Hyperopia (Farsightedness) is a vision condition in which distant objects are usually seen clearly, but close ones do not come into proper focus. Farsightedness occurs if your eyeball is too short or the cornea has too little curvature, so light entering your eye is not focused correctly.
Common signs of farsightedness include difficulty in concentrating and maintaining a clear focus on near objects, eye strain, fatigue and/or headaches after close work, aching or burning eyes, irritability or nervousness after sustained concentration. (More)
Common vision screenings, often done in schools, are generally ineffective in detecting farsightedness. A comprehensive optometric examination will include testing for farsightedness.
In mild cases of farsightedness, your eyes may be able to compensate without corrective lenses. In other cases, your optometrist can prescribe eyeglasses or contact lenses to optically correct farsightedness by altering the way the light enters your eyes.
Myopia (Nearsightedness) is a vision condition in which close objects are seen clearly, but objects farther away appear blurred. Nearsightedness occurs if the eyeball is too long or the cornea, the clear front cover of the eye, has too much curvature. As a result, the light entering the eye isn’t focused correctly and distant objects look blurred. (More)
Nearsightedness is a very common vision condition affecting nearly 30 percent of the U.S. population. Some research supports the theory that nearsightedness is hereditary. There is also growing evidence that it is influenced by the visual stress of too much close work.
Generally, nearsightedness first occurs in school-age children. Because the eye continues to grow during childhood, it typically progresses until about age 20. However, nearsightedness may also develop in adults due to visual stress or health conditions such as diabetes.
A common sign of nearsightedness is difficulty with the clarity of distant objects like a movie or TV screen or the chalkboard in school. A comprehensive optometric examination will include testing for nearsightedness. An optometrist can prescribe eyeglasses or contact lenses that correct nearsightedness by bending the light rays that enter the eyes, focusing the images correctly at the back of the eye. Depending on the amount of nearsightedness, you may only need to wear glasses or contact lenses for certain activities, like watching a movie or driving a car. Or, if you are very nearsighted, they may need to be worn all the time.
Astigmatism is a vision condition that causes blurred vision due either to the irregular shape of the cornea, the clear front cover of the eye, or sometimes the curvature of the lens inside the eye. An irregular shaped cornea or lens prevents light from focusing properly on the retina, the light sensitive surface at the back of the eye. As a result, vision becomes blurred at any distance.
Astigmatism is a very common vision condition. Most people have some degree of astigmatism. Slight amounts of astigmatism usually don't affect vision and don't require treatment. However, larger amounts cause distorted or blurred vision, eye discomfort and headaches. (More)
Astigmatism frequently occurs with other vision conditions like nearsightedness (myopia) and farsightedness (hyperopia). Together these vision conditions are referred to as refractive errors because they affect how the eyes bend or "refract" light.
The specific cause of astigmatism is unknown. It can be hereditary and is usually present from birth. It can change as a child grows and may decrease or worsen over time.
A comprehensive optometric examination will include testing for astigmatism. Depending on the amount present, your optometrist can provide eyeglasses or contact lenses that correct the astigmatism by altering the way light enters your eyes.
Presbyopia is a vision condition in which the crystalline lens of your eye loses its flexibility, which makes it difficult for you to focus on close objects.
Presbyopia may seem to occur suddenly, but the actual loss of flexibility takes place over a number of years. Presbyopia usually becomes noticeable in the early to mid-40s. Presbyopia is a natural part of the aging process of the eye. It is not a disease, and it cannot be prevented.
Some signs of presbyopia include the tendency to hold reading materials at arm's length, blurred vision at normal reading distance and eye fatigue along with headaches when doing close work. A comprehensive optometric examination will include testing for presbyopia. (More)
To help you compensate for presbyopia, your optometrist can prescribe reading glasses, bifocals, trifocals or contact lenses. Because presbyopia can complicate other common vision conditions like nearsightedness, farsightedness and astigmatism, your optometrist will determine the specific lenses to allow you to see clearly and comfortably. You may only need to wear your glasses for close work like reading, but you may find that wearing them all the time is more convenient and beneficial for your vision needs.
Because the effects of presbyopia continue to change the ability of the crystalline lens to focus properly, periodic changes in your eyewear may be necessary to maintain clear and comfortable vision.
