Refractive Procedures

How an Implantable Contact Lens Works

A lens is permanently placed in the front chamber of the eye, between the cornea and the natural lens of the eye. Phakic refers to still having the eye's natural internal lens which is removed in cataract surgery. Implantable Lenses are tiny lenses designed to be placed permanently within the eye to correct vision problems. They are manufactured of materials that are biocompatible, so they can rest within the eye without needing any care. Various types of lenses are designed to rest in selected positions in the front chamber of the eye. Implanting one of these special lenses offers dramatic results that are quite predictable and reversible, if necessary.

One to two weeks before the surgery, the implantable lens patient undergoes a simple laser procedure known as an iridotomy. The surgeon uses an Nd:YAG laser to create two or three small openings in the peripheral iris, the colored part of the eye. These openings help ensure that the placement of the lens will not cause blockage of fluid that flows through the front chamber of the eye. A blockage can lead to an increase of fluid pressure known as glaucoma.

Lens implantation is a simple outpatient procedure. Patients sit in a surgical chair, which is reclined back into a horizontal position. Attentive assistants ensure that patients are very comfortable as they drape them with sterile sheets in preparation for surgery.

Patients are not put to sleep, but they can be sedated with oral or intravenous medications, if necessary. Only the selected eye is "frozen" for this painless surgery. In most cases, topical drops are used to anesthetize the eye, so no injection is necessary.

To begin, the surgeon makes a small incision of 1/8 to 1/4 of an inch (3.0 to 5.0 mm) in either the white sclera or on the edge of the cornea. The surgeon then inserts an open or a folded implantable lens through the incision and carefully positions it behind the cornea, in front of the eye's natural internal lens. The implanted lens, selected with a specified focal power, becomes the eye's third lens. The small incision surgery is usually completed without stitches, since the incision is designed to be self-sealing. The whole procedure takes approximately 20 minutes.

Currently, lens implants cannot correct astigmatism. If needed, other surgical procedures can be combined with lens implantation to solve astigmatism focusing problems.

Who Benefits Most

People benefitting from Implantable Contact Lens have very high degrees of nearsightedness or farsightedness, beyond what is easily corrected by laser or ring segment surgical options that alter the corneal curvature.

After Surgery Expectations

Visual recovery after a lens has been implanted, in most cases, is rapid. A few minutes after the surgery, patients are able to see well enough to engage in regular activities with dramatically increased visual freedom. Full visual recovery may take a few days.

Side effects are minimal. Patients can expect increased light sensitivity for a few days, so sunglasses need to be worn more often than usual during this time. The implanted lens cannot be felt inside the eye.

If the stable visual result is not ideal, a second surgical procedure to adjust or replace the lens is generally possible, but corneal laser surgery (LASIK or PRK) to fine tune the result is usually recommended.

Advantages

• Correction of very high degrees of nearsightedness and farsightedness.
• Predictable outcomes, even in high corrections.
• Fast visual stabilization.
• Does not alter the tissue of the cornea.
• Minimal side effects.
• Can be combined with other corrective options.
• Reversible in effect.

Loma Linda University Eye Institute offers the IntraLase® Femtosecond (FS) laser - the latest technology that eliminates the use of a surgical blade to create the flap for laser refractive surgery procedures.

The LASIK corneal laser refractive procedure involves a 2-step process. The first step involves exposing the deeper corneal tissue in order to prepare the eye for the second step, which reshapes the corneal tissue with an Excimer laser to improve vision. Traditionally, with LASIK, the only way to create a flap was to use a surgical blade in a keratome. With the IntraLase FS laser, we are now able to create the flap for LASIK with a laser instead of a surgical blade, which offers a number of significant advantages. One of the advantages is that the laser-created flap gives the surgeon greater control in creating flaps of more consistent and predictable thickness. This leading edge technology allows for the safer creation of much thinner flaps and for LASIK to be considered when only PRK could be recommended in some cases (i.e., due to a patient's inadequate corneal thickness).

