Noticeable symptoms of glaucoma may be a gradual loss of side vision (above) or blurred vision (below).
Glaucoma is one of the leading causes of blindness in the U.S. It most often occurs in people over age 40. People with a family history of glaucoma, African Americans, and those who are very nearsighted or diabetic are at a higher risk of developing the disease.

The most common type of glaucoma develops gradually and painlessly, without symptoms. A rarer type occurs rapidly and its symptoms may include blurred vision, loss of side vision, seeing colored rings around lights and pain or redness in the eyes.

Glaucoma cannot be prevented, but if diagnosed and treated early, it can be controlled. Vision lost to glaucoma cannot be restored. That is why the American Optometric Association recommends annual eye examinations for people at risk for glaucoma (your doctor may, depending on your condition, recommend more frequent examinations). A comprehensive optometric examination will include a tonometry test to measure the pressure in your eyes; an examination of the inside of your eyes and optic nerves; and a visual field test to check for changes in central and side vision.

The treatment for glaucoma includes prescription eye drops and medicines to lower the pressure in your eyes. In some cases, laser treatment or surgery may be effective in reducing pressure.

The three main types of conjunctivitis are infectious, allergic and chemical. The infectious type, commonly called "pink eye" is caused by a contagious virus or bacteria. Your body's allergies to pollen, cosmetics, animals or fabrics often bring on allergic conjunctivitis. And, irritants like air pollution, noxious fumes and chlorine in swimming pools may produce the chemical form.

Common symptoms of conjunctivitis are red watery eyes, inflamed inner eyelids, blurred vision, a scratchy feeling in the eyes and, sometimes, a puslike or watery discharge. Conjunctivitis can sometimes develop into something that can harm vision so you should see your optometrist promptly for diagnosis and treatment.

A good way to treat allergic or chemical conjunctivitis is to avoid the cause. If that does not work, prescription or over-the-counter eye drops may relieve discomfort. Infectious conjunctivitis, caused by bacteria, can be treated with antibiotic eye drops. Other forms, caused by viruses, cannot be treated with antibiotics. They must be fought off by your body's immune system.

To control the spread of infectious conjunctivitis, you should keep your hands away from your eyes, thoroughly wash your hands before applying eye medications and do not share towels, washcloths, cosmetics or eye drops with others.

Ocular hypertension can occur in people of all ages, but it occurs more frequently in African Americans, those over age 40 and those with family histories of ocular hypertension and/or glaucoma. It is also more common in those who are very nearsighted or who have diabetes.

Ocular hypertension has no noticeable signs or symptoms. Your doctor of optometry can check the pressure in your eyes with an instrument called a tonometer and can examine the inner structures of your eyes to assess your overall eye health.

Not all people with ocular hypertension will develop glaucoma. However, there is an increased risk of glaucoma among those with ocular hypertension, so regular comprehensive optometric examinations are essential to your overall eye health.

There is no cure for ocular hypertension, however, careful monitoring and treatment, when indicated, can decrease the risk of damage to your eyes.

As macular degeneration advances, a distorted, dark, or empty area often appears in the center of vision.
Most people with macular degeneration have the dry form, for which there is no known treatment. The less common wet form may respond to laser procedures, if diagnosed and treated early.

Some common symptoms are a gradual loss of ability to see objects clearly, distorted vision, a gradual loss of color vision and a dark or empty area appearing in the center of vision.

If you experience any of these, contact your doctor of optometry immediately for a comprehensive examination.

Central vision that is lost to macular degeneration cannot be restored. However, low vision devices such as telescopic and microscopic lenses can be prescribed to make the most out of remaining vision.

Recent research indicates certain vitamins and minerals may help prevent or slow the progression of macular degeneration. Ask your doctor of optometry about these. After age 60, an annual, comprehensive eye examination is an important to maintain eye health.

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. Since 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.

Signs of RP usually appear during childhood or adolescence. The first sign is often night blindness followed by a slow loss of side vision. Over the years, the disease will cause further loss of side vision. As the disease develops, people with RP may often bump into chairs and other objects as side vision worsens and they only see in one direction – straight ahead. They see as if they are in a tunnel (thus the term tunnel vision).

Fortunately, most cases of retinitis pigmentosa take a long time to develop and vision loss is gradual. It may take many years for loss of vision to be severe.

