A. Introduction to Laser Vision Correction
Coal Harbour Eye Centre provides this package of information to you to assist you in making an informed decision about whether to undergo Laser vision correction.
Laser vision correction has enabled millions of people worldwide to enjoy a new found freedom – living their lives without the inconvenience of glasses or contact lenses.
Although now viewed as a relatively routine procedure, many people who consider it for themselves become understandably confused and anxious by the multiple choices and widely varied pricing structures available to them. If you’re finding it difficult to make the right decision in this important matter, you owe it to yourself to speak to an eye care professional at Coal Harbour Eye Centre. We hope that the following information will assist you in making an informed decision about laser eye surgery.
A surgical procedure called LASER IN-SITU KERATOMILEUSIS (also called “LASIK” in this material).
LASIK is a form of outpatient corneal surgery in which, under local anesthesia, a surgeon uses a specialized and precise flap-making instrument, called a microkeratome, to create a thin flap of corneal tissue. This flap is raised and laid back while still attached to the cornea. The surgeon then uses an excimer laser to remove a pre-determined amount of corneal tissue from the exposed bed of the cornea. The amount of tissue to be removed is calculated based on the pre-operative determination of the power of your eye and the size of the pupil. The flap is replaced and within minutes natural forces hold the flap down on the cornea. Usually, within a few hours, the surface epithelium (“skin”) of the cornea begins to grow over the cut edge of the flap to seal it into position. LASIK can be used to correct nearsightedness (myopia) and farsightedness (hyperopia) with or without astigmatism.
A surgical procedure called PHOTOREFRACTIVE KERATECTOMY (sometimes called “PRK” in this material).
PRK is a form of outpatient corneal surgery in which a surgeon removes the front surface of the cornea called the epithelium, and then reshapes the corneal bed with the laser in the same way as LASIK. After the procedure you will wear a soft contact lens (bandage lens) until the epithelial layer regenerates. Healing responses vary from patient to patient. This technique is usually used for people whose cornea may be too thin to allow for the creation of the corneal flap required for LASIK. The procedure is used to correct nearsightedness (myopia), farsightedness (hyperopia) and astigmatism.
LASIK and PRK are referred to, collectively, as the “Procedure” in the following materials. This material is in addition to, but does not replace, your discussions with your surgeon and the optometrist. We encourage you to ask questions of and discuss the Procedure with your surgeon and optometrist before you decide to have the Procedure.
B. How the Eye Works
LASIK and PRK are performed on the cornea. The globe of the eye possesses a transparent wall at the front called the cornea. The cornea acts as the major focusing lens of the eye. The cornea itself consists 90% of tissue called the stroma, with an overlying skin called the epithelium. Removal of stromal tissue from the cornea does not usually lead to regeneration of stromal tissue. Removal of epithelial tissue (the “skin”) does lead to re-growth of epithelium. Therefore, removal of stromal tissue can produce permanent re-contouring of the cornea, thereby changing its focusing power.
C. Elective Surgery
LASIK and PRK are elective surgical procedures. There is no medical condition or emergency condition requiring that you have LASIK or PRK. They do not correct all levels of refractive error and are not for everyone. We cannot guarantee that LASIK or PRK will improve your vision, or that it will eliminate your need for glasses or contact lenses. After the Procedure, you may still need glasses or contact lenses for some purposes, either immediately after the Procedure or years later. It is not realistic to expect that the Procedure will always result in perfect vision. It is also remotely possible that your vision will not remain stable, either because the Procedure leads to short-term and long-term changes in the cornea or because your eye may change over time.
D. Who is Eligible for a Procedure?
To be eligible for LASIK or PRK you must be between the ages of 19 and 65 years old and not have had a significant change in your glasses or contact lens prescription for the last twelve (12) months.
Who is Not Eligible?
