Acanthamoeba

On August 4th, 2010, posted in: Eye & Vision Problems by

Acanthamoeba is one of the most ubiquitous organisms in the environment, but rarely causes infections. When infection does occur, however, it can be extremely serious and vision threatening. Recently, there have been multiple reports of increasing incidence of Acanthamoeba keratitis. Co-infection with a bacterial keratitis is common both in the contact lens case and on the cornea, complicating prevention, diagnosis and treatment.

By educating yourself about the symptoms and risk factors for Acanthamoeba keratitis, you can help protect yourself from this potentially sight-threatening infection. The best defense against Acanthamoeba keratitis infection is proper contact lens hygiene. See the Lens Care Guide for detailed contact lens care instructions.

Symptoms

  • Infection from Acanthamoeba is rare, but when it does occur, it can threaten vision.
    A red, (frequently) painful eye infection—especially if the discomfort does not improve with treatment.
  • Foreign body sensation, tearing, light sensitivity, and blurred vision.
  • Red, irritated eyes lasting for an unusually long period of time after removal of contact lenses.

Risk Factors

  • Use of tap water in cleaning and disinfecting contact lenses—including the lens case.
  • Swimming with contact lenses in the eyes, especially in fresh water lakes and rivers. Acanthamoeba keratitis has also been isolated from virtually all water sources—from pools to hot tubs to showers.
  • Failure to follow lens care instructions (see Lens Care Guide below)/poor compliance.

Lens Care Guide

  • Always wash hands before handling contact lenses.
  • Rub and rinse the surface of the contact lens before storing.
  • Use only sterile products recommended by your optometrist to clean and disinfect your lenses. Saline solution and rewetting drops are not designed to disinfect lenses.
  • Avoid using tap water to wash or store contact lenses.
  • Contact lens solution must be discarded upon opening the case, and fresh solution used each time the lens is placed in the case.
  • Replace lenses using your doctor’s prescribed schedule.
  • Do not sleep in contact lenses unless prescribed by your doctor and never after swimming.
  • Never swap lenses with someone else.
  • Never put contact lenses in your mouth.
  • See your optometrist regularly for contact lens evaluation.
  • If you experience RSVP (redness, secretions, visual blurring or pain), return to your optometrist immediately!

 

Information courtesy of the American Optometric Association, 3/14/11

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Amblyopia (Lazy Eye)

On August 4th, 2010, posted in: Eye & Vision Problems by

Lazy eye, or amblyopia, 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(Anisometropia). 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.

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.

 

Information courtesy of the American Optometric Association, 3/14/11

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Anterior Uveitis

On August 4th, 2010, posted in: Eye & Vision Problems by

Anterior uveitis is an inflammation of the middle layer of the eye, which includes the iris (colored part of the eye) and adjacent tissue, known as the ciliary body. If untreated, it can cause permanent damage and loss of vision from the development of glaucoma, cataract or retinal edema. It usually responds well to treatment; however, there may be a tendency for the condition to recur. Treatment usually includes prescription eye drops, which dilate the pupils, in combination with anti-inflammatory drugs. Treatment usually takes several days, or up to several weeks, in some cases.

Anterior uveitis can occur as a result of trauma to the eye, such as a blow or foreign body penetrating the eye. It can also be a complication of other eye disease, or it may be associated with general health problems such as rheumatoid arthritis, rubella and mumps. In most cases, there is no obvious underlying cause.

Signs/symptoms may include a red, sore and inflamed eye, blurring of vision, sensitivity to light and a small pupil. Becuase the symptoms of anterior uveitis are similar to those of other eye diseases, your optometrist will carefully examine the inside of your eye, under bright light and high magnification, to determine the presence and severity of the condition. Your optometrist may also perform or arrange for other diagnostic tests to help pinpoint the cause.

 

Information courtesy of the American Optometric Association, 3/14/11

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Astigmatism

On August 4th, 2010, posted in: Eye & Vision Problems by | 1 Comment

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.

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 at Kaster Eye Clinic will include testing for astigmatism. Depending on the amount present, your optometrist can provide eyeglasses, or contact lenses. These medical devices correct the astigmatism by altering the way light enters your eyes.

Another option for treating astigmatism uses a corneal modification procedure called orthokeratology (ortho-k). Ortho-K is a painless, non-invasive, reversible procedure that involves wearing a series of specially designed rigid contacts overnight to gradually reshape the curvature of the cornea.

Laser surgery is also a possible treatment option for some types of astigmatism. It changes the shape of the cornea by removing a small amount of eye tissue. This is done using a highly focused laser beam on the surface of the eye.

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What causes astigmatism?

Astigmatism occurs due to the irregular shape of the cornea or the lens inside the eye. The cornea and lens are primarily responsible for properly focusing light entering your eyes allowing you to see things clearly.

The curvature of the cornea and lens causes light entering the eye to be bent in order to focus it precisely on the retina at the back of the eye. In astigmatism, the surface of the cornea or lens has a somewhat different curvature in one direction than another. In the case of the cornea, instead of having a round shape like a basketball, the surface of the cornea is more like a football. As a result, the eye is unable to focus light rays to a single point causing vision to be out of focus at any distance.