Amblyopia (Lazy Eye) is the loss or lack of development of central vision in one eye that is unrelated to any eye health problem and is not correctable with lenses. It can result from a failure to use both eyes together. Lazy eye is often associated with crossed-eyes or a large difference in the degree of nearsightedness or farsightedness between the two eyes. It usually develops before the age of 6, and it does not affect side vision.
Symptoms may include noticeably favoring one eye or a tendency to bump into objects on one side. Symptoms are not always obvious. (More)
Treatment for lazy eye may include a combination of prescription lenses, prisms, vision therapy and eye patching. Vision therapy teaches the two eyes how to work together, which helps prevent lazy eye from reoccurring.
Early diagnosis increases the chance for a complete recovery. This is one reason why the American Optometric Association recommends that children have a comprehensive optometric examination by the age of 6 months and again at age 3. Lazy eye will not go away on its own. If not diagnosed until the pre-teen, teen or adult years, treatment takes longer and is often less effective.
Strabismus (Crossed Eyes) is a condition in which both eyes do not look at the same place at the same time. It occurs when an eye turns in, out, up or down and is usually caused by poor eye muscle control or a high amount of farsightedness.
There are six muscles attached to each eye that control how it moves. The muscles receive signals from the brain that direct their movements. Normally, the eyes work together so they both point at the same place. When problems develop with eye movement control, an eye may turn in, out, up or down. The eye turning may be evident all the time or may appear only at certain times such as when the person is tired, ill, or has done a lot of reading or close work. In some cases, the same eye may turn each time, while in other cases, the eyes may alternate turning. (More)
Maintaining proper eye alignment is important to avoid seeing double, for good depth perception, and to prevent the development of poor vision in the turned eye. When the eyes are misaligned, the brain receives two different images. At first, this may create double vision and confusion, but over time the brain will learn to ignore the image from the turned eye. If the eye turning becomes constant and is not treated, it can lead to permanent reduction of vision in one eye, a condition called amblyopia or lazy eye.
Some babies’ eyes may appear to be misaligned, but are actually both aiming at the same object. This is a condition called pseudostrabismus or false strabismus. The appearance of crossed eyes may be due to extra skin that covers the inner corner of the eyes, or a wide bridge of the nose. Usually, this will change as the child’s face begins to grow.
Strabismus usually develops in infants and young children, most often by age 3, but older children and adults can also develop the condition. There is a common misconception that a child with strabismus will outgrow the condition. However, this is not true. In fact, strabismus may get worse without treatment. Any child older than four months whose eyes do not appear to be straight all the time should be examined.
Strabismus is classified by the direction the eye turns:
- Inward turning is called esotropia
- Outward turning is called exotropia
- Upward turning is called hypertropia
- Downward turning is called hypotropia.
Other classifications of strabismus include:
- The frequency with which it occurs – either constant or intermittent
- Whether it always involves the same eye – unilateral
- If the turning eye is sometimes the right eye and other times the left eye – alternating.
Treatment for strabismus may include eyeglasses, prisms, vision therapy, or eye muscle surgery. If detected and treated early, strabismus can often be corrected with excellent results.
Learning Related Vision Problems are the manifestation of deficits in visual efficiency and visual information processing. Visual efficiency problems include uncorrected refractive error, dysfunction of accommodation and vergence control systems and the interaction of these systems, and ocular motility. Accommodative and vergence dysfunctions can be primary deficits or can occur secondary to uncorrected refractive error. Isolated visual efficiency deficits are relatively uncommon; most patients present with multiple deficits. Visual information processing problems include delays or deficits in visual spatial orientation, visual analysis (which encompasses non-motor visual perception), and visual integration skills.
Accommodative and Vergence Dysfunctions are diverse visual anomalies. Any of these dysfunctions can interfere with a child's school performance, prevent an athlete from performing at his or her highest level of ability, or impair one's ability to function efficiently at work. Those persons who perform considerable amounts of close work or reading, or who use computers extensively, are more prone to develop signs and symptoms related to accommodative or vergence dysfunction. Symptoms commonly associated with accommodative and vergence anomalies include blurred vision, headache, ocular discomfort, ocular or systemic fatigue, diplopia, motion sickness, and loss of concentration during a task performance. The prevalence of accommodative and vergence disorders, combined with their impact on everyday activities, makes this a significant area of concern.
An accommodative or vergence dysfunction can have a negative effect on a child's school performance, especially after third grade when the child must read smaller print and reading demands increase. Due to discomfort, the child may not be able to complete reading or homework assignments and may be easily distracted or inattentive. Such children may not report symptoms of asthenopia because they do not realize that they should be able to read comfortably. The clinician should suspect a binocular or accommodative problem in any child whose school performance drops around third grade or who is described as inattentive.
