Amblyopia, commonly known as lazy eye, is a condition where vision in one of the eyes is reduced because the eye and the brain are not working together properly. The visual loss in amblyopia cannot be corrected by just wearing glasses. Amblyopia is the most common cause of visual impairment during childhood. The condition affects approximately 2 to 3 out of every 100 children. It is thought to develop early in life during the critical period of visual development. Unless it is successfully treated in early childhood, amblyopia usually persists into adulthood, and is the most common cause of monocular (one eye) visual impairment among children and young and middle-aged adults.

What causes amblyopia?

Amblyopia may be caused by any condition that affects normal visual development or use of the eyes. Strabismus, which is an imbalance in the positioning of the two eyes, is the most common cause of amblyopia. Strabismus can cause the eyes to cross in (esotropia) or turn out (exotropia). Other causes of amblyopia include childhood cataracts, unequal nearsightedness, farsightedness and astigmatism. There is often a family history of this condition.

How is amblyopia diagnosed?

Amblyopia is usually easily diagnosed with a complete examination of the eyes.

What is the treatment for amblyopia?

In general, the earlier the child has the condition for the development of amblyopia the worse it may become. Similarly, the earlier the treatment is started, the better the opportunity to reverse vision loss. Before treating amblyopia, it may be necessary to first treat the underlying cause. Glasses are commonly prescribed to improve focusing or misalignment of the eyes. Surgery may be performed on the eye muscles to straighten the eyes if non-surgical means are unsuccessful. Surgery can help in the treatment of amblyopia by allowing the eyes to work together better. Eye exercises may also be recommended either before or after surgery to correct faulty visual habits associated with strabismus and to teach comfortable use of the eyes. Following treatment of the underlying cause, patching or covering one eye may be required for a period of time. The better-seeing eye is patched, forcing the “lazy” one to work, thereby strengthening its vision.

The human eye is the organ of sight closely related to the brain and is best compared to a camera. Like a sophisticated camera, the eye has multiple discrete parts which must function together properly to produce clear vision. The function of the eye is to convert light into an electro-chemical signal, which is then transmitted to the brain through the optic nerve. It is in the brain that this signal is converted into “vision.” To illustrate this, we will follow the path that light takes as it travels through the eye and we will discuss the various ocular structures encountered along the path.

Cornea

The first surface encountered by a ray of light is the tear film. The eye’s surface must be kept moist at all times. To achieve this, glands in and near the eyelids produce both tears and a special oil, which mix together and coat the eye. This tear film coats the cornea, which normally is the crystal clear window to the eye. Deficiencies in tear production (dry eyes) can impair vision and cause redness or discomfort. Behind the cornea, we enter a space called the anterior chamber, which is filled with fluid called the aqueous. The aqueous is normally clear like water and is responsible for maintaining the pressure of the eye. Disturbances in the production or drainage of the aqueous can result in high pressure in the eye and even glaucoma.

Iris

Inside the anterior chamber is the iris. This is the part of the eye that is responsible for one’s eye color. It acts like the diaphragm of a camera, dilating and constricting the pupil to allow more or less light into the eye.

Lens

The next structure we encounter is the crystalline lens. The lens is responsible for focusing light onto the retina. It changes shape slightly to allow us to change focus between objects that are near and those that are far. As we age, the lens becomes less flexible and unable to “accommodate” or change focus as well. This is called presbyopia. When a patient becomes presbyopic, they will often need to wear reading glasses or switch to multi-focals. Eventually, the lens loses its original clarity and can become yellowish or cloudy. This is called a cataract and degrades the quality of the image focused on the retina. When the cataract becomes dense enough to interfere with vision, it can be replaced with a clear artificial lens implant during cataract surgery.

Vitreous

Next in our voyage through the eye is the vitreous. This is a jelly–like substance that fills the body of the eye. It is normally clear. In early life, it is firmly attached to the retina behind it. With age, the vitreous becomes more water–like and may detach from the retina. Often, little clumps or strands of the jelly form and cast shadows, which are perceived as “floaters.” While frequently benign, sometimes floaters can be a sign of a more serious condition such as a retinal tear or detachment and should be investigated with a thorough eye examination (see retinal detachment).

Retina

Finally, light reaches the retina, a thin tissue lining the innermost wall of the eye. The retina acts much like the film in a camera. The retina responds to light rays hitting it and converts them to electrical/chemical signals carried by the optic nerve to the brain. The outlying parts of the retina are responsible for peripheral vision while the center area, called the macula, is used for fine central vision and color vision. The very center of the macula is called the fovea. It has a very high concentration of special cells called cones, which make it the only part of the retina capable of 20/20 vision. Any disease that affects the macula, such as macular degeneration, will result in a decrease in straight ahead central vision.

