Procedures

Corneal Surgery 


Overview:
The cornea is a thin, clear tissue which serves as the front wall of the eye and plays a critical role in transmitting light from the outside world into the eye. Several eye diseases can damage the clarity or shape of the cornea and prevent the uninterrupted passage of light through it. Additionally, the cornea may play a role in refractive error of the eye, resulting in an improperly focused image on the retina. Several surgical options are available for treating corneal diseases and correcting refractive error.

Corneal anatomy:
In order to understand how corneal surgery can help treat corneal disease and refractive error, it is helpful to review the important parts of the corneal anatomy.

The cornea, which is about the thickness of a credit card, is comprised of several layers of tissue. The surface of the cornea is covered by a very thin layer of skin cells called the epithelium, which rest on a fine collagen membrane called Bowman’s membrane. The bulk of the cornea, which lies underneath the epithelium and Bowman’s membrane, is called the stroma. Underneath the stroma lies Descemet’s membrane, which separates the stroma from the innermost lining of the cornea. The innermost portion of the cornea is a thin layer of cells called the endothelium, which are responsible for keeping the fluid inside the eye out of the cornea.

The cornea plays an important role in focusing light that enters the eye. When light passes through the cornea from the outside world, it is bent, or refracted, as if passing through a lens. In fact, the cornea works in concert with the crystalline lens inside to help focus light on the retina, much like the lens system of a camera.

The unhealthy cornea
A cornea can become unhealthy in several ways. First, injury to the cornea can result in scarring. A scar, which is dense and white, can directly impede the passage of light through the cornea. Further, a scar can cause the shape of the cornea to become abnormal and warped, which can cause incoming light to be bent in an irregular fashion as it passes through the cornea. Warping of the cornea can also occur in certain diseases, such as keratoconus, where portions of the cornea becomes abnormally thin or irregularly shaped. Disease or injury can also cause the cornea to become swollen. When the cornea swells, it also becomes cloudy, impeding the clear passage of light. Lastly, though a cornea may otherwise be clear and regularly shaped, it must work in concert with the crystalline lens(link to glossary) of the eye to focus light crisply on the retina. If these two structures are not correctly balanced, refractive error(link to glossary) occurs. As such, a cornea could be to flat or steep for an eye and its lens, resulting in hyperopic or myopic refractive error and blurry vision without the use of glasses or contacts.

Penetrating Keratoplasty: The complete corneal transplant:
When the cornea becomes extremely swollen, scarred or warped, light cannot easily pass through to the retina, and vision is lost. Several diseases can result in a cloudy or warped cornea, such as corneal swelling after eye surgery, Fuchs Dystrophy, Keratoconus or scarring after corneal trauma. In these cases, a complete replacement of the cornea may be needed. The surgical procedure to accomplish a complete corneal transplant is called Penetrating keratoplasty(PK). During a PK, the entire cornea is removed, much like a man-hole cover, and replaced with a complete donor cornea. The donor tissue is secured in place with many sutures which are finer than a human hair, usually placed in a spoke like fashion around the outside edge of the transplant. These sutures remain in place for several months, and then are slowly removed over the course of one to two years. Many eye medications are required after corneal transplantation, and a lifetime commitment to eye drops and regular eye examinations is required in order to keep the transplant healthy and prevent rejection.

DSEK: The partial corneal transplant
Some disease processes, like forms of Fuchs Dystrophy and select cases of corneal swelling after eye surgery, are due to dysfunction of the inside lining cells of the cornea. This layer of cells, called the endothelium, can be replaced surgically in a procedure called Descemets Stripping Endothelial Keratoplasty (DSEK). In DSEK, the endothelial lining of the cornea is removed through a small incision in the eye and replaced with a small disc of endothelial cells from a donor. The replacement of the malfunctioning endothelial cells allows the cornea to once again become clear by restoring the lost function of the endothelial cells. DSEK is performed through small incisions and has a relatively fast recovery period. Usually, the cornea can be greatly cleared by 4 to 6 weeks after the procedure. Occasionally, however, the donor endothelial cells become dislodged from the inside of the cornea and have to be repositioned surgically or replaced entirely. Like penetrating keratoplasty, DSEK is a corneal transplant procedure, so lifetime eye drops and eye examinations are needed afterwards.

Superficial and Phototherapeutic keratectomy: Removal of small corneal scars
When scar tissue forms on the surface of the cornea, it can be removed by a procedure called superficial keratectomy. In this procedure, the eye is numbed using eye drops. The corneal epithelial surface cells are first removed, then scar tissue is then peeled off the front of the cornea. The epithelial cells then heal over the wound, usually in about 5 to 7 days, just like the healing of a cut on the skin.

