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Eye Disorders

Refractive Errors

Nearsightedness

Myopia is the medical term for “nearsightedness”. Twenty five percent of the world today is myopic. More than 70 million people in North America are nearsighted. Myopia occurs when an eye is too long for the cornea’s curvature. Light rays entering the eye do not come to a sharp focus on the retina at the back of the eye. Instead, they focus further forward, producing a blurred image.

 

The term “nearsighted” means that you can see “near” objects clearly without your glasses, but objects further in the distance are blurry. There are varying degrees of myopia or nearsightedness. The more myopic you are, the more blurred objects appear in the distance, the higher your eyeglass prescription and the thicker your glasses.

 

Of all myopic people, about 90% have corrections less than -6.00 diopters.

The table below shows the categories of severity for myopia:

 

Mild Myopia               less than 3.00 diopters

Moderate Myopia      – 3.00 to – 6.00 diopters

Severe Myopia           – 6.00 to – 9.00 diopters

Extreme Myopia        greater than 9.00 diopters

 

Almost everyone feels that their myopia is severe, because of how dramatically dependent they are on glasses and contact lenses. However, only one in ten myopic people are actually in the severe and extreme categories. Cataract surgery can reduce or eliminate myopia, even high myopia, by selecting an appropriate powered lens implant.

 

Farsightedness

Hyperopia is the medical term for “farsightedness”. It occurs when an eye is too short for the cornea’s curvature. Light rays entering the eye try to focus behind the retina, and as a result a blurred image is produced.

 

Farsighted individuals, however, can use their focusing muscles to “pull” the image forward onto the retina. In a young person with severe hyperopia, or once presbyopia sets in around age 45, distant objects are seen more clearly than near objects. Cataract surgery can reduce or eliminate farsightedness, even extreme farsightedness, by selecting an appropriate powered lens implant.

 

Astigmatism

Many patients with myopia have some degree of astigmatism, or ovalness to their corneas. It is the most common refractive condition, and occurs to some extent in most eyes. Astigmatism occurs when the cornea is shaped more like a football/rugby ball than a basketball. With astigmatism, different parts of the cornea have different focusing powers. As a result, patients with astigmatism experience distortion or tilting of images because of unequal bending of light rays entering the eye. Patients with high degrees of astigmatism have blurred vision not only for distant objects, as with myopia, but for near objects as well.

 

Astigmatism is measured in diopters. Of all myopic people, 50% or more have astigmatism as well. Most of these people have corrections of less than 1 diopter.

 

Astigmatism can be corrected at the time of cataract surgery using toric lens implants or limbal relaxing incisions on the cornea. The table below shows the categories of severity for astigmatism:

 

Mild Astigmatism                   less than 1.00 diopters

Moderate Astigmatism         1.00 to 2.00 diopters

Severe Astigmatism              2.00 to 3.00 diopters

Extreme Astigmatism            greater than 3.00 diopters

 

Presbyopia

Presbyopia is the normal process of aging, where the natural lens of the eye loses some of the flexibility that characterizes a younger eye. This usually occurs between ages 40-50. Everyone experiences presbyopia, some sooner, some later. Because of this normal process, nearsighted people begin to wear bifocals in their forties, and those who never needed glasses before may require reading glasses.

 

The Crystalens™ implanted during cataract surgery treats two problems. First the cloudy cataract will be replaced with a clear lens, restoring your sight. Second, the Crystalens™ treats presbyopia by flexing and changing focus at different distances. Patients who select the Crystalens™ are less dependant on eyeglasses after their surgery.

 

How the Eye Works

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The human eye is the organ which gives us the sense of sight, allowing us to learn more about the surrounding world than any of the other five senses. We use our eyes in almost everything we do, whether reading, working, watching television, writing a letter, driving a car, and countless other activities. Sight is the most precious of the five senses, and many people fear blindness more than any other disability.