Retinal Layers

Like film, the retina is composed of several layers with different roles. The first layer encountered by light is called the nerve fiber layer. Here, the nerve cells travel from all the parts of the retina to the optic nerve. Under this layer are most of the retinal blood vessels. They are responsible for nourishing the inner parts of the retina. The outermost layer is the photoreceptor layer. The photoreceptor layer, composed of cones for fine and color vision, and rods for vision in dim light, consists of the cells that actually convert light into nerve impulses. There are approximately 120 million rods and 6 million cones in a human retina. Most of the cones are located in the macula. The photoreceptor cells lie on top of a layer of cells called the retinal pigment epithelium or RPE. The RPE is responsible for keeping the photoreceptors healthy and functioning well. Under the RPE is the retina’s second set of blood vessels, which are in a layer called the choroid. The RPE, fed by the blood vessels of the choroid, nourish the photoreceptors.

Optic Nerve

The optic nerve is the structure which takes the information from the retina s and delivers it to the brain, where this information is interpreted as a visual image. The optic nerve consists of a bundle of about one million nerve fibers. The position in the back of the eye where the nerve enters the globe corresponds to the “blind spot” since there are no rods or cones in this location. Normally, a person does not notice this blind spot because of its off center location and rapid movements of the eye which allow the brain compensate for this absent information. In glaucoma, the nerve becomes damaged often due to high pressure within the eye.

Astigmatism is a common eye condition that is corrected by eyeglasses, contact lenses, or surgery. Astigmatism is characterized by unequal curvatures of the cornea. Astigmatism can occur in nearsighted, farsighted persons, or can be found alone , in all cases it results in blurry vision.

A person’s cornea is spherical in shape amd when light enters the eye, the cornea refracts or bends light creating a clear image of the object. However, the eye of a person with astigmatism is shaped more like a football or the back of a spoon. For this person, when light enters the eye it is refracted more by one curve than the other, resulting in a blurry image.

What Causes Astigmatism?

Astigmatism can be hereditary and is often present at birth but can change with age and growth.

What Are the Symptoms of Astigmatism?

People with undetected astigmatism often experience headaches, fatigue, eyestrain, and blurred vision at all distances. While these symptoms may not necessarily be the result of astigmatism, you should schedule an eye exam if you are experiencing one or more symptoms.

How Are Astigmatisms Treated?

Almost all degrees of astigmatism can be corrected with properly prescribed eyeglasses or contact lenses.

-Corrective lenses (eyeglasses or contact lenses).
For astigmatism, special corrective lenses called toric lenses are prescribed. Toric lenses have greater light bending power in one direction than the other. After performing various tests, your eye doctor will determine the ideal toric lens prescription for your astigmatism.

-Refractive surgery.
Another method for correcting astigmatism is by changing the shape of the cornea through refractive or laser eye surgery. While there is more than one type of refractive surgery, specific treatments are recommended on an individual basis.

What can cause contact lenses-related eye infections?

While contact lenses are safely worn by many, there is a risk of developing eye infections. Factors that contribute to an infection can include:

• Use of extended-wear lenses
• Reduced tear exchange under the lens
• Environmental factors
• Poor hygiene

How can I avoid getting an eye infection due to contact lenses?

The best way to avoid eye infections due to wearing contact lenses is to follow proper lens care guidelines as recommended by your optometrist. Single usage one day throw away lenses are affordable, extremely safe, easy to manage and are available in most prescriptions. Best of all you don’t have to carry around contact lens solutions which are costly and cumbersome.

Below are some of the most common eye infections associated with wearing contact lenses.

What are corneal ulcers?

A corneal ulcer is an erosion or exposed sore on the surface of the cornea. Corneal ulcers are most commonly caused by germs. Other causes of corneal ulcers include viruses, injury and inadequate eyelid closure. Sometimes when wearing a contact lens we are less sensitive to these conditions as they begin, like having a band aid on a cut, so it is important to remove your lenses as instructed. Being aware of how your eyes look and feel. when your lens are on is a important aspect of proper contact lens care.

What are the symptoms of corneal ulcers?

The symptoms of corneal ulcers include:

• Redness
• Pain
• Tearing
• Discharge
• White spot on the cornea
• Blurry vision
• Burning
• Itching
• Light sensitivity

How are corneal ulcers diagnosed and treated?