Photopsia, called flashes, sometimes appear with floaters. Flashes look like flashing lights or lightning streaks, even though no light is actually flashing. Flashes are similar to the sensation of "seeing stars" when a person is hit on the head. Flashes are usually noticed at night or in a dark room. Some people experience flashes as jagged lines or "heat waves" in both eyes. Flashes often last 10-20 minutes. These types of flashes are usually caused by a spasm of blood vessels in the brain, called migraine. Some migraines are followed by a headache.
Floaters, called spots, are small, semi-transparent or cloudy specks or particles within the vitreous, which is the clear, jelly-like fluid that fills the inside of your eyes. They appear as specks of various shapes and sizes, threadlike strands or cobwebs. Because they are within your eyes, they move as your eyes move and seem to dart away when you try to look at them directly.
Spots are often caused by small flecks of protein or other matter trapped during the formation of your eyes before birth. They can also result from deterioration of the vitreous fluid, due to aging; or from certain eye diseases or injuries.
Most spots are not harmful and rarely limit vision. But, spots can be indications of more serious problems, and you should see your optometrist for a comprehensive examination when you notice sudden changes or see increases in them.
By looking in your eyes with special instruments, your optometrist can examine the health of your eyes and determine if what you are seeing is harmless or the symptom of a more serious problem that requires treatment.
Cataracts - Most cataracts are due to age-related changes in the lens. However, other factors can contribute to their development including:
- Diabetes mellitus—Persons with diabetes are at higher risk for cataracts.
- Drugs—Certain medications have been found to be associated with the development of a cataract. These include:
- Chlorpromazine and other phenothiazine related medications
- Ultraviolet radiation—Studies have shown that there is an increased chance of cataract formation with unprotected exposure to ultraviolet (UV) radiation.
- Smoking - An association between smoking and increased lens opacities has been reported.
- Alcohol - Several studies have shown increased cataract formation in patients with higher alcohol consumption compared with people who have lower or no alcohol consumption.
- Nutritional deficiency—Although the results are inconclusive, studies have suggested an association between cataract formation and low levels of antioxidants (e.g. vitamin C, vitamin E, carotenoids). Further studies may show that antioxidants have a significant effect on decreasing cataract development.
Rarely, cataracts can be present at birth or develop shortly after. They may be inherited or develop due to an infection, i.e. rubella, in the mother during pregnancy. A cataract may also develop following an injury to the eye or surgery for another eye problem, such as glaucoma. (More)
While there are no clinically proven approaches to preventing cataracts, simple preventive strategies include reducing exposure to sunlight through UV blocking lenses, decreasing or discontinuing smoking and increasing antioxidant vitamin intake through consumption of leafy green vegetables and nutritional supplements.
Diagnosis of cataracts - Cataracts can be diagnosed through a comprehensive eye examination. This examination may include:
- Patient history to determine vision difficulties experienced by the patient that may limit their daily activities and other general health concerns affecting vision.
- Visual acuity measurement to determine to what extent a cataract may be limiting clear vision at distance and near.
- Refraction to determine the need for changes in an eyeglass or contact lens prescription.
- Evaluation of the lens under high magnification and illumination to determine the extent and location of any cataracts.
- Evaluation of the retina of the eye through a dilated pupil.
- Measurement of pressure within the eye.
- Supplemental testing for color vision and glare sensitivity.
Vitreous Detachment is a tearing or separation from the retina, the light sensitive lining at the back of the eye, from the underlying tissue. The Vitreous as a jelly-like substance inside the eye, behind the lens and in front of the retina. It has strong attachments to the optic nerve and inside the eye just posterior to the ciliary body. A vitreous detachment happens when the vitreous loses its strong attachment and pull away from the retina.
Conjunctivitis is an inflammation or infection of the conjunctiva, the thin transparent layer of tissue that lines the inner surface of the eyelid and covers the white part of the eye. Conjunctivitis, often called “pink eye,” is a common eye disease, especially in children. It may affect one or both eyes. Some forms of conjunctivitis can be highly contagious and easily spread in schools and at home. While conjunctivitis is usually a minor eye infection, sometimes it can develop into a more serious problem. (More)
Conjunctivitis may be caused by a viral or bacterial infection. It can also occur due to an allergic reaction to irritants in the air like pollen and smoke, chlorine in swimming pools, and ingredients in cosmetics or other products that come in contact with the eyes. Sexually transmitted diseases like Chlamydia and gonorrhea are less common causes of conjunctivitis.