Currently, there is no cure for RP, but there is research that indicates that vitamin A and lutein may slow the rate at which the disease progresses. Your doctor of optometry can give you more specific information on nutritional supplements that may help you.

Also, there are many new low vision aids, including telescopic and magnifying lenses, night vision scopes as well as other adaptive devices, that are available that help people maximize the vision that they have remaining. An optometrist, experienced in low vision rehabilitation, can provide these devices as well as advice about other training and assistance to help people remain independent and productive.

Since it is an inherited disease, research into genetics may one day provide a prevention or cure for those who have RP.

No one knows exactly what causes cataracts, but it is known that a chemical change occurs within your eye to cause the lens to become cloudy. This may be due to advancing age, heredity or an injury or disease. Excessive exposure to ultraviolet radiation in sunlight, cigarette smoking or the use of certain medications are also risk factors for the development of cataracts.

Although cataracts develop without pain or discomfort, there are some indications that a cataract may be forming. These include blurred or hazy vision, the appearance of spots in front of the eyes, increased sensitivity to glare or the feeling of having a film over the eyes. A temporary improvement in near vision may also indicate formation of a cataract.

Currently, there is no proven method to prevent cataracts from forming. During a comprehensive eye examination, your optometrist can diagnose a cataract and monitor its development and prescribe changes in eyeglasses or contact lenses to maintain good vision.

If your cataract develops to the point that it affects your daily activities, your optometrist can refer you to an eye surgeon who may recommend surgery. During the surgery, the eye's natural lens is removed and usually replaced with a plastic artificial lens. After surgery, you can return to your optometrist for continuing care.

If you have dry eye, your symptoms may include irritated, scratchy, dry, uncomfortable or red eyes, a burning sensation or feeling of something foreign in your eyes and blurred vision. Excessive dry eyes may damage eye tissue, scar your cornea (the front covering of your eyes) and impair vision and make contact lens wear difficult.

If you have symptoms of dry eye, see your optometrist for a comprehensive examination. Dry eye cannot be cured, but your optometrist can prescribe treatment so your eyes remain healthy and your vision is unaffected. Some treatments that your optometrist might prescribe include blinking more frequently, increasing humidity at home or work, using artificial tears and using a moisturizing ointment, especially at bedtime. In some cases, small plugs are inserted in the corner of the eyes to slow tear drainage. Sometimes, surgical closure of the drainage ducts may be recommended.

Blurred central or side vision (above, blurred side vision) or a blind spot in central vision (below) may indicate diabetic retinopathy.
The early stages of diabetic retinopathy may cause blurred vision, or they may produce no visual symptoms at all. As the disease progresses, you may notice a cloudiness of vision, blind spots or floaters.

If left untreated, diabetic retinopathy can cause blindness, which is one reason why it is important to have your eyes examined regularly by your doctor of optometry. This is especially true if you are a diabetic or if you have a family history of diabetes.

To detect diabetic retinopathy, your optometrist can look inside your eyes with an instrument called an ophthalmoscope that lights and magnifies the blood vessels in your eyes. If you have diabetic retinopathy, laser and other surgical treatments can be used to reduce its progression and decrease the risk of vision loss. Early treatment is important because once damage has occurred, the effects are usually permanent.

If you are a diabetic, you can help prevent diabetic retinopathy by taking your prescribed medication as instructed, sticking to your diet, exercising regularly, controlling high blood pressure and avoiding alcohol and smoking.

November is National Diabetes Month. Members of the American Optometric Association are joining with members of other health care organizations in an effort to prevent blindness in Americans with diabetes. If you or a member of your family has not received a dilated eye examination in the past year, you should contact your optometrist for an appointment.