Early diagnosis is important in treating corneal ulcers. Your optometrist will ask you questions to determine what caused the ulcer. Your eyes will then be examined, sometimes a special dye may be placed in your eye to aid in the diagnosis don’t worry it doesn’t hurt at all. Treatment usually involves eye drops and is very effective when treatment is started early.

What is Contact Lens Induced Acute Red Eye (CLARE)?

CLARE is an inflammatory reaction of the cornea and conjunctiva (a thin and transparent membrane that covers the sclera, the white part of the eye). This infection is mostly caused by sleeping with contact lenses and is characterized by awaking with red eyes.

What is the treatment for CLARE?

In most cases, no treatment is required. It is recommended that patients discontinue lens wear, which usually remedies the condition. However, if redness or irritation persists after 24 hours, you should see your optometrist. If you experience pain, sensitivity to light or decrease in vision, you should see your optometrist immediately.

What is Contact Lens Papillary Conjunctivitis also known as Giant Papillary Conjunctivitis (GPC)?

GPC is an inflammatory reaction of the upper eye lid and is very common among those that over wear their contact lenses. One day lenses are a excellent choice for those who have experienced this.

What are the symptoms of GPC?

The symptoms of GPC include small, red bumps on the inflamed tissue on the underside of the upper eyelids. There is usually itchiness, discharge, increased lens awareness and decreased lens tolerance.

What is the treatment for GPC?

Your optometrist may prescribe eye drops to control the inflammation. Once under control usually a different type of lenses will be prescribed.

If you have been diagnosed with diabetes, you may be at risk of losing your vision since your body does not utilize sugar properly and, when the sugar levels rise, damage to the retinal blood vessels may occur. This injury to the retinal vessels is known as Diabetic Retinopathy. Diabetic Retinopathy is the leading cause of blindness in working-age adults.

What are the symptoms of diabetic retinopathy?

Often, one may not be aware of any symptoms even when significant diabetic retinopathy is present. When macular edema occurs, vision often becomes blurry and may fluctuate. If abnormal new blood vessels form, as in proliferative diabetic retinopathy, they may bleed and result in small specks or large floaters obscuring the vision. If a large hemorrhage occurs, vision often becomes very blurry.

How is diabetic retinopathy diagnosed?

A comprehensive eye examination by an optometrist or retina specialist is the only reliable means of detecting diabetic retinopathy. After the pupil is dilated, a device called an ophthalmoscope is used to view the retina and determine the extent of the retinopathy. If diabetic retinopathy is discovered, a fluorescein dye test and/or optical coherence tomogram (OCT) may be recommended. A fluorescein angiogram involves the injection of a dye into a vein in the arm followed by several minutes of intermittent photos with a special digital camera focused on the retina. An OCT is a non-invasive photo that creates a detailed cross-sectional image of the macula.

What is the treatment for diabetic retinopathy?

The best therapy for diabetic retinopathy is prevention. Studies show that strict control of blood sugar levels can significantly lower the risk of vision loss from diabetic retinopathy. High blood pressure and kidney problems should also be treated to minimize their effect on the retinopathy. Laser surgery is often the first line of treatment if macular edema or proliferative retinopathy is present. For macular edema, the laser is focused on leaky areas of the retina to aid in reabsorbing the excess fluid. The primary goal of this treatment is to prevent further vision loss. It is uncommon for people to recover significant vision following treatment but some do experience partial restoration. Laser surgery is not a cure for diabetic retinopathy and is not guaranteed to prevent further loss of vision. Other treatments for diabetic retinopathy include medications like steroids or a novel class of medication called anti-VEGF.

If you have been diagnosed with diabetes, you may be at risk of losing your vision since your body does not utilize sugar properly and, when the sugar levels rise, damage to the retinal blood vessels may occur. This injury to the retinal vessels is known as Diabetic Retinopathy. Diabetic Retinopathy is the leading cause of blindness in working-age adults.

What are the symptoms of diabetic retinopathy?

Often, one may not be aware of any symptoms even when significant diabetic retinopathy is present. When macular edema occurs, vision often becomes blurry and may fluctuate. If abnormal new blood vessels form, as in proliferative diabetic retinopathy, they may bleed and result in small specks or large floaters obscuring the vision. If a large hemorrhage occurs, vision often becomes very blurry.

How is diabetic retinopathy diagnosed?

A comprehensive eye examination by an optometrist or retina specialist is the only reliable means of detecting diabetic retinopathy. After the pupil is dilated, a device called an ophthalmoscope is used to view the retina and determine the extent of the retinopathy. If diabetic retinopathy is discovered, a fluorescein dye test and/or optical coherence tomogram (OCT) may be recommended. A fluorescein angiogram involves the injection of a dye into a vein in the arm followed by several minutes of intermittent photos with a special digital camera focused on the retina. An OCT is a non-invasive photo that creates a detailed cross-sectional image of the macula.

