back of the eye and is a multi-layered tissue that detects visual images and transmits them to the brain. Retinitis pigmentosa (RP) refers to a group of related diseases that 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 glaucoma or cataracts. Low vision aids may be prescribed. In some cases, retinitis pigmentosa may be associated with other disease processes that 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.