For reasons of safety and improved quality of vision, Loma Linda University Ophthalmology surgeons choose IntraLase as their preferred method of flap creation for patients who are suitable candidates for LASIK and who prefer LASIK over other refractive procedure options. Thousands of these tiny bubbles are precisely positioned to define the flap's architecture (exact diameter, depth, hinge location, centration, side cut, etc.) and laser pulses are also stacked along the edge of the flap up to the corneal surface to complete the flap.

Tired of hassling with your contacts or glasses? Join the millions of Americans enjoying a lifestyle free of contacts or glasses. American Board Certified Ophthalmologist Frank Hwang, MD brings LASIK and years of experience in refractive surgery to Loma Linda University Eye Institute.

Using remarkable laser technology, the cornea can be reshaped to conform to your glasses or contact lens prescription. LASIK, or Laser in Situ Keratomileusis surgery, reduces the need for corrective lenses in just minutes.

Who Should Have LASIK?

Not everyone is an ideal candidate for refractive surgery. LASIK is best performed on people with low, moderate, and high degrees of nearsightedness. However, refractive surgery has also been found effective for correcting low and moderate degrees of farsightedness as well as astigmatism. The ideal candidate for LASIK should meet the following criteria:

• Must be at least 21 years of age
• Maintain stable vision for one year - minor fluctuations may not disqualify you
• Have a correctable vision problem
• Have eyes free of complicating injuries and diseases - individual assessment required.
• Must not be pregnant or nursing

How LASIK Works

LASIK is a laser surgical procedure effective for correcting refractive errors or focusing ability. During the procedure, the patient lies on their back in a horizontal position. A surgical assistant applies topical anesthetic drops to "freeze" the eye for a painless correction. Assistants then carefully drape the patient's face around the eye to ensure a perfectly clean surrounding area for the surgery.

To perform LASIK, the surgeon first creates a flap of tissue on the surface of the eye using a precise cutting instrument, called a microkeratome. The microkeratome cuts through 1/4 to 1/3 of the thickness of the cornea, creating a flap of tissue. This clear flap is lifted up and folded open, to the side or the top of the eye, still securely attached by the "hinge".

In recent years, the IntraLase laser has become available to create a flap using multiple short pulses. These pulses are so close together they create an almost complete separation of the flap from the rest of the cornea, but they do not actually lift the flap. If the flap pattern is judged to be complete and satisfactory, a delicate separation of the flap is performed with a few gentle manipulations using a surgical instrument.

Learn more about IntraLase.

The surgeon then positions the patient's eye under the excimer laser which is programmed to remove microscopic layers of tissue from the internal part of the cornea, called the stroma, under the flap. The cool laser beam vaporizes tissue away, one microscopic layer at a time, without burning or cutting. This tissue does not replace itself after it is removed. Since the excimer laser light is created at a specified wavelength that does not pass through the cornea, no other part of the eye is affected.

Myopia/Nearsightedness

To correct nearsightedness, the laser removes central tissue to decrease the curvature, allowing light rays to focus farther back in the eye to reach the retina.

Hyperopia/Farsightedness

To correct farsightedness, the central cornea is made steeper by removing small portions of peripheral tissue to increase the curvature so light can focus within a shorter distance.

Astigmatism

To correct astigmatism, the laser removes tissue in designated areas to equalize the curvatures of the cornea. After the tissue has been removed, the surgeon places the flap back in its original position where it heals into place with no stitches. The cornea has amazing natural bonding qualities. Within a few minutes, the flap adheres to the underlying tissue. The edges of the flap heal over in 12 to 48 hours, with the entire flap gaining adhesive strength as it continues to heal in the following weeks and months. For each eye, the laser application time is usually less than one minute and the whole LASIK procedure around 15 minutes.

