Laser In Situ Keratomileusis (LASIK) and Photo-Refractive Keratectomy (LASIK) are two surgical techniques which utilize lasers to reshape or change the curvature of the cornea.

LASIK
LASIK had its origins about thirty years ago and was originally developed to treat patients who had very poor vision due to corneal disease. It has now evolved into a successful technique for correcting refractive errors. The current procedure, done on an outpatient basis, involves both the use of conventional and laser surgery to correct nearsightedness, farsightedness and astigmatism. LASIK can correct a much higher degree of nearsightedness, with or without astigmatism, than any other refractive procedure, with excellent results (95% of patients achieve 20/40 vision or better).

In performing LASIK, eye drop anesthetic is used to numb the eye. The surgeon then uses a special instrument to cut into and behind a layer of the cornea. A portion of the cornea is peeled back to create a flap and expose the inner portions of corneal tissue. The eye is then positioned under the excimer laser, which has been computer programmed to remove microscopic amounts of the internal corneal tissue. Removal of the tissue changes the curvature of the cornea. If the patient is nearsighted, tissue closer to the central part of the cornea is removed to decrease the curvature and effectively flatten the cornea. If a patient is farsighted, tissue in the peripheral part of the cornea is removed to increase the curvature of the cornea. To correct for astigmatism, selected tissue at certain angles is removed to ensure that the cornea curves equally in all directions. After the laser has been used, the flap is returned to its original position. The corneal tissue has extraordinary natural bonding qualities that allow effective healing without the use of stitches.

Since only local anesthetic is used, patients remain awake during the procedure. The entire procedure takes only a few minutes. Improved vision is often possible on the day following the surgery. After surgery, eye drops may be prescribed, and it may be necessary to wear a protective eye shield at night.

Advantages of LASIK include:

• Faster healing time than other refractive surgical methods
  
• Rapid visual recovery
  
• Less risk of scarring
  
• Less risk of corneal haze
  
• Less post-op discomfort
  
• The second eye can be done within a week
  
• Treatment of a wider range of nearsightedness
  

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LASEK

Some patients are unable to undergo the LASIK procedure -- often because their corneas are too thin. People with thin corneas are not good candidates for LASIK, because they are more likely to suffer complications related to the corneal flap that is created with the microkeratome in LASIK. The LASEK (laser epithelial keratomileusis) procedure does not require the use of a microkeratome and may be a good option for some refractive surgery patients, including those with thin corneas.

In LASEK, only the outer layers of cells (the epithelium) is peeled back from the cornea. This is done using a special instrument, which creates tiny perforations in the epithelium, and an alcohol solution. The alcohol solution loosens the epithelial tissue so that is can be carefully pushed back. Then, as in LASIK, a laser is used to reshape the underlying corneal tissue. When the procedure is complete, the epithelial tissue is put back in place, where it heals with the help of a special eye bandage.

Like LASIK, LASEK improves vision by changing the curvature of the cornea. But LASEK is a better option for some people, such as those patients with thin corneas. LASEK does have a slightly longer recovery period than LASIK, with best vision being achieved within a week of surgery rather than within a day or two.

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CK

Presbyopia (Greek for “aging eye”) is America’s most prevalent eye condition. 90 million people either have presbypia or will develop it tn the next 10 years. The condition causes near vision to fade with age, affecting most people by the age of 40 and everyone by the age of 51. The three-minute NearVision CK procedure uses radio waves, instead of a laser or scalpel, to bring near vision back to focus, without cutting or removing any tissue. The procedure boasts one of the highest safety profiles in the refractive market.

How is NearVision CK performed?

NearVision CK uses radio waves, instead of a laser or scalpel, to reshape the cornea and bring near vision back into focus. CK is performed using a small tip, thinner than a strand of human hair, that releases radio waves. The tip is applied in a circular pattern on the outer cornea to shrink small areas of collagen. This circular shrinkage pattern creates a constrictive band (like the tightening of a belt), increasing the overall curvature of the cornea. The treatment, which takes just a few minutes to perform, is performed using only topical anesthesia (numbing eye drops).

Will you be cutting the cornea?

No. NearVision CK is performed without the cutting or removal of tissue. It is a safe, minimally invasive treatment for baby boomers who struggle to read a newspaper, menu, alarm clock, or computer.

Is radiofrequency (RF) energy safe for use on the eye?