 

The eye allows us to see and interpret the shapes, colors, and dimensions of objects in the world by processing the light they reflect or give off. The eye is able to see in dim light or bright light, but it cannot see objects when light is absent. The eye changes light rays into electrical signals then sends them to the brain, which interprets these electrical signals as visual images.

 

The eye is set in a protective cone-shaped cavity in the skull called the orbit or socket and measures approximately one inch in diameter. The orbit is surrounded by layers of soft, fatty tissue which protect the eye and enable it to turn easily. Six muscles regulate the motion of the eye. Among the more important parts of the human eye are the iris, cornea, lens, retina, conjunctiva, the macula, and the optic nerve.

 

Our ability to “see” starts when light reflects off an object at which we are looking and enters the eye. As it enters the eye, the light is unfocused. Light entering the eye is first bent, or refracted, by the cornea — the clear window on the outer front surface of the eyeball. The cornea actually provides most of the eye’s optical power or light-bending ability. After the light passes through the cornea, it is bent again, to a more finely adjusted focus, by the crystalline lens inside the eye. The lens focuses the light on the retina. This is achieved by tiny muscles in the eyeball that change the shape of the lens, bending or flattening it to focus the light rays. This adjustment in the lens, known as accommodation, is necessary for bringing near and far objects into focus. The process of bending light to produce a focused image on the retina is called refraction. Once the light is focused on the retina, it stimulates cells which send millions of electrochemical impulses along the optic nerve to the brain. The brain interprets the impulses, enabling us to “see” the object.

 

DEFINITIONS OF EYE RELATED TERMS

 

Cornea

The cornea is sometimes referred to as the ‘window of the eye’. It provides most of the focusing power when light enters your eye. The cornea is composed of 5 layers of tissue. The outer layer (the epithelium), is the eye’s protective layer. This layer is made up of highly regenerative cells that have the ability to grow back within 3 days, and therefore, allow for fast healing of superficial injuries. Most of the inner layers provide strength to the eye. 

 

Lens

The lens is the clear structure located behind the pupil. Its primary function is to provide fine-tuning for focusing and reading. The lens performs this function by altering its shape. At about the age of 40-50, the lens becomes less flexible and presbyopia sets in. At about the age of 60 or 70, the lens becomes cloudy and hard (cataract formation), preventing light from entering the eye. 

 

Pupil

The pupil is the ‘black circle’ that you see in people’s eyes. The primary function of the pupil is to control the amount of light entering the eye. When you are in a bright environment, the pupil becomes smaller to allow less light through. When it is dark, the pupil expands to allow more light to reach the back of the eye. 

 

Iris

This is the colored part you see in people’s eyes (i.e. blue/green/brown/hazel). The primary function of the iris is to control the size of the pupil. This is achieved through contraction or expansion of the muscles of the iris. 

 

Vitreous Body

This is the clear ‘gel like’ substance located inside the eye’s cavity. Its purpose is to provide a spherical shape to the eye. The vitreous may develop small clumps known as ‘floaters’, which are more common in nearsighted people than in the rest of the population. 

 

Optic Nerve

The optic nerve carries images from the retina to the brain. 

 

Retina

The retina consists of fine nerve tissue which lines the inside wall of the eyes and acts like the film in a camera. Its function is to convert light into electrical signals that are later sent down the optic nerve to the brain. 

 

Sclera

This is the ‘white part’ that we see in people’s eyes. The sclera’s purpose is to provide structure, strength and protection to the eye.  

 

Glaucoma

image010Glaucoma is when the pressure in the eye is too high, damaging the main nerve in back of the eye, the optic nerve.

Dr. Segal uses the latest technology to follow his glaucoma patients including computerized visual field testing and infrared optic nerve imaging analysis. Treatment of glaucoma involves eye drops, office laser treatments and surgery.

 

Glaucoma treatment can also prevent blindness. Since glaucoma usually has no symptoms, you should have an eye exam every year over age 40 to detect preventable causes of blindness.