When the corneal scar tissue extends into the upper parts of the corneal stroma, or is very irregular in nature, the excimer laser can be used to sand down the scar in a procedure called phototherapeutic keratectomy. A similar process is involved as in superficial keratectomy, though the excimer laser removes the scar tissue, rather than the surgeon manually dissecting it from the cornea.

Pterygium Excision: Removal of abnormal conjunctival tissue from the cornea
In the disease called pterygium, the conjunctiva of the eye begins to grow in an abnormal fashion across the surface of the cornea. As the conjunctiva is not clear, light is impeded from passing through the cornea in the area where the pterygium has grown. Pterygia can also bring scar tissue onto the surface of the cornea as they grow, further impeding the passage of light and causing astigmatism to occur. Pterygia can be removed surgically and the scar tissue sanded off the cornea, usually with a fine diamond-tipped corneal sander. As pterygia can recur after surgical removal, several additional techniques are used during the surgery to help prevent the abnormal tissue from growing again. Most commonly, a small amount of normal conjunctiva is moved into position over the sclera area where the pterygium was removed. A medication called mitomycin-C is also sometimes used to help prevent abnormal pterygium cells from recurring.

INTACS: Support for a warped cornea and correction of myopia
In keratoconus, sometimes the main cause of poor vision is warping of the cornea. In keratoconus, the cornea starts to thin and protrude forward at a point just below its center. This results irregularly curved corneas and high levels of astigmatism that are difficult to correct with ordinary glasses and contact lenses. To help correct this warping, small plastic ring segments, called Intacs can sometimes help normalize the central corneal shape and improve vision by making the corneal shape more regular. Intacs can also be used to correct low levels of myopia.

LASIK and PRK: Correction of refractive error
The most common corneal surgery performed in the United States today is excimer laser corneal refractive surgery, such as LASIK and PRK. In these procedures a small amount of corneal tissue is removed to reshape the cornea and help focus light more crisply on the retina.

Conductive keratoplasty: corneal correction of hyperopia and presbyopia.
In hyperopic refractive error, the cornea may be too flatly curved for the eye to allow incoming light to form a clear image on the retina. With Conductive Keratoplasty (CK) surgery, however, the shape of the cornea can be changed in order to help light focus more crisply on the retina. In this surgery, a small probe is used to apply radiofrequency energy to the outside edge of the cornea, resulting in a steeper central shape of the cornea. CK can also be used to create monovision in one eye and help relieve the symptoms of presbyopia.

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Corneal Transplants


What is the cornea?
The cornea is the clear front of the eye that covers the colored iris and the round pupil. Light is focused while passing through the cornea so we can see. To stay clear the cornea must be healthy.

How can an unhealthy cornea affect vision?
If the cornea is damaged it may become swollen or scarred. In either case, its smoothness and clarity may be lost. The scars, swelling or an irregular shape cause the cornea to scatter or distort light, resulting in glare or blurred vision.

The operation
The eyelid is gently opened. Looking through a surgical microscope, your doctor measures the eye for the size of the corneal transplant. The diseased or injured cornea is carefully removed from the eye. Any necessary additional work within the eye, such as removal of a cataract, is completed. The clear donor cornea is then sewn into place.

Corneal Transplants are generally performed on an outpatient basis. You will have a short stay in the recovery area and then be allowed to return home. You should plan to have a friend or relative drive you home.

A successful corneal transplant requires care and attention on the part of both patient and physician. However, no other surgery has so much to offer when the cornea is deeply scared or swollen. The vast majority of people who undergo corneal transplants are happy with their improved vision.

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ReStor IOL


The AcrySof ReSTOR lens is a foldable IOL that represents breakthrough technology because of its unique, patented optic design, which allows patients to experience the highest level of freedom from glasses ever achieved in IOL clinical trials.

The AcrySof ReSTOR IOL uses a combination of three complementary technologies: apodization, diffraction and refraction, to allow patients to experience a full range of high-quality vision without the need for reading glasses or bifocals. This range of vision without glasses is achieved through the optical properties of the IOL.

The benefit for patients is a high level of spectacle freedom. Alcon has patented the application of apodization technology to an IOL, making the AcrySof ReSTOR lens the first and only apodized diffractive IOL.

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Wavefront Lasik


Wavefront analysis works by measuring the distortion or irregularities of the eye, known as higher-order aberrations. When a ray of light first enters the eye, it passes through the cornea to the lens and vitreous, ultimately reaching the retina. As it bounces off the retina and returns back through the cornea, the wavefront analysis detects and documents these distortions, which are unique to each individual. Because each patient has a unique visual optical system, the wavefront data has been likened to a fingerprint.

