Medic Partners - Vision correction - Vision correction procedures decription

Treatment methods

4. Differences of medical treatment methods

1. PRK (photorefractive keratectomy)

Description - PRK is performed with an excimer laser, which uses a cool ultraviolet light beam to precisely remove very tiny bits of tissue from the surface of the cornea in order to reshape it. When cornea is reshaped, it works better to focus light into the eye and onto the retina, providing clearer vision than before.

Both nearsighted and farsighted people can be treated with PRK. The goal with nearsighted patients is to flatten the too-steep cornea; with farsighted patients, a steeper cornea is desired. Astigmatism can also be corrected with excimer laser, by smoothing an irregular cornea into a more normal shape.

Examination - the doctor examines the eyes to determine exactly what kind of vision correction you need and how much laser ablation is needed. Corneal topographer will be used to photograph your eye and create the "map" of your cornea. No one has a perfectly rounded cornea, and the topographer will display the corneal irregularities and the actual steepness or flatness that the surgeon must address.

Procedure - PRK is an ambulatory procedure that can be performed the same day. Patient can leave home right after the surgery. In fact, the actual surgery usually takes less than a minute, and patient is awake the whole time. Occasionally, the doctor gives a mild oral sedative before the procedure.

Most people do not experience pain during PRK. Eyes are anesthetized with special drops. The doctor will have you lie down and then make sure your eye is positioned directly under the laser. (Only one eye is operated at a time.) A kind of retainer is placed over your eye to keep your eyelids open — normally, this is not uncomfortable. It has a suction ring that keeps your eye pressurized and immobile.

The doctor uses a computer to adjust the laser for your particular prescription. You will be asked to look at a target light for a short time while doctor watches your eye through a microscope to make sure it remains in the correct position while the laser sends pulses of light to your cornea that painlessly remove the tissue. It's important to keep your gaze fixated on that target light in order to get the best results.

The laser machine will make a steady clicking sound while the laser pulses are happening, and you may smell a faintly acrid odor during the tissue removal. Don't worry, that's normal.

The higher your prescription, the more time the surgery will take.

The surgeon has full control of the laser and can turn it off at any time. After the procedure is finished, you will rest for a little while. If you have your both eyes done at the same day, the surgeon will probably do the other eye after a short period of time.

After PRK procedure - the doctor may prescribe medication for any postoperative pain, but many patients feel no more than mild discomfort or "scratchiness" afterward.

As with any kind of eye surgery, it's important that you follow your doctor's instructions. Get proper rest, fill and use any necessary prescriptions, and call your doctor immediately if you suspect a problem. What occurs after the surgery can affect your vision just as much as the surgery itself.

Immediately after PRK, the doctor will have you rest for a bit, then you can go home (someone else must drive). At home, you should relax for at least a few hours.

You may be able to go to work the next day, but many doctors advise to take a few days off. They also recommend do not make any tough exercise for up to a week, since this can traumatize the eye and affect the healing.

Avoid rubbing your eye (your doctor will tell you for how long). In fact, you will be examined just about every day to make sure the epithelium is healing properly. You will probably wear a special "bandage" contact lens, use antibiotic drops for a few days, and apply anti-inflammatory drops for several weeks.

Most people achieve 20/20 or better vision with PRK (also true of LASIK). Some may achieve only 20/40 or not quite as good. In fact, 20/40 is fairly good vision. Some patients may still need glasses or contact lenses following laser vision correction, though their prescription level will be much lower than before.

Complications - postoperative complications can include infection and/or night glare (starbursts or halos that are most noticeable when you're viewing lights at night, such as while you're driving).

Even if you see perfectly after laser eye surgery, you may still need reading glasses or bifocal contact lenses once you hit your 40s. This is because the eye's lens stiffens as you age, a condition called presbyopia. Your distance vision will probably remain crisp, but seeing up close will be more difficult. Back

2. LASIK (laser in situ keratomileusis)

LASIK is the most commonly performed refractive surgery procedure. It has advantages over other procedures, including a relative lack of pain afterward and the fact that good vision is usually achieved by the very next day.