What is the treatment for diabetic retinopathy?

The best therapy for diabetic retinopathy is prevention. Studies show that strict control of blood sugar levels can significantly lower the risk of vision loss from diabetic retinopathy. High blood pressure and kidney problems should also be treated to minimize their effect on the retinopathy. Laser surgery is often the first line of treatment if macular edema or proliferative retinopathy is present. For macular edema, the laser is focused on leaky areas of the retina to aid in reabsorbing the excess fluid. The primary goal of this treatment is to prevent further vision loss. It is uncommon for people to recover significant vision following treatment but some do experience partial restoration. Laser surgery is not a cure for diabetic retinopathy and is not guaranteed to prevent further loss of vision. Other treatments for diabetic retinopathy include medications like steroids or a novel class of medication called anti-VEGF.

Keratoconus is an eye condition in which the shape of the cornea becomes distorted. The cornea is a clear structure that covers the front of the eye and does 85% of the focusing of the light as it passes through the eye. In a healthy eye, the cornea curves like a dome. In an eye with keratoconus, the center of the cornea slowly thins and bulges so that it sags and has a cone shape distorting vision.

What causes keratoconus?

The cause of keratoconus is unknown but does follow some genetic lines.

What are the symptoms of keratoconus?
Keratoconus tends to affect people in there early teens with symptoms of blurring vision and rapidly changing prescriptions. Often, eyeglass can not correct vision fully and specially designed medical contact lenses are needed to restore useful vision.

Symptoms include:

• Difficulty driving at night
• Halo’s and ghosting, especially at night
• Eye strain
• Headaches and general eye pain
• Headaches and general eye pain

How is keratoconus diagnosed?

Keratoconus can usually be diagnosed with a slit-lamp examination as well as corneal topography which precisely measures the curvature of the cornea. Your optometrist will look for signs such as corneal thinning, stress lines, and scarring at the apex of the corneal cone. Keratoconus, especially in the early stages, can be difficult to diagnose and its symptoms could be associated with other eye problems. Simply recognizing symptoms does not by itself diagnose the condition. Only a complete eye examination by a qualified expert can diagnose the condition in its earliest stages when it is easiest to treat and correct.

What is the treatment for keratoconus?

The primary treatment options for keratoconus are contact lenses and surgery. In the very early stages of keratoconus, vision problems can be corrected with prescription glasses or contact lenses. As keratoconus progresses, special gas permeable contact lenses may be necessary. Advanced keratoconus may require surgery. There are new treatments for this condition being advance all the time and by speaking with an expert you are sure to get the best care.

The term “macular degeneration” includes many different eye diseases, all of which affect central, or detail vision. Age-related macular degeneration is the most common of these disorders, mainly affecting people over the age of 60. Although there are many types of macular degeneration, age-related macular degeneration (AMD or ARMD) is the most common type. Age-related macular degeneration occurs in two forms: “wet” age-related macular degeneration and “dry” age-related macular degeneration. “Wet” age-related macular degeneration is less common but more aggressive in its development to severe central vision loss. “Dry” age-related macular degeneration is the more common type and is more slowly progressive in causing loss of vision.

What is wet age-related macular degeneration?

Wet age-related macular degeneration occurs when abnormal blood vessels begin to grow underneath the retina. These new blood vessels (known as choroidal neovascularization or CNV) tend to be very fragile and often leak blood and fluid. The blood and fluid raise the macula from its normal place at the back of the eye and interfere with the retina’s function and causes the central vision to blur. Under these circumstances, vision loss may be rapid and severe. Some patients, however, do not notice visual changes despite the onset of CNV. Therefore, periodic eye examinations are very important for patients at risk for CNV. Once CNV has developed in one eye, whether there is a visual loss or not, the other eye is at relatively high risk for the same change.

What is dry age-related macular degeneration?

In dry AMD, the light-sensitive cells in the macula slowly break down. With less of the macula functioning, central vision diminishes. Dry AMD often occurs in just one eye at first. Later, the other eye can be affected. The cause of dry AMD is unknown. The dry form is much more common than the wet form. Dry AMD can advance and cause vision loss without turning into wet AMD. Dry AMD can also rapidly transform into the wet form by the growth of new blood vessels.

What causes macular degeneration?

We do not know the precise cause for the development of ARMD. However, we do know that there are certain risk factors for the development of age-related macular degeneration.