Sometimes astigmatism may develop following an eye injury or eye surgery. There is also a relatively rare condition called keratoconus where the cornea becomes progressively thinner and cone shaped. This results in a large amount of astigmatism resulting in poor vision that cannot be clearly corrected with spectacles. This disease usually requires rigid contact lenses for clear vision, and it may eventually progress to a point where a corneal transplant is necessary.

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How is astigmatism diagnosed?

Astigmatism can be diagnosed through a comprehensive eye examination. Testing for astigmatism measures how the eyes focus light and determines the power of any optical lenses needed to compensate for reduced vision. This examination may include:

  • Visual acuity – As part of the testing, you’ll be asked to read letters on a distance chart. This test measures visual acuity, which is written as a fraction such as 20/40. The top number is the standard distance at which testing is done, twenty feet. The bottom number is the smallest letter size you were able to read. A person with 20/40 visual acuity would have to get within 20 feet of a letter that should be seen at forty feet in order to see it clearly. Normal distance visual acuity is 20/20.
  • Keratometry – A keratometer is the primary instrument used to measure the curvature of the cornea. By focusing a circle of light on the cornea and measuring its reflection, it is possible to determine the exact curvature of the cornea’s surface. This measurement is particularly critical in determining the proper fit for contact lenses. A more sophisticated procedure called corneal topography may be performed in some cases to provide even more detail of the shape of the cornea.
  • Refraction – Using an instrument called a phoropter, your optometrist places a series of lenses in front of your eyes and measures how they focus light. This is performed using a hand held lighted instrument called a retinoscope or an automated instrument that automatically evaluates the focusing power of the eye. The power is then refined by patient’s responses to determine the lenses that allow the clearest vision.

Using the information obtained from these tests, your optometrist can determine if you have astigmatism. These findings, combined with those of other tests performed, will allow the optometrist to determine the power of any lens correction needed to provide clear, comfortable vision, and discuss options for treatment.

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How is astigmatism treated?

Persons with astigmatism have several options available to regain clear vision. They include:

Eyeglasses are the primary choice of correction for persons with astigmatism. They will contain a special cylindrical lens prescription to compensate for the astigmatism. This provides for additional lens power in only specific meridians of the lens. An example of a prescription for astigmatism for one eye would be -1.00 -1.25 X 180. The middle number (-1.25) is the lens power for correction of the astigmatism. The “X 180” designates the placement (axis) of the lens power. The first number (-1.00) indicates that this prescription also includes a correction for nearsightedness in addition to astigmatism.

Generally, a single vision lens is prescribed to provide clear vision at all distances. However, for patients over about age 40 who have the condition called presbyopia, a bifocal or progressive addition lens may be needed. These provide different lens powers to see clearly in the distance and to focus effectively for near vision work.

A wide variety of lens types and frame designs are now available for patients of all ages. Eyeglasses are no longer just a medical device that provides needed vision correction. Eyeglass frames are available in a many shapes, sizes, colors and materials that not only allow for correction of vision, but also enhance appearance.

For some individuals, contact lenses can offer better vision than eyeglasses. They may provide clearer vision and a wider field of view. However, since contact lenses are worn directly on the eyes, they require regular cleaning and care to safeguard eye health.

Soft contact lenses conform to the shape of the eye, therefore standard soft lenses may not be effective in correcting astigmatism. However, special toric soft contact lenses are available to provide a correction for many types of astigmatism. Because rigid gas permeable contact lenses maintain their regular shape while on the cornea, they offer an effective way to compensate for the cornea’s irregular shape and improve vision for persons with astigmatism and other refractive errors.

Orthokeratology (Ortho-K) involves the fitting of a series of rigid contact lenses to reshape the cornea, the front outer cover of the eye. The contact lenses are worn for limited periods, such as overnight, and then removed. Persons with moderate amounts of astigmatism may be able to temporarily obtain clear vision without lenses for most of their daily activities. Orthokeratology does not permanently improve vision and if you stop wearing the retainer lenses, your vision may return to its original condition.

Astigmatism can also be corrected by reshaping the cornea using a highly focused laser beam of light. Two commonly used procedures are photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK).

PRK removes tissue from the superficial and inner layers of the cornea. LASIK does not remove tissue from the surface of the cornea, but only from its inner layer. To do this, a section of outer corneal surface is cut and folded back to expose the inner tissue. Then a laser is used to remove the precise amount of tissue needed and the flap of outer tissue is placed back in position to heal. Both procedures allow light to focus on the retina by altering the shape of the cornea.

Individuals with astigmatism have a wide range of options to correct their vision problem. In consultation with your optometrist, you can select the treatment that best meets your visual and lifestyle needs.