In its earliest stages, keratoconus causes slight blurring and distortion of vision and increased sensitivity to glare and light. These symptoms usually appear in the late teens or late twenties. Keratoconus may progress for 10-20 years and then slow in its progression. Each eye may be affected differently. As keratoconus progresses, the cornea bulges more and vision may become more distorted. In a small number of cases, the cornea will swell and cause a sudden and significant decrease in vision. The swelling occurs when the strain of the cornea's protruding cone-like shape causes a tiny crack to develop. The swelling may last for weeks or months as the crack heals and is gradually replaced by scar tissue. If this sudden swelling does occur, your doctor can prescribe eyedrops for temporary relief, but there are no medicines that can prevent the disorder from progressing.
Eyeglasses or soft contact lenses may be used to correct the mild nearsightedness and astigmatism that is caused by the early stages for keratoconus. As the disorder progresses and cornea continues to thin and change shape, rigid gas permeable contact lenses can be prescribed to correct vision adequately. In most cases, this is adequate. The contact lenses must be carefully fitted, and frequent checkups and lens changes may be needed to achieve and maintain good vision.

In a few cases, a corneal transplant is necessary. However, even after a corneal transplant, eyeglasses or contact lenses are often still needed to correct vision.

Seborrheic blepharitis is often associated with dandruff of the scalp or skin conditions like acne. It can appear as greasy flakes or scales around the base of the eyelashes and a mild redness of the eyelid. It may also result in a roughness of the normally smooth tissue that lines the inside of the eyelid.

Blepharitis is a chronic inflammation that affects the eyelids (1) and the eyelash hair follicles (2). Careful eyelid hygiene can do much to control blepharitis.
Ulcerative blepharitis is less common, but more serious. It is characterized by matted, hard crusts around the eyelashes, which when removed, leave small sores that ooze or 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.

In many cases, good eyelid hygiene and a regular cleaning routine may control blepharitis. This includes frequent scalp and face washing; warm soaks of the eyelids; and eyelid scrubs. In cases where bacterial infection is a cause, eyelid hygiene may be combined with various antibiotics and other medications. Eyelid hygiene is especially important upon awakening because debris can build up during sleep.

If you experience symptoms of blepharitis, your doctor of optometry can determine the cause and recommend the right combination of treatments specifically for you.

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.
4 Repeat several times daily.

Directions For An Eyelid Scrub
1 Wash your hands thoroughly.
2 Mix warm water and a small amount of shampoo that does not irritate the eye (baby shampoo) or use a commercially prepared lid scrub solution recommended by your optometrist.
3 Close one eye and using a clean wash cloth (a different one for each eye), rub the solution back and forth across the eyelashes and the edge of the eyelid.
4 Rinse with clear, cool water.
5 Repeat with the other eye.

At about age six months, you should take your baby to your doctor of optometry for his or her first thorough eye examination. Things that the optometrist will test for include excessive or unequal amounts of nearsightedness, farsightedness, or astigmatism and eye movement ability as well as eye health problems. These problems are not common, but it is important to identify children who have them at this stage. Vision development and eye health problems can be more easily corrected if treatment is begun early.

Unless you notice a need, or your doctor of optometry advises you otherwise, your child's next examination should be around age three, and then again before he or she enters school.

Between birth and age three, when many of your baby's vision skills will develop, there are ways that you can help.

During the first four months of life, your baby should begin to follow moving objects with the eyes and reach for things, first by chance and later more accurately, as hand-eye coordination and depth perception begin to develop.

To help, use a nightlight or other dim lamp in your baby's room; change the crib's position frequently and your child's position in it; keep reach-and-touch toys within your baby's focus, about eight to twelve inches; talk to your baby as you walk around the room; alternate right and left sides with each feeding; and hang a mobile above and outside the crib.

Between four and eight months, your baby should begin to turn from side to side and use his or her arms and legs. Eye movement and eye/body coordination skills should develop further and both eyes should focus equally.

You should enable your baby to explore different shapes and textures with his or her fingers; give your baby the freedom to crawl and explore; hang objects across the crib; and play "patty cake"and "peek-a-boo" with your baby.

From eight to twelve months, your baby should be mobile now, crawling and pulling himself or herself up. He or she will begin to use both eyes together and judge distances and grasp and throw objects with greater precision. To support development don't encourage early walking - crawling is important in developing eye-hand-foot-body coordination; give your baby stacking and take-apart toys; and provide objects your baby can touch, hold and see at the same time.

From one to two years, your child's eye-hand coordination and depth perception will continue to develop and he or she will begin to understand abstract terms. Things you can do are encourage walking; provide building blocks, simple puzzles and balls; and provide opportunities to climb and explore indoors and out.