Certain conditions may interfere with the healing process or cause additional problems, risks or complications, which may require additional care or may make you a questionable candidate for the Procedure. Those conditions include, but are not limited to:
a. Eye inflammation or infection;
b. Severely dry eyes;
c. Excessive corneal disease or scarring;
d. Degenerative disease of the cornea;
e. Uncontrolled diabetes;
f. Use of certain drugs;
g. Pregnancy and Nursing mothers;
h. Inadequate corneal tissue; Certain rheumatological conditions (e.g. lupus, rheumatoid arthritis); and
If you have or have been advised that you may have any of these conditions, you should discuss them thoroughly with your eye care professional and your surgeon.
E. Informed Consent
You have the right to consent to or to refuse any treatment or procedure at any time prior to its performance. Consent is a process that involves many steps. The clinical and professional staff and surgeon have provided important information to you. Please ensure that your questions are answered and your concerns are addressed.
During your pre-operative evaluation, an optometrist or other eye care professional will examine your eyes to determine if you are a candidate for LASIK or for PRK according to criteria that are set by the surgeon. An optometrist or other eye care professional will provide you with an explanation of the procedure, the risks and complications, expected benefits, alternatives and any particular conditions that might affect your decision to undergo the Procedure.
To assist you in making an informed decision, your surgeon will provide you with a description of the procedure, the risks and complications, expected benefits, and the alternatives. This information must be provided in language and terms that you understand; therefore, you must ensure that your surgeon is aware if you have unanswered questions or if you do not understand any topic. However, your surgeon must provide you with information that would be material for a reasonable person in your position to use in deciding whether or not to undergo the Procedure.
Patient Consent Form
Before your surgery, Coal Harbour Centre will send you a Patient Surgical Handbook and the Patient Consent Form. If, after reading this material and speaking with an optometrist, eye care professional, and your surgeon, you decide to undergo the Procedure, you will need to sign the Patient Consent Form, indicating that you have been advised of the nature of the Procedure, its risks, benefits and alternatives, and that you are making an informed decision to undergo the Procedure. You will be asked to sign this document in front of witnesses on the day of surgery.
F. Refractive Errors
In order to decide whether to undergo the Procedure, it is helpful to understand how the eye works. The eye is like a camera. The cornea is the clear, dome-shaped window that forms the front wall of the eye. The retina is the light-sensitive tissue in the back of the eye that connects to the brain. The retina acts like the film in a camera. The cornea at the front of the eye acts as a lens that focuses light onto the retina, producing an image on the retina that gets transmitted to the brain and interpreted as vision. The curve of the cornea determines the power of the corneal lens and whether the incoming light rays from distant objects focus directly onto the retina. When light does not focus directly on the retina, the eye has a refractive error. This means that with the appropriate “refractive correction” lenses, incoming light rays become focused onto the retina producing clear vision.
Myopia / Nearsightedness
In the normal eye, the cornea focuses light rays directly on the retina, resulting in clear vision without glasses or contact lenses. In myopia, or nearsightedness, the eye is longer than normal. The light rays come together at a point in front of the retina, and are out of focus on the retina. Distant objects are blurred, while nearby objects can be clear.
Hyperopia / Farsightedness
In hyperopia, or farsightedness, the eye is shorter than normal. The light rays come together at a point behind the retina, and are therefore out of focus on the retina. Nearby objects can appear blurry, while distant objects are clearer. Very farsighted patients will report that even distant objects appear blurry.
In the normal eye, the cornea is curved the same in the horizontal and vertical directions, like a baseball. When the light rays hit the cornea, they focus at a single point. In astigmatism, the curve of the cornea is not the same in the horizontal and vertical directions. The cornea looks like a football, with a steep curve on one side and a flat surface on the other. As a result, light rays entering the cornea do not focus at a single point, causing distorted vision. Many people with myopia or hyperopia have some degree of astigmatism.