Yes. The use of RF energy is one of today’s most advanced surgical techniques. In addition to its use in NearVision CK, RF technology is being used in prostate cancer therapy, back surgery, even cardiovascular procedures.

What are the risks and side effects of NearVision CK?

Because NearVision CK is minimally invasive, the treatment has exhibited minimal risk and almost no side effects. During the first 24 to 48 hours after NearVision CK, you may experience tearing and some discomfort, including a foreign-object sensation in the eyes. You may also experience initial slight overcorrection of your vision, which stabilizes during the following weeks. Because NearVision CK doesn’t cut or remove tissue, many of the side effects associated with other vision correction procedures have not been observed with NearVision CK.

What will I feel during the NearVision CK treatment?

You will experience minimal to no pain during the NearVision CK treatment. You will be aware of a support (speculum), which helps to hold your eye open. The most common sensation that patients experience is a feeling of pressure on the eye. After the procedure, there may be some mild discomfort, and many patients experience a foreign-object sensation or "scratchiness" in the eye. This usually subsides within 24 hours of the procedure.

Will my vision improve immediately after the NearVision CK treatment?

Patients usually notice an immediate improvement in their vision after the NearVision CK procedure. However, it usually takes several weeks for the eyes to adjust to the final level of treatment.

How soon can I return to work?

With NearVision CK, the majority of patients are able to return to work and other normal activities the day after treatment. Although recovery is fairly quick, it is advisable to be careful with your eyes and to avoid any strain. Those whose jobs demand intense clarity of vision (such as dentistry, surgery or computer work) may want to give their eyes some extra rest for a couple of days following the procedure before going back to work.

PRK

Photo-Refractive Keratectomy, or PRK, is another method of surgically reshaping the cornea using the excimer laser. The difference between LASIK and PRK is that for PRK, the corneal flap is not created. That is, the outer layer of the cornea remains in place and the laser removes tissue directly from this outer layer. During LASIK, a part of the cornea is peeled back so that the laser removes tissue from the inner corneal layers. PRK is used for low to moderate amounts of nearsightedness.

Just as in LASIK, the laser treatment requires less than a minute. But unlike LASIK, the healing period time is longer. The correction for nearsightedness, farsightedness, and astigmatism is the same as in LASIK. The corneal curvature is changed so that the visual images are properly focused on the back of the eye.

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Glasses: Protecting your Assets

In California, we are fortunate to be able to enjoy outdoor living almost year around. However, studies suggest that long hours of sun exposure may be dangerous to your eyes. Cataracts, skin cancer, macular degeneration and pterygium have all been implicated as consequences of UV (ultraviolet and invisible) radiation from the sun. Protection from UV-absorbent sunglasses and a brimmed hat are recommended whenever you are out in the sun long enough to get a suntan or sunburn. The variety of sunglasses for sale can be confusing. Sunglasses should block 99% of ultraviolet rays. The price of a pair of sunglasses and the material from which they are made are no indication of the effectiveness of UV filtering.

Color and darkness of lenses are no indication of the ability to protect. Tint color only affects the perception of color, so that dark grey or dark green tints probably allow the most normal color vision. Lenses that block all blue light are usually amber and make your surroundings look yellow or orange. This tint makes distant objects appear more distinct, especially in snow or haze. Darkness may be a risk if the lenses are not properly blocking ultraviolet rays. Since the pupil of the eye dilates in dimmer light, an unprotected eye would receive more than the normal dose of toxic rays if the lenses are dark.

Polarized lenses are great for reducing glare, especially for driving and boating. Although polarization does not block UV, they are usually combined with UV blocking substances to provide maximum comfort and protection. Mirror finishes, on the other hand, reduce the amount of visible light passing through, but are not fully UV repellent.

Although price is not the only feature, you can check lenses to determine if they are made properly. Non-prescription glasses may be held to look at a rectangular pattern, such as a floor tile or a window panel. At a comfortable distance, covering one eye, move the glasses side to side as well as up and down. The lines of the rectangle should remain straight, especially in the center of the lens. Lenses are not unbreakable, but they must meet impact standards set by the Food and Drug Administration. Plastic lenses are less likely to shatter than glass lenses, but plastic scratches more easily.