Once the wavefront data has been documented for an individual patient, the next step is to use this information to utilize the excimer laser to correct the higher-order visual aberrations. The surgeon can then determine what adjustments must be made to the corneal surface to produce a clear, crisp image for the unique individual needs of each patient. The use of wavefront technology to provide a more precise laser vision correction is known as, "Custom LASIK" or "Wavefront-Driven LASIK". Early data suggests that the 5-10 percent of patients who demonstrate higher-order aberrations are the patients that will significantly benefit from Custom LASIK treatments. Other patients may benefit from Custom LASIK to a smaller degree.

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Cataract Surgery


Using the most up to date methods and instrumentation, cataract surgery is typically performed using a small incision phacoemulsification technique. This means that the cataract surgery is accomplished using the smallest possible incision, and removal of the lens material is accomplished using an ultrasonic needle.

There is a common misconception that cataract surgery is done using a laser. This is not the case, and has never been the case. The use of laser energy produces too much heat to be adapted for this purpose, and would cause irreversible damage to the delicate tissues inside the eye.

Following proper dilation of the pupil and preparation of the surgical area using betadine or other cleansers, a topical anesthetic is administered to the surface of the eye. An incision of 2.5 to 3 millimeters in length is then created at the junction of the cornea (the clear domed structure on the front of the eye) and the sclera (the white part of the eye).

Another dose of anesthetic is then administered inside the eye through this incision. The front part of the lens envelope, known as the lens capsule, is carefully opened so that the lens material can be removed. This is accomplished using a needle-like ultrasonic device which pulverizes the hardened and yellowed lens proteins. The pulverized material is simultaneously vacuumed from the eye.

Once all of the cataract material has been removed, and assuming that the lens capsule which was opened at the beginning of the surgery remains strong enough to support the lens implant, a folded intraocular lens specifically chosen by the surgeon to suit your individual needs is then inserted through the original incision and maneuvered into the lens capsule and then centered. The lens will remain inside your eye in this location without moving. Intraocular lenses cannot be felt or sensed in any way by the patient.

In most cases, once the lens is centered within the lens capsule, the instruments are removed, and the surgery is therefore complete. Under most normal circumstances stitches (or sutures) are not required to keep the incision sealed. Should the incision require a suture to be placed for proper sealing, this suture is generally removed within the first week following surgery.

Recovery from surgery is generally very quick, with most patients achieving noticeably better vision within the first 24 hours of the procedure. Patients are generally asked to use two different eye medications, administered as drops several times daily for the first few weeks after surgery. It is important that during the first 7 post-operative days patients refrain from strenuous activity such as lifting weights for exercise or lifting other heavy objects. Patients should also refrain from eye rubbing during the first few weeks following surgery.

If glasses are required following surgery to achieve the best possible vision either for close up work such as reading, or for distance purposes, these will be prescribed three to four weeks after surgery when full recovery is expected. If both eyes are scheduled to have surgery within a few weeks of each other, then glasses, if needed, will be prescribed following full recovery of the second eye.

Patients should realize that it is not possible in all patients to totally eliminate the need for eyeglasses.

Intraocular Lenses
Intraocular lens come in a variety of materials and designs. Your surgeon generally chooses a lens made of a material that is best suited to your individual situation. All intraocular lenses used in our practice are coated with UV filters. Some lenses are yellow in color. These lenses are theoretically better at blocking the light rays in the blue spectrum which are thought to be related to the development of macular degeneration in some patients. Some intraocular lenses are designed to be multifocal in certain lighting circumstances, which may enable patients to see both at distance and near without the aid of spectacles. This effect has been shown in all patients in whom the lens has been implanted, and it is once again important for patients to realize that while cataract surgery with intraocular lens implantation frequently results in a reduced dependency on eye glasses it is never guaranteed to eliminate this need totally.

Astigmatism
Modern cataract surgery has evolved to the point of being able to be used in many patients as a predictable means of reducing dependence on eye glasses. The ability to achieve this result is dependent on two factors: (1) the ability of instrumentation used to measure a patient’s eye ball accurately, (2) the ability of the surgeon to reduce the amount of corneal astigmatism surgically.