Description - an instrument called a microkeratome is used in LASIK eye surgery to create a thin, circular flap in the cornea. Another, newer way of making the flap is with a laser. Then the surgeon folds the flap back and removes some corneal tissue underneath using an excimer laser. The excimer laser uses a cool ultraviolet light beam to precisely remove very tiny bits of tissue from the cornea to reshape it. When the cornea is reshaped in the right way, it works better to focus light into the eye and onto the retina, providing clearer vision than before. The flap is then laid back in place, covering the area where the corneal tissue was removed.

Both nearsighted and farsighted patients can be treated with LASIK procedure. With nearsighted people, the goal is to flatten the too-steep cornea; with farsighted people, a steeper cornea is desired. Excimer lasers can also correct astigmatism by smoothing an irregular cornea into a more normal shape.

Examination - the doctor examines the eyes to determine their health, what kind of vision correction you need, and how much laser ablation is required.

Procedure - LASIK is an ambulatory procedure. Patient can go home after the procedure is performed. In fact, the actual surgery usually takes less than five minutes, and you're awake the whole time. Occasionally, the doctor gives mild oral sedative before the procedure.

Most people do not feel pain during LASIK surgery. The eyes are anesthetized with special drops.

The doctor will have you lie down and then make sure your eye is positioned directly under the laser. (One eye is operated at a time.) A kind of retainer is placed over your eye to keep your eyelids open — normally, this is not uncomfortable. It has a suction ring that keeps your eye pressurized and still, which is important in LASIK for allowing the surgeon to cut the corneal flap.

The doctor uses an ink marker to mark the cornea before the flap is created. The flap is then created with either a microkeratome or with a laser, depending on the surgeon's preference. During the procedure you won't actually see the creation of the flap, which is very thin.

The doctor uses a computer to adjust the laser for your particular prescription. You will be asked to look at a target light for a short time while the doctor watches your eye through a microscope while the laser sends pulses of light to your cornea.

The laser light pulses painlessly reshape the cornea. You will hear a steady clicking sound as the laser is operating. You are also likely to smell a mildly acrid odor due to the tissue removal. The higher your prescription, the more time the surgery will take. The surgeon has full control of the laser and can turn it off at any time.

After the LASIK procedure - after the procedure is finished, you will rest for a little while. If you're having both eyes done the same day, the surgeon will probably do the other eye after a short period of time.

Someone has to accompany you to drive you back home after the procedure.

Complications - it's extremely rare for complications from this procedure to cause permanent, significant vision loss. Also, many complications can be resolved through re-treatment or enhancements of the eye.

Even if you are not qualified for LASIK, you might still be able to undergo vision correction through other means such as PRK or PTK.

Public confidence in the LASIK procedure has grown in recent years because of a solid success rate involving millions of successful procedures. With increasingly sophisticated technology used for the procedure, most LASIK outcomes these days are very favorable.

Experienced LASIK surgeons now report in trade journals that serious complication rates can be held well below 1%, but only if surgical candidates are selected very carefully. You may be eliminated as a LASIK candidate, for example, if you have certain conditions such as pregnancy or diabetes that affect how well your eye heals.

Side effects are rear but it can be that a patient may see 20/20 or better with uncorrected vision while at the same time having symptoms such as double vision (diplopia), unresolved dry eye, or difficulty seeing at night because of glare or halos around lights.

Any health condition you have that might hamper your ability to heal should be mentioned and discussed in detail with your eye surgeon. Large pupil sizes also might be risk factors for LASIK complications, because pupils in dark conditions could expand beyond the area of the eye that was treated. Again, make sure you discuss any concerns about these or other matters with the eye surgeon and consider the fact that it is absolutely true that no surgical procedure is ever risk-free. You should understand that, even in the best of circumstances, there is a slight chance that something unintended could occur. Even so, most problems eventually can be resolved.

When LASIK complications occur, they may be associated with the creation of a hinged flap in the clear front covering of the eye (cornea), which is lifted for laser re-shaping of the eye. If the LASIK flap is not made correctly, it may fail to adhere correctly to the eye's surface. The flap also might be cut too thinly or thickly. After the flap is placed back on the eye's surface, it might begin to wrinkle. These types of flap complications can lead to an irregularly shaped eye surface. But problems often are resolved through re-treatment or enhancements of the eye. Back

3. PTK (phototherapeutic keratectomy)

Description - PTK uses the excimer laser to treat corneal surface diseases and scars. PTK is performed by removing the epithelium (outer skin of the cornea) and then applying the laser to the surface of the cornea. The goal is to produce a smoother and clearer cornea, and not necessarily to reduce dependency upon eyeglasses or contact lenses. In contrast, the goal in PRK is to reduce dependency upon eyeglasses or contact lenses. PRK is often combined with PTK.