What to Expect with LASIK

Visual recovery is rapid after LASIK. Within one or two days, most patients see clearly, with minimal side effects. These quick results are possible because the epithelial membrane on the surface of the eye has not been disrupted, except for a thin line outlining where the flap was created. Most patients experience little or no discomfort following surgery and vision generally stabilizes within one month.

Antibiotic, anti-inflammatory, and moisturizing drops are required for at least a few days after surgery, and patients wear an eye shield at night to protect the eye while sleeping during the initial healing process. 

The temporary side effects following LASIK are minimal and are most often limited to slightly drier eyes, minor increases in light scattering, decreased clarity in dim light, and seeing halos around bright lights at night.  These effects are most common when the pupil is larger than normal and the correction is high. (LASIK is therefore not recommended for people with the combination of a very large pupil opening and a high focusing problem.) It is rare for these side effects to interfere with normal activities, and they diminish as the eye heals.

Most patients receive full correction in one treatment. For those who do not, a second treatment or enhancement is generally possible. For several months after the initial surgery, the surgeon can use instruments to lift the flap and remove more tissue with the laser to "fine tune" the results. If an enhancement is needed after a longer healing period, another flap can be created or an alternative procedure may be recommended.

Successful outcomes of LASIK vision correction include the following life changing benefits for people with focusing problems:

• Clear vision without the inconvenience and limitations of corrective lenses Increased independence
• Wider field of vision than with glasses
• Reduced fear about losing corrective lenses at critical times
• Expanded career opportunities
• Greatly increased recreational possibilities More natural appearance without glasses
• Eliminate risks associated with long-term contact lens usage
• Can have corrective lens requirements removed from drivers' license

Possible Complications

LASIK correction is a very safe procedure. When complications do arise, they can generally be effectively treated with further surgery. The following are the most common, yet rare, complications associated with LASIK:

Infection

Infections are very rare, but they can damage the cornea if not resolved with early treatment. They are usually identified early and effectively treated with medications.

Difficulty Creating a Flap

The unusual shape or characteristics of some eyes can make it difficult for a surgeon to create a proper flap, although surgeon skill and microkeratome quality and maintenance are also factors. When difficulties are encountered, they are often resolved with adjustments. However, effective adjustments are not always possible, resulting in the LASIK procedure being discontinued. When discontinued, the procedure is postponed or another corrective option may be recommended.

Haze and Irregular Astigmatism

Sometimes a slight haze or a small amount of uneven astigmatism results from surgery. These problems usually resolve as the eye heals. However, if they do not, they are usually treatable through a second surgery.

Epithelial Growth under the Flap

Cells from the protective surface layer of the cornea can get into the incision area and interfere with the healing process. This problem is resolved by the surgeon gently lifting the flap, removing the interfering cells and then positioning the flap again.

Shifting or Wrinkling of the Flap

Occasionally wrinkles develop during the healing process. This problem usually resolves itself within three to six months. In cases where the flap has significantly shifted, a repositioning is necessary. The surgeon gently lifts the flap and replaces it in the proper position. Retreatments may be performed if vision is affected significantly from either of these situations.

Interface Inflammation

Most LASIK patients show some interface inflammation as a normal part of the healing process. This inflammation is usually self-limiting and requires no treatment. In cases of increased inflammation, medicated drops are used to treat the symptoms.

How PRK Works

This technique is the most simple and straightforward method of laser correction. To perform PRK, the surgeon uses the excimer laser to vaporize away microscopic layers of tissue from the surface of the eye. By modifying the shape of the cornea, light rays can focus correctly within the eye to provide clear vision. PRK is less invasive than LASIK since only the surface tissue of the eye is affected.

For the procedure, the patient sits in a surgical chair which is reclined into a horizontal position. A surgical assistant instills topical anaesthetic drops on the eye to "freeze" it for a painless correction.

The cornea consists of different layers of tissue. The surface layer, known as the epithelium, is a soft, protective layer that regenerates quickly.

Before laser correction, the surgeon removes this outer membrane by gently rubbing it away with an instrument. Within a few days of the surgery, the epithelium regenerates itself, again forming a protective layer over the eye.