 

Retina

The retina is a delicate film in back of the eye that converts light into nerve signals that are sent to the brain. The retina is like the film in the back of a camera, and it is essential for vision.

 

Many conditions can damage the retina including macular degeneration, strokes, diabetes and retinal detachments. If you see flashes and floaters you may have a tear in the retina which needs a simple office laser treatment to prevent a blinding retinal detachment. If you see distortion in straight lines you may have active macular degeneration requiring treatment. Any changes in your vision should be reported to Dr. Segal for evaluation.

image001This is a picture of a normal retina, the delicate film in back of the eye. The dark spot in the center is the macula and is required for clear vision.
Any problem with the retina reduces vision.
image003This patient has diabetic retinopathy. This macula has bleeding and leakage that must be treated. All diabetics must be followed by an ophthalmologist to prevent loss of vision.
image004This patient has macular degeneration and if there is leaking then treatment is required to prevent blindness (wet macular degeneration). Dr. Segal advises all macular degeneration patients to monitor their vision for distortion and take special nutritional supplements to preserve vision.
image014This patient has a retinal detachment of the upper retina and needs surgery to prevent blindness. Patients may initially see floaters and flashes and need an office laser to treat the retina before it gets to this stage.

 

 

Irritated Eyes

Dr. Segal specializes in treating irritated eyes. Other ophthalmologists send their most difficult irritated eyen cases to Dr. Segal. Eyes can become irritated from dry eyes, allergy, blepharitis (a dandruff condition) and eyelid abnormalities.

 

Dry eyes are treated with artificial tear drops, lacrimal punctual plugs, nutritional supplements, and prescription medication. Allergies are treated with prescription eye drops, allergy testing and immunotherapy to retrain the immune system to ignore the allergen. The correct cause of the irritation must be identified to treat the condition. Dr. Segal can usually make irritated eyes much more comfortable, even in the most difficult cases.

 

Corneal disease

image009The cornea is the clear window in front of the eye. Dr. Segal has completed additional training to specialize in treating the most challenging corneal diseases. Any damage to the cornea heals as a scar, which can impede vision. Therefore it is essential to heal a damaged cornea without a scar that will block clear vision. There are many diseases of the cornea that can cause pain and loss of vision. Other ophthalmologists refer corneal disease to Dr. Segal for his expert opinion and treatment.

 

Eyelid Disorders

image006The eyelid must be healthy or else one experiences eye pain and possible vision loss. If the eyelids do not close, the eye dries out. In addition, if your eyelids turn in or out, you may require surgery to correct this problem. Eyelashes rubbing on the eye can also cause severe pain.

 

Problems with the eyelids tear drain can cause excessive tearing. A sty or chalazion is a painful swelling that responds to hot compresses, medication and sometimes surgery. The skin of the eyelid can develop many irritating problems and skin cancer. Local dermatologists send Dr. Segal eyelid skin conditions and lesions for biopsy and cancer reconstruction.

 

Low Vision

When vision is permanently reduced we can help with low vision magnification and telescope systems. Legally blind patients need special optical aids when eyeglasses are not enough. The patient is carefully examined and a device is designed to maximize the vision that the patient has left. The patient is then trained to use their new device.

Our goal for low vision patients is to restore independence and help their improve quality of life.

 

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Eye Emergencies

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We make every effort to attend to emergency visits immediately and see several unscheduled emergencies every day. Usually we have patients with loss of vision, infections, pain or trauma come right in for urgent care. Patients coming in for emergencies have the distinct advantage of seeing an ophthalmologist right away, which is more effective than going to a walk-in clinic or ER. Dr. Segal accepts several workers comp plans and has experience treating workplace injuries and injured police officers.

 

Corneal abrasions are a common eye emergency; watch this video to learn more about them:

http://www.geteyesmart.org/eyesmart/diseases/corneal-abrasion.cfm