There are many other affectionate and loving ways in which you can aid your baby's vision development. Use your creativity and imagination. Ask your doctor of optometry to suggest other specific activities.

As a parent, you should watch for signs that may indicate a vision development problem, including a short attention span for the child's age; difficulty with eye-hand-body coordination in ball play and bike riding; avoidance of coloring and puzzles and other detailed activities.

There are everyday things that you can do at home to help your preschooler's vision develop as it should.

These activities include reading aloud to your child and letting him or her see what you are reading; providing a chalkboard, finger paints and different shaped blocks and showing your child how to use them in imaginative play; providing safe opportunities to use playground equipment like a jungle gym and balance beam; and allowing time for interacting with other children and for playing independently.

By age three, your child should have a thorough optometric eye examination to make sure your preschooler's vision is developing properly and there is no evidence of eye disease. If needed, your doctor can prescribe treatment including glasses and/or vision therapy to correct a vision development problem.

Here are several tips to make your child's optometric examination a positive experience: 1) Make an appointment early in the day. Allow about one hour. 2) Talk about the examination in advance and encourage your child's questions. 3) Explain the examination in your child's terms, comparing the E chart to a puzzle and the instruments to tiny flashlights and a kaleidoscope.

Unless your doctor of optometry advises otherwise, your child's next eye examination should be at age five. By comparing test results of the two examinations, your optometrist can tell how well your child's vision is developing for the next major step...into the school years.

The basic vision skills needed for school use are:
• Near vision. The ability to see clearly and comfortably at 10-13 inches.
• Distance vision. The ability to see clearly and comfortably beyond arm's reach.
• Binocular coordination. The ability to use both eyes together.
• Eye movement skills. The ability to aim the eyes accurately, move them smoothly across a page and shift them quickly and accurately from one object to another.
• Focusing skills. The ability to keep both eyes accurately focused at the proper distance to see clearly and to change focus quickly.
• Peripheral awareness. The ability to be aware of things located to the side while looking straight ahead.
• Eye/hand coordination. The ability to use the eyes and hands together.

If any of these or other vision skills is lacking or not functioning properly, your child will have to work harder. This can lead to headaches, fatigue and other eyestrain problems. As a parent, be alert for symptoms that may indicate your child has a vision or visual processing problem. Be sure to tell your optometrist if your child frequently:
• Loses their place while reading;
• Avoids close work;
• Holds reading material closer than normal;
• Tends to rub their eyes;
• Has headaches;
• Turns or tilts head to use one eye only;
• Makes frequent reversals when reading or writing;
• Uses finger to maintain place when reading;
• Omits or confuses small words when reading;
• Consistently performs below potential.

Since vision changes can occur without you or your child noticing them, your child should visit the optometrist at least every two years, or more frequently, if specific problems or risk factors exist. If needed, the doctor can prescribe treatment including eyeglasses, contact lenses or vision therapy.

Remember, a school vision or pediatrician's screening is not a substitute for a thorough eye examination.

Your vision is composed of many skills, and just as exercise and practice can increase your speed and strength, it can improve your vision skills. You can select from the list below to see explanations of specific vision skills and tips to improve them. The definitions and suggestions that follow are general and should not be considered complete or thorough. They are to give you a general idea of the types of exercises that can be helpful when incorporated into a total program of sports vision care.

Some athletes will have visual difficulties that will need individual, professional attention and will not benefit from these exercises alone. An evaluation by a sports vision optometrist can pinpoint your individual problems and needs as related to your sport. Remember, a thorough eye examination by your doctor of optometry is a great place to begin "getting the winning edge."

Always wear the proper eye protection for your sport. When appropriate, use proper eye protection when you are tyring these exercises. Your doctor of optometry can advise you about what is best for you.

Read More from the American Optometric Association, here

Source: Contact Lens Institute
May 2003

Rigid gas-permeable (RGP)-Made of slightly flexible plastics that allow oxygen to pass through to the eyes. Excellent vision...short adaptation period...comfortable to wear...correct most vision problems...easy to put on and to care for...durable with a relatively long life...available in tints (for handling purposes) and bifocals. Require consistent wear to maintain adaptation...can slip off center of eye more easily than other types...debris can easily get under the lenses...requires office visits for follow-up care.