The interior part of the cornea, known as the stroma, does not regenerate itself when removed. For PRK, the surgeon programs and positions the laser to remove a small portion of this stromal tissue to permanently change the shape of the cornea. In most cases, only 5 to 15% of the corneal thickness is treated, leaving the structural integrity of the cornea intact. The cool laser beam vaporizes tissue away, one microscopic layer at a time, without burning or cutting. Since the excimer laser light is created at a specified wavelength that does not pass through the cornea, no other part of the eye is affected.

To correct nearsightedness, the laser removes central tissue to reduce the curvature of the cornea so light rays will focus farther back and reach the retina. To correct astigmatism, the laser removes tissue from designated areas to equalize the curvatures of the cornea so light rays from the full scope of vision can focus evenly on the retina.

After the tissue has been removed, the surgeon places a special soft contact lens on the eye to protect it for the first few days of healing. This lens remains on the eye both day and night for up to four days, although it may be replaced on the second or third day.

The laser correction itself usually takes less than one minute per eye, although the patient is in the surgery suite for about 15 minutes.

Who Benefits Most

• People with low and moderate degrees of nearsightedness
• People with low and moderate degrees of astigmatism

After Surgery Expectations

Patients normally require several days of healing to achieve good functional vision after PRK correction. Patients can see immediately after the surgery, but vision is not clear. The protective epithelium layer must heal back and become smooth again to allow clear vision. This healing usually occurs within a week, allowing most patients to then drive and go back to work, wearing no corrective lenses.

• After PRK correction, most people experience some temporary side effects associated with the healing of the eye. These include initial exaggerated results, increased light sensitivity, halos or glare from bright lights at night, decreased clarity in dim light and slightly drier eyes. Four to six weeks after correction, most of these side effects have disappeared, and vision is generally very good. Complete visual stabilization usually occurs within one to four months.

• Patients should expect mild to moderate discomfort for one or two days after the surgery but most do not need more than over-the-counter medications to control it. A small percentage of patients do experience significant discomfort requiring pain medication.

• Antibiotic, anti-inflammatory and moisturizing drops are required for at least a few days after surgery. As the healing process continues, steroid drops may be required to optimize the surgical result.

• The majority of patients receive full correction in one treatment. For those who do not, a second treatment or enhancement is generally possible.

Specific Advantages of PRK

• Over a decade of surgical success
• No incision necessary
• Non-complex corrective procedure
• Permanent tissue modification for lasting correction

Possible Complications

• PRK is a very safe procedure
  Significant complications are rare, and even if they do occur, they can usually be resolved with medications or further surgery.

• Infection (less than 1/5,000)
  Infections are very rare, but they can damage the cornea if not resolved by early treatment. They are identified early during after-surgery checkups and effectively treated with medications.

• Corneal haze or scarring (1-2%)
  Microscopic haze, generally unnoticed by the patient, is normal for a few weeks following the surgery. It clears as the eye heals. However, it occasionally appears more noticeable or more lasting than normal. High PRK corrections have a higher incidence of haze problems. Healing time and additional treatments are used to resolve the problem. A slight scarring resulting from an uneven healing process is also possible. A second laser treatment to smooth the cornea generally solves the problem, but complete smoothing is not always achievable.

How Refractive Lens Exchange Works

Unlike laser corrective surgeries which alter the shape of the cornea, a refractive lens exchange changes the focusing power of the lens within the eye. For this procedure, the eye's natural lens is removed and replaced by a manufactured lens implant which has been selected to provide clear focusing ability. The lens implant remains within the eye, without needing any further care after surgery. It provides a wide range of focusing freedom, but since it is a fixed focus lens, glasses are necessary for all near vision activities such as reading.

A refractive lens exchange is not generally recommended for people under 45 years of age, unless the diagnosis and careful testing reveals it to be the best option. People under 45 still have significant flexibility in their natural lens which allows them to vary their focus naturally. This ability is lost in a lensectomy procedure.