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Information courtesy of the American Optometric Association, 3/14/11

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Blepharitis

On August 4th, 2010, posted in: Eye & Vision Problems by

Blepharitis is an inflammation of the eyelids causing red, irritated, itchy eyelids and the formation of dandruff-like scales on eyelashes. It is a common eye disorder caused by either bacterial or a skin condition such as dandruff of the scalp or acne rosacea. It affects people of all ages. Although uncomfortable, blepharitis is not contagious and generally does not cause any permanent damage to eyesight.

Blepharitis is classified into two types:

  1. Anterior blepharitis occurs at the outside front edge of the eyelid where the eyelashes are attached.
  2. Posterior blepharitis affects the inner edge of the eyelid that comes in contact with the eyeball.

Individuals with blepharitis may experience a gritty or burning sensation in their eyes, excessive tearing, itching, red and swollen eyelids, dry eyes, or crusting of the eyelids. For some people, blepharitis causes only minor irritation and itching. However, it can lead to more severe signs and symptoms such as blurring of vision, missing or misdirected eyelashes, and inflammation of other eye tissue, particularly the cornea.

In many cases, good eyelid hygiene and a regular cleaning routine can control blepharitis. This includes frequent scalp and face washing, using warm compresses to soak the eyelids, and doing eyelid scrubs. In cases where a bacterial infection is the cause, various antibiotics and other medications may be prescribed along with eyelid hygiene.

What causes blepharitis?

Anterior blepharitis is commonly caused by bacteria (staphylococcal blepharits) or dandruff of the scalp and eyebrows (seborrheic blepharitis). It may also occur due to a combination of factors, or less commonly may be the result of allergies or an infestation of the eyelashes.

Posterior blepharitis can be caused by irregular oil production by the glands of the eyelids (meibomian blepharitis) which creates a favorable environment for bacterial growth. It can also develop as a result of other skin conditions such as acne rosacea and scalp dandruff.

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How is blepharitis diagnosed?

Blepharitis can be diagnosed through a comprehensive eye examination. Testing, with special emphasis on evaluation of the eyelids and front surface of the eyeball, may include:

  • Patient history to determine any symptoms the patient is experiencing and the presence of any general health problems that may be contributing to the eye problem.
  • External examination of the eye, including lid structure, skin texture and eyelash appearance.
  • Evaluation of the lid margins, base of the eyelashes and meibomian gland openings using bright light and magnification.
  • Evaluation of the quantity and quality of tears for any abnormalities.

A differentiation among the various types of blepharitis can often be made based on the appearance of the eyelid margins:

  • Staphyloccal blepharitis patients frequently exhibit mild sticking together of the lids, thickened lid margins, and missing and misdirected eyelashes.
  • Seborrheic blepharitis appears as greasy flakes or scales around the base of eyelashes and a mild redness of the eyelids.
  • Ulcerative blepharitis is characterized by matted, hard crusts around the eyelashes that when removed, leave small sores that ooze and bleed. There may also be a loss of eyelashes, distortion of the front edges of the eyelids and chronic tearing. In severe cases, the cornea, the transparent front covering of the eyeball, may also become inflamed.
  • Meibomian blepharitis is evident by blockage of the oil glands in the eyelids, poor quality of tears, and redness of the lining of the eyelids.

Using the information obtained from testing, your optometrist can determine if you have blepharitis and advise you on treatment options.

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How is blepharitis treated?

Treatment depends on the specific type of blepharitis. The key to treating most types of blepharitis is keeping the lids clean and free of crusts.

  • Warm compresses can be applied to loosen the crusts, followed by gentle scrubbing of the eyes with a mixture of water and baby shampoo or an over-the-counter lid cleansing product. In cases involving bacterial infection, an antibiotic may also be prescribed.
  • If the glands in the eyelids are blocked, the eyelids may need to be massaged to clean out oil accumulated in the eyelid glands.
  • Artificial tear solutions or lubricating ointments may be prescribed in some cases.
  • Use of an anti-dandruff shampoo on the scalp can help.
  • Limiting or stopping the use of eye makeup is often recommended, as its use will make lid hygiene more difficult.
  • If you wear contact lenses, you may have to temporarily discontinue wearing them during treatment.

Some cases of blepharitis may require more complex treatment plans. Blepharitis seldom disappears completely. Even with successful treatment, relapses may occur.

Blepharitis seldom disappears completely. Even with successful treatment, relapses may occur.

Self-care

An important part of controlling blepharitis involves treatment at home.

Directions for a Warm Soak of the Eyelids:

  1. Wash your hands thoroughly.
  2. Moisten a clean washcloth with warm water.
  3. Close eyes and place washcloth on eyelids for about 5 minutes, reheating the washcloth as necessary.
  4. Repeat several times daily.

Directions for an Eyelid Scrub:

  1. Wash your hands thoroughly.
  2. Mix warm water and a small amount of non-irritating (baby) shampoo or use a commercially prepared lid scrub solution recommended by your optometrist.
  3. Using a clean cloth (a different one for each eye) rub the solution back and forth across the eyelashes and edge of the closed eyelid.
  4. Rinse with clear water.
  5. Repeat with the other eye.

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American Optometric Association, 8/4/10

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