Daily-wear soft lenses - Made of soft, flexible plastic that allow oxygen to pass through to the eyes. Very short adaptation period...more comfortable and more difficult to dislodge than RGP lenses...available in tints and bifocals...great for active lifestyles. Do not correct all vision problems...vision may not be as sharp as with RGP lenses...require regular office visits for follow-up care...lenses soil easily and must be replaced.

Extended-wear - Available for overnight wear in soft or RGP lenses. Can usually be worn up to seven days without removal. Do not correct all vision problems...require regular office visits for follow-up care...increases risk of complication...requires regular monitoring and professional care.

Extended-wear disposable - Soft lenses worn for an extended period of time, from one to six days and then discarded. Require little or no cleaning...minimal risk of eye infection if wearing instructions are followed...available in tints and bifocals...spare lenses available. Vision may not be as sharp as RGP lenses...do not correct all vision problems...handling may be more difficult.

Planned replacement - Soft daily wear lenses that are replaced on a planned schedule, most often either every two weeks, monthly or quarterly. Require simplified cleaning and disinfection...good for eye health...available in most prescriptions. Vision may not be as sharp as RGP lenses...do not correct all vision problems...handling may be more difficult.

Do:
• Listen and watch closely as instructions are given and demonstrated. Practice the care routine in your optometrist's office.
• Follow lens care and wearing instructions/schedules to the letter.
• Schedule follow-up visits to your optometrist both during and after your adaptation period.
• This is important to maintaining good eye health and safe contact lens wear.
• Wash hands thoroughly before handling your lenses.
• Handle contact lenses over a clean towel. If your drop your lenses, they will stay clean and undamaged.
• Store your lenses in the case made for them and keep the case clean.

Don't:
• Use cream soaps. They can leave a film on your hands that can transfer to the lenses.
• Put contact lenses in your mouth or moisten them with saliva, which is full of bacteria and a potential source of infection.
• Use homemade saline solutions. Improper use of homemade saline solutions has been linked with a potentially blinding condition among soft lens wearers.

Here are some tips to help you wear your contacts and your cosmetics safely and comfortably together:
• Put on soft contact lenses before applying makeup.
• Put on rigid gas-permeable (RGP) lenses after makeup is applied.
• Avoid lash-extending mascara, which has fibers that can irritate the eyes and waterproof mascara, which cannot be easily removed with water and may stain soft contact lenses.
• Remove lenses before removing makeup.
• Choose an oil-free moisturizer.
• Don’t use hand creams or lotions before handling contacts. They can leave a film on your lenses.
• Use hairspray before putting on your contacts. If you use hairspray while you are wearing your contacts, close your eyes during spraying and for a few seconds afterwards.
• Blink your eyes frequently while under a hair drier or blower to keep your eyes from getting too dry.
• Keep false eyelash cement, nail polish and remover, perfume and cologne away from the lenses. They can damage the plastic.
• Choose water-based, hypo-allergenic liquid foundations. Cream makeup may leave a film on your lenses.

Monovision means wearing a contact lens for near vision on one eye and, if needed, a lens for distance vision on the other eye.

Most people who try monovision are able to adjust to it.

Alternative treatments for presbyopia include a combination of contact lenses and reading glasses, or your doctor may also prescribe bifocal contact lenses.

However, here is a list of some signs that things may not be going well. If you experience any of these, contact your optometrist as soon as possible.
• Blurred or fuzzy vision, especially of sudden onset.
• Red, irritated eyes.
• Uncomfortable lenses.
• Pain in and around the eyes.

If you already wear lenses and need replacements, or if you want a spare pair, the total cost might include the actual cost of the lenses plus the fee the doctor might charge for his or her professional time. Again, every optometrist individually determines his or her fees, and there is no formula or standard fee for contacts or professional services.

It is certainly important to check out costs when considering contacts, but cost is just one factor in making your decision. All types of lenses are not the same. It is important for you to get the lenses that are healthiest for you and the professional services and follow-up care to help you wear your lenses successfully.

All corneal modification procedures are intended to alter the curvature of the cornea so that incoming light is refracted at an angle that allows it to focus precisely on the retina. This may eliminate the need for eyeglasses or contact lenses, or reduce the power of prescription lenses needed.