The natural human lens is an effective UV absorber. In the past, people who had undergone cataract surgery, in which the natural lens is replaced with an artificial intraocular lens, were at increased risk of UV damage. Currently, however, the materials used for this surgery are usually fully UV absorbent. Contact lenses are not necessarily UV absorbent, but are increasingly being produced with UV protection. In addition, there are certain drugs that make the skin more sensitive to light (photosensitizing). These include: psoralens (for psoriasis), tetracycline, doxycycline, allopurinol, and phenothiazines. In summary, the best sunglasses offer 100% UV absorption, contain a medium tint, and are of best optical quality. Yet they don't have to be expensive.

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Contact Lenses

Most people suffer from some form of refractive error. Regardless how well one sees, there is some form of optical correction which will improve sight.

Some people are nearsighted, or myopic, so that their vision without correction is better up close than far away. This affects about 50 million Americans, supplying the vast majority of spectacle wearers and contact lens users. Almost all persons start with glasses. Spectacles, or glasses, are the easiest to use. Easy to put on and easy to remove. Simple to decide when to wear them, moment to moment. The lower the prescription power, the thinner the lens, the less the distortion of vision with spectacles. As lens power grows, thickness and weight increase, as well. Spectacles provide physical safety. Lenses are extremely shatter-resistant. Frames protect the eyes and the orbits from direct injury. Over time, glasses are usually a less costly form of vision correction.

While glasses correct vision well, contact lenses are increasingly popular. Contact lenses may correct nearsightedness, farsightedness (hyperopia), astigmatism or presbyopia (reading). Despite the mind-boggling assortment of lens systems on the market, not all patients can wear all lenses.

The first-time contact lens wearer may be of any age. Infants with congenital cataracts benefit from contact lenses after cataract surgery. This would be the only situation in which the contact lens wearer is not fully responsible for care and maintenance of the lenses. When asked if an adolescent is old enough to wear contact lenses, the answer is based on the child's ability to fully care for the lenses, rather than age.

Originally quite thick, few patients still wear hard contact lenses. These lenses provide excellent clarity, correct astigmatism and are very durable. Care and maintenance is simple and forgiving. Cost is low.

Rigid gas permeable contact lenses (RGPs) have generally replaced hard lenses. Made of state-of-the-art materials, these lenses also provide excellent vision, correct astigmatism and are very durable. Gas permeable contacts have an extended wear time. Most importantly, their nutritional permeability keeps the cornea much healthier, increasing safety. RGPs may be used for therapeutic care, as in keratoconus, corneal scars and corneal injuries. In color blindness, specially tinted lenses may provide some color perception.

All lenses have a finite life expectancy, and, in general, soft lenses must be replaced more often than RGPs. Soft lenses may be categorized as daily wear (removal every night), extended wear, astigmatic (toric), and planned replacement.

Standard daily wear soft lenses are replaced as the lenses become coated with deposits. A plethora of contact care systems greets the consumer at the store. Sensitive patients should consider nonpreserved systems to minimize chance of allergy. Extended wear soft lenses were developed to extend, or increase, the wear time of soft lenses. While some patients may sleep in these lenses, the increased wear time often serves to allow more hours of daily wear. More recently, "disposable" lenses have come to market. Originally planned to diminish reactions to contact lens allergies and solutions, planned replacement lenses have become extremely popular. One variety provides daily wear lenses every two weeks. Another variety is kept in the eye 24 hours a day for one week, discarded and replaced with a brand new lens. More recently, daily disposable lenses have been offered as lenses to be discarded after each use.

More mature patients not only have to deal with their refractive error for distance, nearsightedness or farsightedness, but also the increased need for optical help at near, for reading. Provided in glasses with bifocals or multifocal progressive lenses, contact lenses also play a role. Contact lenses may be prescribed to correct distance vision while using reading glasses. To avoid glasses altogether, monovision or bifocal contacts may be tried. Monovision takes advantage of the innate difference in vision between the two eyes, leaving one corrected for distance and the other for near. In appropriate cases, bifocal contact lenses may be successful.

The notion that contact lenses are carefree devices is slowly giving way to the realization that these are medical devices that must be handled and worn with care. Used properly, contact lenses are relatively safe. On the other hand, if things go wrong, they can do so in a major way. It is known that the more hours a contact lens is worn, the greater the risk of infectious corneal disease. Contact lens wear, even on a daily wear basis, entails more risk than do spectacles. Scrupulous attention to wear and care routines and frequent follow-up examinations are necessary to avoid or minimize the risk of complications.

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