What are risk factors for macular degeneration?

The greatest risk factor is age. Although AMD may occur during middle age, studies show that people over age 60 are clearly at greater risk than other age groups.

What are the symptoms of macular degeneration?

Neither dry nor wet AMD cause any eye pain. The most common early symptom in dry AMD is blurred vision. Dry macular degeneration symptoms usually develop gradually and do not include total blindness. However, the symptoms may worsen the quality of life by making reading, driving, and facial recognition difficult. Other symptoms may include decreased night vision, a decrease in the intensity or brightness of colors, increase in the haziness of overall vision. All of the above symptoms may also be noticed in the wet form of AMD. In addition, the most common symptom in wet macular degeneration is straight lines appearing crooked or wavy.

How is macular degeneration diagnosed?

A thorough examination by an eye doctor is the best way to determine if you have macular degeneration or if you are at risk for developing the condition. The exam begins by testing your visual acuity or the sharpness of your vision. There are several different tests for visual acuity. The most familiar one has lines of black letters on a white chart. Next, your eyes may be tested with an Amsler grid. This test helps your doctor determine if you are experiencing areas of distorted or reduced vision, both common symptoms of macular degeneration. If you do have macular degeneration, your doctor will use the Amsler grid to determine if your vision has changed. After these visual tests, the front part of your eyes will be examined to determine if everything is healthy. Your doctor may put anesthetic drops in your eyes before measuring the pressure in each eye. Drops are also administered, which cause your pupils to dilate. This will allow your doctor to examine the retina through the enlarged pupil. After the dilating drops are administered and allowed time to work, the eye doctor will then use a slit-lamp to examine the eyes. The slit-lamp is a special microscope that enables the doctor to examine the different parts of the eye under magnification. When used with handheld lenses or special contact lenses, the slit-lamp gives the examiner a highly magnified view of the retina.

What is the treatment for wet macular degeneration?

Wet AMD can be treated with laser surgery, photodynamic therapy, and injections into the eye. None of these treatments is a permanent cure for wet AMD. The disease and loss of vision may continue to grow despite treatment.

What is the treatment for dry macular degeneration?

There is currently no treatment available to reverse dry macular degeneration. However, dry macular degeneration usually develops at a slower pace and most patients with this condition are able to live relatively normal, productive lives. Often one eye is affected more than the other.

Can macular degeneration be prevented?

Your lifestyle can play a role in reducing your risk of developing AMD. This includes:

• Eating a healthy diet high in green, leafy vegetables and fish
• Not smoking
• Maintaining blood pressure and weight at normal levels
• Engaging in regular, moderate exercise

Presbyopia is an age-related condition that causes blurred near vision. It typically starts at around age 40 and affects everyone, even those who’ve never had vision problems before.

When presbyopia begins, people will squint or hold reading materials at arm’s length to help their eyes focus. Eye strain, headache and fatigue are common symptoms of presbyopia.

Most experts believe presbyopia is caused by changes to the lens inside the eye. As people age, the lens becomes harder and less elastic, making it more difficult for the eye to focus on close objects.

For centuries presbyopia was corrected with the use of bifocal eyeglasses. Presbyopia can be corrected with eyeglasses, contact lenses, or surgery.

Contact Lenses for Presbyopia

Bifocal contact lenses are now available in many soft and gas permeable lens designs. Similar to bifocal eyeglasses, bifocal contacts have two prescriptive powers for distance and near vision. Multifocal contact lenses are also available with additional variations in power to correct near, intermediate, and far vision.

Monovision is another contact lens option for correcting presbyopia, where one eye wears a near vision lens and the other eye wears a distance vision lens. Your eyes automatically focus properly depending on the visual situation.

Contact lens wearers can also use a distance lens in both eyes and then wear reading glasses for close-up work.

The gradual loss of your eyes’ ability to focus actively on nearby objects is a not-so-subtle reminder that you’ve reached middle age. A natural, often annoying part of aging, presbyopia usually becomes noticeable in your early to mid-40s and continues to worsen until around age 65.

You may become aware of presbyopia when you start holding books and newspapers at arm’s length to be able to read them. If you’re nearsighted, you might temporarily manage presbyopia by reading without your glasses.

A basic eye exam can confirm presbyopia. You can correct the condition with prescription eyeglasses.

What Is Eye Angiography?

Fluorescein and indocyanine green (ICG) angiography are diagnostic tests which use special cameras to photograph the structures in the back of the eye. These tests are very useful for finding leakage or damage to the blood vessels which nourish the retina (light-sensitive tissue). In both tests, a colored dye is injected into a vein in the arm of the patient. The dye travels through the circulatory system and reaches the vessels in the retina and those of a deeper tissue layer called the choroid (see Fig. 1 below). Neither test involves the use of X-rays or harmful forms of radiation.