Those interested in any of the corneal modifications should first have a comprehensive eye examination to evaluate their eye health and determine their vision needs.

Ortho-K is a non-surgical procedure that involves the wearing of a series of specially designed rigid contact lenses to progressively reshape the curvature of the cornea over time. The results of the painless procedure are not permanent; thus, retainer contact lenses must be worn periodically to maintain improvements made in vision. Ortho-K is used to treat low to moderate nearsightedness and low degrees of astigmatism.

Astigmatic Keratotomy (AK)
Incisional surgical procedure used to correct corneal astigmatism. Arcuate incisions are placed in the corneal midperipheral zone of the steep meridian at approximately 90% depth.

Automated Lamellar Keratoplasty (ALK)
A refractive surgical procedure in which the surgeon creates a flap of the uppermost layer of the cornea using a microkeratome. A second pass of the microkeratome is made in order to remove a wedge of tissue.

Broad Beam Laser
Excimer laser where the beam size used to ablate the cornea is from approximately 6.0 to 8.0 millimeters.

Conductive Keratoplasty (CK)
CK is a non-ablative, collagen-shrinking procedure for the treatment of mild and moderate hyperopia. Radiofrequency energy is delivered through a fine tip inserted into the corneal stroma. The collagen lamellae in the area surrounding the tip shrink and tighten, increasing the radius of curvature of the cornea. The spots are placed in the circumference of the mid- and peripheral cornea. Based on the amount of refractive change targeted, the number and location of treatment spots may be determined, with larger treatments requiring more spots and rings.

Conventional Refractive Surgery
Method of optical correction by Excimer laser photoablation, which changes the shape of the cornea to change the refraction error. The treatments are symmetrical and correct lower order or spherocylindrical aberrations, which include myopia, hyperopia, and astigmatism.

Customized Refractive Surgery
Wavefront-driven excimer laser photoablation, which changes the shape of the cornea to change refractive error. In addition to treating lower-order aberrations (sphere and cylinder), custom refractive surgery treats higher-order aberrations up to the 6th order. Wavefront-guided ablations create treatment profiles based on wavefront maps and the treatment may be asymmetrical and is customized for the individual patient. The treatment parameters vary according to the system utilized. The first customized laser platform was FDA approved in the fall of 2002.

Ectasia
Progressive corneal thinning and associated protrusion.

Epi-LASIK
Refractive surgical procedure.
This new procedure is believed to avoid risks associated with laser-assisted in situ keratomileusis (LASIK) and offers improved postoperative recovery compared with Photorefractive Keratectomy (PRK). Rather than creating a flap with a microkeratome as in LASIK or removing the epithelium as in PRK, Epi-LASIK separates an epithelial sheet using the Centurion SES EpiEdge epikeratome (CIBA Vision).

Epithelial Ingrowth
A LASIK complication wherein epithelial cells proliferate underneath the corneal flap.

Excimer Laser
Type of laser used in all laser refractive surgical procedures in order to reduce refractive error. The laser utilizes a 193 nm argon-fluoride beam to reshape the anterior corneal stroma by breaking collagen bonds and expelling or ablating corneal tissue with each laser pulse. It is termed a “cold” laser because the collagen bonds are broken without damaging adjacent cells. The pulses are fired centrally to flatten the cornea to an oblate shape in myopia and fired peripherally to steepen the cornea to a prolate shape in hyperopia.

Femtosecond Laser
High-frequency laser now used to make flaps in the LASIK procedure. The high-frequency energy can be focused through the anterior cornea to a specified depth. A sweeping back and forth (raster) pattern creates a horizontal, then vertical cleavage plane to create the flap.

Intrastromal Corneal Ring Segments
A reversible procedure used in the treatment of low amounts of myopia (-1.00 to -3.00 D) by placing rings of polymethylmethacrylate (PMMA) in the midperipheral corneal stroma to flatten the radius of curvature. Intrastromal corneal ring segments are currently being investigated to reduce myopia in patients with keratoconus and corneal ectasia.

Keratomileusis
The sculpting of the cornea, formerly done with a lathe and blade, now done with an excimer laser.

Keratoplasty
The replacement of the cornea. Keratoplasty can be lamellar (replacement of the superficial layers) or penetrating (transplantation or replacement of the full thickness of the cornea).