PTK is for those of any age who have corneal surface diseases such as:
• Recurrent epithelial erosion syndrome.
• Shallow corneal scars.
• Corneal dystrophies, such as lattice dystrophy or granular dystrophy.

While some of these conditions can be treated by mechanical superficial keratectomy techniques, PTK may minimize tissue removal and surgical trauma. The smoother stromal surface achieved by the excimer laser procedure may improve surface smoothness of the cornea, improve postoperative corneal clarity and decrease postoperative scarring, and facilitate subsequent epithelial adhesion. Moreover, superficial corneal disorders which, in some cases, would otherwise require corneal transplant may be amenable to treatment with the PTK procedure. Phototherapeutic keratectomy is performed with topical anesthesia.

When PTK is used to remove only the epithelial surface of the cornea, the alternative technology is mechanical superficial keratectomy, i.e., corneal scraping. When PTK is used to remove deeper layers of the cornea, (extending into Bowman’s layer), competing technologies include lamellar keratoplasty. Candidates for PTK should first exhaust medical approaches. For example, recurrent corneal erosions can be treated conservatively with lubricants, patching, bandage contact lenses, or anterior stromal punctures, while keratoconus can be treated with rigid contact lenses to correct the astigmatism.

Examination - decision to have PTK is an important one that only you can make. The doctor will examine your eyes condition and will suggest the method of treatment and determine if PTK is an option for you. If you are a good candidate, you will be given additional information about the procedure that will allow you to make an informed decision about whether to proceed. Be sure you have all your questions answered to your satisfaction.

The goal of any laser surgery is to improve your visual experience. However, we cannot guarantee you will have the results you desire. The majority of our patients are extremely happy with their vision after PTK.

Procedure - you will be prepared for surgery and given oral sedatives. The area around your eyes will be cleaned and a sterile drape will be applied around your eye. Anesthetic eye drops will be used to numb your eyes. When your eye is completely numb, an eyelid holder will be placed between your eyelids to keep you from blinking during the procedure. The doctor will remove the epithelium, a thin layer of protective skin that covers the cornea. Then, the methylcellulose solution is applied and the excimer laser is used to ablate the exposed corneal tissue. You will be asked to look directly at a target light while the laser reshapes your cornea. The laser will be programmed with the information

The laser treatment will be completed in less than a minute or two, depending on the amount of correction needed.

After PTK - following the procedure, your eye(s) will be examined with a slit lamp microscope. Your eyes may be shielded for protection. Your vision may be blurry or hazy for one to five days. Some discomfort may be experienced for the first few days after the surgery while the epithelium as it heals and covers the treated area. The use of prescription eye drops and bandage contact lenses dramatically reduces the discomfort during this initial recovery period. In some cases, the deep layer of the cornea may assume a hazy appearance, but this usually improves with time as the deep healing progresses. Most patients resume normal activities within one to three days. Vision can fluctuate for up to six months.

Complications - PTK is a safe, effective and permanent procedure, but like any surgical procedure, it does have some risks that include refractive errors, most commonly hyperopia, corneal scarring, and glare.

After PTK, almost everyone experience some visual side effects. These visual side effects are usually mild and temporary and have a tendency to diminish over time. But there is a slight chance that some of these side effects won’t go away completely, including light sensitivity, glare and halos. Serious complications to PTK are extremely rare. Back

4. Differences of medical treatment methods

Both methods – PRK and LASIK belong to the same laser eye surgery group, but each of them is a little different when it comes to advantages and disadvantages. LASIK patients have less discomfort and obtain good vision more quickly, while PRK patients vision improves gradually, over a few days or even months. Although many surgeons prefer PRK for patients with larger pupils or thin corneas.

PTK is different from PRK and LASIK techniques, that involve the use of the excimer laser to correct refractive errors of the eye (e.g., myopia, astigmatism, hyperopia, and presbyopia). PTK treatments vary with different corneal disorders, and the clinical goals of the procedure may, likewise, vary depending upon the patient's symptoms. Back