This ability is lost during the natural aging process, so those over 50 to 55 may not lose a significant amount of natural focusing flexibility through the procedure.

A refractive lens exchange is a simple outpatient procedure. Patients sit in a surgical chair, which is reclined back into a horizontal position. Attentive assistants ensure that patients are very comfortable as they drape them with sterile sheets in preparation for surgery.

Patients are not put to sleep, but they can be sedated with oral or intravenous medications, if necessary. Only the selected eye is "frozen" for this painless surgery. In most cases, topical drops are used to anesthetize the eye, so no injection is necessary.

A refractive lens exchange procedure is similar to modern cataract surgery. To begin, the surgeon makes a small incision of 1/8 of an inch (2.8 mm) in either the white sclera or on the edge of the cornea. The surgeon inserts a delicate instrument to create a smooth, round opening in the outer capsule of the natural lens. Using an ultrasonic suction probe, the surgeon proceeds to gently break up and suction out the gel from the lens capsule.

Then, the surgeon inserts a high quality lens implant of appropriate power and positions it securely within the natural lens capsule. Foldable lens implants are generally used. They are inserted through tiny incisions and then open up inside the eye where they are positioned to provide clear vision.

For extremely high corrections, foldable lenses are not manufactured, so the incision is enlarged for the placement of a more rigid lens implant. The surgery is usually completed without stitches, since the incision is designed to be self-sealing. The whole procedure takes around 15 minutes.

Some lens implants can correct astigmatism. If needed, other surgical procedures can be combined with lens implantation to solve astigmatism focusing problems.

Who Benefits Most

• People with extreme degrees of nearsightedness or farsightedness, beyond what is easily corrected with laser corrective options.
• People with signs of early cataract development.
• Most people over 60 years of age who are dependent on corrective lenses for distance vision.

After Surgery Expectations

Visual recovery from a refractive lens exchange, in most cases, is fast and dramatic. A few minutes after the surgery, patients are usually able to see well enough to engage in regular activities with increased visual freedom.

Side effects are minimal. Most patients experience some temporary blurring for a few days from tear film variations or some fluid in the cornea. Patients can also expect increased light sensitivity for a few weeks, so sunglasses need to be worn more often than usual during this time.

The lens capsule closes around the new lens implant in the weeks following surgery, sometimes changing the focusing range to a small degree because of a shift in position. If the stable visual result is not ideal, a second surgical procedure to adjust or replace the lens is possible. An additional laser surgery to improve the focus is also possible.

Specific Advantages of Refractive Lens Exchange

• Correction for most ranges of nearsightedness and farsightedness
• Predictable outcome
• Fast visual stabilization
• Minimal side effects
• Can be combined with laser or incision corrective options to correct astigmatism
• Eliminates the need for cataract surgery in the future
• Long history of successful outcomes

Possible Complications

As with any surgery, there are some possible complications to a refractive lens exchange. However, the risks are minimal.

Increased Possibility of Retinal Detachment (less than 1%)

Farsighted people have a very low risk of detachment, however, most nearsighted people have eyes that are longer than normal, resulting in retinas which are more vulnerable to detachments. The risk of retinal problems because of surgery is extremely small. A retinal examination required before the surgery helps to determine the risk factors for each patient. Even if a detachment occurs, it can generally be effectively repaired.

Inner Eye Surgery Complications (less than 1%)

The following complications are very uncommon, but they can occur: hemorrhage or infection within the eye, swelling around the eye, reflections or sight distortions from the lens implant, an increase of floaters, loss of corneal clarity, dislocation of the lens implant, wound leak, glaucoma and uveitis (inflammation). Most of these complications can be effectively treated if they occur.

Corneal Surface Surgery Complications (less than 1%)

The corneal surface problems of induced astigmatism and slightly increased dryness are not generally serious and may be effectively treated.