Why Is Eye Angiography Performed?

Both tests can help retina specialists diagnose and evaluate specific eye diseases. Fluorescein dye is best for studying the retinal circulation (below) while indocyanine green is often better for studying the deeper choroidal blood vessel layer (below). Certain eye disorders, such as diabetic retinopathy and retinal vascular occlusive disease affect primarily the retinal circulation and are usually imaged with fluorescein dye. In other disorders, such as age-related macular degeneration, where leakage is from the deeper choroidal vessels, both tests may be useful. Indocyanine green angiography is especially helpful when there is leakage of blood, which may make interpretation of fluorescein studies difficult.

When abnormal vessels or leakage is identified with an angiogram, laser treatment or pharmacological therapies may be indicated to prevent vision loss. The tests can also be useful for following the course of disease or response to treatment. Fluorescein and ICG angiography are universally employed throughout the world as diagnostic tests. The doctors of Vitreous-Retina-Macula consultants contributed extensively to the development and understanding of these techniques. They have published numerous peer–reviewed papers on the subject, a major textbook, and a CD–ROM.

What Are The Risks Of Eye Angiography

Both fluorescein angiography and indocyanine green angiography are considered very safe and serious side-effects from these tests are uncommon. However, there is the possibility that a patient may have a reaction to the dyes. While fluorescein contains no iodine and is safe in patients known to be allergic, indocyanine green is currently formulated with iodine and should not be used in these individuals. Some people may experience slight nausea after dye injection that usually passes quickly. Patients who are allergic to the dye can develop itching and a skin rash. These symptoms generally respond quickly to oral medications such as anti–histamines or steroids. Very rarely, a sudden life-threatening allergic reaction called anaphylaxis can occur. This condition requires medical treatment. There is also a possibility of an infiltrate of the dye into the skin at the injection site; this would cause some discomfort or discoloring of the skin for several days. Fluorescein dye will also turn a patient’s urine orange and may slightly discolor the skin as well for a brief period. For special patient populations there may be individual risks of these procedures which your physician will specify for you.

Optical Coherence Tomography (OCT)

Optical Coherence Tomography (OCT) is a diagnostic test that allows for the imaging and measurement of retinal thickness. OCT is very useful in detecting retinal swelling or fluid accumulation secondary to a variety of retinal conditions. It provides very valuable information and is also useful for following the response to a treatment. OCT testing has become a standard of care for the assessment and treatment of most retinal conditions. OCT uses rays of light to measure retinal thickness and can be performed in a few minutes. No radiation or x-rays are used in this test.

Ultrasound (B–Scan)

Ultrasound is a test that uses sound waves to assess ocular and retinal conditions. If your doctor cannot view the retina because of some opacity that blocks the view, they may use an ultrasound to determine the general status of the retina. Ultrasound is commonly used to assess the retina in patients with a dense cataract or vitreous hemorrhage. Ultrasound is simple to perform, painless, and does not involve any radiation.

Strabismus (also called crossed eyes, deviation, heterotropia, squint, tropia) is a condition where both of your eyes do not look toward the same object together. There are six different muscles that surround the eyes and work together so that both eyes can focus on the same object. For someone with strabismus, these muscles do not work together. As a result, one eye looks at one object, while the other eye turns in a different direction and is focused on another object. When this happens, two different images, one from each eye, are sent to the brain. This confuses the brain, and the brain may learn to ignore the image from the weaker eye. Strabismus is a common condition among children but it can also occur later in life.

When presbyopia begins, people will squint or hold reading materials at arm’s length to help their eyes focus. Eye strain, headache and fatigue are common symptoms of presbyopia.

What are the symptoms of strabismus?

The main sign of strabismus is an eye that is not directed straight. Sometimes a child or young person will squint with one eye in bright sunlight. Symptoms of faulty depth perception may also be noticed. Adults with strabismus will usually have double vision.

How is strabismus diagnosed?

Strabismus is usually diagnosed with a physical examination that includes a detailed examination of the eyes. Tests are done to determine how much the eyes are out of alignment. These eye tests may include corneal light reflex, cover/uncover test, retinal exam, standard ophthalmic exam and visual acuity.

What is the treatment for strabismus?

Treatment of strabismus may consist of eyeglasses, patching, eye coordination exercises (called orthoptics) and/or surgery on the eye muscles. Eyeglasses, with or without patching, are often the treatment tried first and can usually reduce the amount of deviation.