People with conjunctivitis may experience the following symptoms:
- A gritty feeling in one or both eyes
- Itching or burning sensation in one or both eyes
- Excessive tearing
- Discharge coming from one or both eyes
- Swollen eyelids
- Pink discoloration to the whites of one or both eyes
- Increased sensitivity to light
What causes conjunctivitis? The cause of conjunctivitis varies depending on the offending agent. There are three main categories of conjunctivitis: allergic, infectious and chemical.
- Allergic Conjunctivitis occurs more commonly among people who already have seasonal allergies. At some point they come into contact with a substance that triggers an allergic reaction in their eyes.
- Giant Papillary Conjunctivitis is a type of allergic conjunctivitis caused by the chronic presence of a foreign body in the eye. This condition occurs predominantly with people who wear hard or rigid contact lenses, wear soft contact lenses that are not replaced frequently, have an exposed suture on the surface or the eye, or have a glass eye.
- Bacterial Conjunctivitis is an infection most often caused by staphylococcal or streptococcal bacteria from your own skin or respiratory system. Infection can also occur by transmittal from insects, physical contact with other people, poor hygiene (touching the eye with unclean hands), or by use of contaminated eye makeup and facial lotions.
- Viral Conjunctivitis is most commonly caused by contagious viruses associated with the common cold. The primary means of contracting this is through exposure to coughing or sneezing by persons with upper respiratory tract infections. It can also occur as the virus spreads along the body’s own mucous membranes connecting lungs, throat, nose, tear ducts, and conjunctiva.
- Ophthalmia Neonatorum is a severe form of bacterial conjunctivitis that occurs in newborn babies. This is a serious condition that could lead to permanent eye damage unless it is treated immediately. Ophthalmia neonatorum occurs when an infant is exposed to Chlamydia or gonorrhea while passing through the birth canal.
Glaucoma is a group of eye disorders leading to progressive damage to the optic nerve, and is characterized by loss of nerve tissue resulting in loss of vision. The optic nerve is a bundle of about one million individual nerve fibers and transmits the visual signals from the eye to the brain. The most common form of glaucoma, primary open-angle glaucoma, is associated with an increase in the fluid pressure inside the eye. This increase in pressure may cause progressive damage to the optic nerve and loss of nerve fibers. Vision loss may result. Advanced glaucoma may even cause blindness. Not everyone with high eye pressure will develop glaucoma, and many people with normal eye pressure will develop glaucoma. When the pressure inside an eye is too high for that particular optic nerve, whatever that pressure measurement may be, glaucoma will develop. (More)
Glaucoma is the second leading cause of blindness in the U.S. It most often occurs in people over age 40, although a congenital or infantile form of glaucoma exists. People with a family history of glaucoma, African Americans over the age of 40, and Hispanics over the age of 60 are at an increased risk of developing glaucoma. Other risk factors include thinner corneas, chronic eye inflammation, and using medications that increase the pressure in the eyes.
The most common form of glaucoma, primary open-angle glaucoma, develops slowly and usually without any symptoms. Many people do not become aware they have the condition until significant vision loss has occurred. It initially affects peripheral or side vision, but can advance to central vision loss. If left untreated, glaucoma can lead to significant loss of vision in both eyes, and may even lead to blindness.
A less common type of glaucoma, acute angle closure glaucoma, usually occurs abruptly due to a rapid increase of pressure in the eye. Its symptoms may include severe eye pain, nausea, redness in the eye, seeing colored rings around lights, and blurred vision. This condition is an ocular emergency, and medical attention should be sought immediately, as severe vision loss can occur quickly.
Glaucoma cannot currently be prevented, but if diagnosed and treated early it can usually be controlled. Medication or surgery can slow or prevent further vision loss. However, vision already lost to glaucoma cannot be restored. That is why the American Optometric Association recommends an annual dilated eye examination for people at risk for glaucoma as a preventive eye care measure. Depending on your specific condition, your doctor may recommend more frequent examinations.