Astigmatism is present to some extent in all patients. Astigmatism is not a disease, it is simply the occurrence of a corneal shape that is not perfectly spherical. Astigmatism of more than ¾ diopter generally requires a special type of contact or spectacle lens for proper non-surgical correction. Surgical correction of astigmatism is possible in many patients undergoing cataract surgery. This technique involves the creation of relaxing incisions in the peripheral part of the cornea. It can be done quickly and simply during a routine cataract procedure. However, in many patients the astigmatism is too great to be corrected using the conventional method typically favored during cataract surgery and for those situations, it will be necessary to correct this astigmatism with spectacles or contact lenses following surgery. There are other surgical methods of treatment for astigmatism, but none of the other options are covered by Medicare or other insurers. For further information about these options, please feel free to ask your doctor.

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CK


Near vision CK is the only FDA-approved vision procedure that can help people over the age of 45 to improve their vision, thereby substantially reducing their need for reading glasses. CK is usually performed on one eye to restore near vision without affecting the patient’s binocular distance vision. This is achieved by reshaping the cornea in a blended fashion.

CK is usually performed on one eye to restore near vision without affecting the patient’s binocular distance vision. This is achieved by reshaping the cornea in a blended fashion.

Presbyopia is a progressive condition that causes near vision to fade with age. There are approximately 90 million Americans suffering from this condition. CK offers a safe, effective and minimally invasive procedure to correct the aging eye. CK may turn back the clock on the aging eye, but it will not stop the clock from ticking.

CK is the only FDA approved technology for the improving near vision in baby boomers.

The clinical trials revealed that 98% of patients who participated could read magazine and newspaper-size print in the eye that was treated with CK. 87% could see 20/20 in the distance and read phone book sized print. CK uses radio frequency energy. No cutting. No laser. No removal of tissue. This gives the procedure one of the highest safety profiles among refractive procedures. No serious sight threatening events were reported in clinical trials.

In a 5-minute procedure, using eye drop anesthesia, the cornea is gently reshaped with a probe thinner than a strand of human hair to apply radio waves on the outer cornea, causing a central steepening. This constrictive band acts like a tightening belt, increasing the curvature of the corneas to improve the patients near vision.

THE CK PROCEDURE
A complete eye exam and a topography test with a computer are done to determine the cornea curvature. After anesthetic eye drops are applied, the doctor imprints a treatment pattern on the cornea-using coloring that is later rinsed away. The radio frequency energy is then applied following the points on the treatment pattern. Patients feel a sensation of pressure on the eye during the procedure, but not pain.

After the procedure, antibiotic eye drops are used for three days. The patient may need artificial tears for up to one week. For a few days, there may be mild discomfort and light sensitivity. Many patients feel a foreign body sensation for the first 24 hours following the procedure.

WHO IS A CANDIDATE FOR CK?

If you answer yes to all of the following 3 KEY QUESTIONS you are a candidate for this procedure.

1. Did you have great distance vision without glasses most of your life?
2. Are you 45 years or older?
3. Are you tired of your reading glasses?

The Arrowhead Eye Center is pleased to be one of the first ophthalmology practices in Arizona to offer this procedure. Our reputation for being a leader in vision correction procedures along with our genuine concern for our patients' satisfaction have made this possible for us.
 
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What is Glaucoma?


Glaucoma refers to a group of different eye diseases which in most cases produce increased pressure within the eye. This elevated pressure is caused by a backup of fluid in the eye. Over time, it causes damage to the optic nerve. Through early detection, diagnosis and treatment, you and your doctor can help to preserve your vision.

Think of your eye as a sink, in which the faucet is always running and the drain is always open. The aqueous humor is constantly circulating through the anterior chamber. It is produced by a tiny gland, called the ciliary body, situated behind the iris. It flows between the iris and the lens and, after nourishing the cornea and lens, flows out through a very tiny spongy tissue, only one-fiftieth of an inch wide, called the trabecular meshwork, which serves as the drain of the eye. The trabecular meshwork is situated in the angle where the iris and cornea meet. When this drain becomes clogged, aqueous cannot leave the eye as fast as it is produced, causing the fluid to back up. But since the eye is a closed compartment, your `sink´ doesn´t overflow; instead the backed up fluid causes increased pressure to build up within the eye. We call this open (wide) angle glaucoma.

To understand how this increased pressure affects the eye, think of your eye as a balloon. When too much air is blown into the balloon, the pressure builds, causing it to pop. But the eye is too strong to pop. Instead, it gives at the weakest point, which is the site in the sclera at which the optic nerve leaves the eye.

As we mentioned earlier, the optic nerve is the part of the eye which carries visual information to the brain. It is made up of over one million nerve cells, and while each cell is several inches long, it is extremely thin – about one twenty-thousandth of an inch in diameter.

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