Retinal detachment affects approximately 1 in 10,000 people each year. If left untreated, most retinal detachments will lead to loss of vision. An understanding of some of the normal anatomy of the eye may be useful in understanding how retinal tears and detachment occur and the symptoms which they may cause. The retina is a thin tissue that lines much of the inside of the eye. The center portion of the retina is called the macula. The macula is responsible for fine central vision and for color vision. The more peripheral parts of the retina provide peripheral vision. The vitreous is a jelly like substance, which fills the center of the eye. The vitreous is normally clear and as such will normally not affect vision. The vitreous is attached to the retina in many areas. In some regards, the way in which the eye works may be compared to a camera. In a camera, light is focused by the lens onto a film, where an image is formed. In the eye, the cornea (a clear structure forming part of the front wall of the eye) and the lens focus light onto the retina where an image is formed. The retina then converts this image into neural signals, which are transmitted to the brain.

Floaters, flashing lights and posterior vitreous detachment:

When we are young, the vitreous is normally a clear structure which does not affect our vision. As we age, however, changes may occur within the vitreous. Some parts of the vitreous may become more liquefied; other parts of the vitreous may condense and start to shrink. As the vitreous shrinks it may pull away from its attachments to the back part of the eye. This separation of the vitreous from its attachments to the back part of the eye is called a posterior vitreous detachment. Posterior vitreous detachments occur as a normal aging event but may be more common or occur earlier in people who are nearsighted (myopic), have undergone cataract surgery or who have had eye trauma or inflammation.

As a result of these changes within the vitreous, small clumps or strands may develop in the vitreous. As light passes through the vitreous, these small clumps or strands may cast shadows on the retina. We see these shadows as floaters. Although the floaters appear to us to be outside of the eye, they are actually within the eye. The floaters can have many different shapes. While most often they appear as dots or lines, sometimes they can also appear like circles, clouds, cobwebs or even like a spider or a fly. Most of the time, these objects will appear to move. Floaters can also be caused by bleeding or inflammation in the eye.

The vitreous pulling away from the retina can also cause the sensation of seeing flashing lights. These sometimes appear like “lightening streaks” in the eye. The sensation of flashing lights is not, however always a sign of the vitreous pulling on the retina. Other conditions such as a migraine can also cause the sensation of seeing flashing lights.

At times, a posterior vitreous detachment may occur without associated symptoms. While most posterior vitreous detachments do not lead to more serious problems, sometimes a retinal tear or detachment may arise as a result of a posterior vitreous detachment. Because of the risk of there being an associated retinal tear or detachment, anyone having the new onset of floating spots or flashing lights should undergo a careful retinal evaluation.

Retinal tear and detachment:

As the vitreous pulls away from the retina during a posterior vitreous detachment, the retina may at times tear. Retinal detachment occurs if fluid from within the vitreous passes through the tear and collects under the retina, causing the retina the separate from the underlying tissue (retinal pigment epithelium). The retinal tear may be associated with the symptoms of a posterior vitreous detachment (flashing lights and floaters). However as most retinal tears occur in the more peripheral parts of the retina, a retinal tear will usually not cause loss of vision unless there is progression to retinal detachment. The detached retina is not capable of normal sight and as the retinal detachment enlarges and approaches the central part of the retina there will be an enlarging area of vision loss. This is sometimes described as a shadow or veil covering the vision. Sometimes retinal tears occur without associated floaters or flashing lights. In these cases, the first symptoms to occur may be the loss of vision due to retinal detachment.

Not all retinal tears will lead to retinal detachment. At times, a retinal hole or tear may be found during a routine eye exam without there having been any associated symptoms. In this situation, the risk of progression to retinal detachment may be low and treatment of the retinal tear in this situation may not always be needed. However, retinal tears associated with symptoms suggesting that there has been a recent posterior vitreous detachment are usually felt to be of high risk of progression to retinal detachment and should, under most circumstances be treated in order to minimize the risk of progression to retinal detachment. Retinal tears, if detected early, can usually be treated in such a way as to avoid retinal detachment.

Treatment of Retinal Tears:

Retinal tears can be treated using either laser photocoagulation or cryotherapy. Laser photocoagulation is a procedure where a special light is directed to the retina and used to create burns in the retina surrounding the retinal tear. Cyrotherapy is a procedure where a freeing probe is placed on the surface of the eye and used to create a freeze extending to the retina surrounding the retinal tear. Whether laser photocoagulation or cryotherapy is used, as the eye heals a scar will form sealing the retinal tear and in most cases preventing a retinal detachment from occurring. Both laser photocoagulation and cryotherapy are usually performed in the doctor’s office. Treatment of retinal tears is usually successful in preventing retinal detachment. Unfortunately, occasionally even after treatment of a retinal tear, retinal detachment may still occur. Therefore, if any new symptoms arise following treatment of a retinal tear, the retina should be re-examined and even in the absence of new symptoms, continued follow-up after treatment of a retinal tear is needed.