Age-Related Macular Degeneration (AMD) is the leading cause of severe vision loss in adults over age 50. The Centers for Disease Control and Prevention estimate that 1.8 million people have AMD and another 7.3 million are at substantial risk for vision loss from AMD. Caucasians are at higher risk for developing AMD than other races. Women also develop AMD at an earlier age than men. This eye disease occurs when there are changes to the macula, a small portion of the retina that is located on the inside back layer of the eye. AMD is a loss of central vision that can occur in two forms: “dry” or atrophic and “wet” or exudative.
Symptoms of AMD
- Gradual loss of ability to see objects clearly
- Objects appear distorted in shape. Straight lines look wavy or crooked.
- Loss of clear color vision
- A dark or empty area appears in the center of vision.
Diagnosis of AMD
In its early stages, signs of macular degeneration can go unnoticed. Yet, if you experience any signs/symptoms, contact your doctor of optometry immediately. In a comprehensive eye exam, your optometrist will perform a variety of tests to determine if you have macular degeneration, or any other eye health problems.
Treatment of AMD
With “dry” macular degeneration, the tissue of the macula gradually becomes thin and stops functioning properly. There is no cure for dry AMD, and any loss in central vision cannot be restored. However, doctors now believe there is a link between nutrition and the progression of dry AMD. Dietary changes favoring low-fat content and dark green leafy vegetables can slow vision loss. Nutritional supplements also may be beneficial.
Less common, “wet” macular degeneration results when fluids leak from newly formed blood vessels under the macula and blur central vision. Vision loss can be rapid and severe. If detected early, “wet” AMD can be treated with laser treatment, which is often called photocoagulation. A highly focused beam of light seals the leaking blood vessels that damage the macula. Photodynamic Therapy (PDT) uses a medication injected into the bloodstream, which is then activated with a laser shone into the eye. A new therapy available, where a medication is injected into the back of the eye, is showing favorable results. These are not permanent cures but are used to slow the rate of central vision loss.
Researchers have linked eye-friendly nutrients such as lutein/zeaxanthin, vitamin C, vitamin E, and zinc to reducing the risk of certain eye diseases, including macular degeneration. For more information on the importance of good nutrition and eye health, please see the diet and nutrition section.
Diabetic Retinopathy is a condition occurring in persons with diabetes, which causes progressive damage to the retina, the light sensitive lining at the back of the eye. It is a serious sight-threatening complication of diabetes.
Diabetes is a disease that interferes with the body's ability to use and store sugar, which can cause many health problems. Too much sugar in the blood can cause damage throughout the body, including the eyes. Over time, diabetes affects the circulatory system of the retina.
Diabetic retinopathy is the result of damage to the tiny blood vessels that nourish the retina. They leak blood and other fluids that cause swelling of retinal tissue and clouding of vision. The condition usually affects both eyes. The longer a person has diabetes, the more likely they will develop diabetic retinopathy. If left untreated, diabetic retinopathy can cause blindness. (More)
Symptoms of diabetic retinopathy include:
- Seeing spots or floaters in your field of vision
- Blurred vision
- Having a dark or empty spot in the center of your vision
- Difficulty seeing well at night
In patients with diabetes, prolonged periods of high blood sugar can lead to the accumulation of fluid in the lens inside the eye that controls eye focusing. This changes the curvature of the lens and results in the development of symptoms of blurred vision. The blurring of distance vision as a result of lens swelling will subside once the blood sugar levels are brought under control. Better control of blood sugar levels in patients with diabetes also slows the onset and progression of diabetic retinopathy.
Often there are no visual symptoms in the early stages of diabetic retinopathy. That is why the American Optometric Association recommends that everyone with diabetes have a comprehensive dilated eye examination once a year. Early detection and treatment can limit the potential for significant vision loss from diabetic retinopathy.
Treatment of diabetic retinopathy varies depending on the extent of the disease. It may require laser surgery to seal leaking blood vessels or to discourage new leaky blood vessels from forming. Injections of medications into the eye may be needed to decrease inflammation or stop the formation of new blood vessels. In more advanced cases, a surgical procedure to remove and replace the gel-like fluid in the back of the eye, called the vitreous, may be needed. A retinal detachment, defined as a separation of the light-receiving lining in the back of the eye, resulting from diabetic retinopathy, may also require surgical repair.
If you are a diabetic, you can help prevent or slow the development of diabetic retinopathy by taking your prescribed medication, following you doctor’s recommendations, adhering to your diet, exercising regularly, controlling high blood pressure and avoiding alcohol and smoking.