Keratotomy
A surgical incision of the cornea.

LASER
An acronym for light amplification by stimulated emission of radiation.

Laser-Assisted In Situ Keratomileusis (LASIK)
Approved by the FDA for the correction of myopia, hyperopia and astigmatism. LASIK is a combination of two refractive technologies: Use of a microkeratome, to create a thin flap of tissue (approximately 130 to 180 microns thick) followed by excimer laser ablation to reshape the stromal tissue beneath the flap.

Laser Epithelial Keratomileusis (LASEK)
A hybrid of photorefractive keratectomy (PRK) and laser-assisted in situ keratomileusis (LASIK), the goal of LASEK is the preservation of the corneal epithelium. Rather than creating a flap with a microkeratome (as in LASIK) or scraping and removing the patient’s epithelium (as in PRK), LASEK treats the epithelium with alcohol to loosen and separate it from the stroma and it is then rolled back. The underlying stroma is ablated with an excimer laser and the epithelial cells are rolled back out, repositioned, and smoothed. The potential advantages of LASEK are to reduce postoperative haze, speed visual recovery, and decrease postoperative pain over traditional PRK.
LTK

Laser Thermal Keratoplasty (LTK)
Approved by the FDA in 2000 for the temporary correction of hyperopia ranging from +0.75 to +2.50 D with less than 1.0 D of astigmatism. LTK uses a Holmium:YAG laser comprised of a slit-lamp delivery system that creates spots around the circumference of the peripheral cornea. The treatment consists of either one or two rings of spots set at an optical zone of 6.0 and/or 7.0 mm.

Micron
One thousandth of a millimeter. One millionth of a meter.

Microkeratome
Instrument used for the creation of a lamellar flap (130 to 180 mm) during laser-assisted in situ keratomileusis (LASIK). A microkeratome is comprised of a suction ring that adheres to the globe, providing stability for the cutting blade that rolls along a tongue and groove track, creating the flap.

Nomogram
The surgical adjustment to a laser’s computer calculation to further refine results.

Pachymetry
Measurement of corneal thickness. Methods of measurement are based on wave reflection of optical light or ultrasonic energy through the corneal tissue.
PRK

Photorefractive Keratectomy (PRK)
A procedure involving the removal of the epithelium by gentle scraping away of the corneal epithelium and use of a computer-controlled excimer laser to reshape the stroma.

Phototherapeutic Keratotomy (PTK)
PTK involves ablative photodecomposition of the epithelium by ablating microscopically thin layers and etching away surface irregularities. Candidates for PTK are patients with significant visual compromise due to corneal scars and opacities (from trauma or inactive infections), dystrophies (Reis-Buckler’s, lattice, anterior basement membrane dystrophy [ABMD]), irregular corneal surface associated with filamentary keratitis and Salzmann’s nodular degeneration, recurrent corneal erosions (RCE) (unresponsive to lubricants, debridement, or stromal puncture), band keratopathy, scars resulting from previous pterygium excision, Thygeson’s superficial keratitis, and irregular astigmatism.

Radial Keratotomy (RK)
Refractive surgical procedure popular in the 1980s, RK treated low amounts of myopia ranging from -1.00 to -4.00 D. In order to flatten the cornea, radial incisions (like the spokes of a wheel) were created using a diamond-blade micrometer knife, leaving a central unaltered optical zone of approximately 3.0 mm.

Refractive Surgery
A surgical method of vision correction by changing the refractive properties of the eye.

Scleral Expansion Bands (SEB)
Procedure potential is for the reversal of presbyopia. Increasing lens zonular tension by implanting small polymethylmethacrylate (PMMA) bands in the sclera over the ciliary body will allow accommodation to occur.

Wavefronts
Wavefront capture by an aberrometer is the measurement of lower- and higher-order aberrations. As a wavefront passes through multiple refractive surfaces, ocular aberrations are induced that prevent individual light beams from focusing at the same point on the macula. Ocular aberrations increase as a function of pupil size and become visually significant with pupil dilation. In a perfect optical system the wavefront would be flat. Optical aberrations are as unique as a person’s fingerprint, with each eye producing its own unique wavefront . Once a patient’s wavefront is captured, it is incorporated into the refractive surgical procedure for a customized treatment.

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