Treatment of Retinal Detachment:

Some retinal detachments, if diagnosed when the detachment is small, may be treatable with only laser photocoagulation or cryotherapy. More often, however, if retinal detachment occurs, more extensive surgery is usually needed. The surgical procedures, which are frequently used for repair of retinal detachment, include pneumatic retinopexy, scleral buckle and vitrectomy.

When pneumatic retinopexy is used for repair of a retinal detachment, a gas bubble is injected into the vitreous cavity. The patient is then positioned in such a way so that the gas bubble pushes against the retinal tear and temporarily seals the tear, which has caused the retinal detachment. With the retinal tear covered by the gas bubble, the fluid that has accumulated under the retina will usually be reabsorbed by the eye within one or two days. As the gas bubble will also be reabsorbed by the body, it is necessary to also create a more permanent seal surrounding the retinal tear. To create this permanent seal, pneumatic retinopexy is done in conjunction with either retinal cryopexy or laser photocoagulation. Sometimes the retinal cryopexy will be done prior to the injection of the gas bubble. On other occasions, however, the cryopexy or laser photocoagulation will be done on a subsequent day, after there has been clearing of the subretinal fluid. Depending on which gas is used, the bubble takes between two and six weeks to be cleared from the eye. Pneumatic retinopexy can usually be performed in the doctor’s office. While pneumatic retinopexy is a good option for the repair of many retinal detachments, not all retinal detachments are suitable for this type of repair.

Scleral buckling surgery is another good option for repair of many retinal detachments. In scleral buckling surgery a buckling element, usually a piece of silicone, is sutured to the sclera (the outer wall of the eye) in such a way as to indent the wall of the eye. This indentation reduces the traction that is created by the vitreous pulling on the retinal tear, thereby allowing the tear to close. Cryotherapy is usually used in this procedure as well, to create a permanent seal surrounding the retinal tear. The fluid which has collected under the retina is either surgically removed or is allowed to spontaneously reabsorb. Sometimes a gas bubble will also be injected into the vitreous cavity as part of this procedure. Scleral buckling surgery is performed in an operating room. It is frequently done under local anesthesia and the patient will usually return home the same day as the surgery.

Sometimes, particularly in more complicated retinal detachments; it may be preferable or necessary to remove the vitreous in order to reattach the retina. This procedure is called a vitrectomy (also called pars plana vitrectomy). Vitrectomy may be used in combination with the other techniques already described. During vitrectomy surgery, small incisions are made through the sclera, which allow microsurgical instruments to be introduced into the vitreous. The vitreous, along with any scar tissue, which may also be present, is removed. In this way the traction on the retina is eliminated. The fluid that has collected under the retina is surgically removed. The vitreous cavity is then usually filled with a gas bubble. Sometimes in more complicated retinal detachments the vitreous cavity may instead be filled with silicone oil. The retina tear is surrounded with laser photocoagulation. A scleral buckle may be placed in conjunction with vitrectomy. Vitrectomy surgery is performed in an operating room. The patient will usually return home the same day as the surgery.

The choice of which of these procedures is most appropriate for the repair of a retinal detachment is dependent on many factors. These include the location of the responsible retinal tears and the presence or absence of scar tissue on the retina (proliferative vitreoretinopathy). The decision of which method of retinal detachment surgery is best can only be made after a careful evaluation. Fortunately, with these techniques, it is possible to successfully repair most retinal detachments. While most retinal detachments are successfully repaired with a single operation, in some cases more than one operation may be needed.

The amount of vision recovered after successful retinal detachment surgery is variable. The most important factors influencing the postoperative vision are whether the macula is detached prior to surgery and the duration the detachment has been present. If retinal detachment surgery can be done before the detachment has extended to the macula (the center portion of the retina which is responsible for central vision) the likelihood of maintaining good central vision is excellent. In many cases, however, a retinal detachment may not be detected until after the central vision is affected. If the macula is detached prior to the surgical repair, there is usually some permanent vision loss even after successful retinal detachment surgery. While it is common to obtain some improvement in vision shortly after surgery, the final best vision may at times take 6 months, a year, or even longer to obtain.