In all of these conditions, the person needs some type of corrective lens, such as glasses or contact lenses to focus the light properly. LASIK and PRK are used to change the shape and curve of the cornea in order to correct or reduce these types of refractive errors.
G. Description of the Procedure
The Procedure is performed on an outpatient basis at the Centre. You will be able to go home after the Procedure, but you will need to arrange for someone to drive you home and bring you back the next day for a follow-up visit. The Procedure generally requires twenty (20) minutes of operating room time, but the actual duration of the Procedure may vary according to the type and amount of correction needed.
A mild sedative may be taken to help you relax. You will be given eye drops to numb your eyes. During the Procedure, you will be lying on the laser bed and your eyelids will be held open with a device called a lid speculum. You will be asked to focus on a special fixation light in a microscope.
Looking through a microscope, your surgeon will use an instrument, called a microkeratome, to create a flap of tissue in the cornea. This flap is then lifted up like the page of a book to expose the tissue just below the cornea’s surface.
Next, looking through the microscope, your surgeon uses a device called an excimer laser to reshape the cornea by removing an ultra-thin amount of the exposed tissue of the cornea. A computer inside the excimer laser is used to control how much corneal tissue is removed. Your surgeon then replaces the flap over the cornea.
No stitches (sutures) are generally required to keep the corneal flap in place. A scar gradually develops around the edge of the flap increasing the flap adhesion further (note that the scar is located well away from the centre of your vision).
You must wear protective shields or eye patches for the first several nights to prevent rubbing your eyes, and you will be required to use eye drops on a regular basis for a few weeks after the Procedure. You may need to use lubrication eye drops for several months after the Procedure. In very rare circumstances you may need to wear a special contact lens on a temporary basis after the Procedure. Generally your vision will be stable in a matter of weeks.
The PRK technique is used for people whose cornea may be too thin to allow for the creation of the corneal flap required for the LASIK procedure. During PRK a small area on the corneal outer surface is gently polished away. The laser reshapes the corneal surface in exactly the same way as for the LASIK procedure.
After the Procedure, your surgeon will place a soft contact lens on the cornea to protect the eye and reduce discomfort while healing. Until the contact lens is removed, your vision will be blurred. You will be required to use medicated and lubricating eye drops to assist the healing process. It will generally take a few weeks for your vision to stabilize.
For the first few days after either Procedure, you may experience discomfort, ranging from scratchiness, to actual pain. During this time, your vision may be blurry and/or may fluctuate between being clear and being blurry. In some cases, a patient’s vision improves immediately after the Procedure, but later becomes blurry. These conditions affect patients differently.
You should not drive for at least twenty-four (24) hours after either Procedure, and in no event should you drive until your vision is clear. You may need glasses or other corrective lenses after the Procedure on a temporary or permanent basis. LASIK or PRK will not prevent, and may unmask, the need for reading glasses, particularly for patients over forty (40) years of age.
The final outcomes of PRK and LASIK are identical; the difference is the healing time.
All surgical procedures, including LASIK and PRK, involve risks of unsuccessful results, complications, infection, and serious injury from known and unforeseen causes. Neither your surgeon, nor your optometrist, nor any staff member can promise or guarantee that the Procedure will be effective or make your vision better than it was before the Procedure.
It is possible that the Procedure or a complication arising from the Procedure could make your vision worse or could injure your cornea or your retina, which could result in partial or total blindness, or could require a cornea transplant. Certain inflammatory conditions can cause severe post-operative complications such as cornea or flap inflammation, or thinning of the corneal flap, which could result in permanent loss of vision. Although it is not possible to list every potential risk or complication that may result from the procedure, the following are identified risks of the procedure.
Halos / Starbursts
Some patients do not see as clearly at night or in dim light and may notice an optical effect called a “halo” or a “starburst” around lights and illuminated objects after the Procedure. Patients who notice these effects may need to wear glasses to drive at night. These effects are for the most part temporary, but could be permanent and uncorrectable. Further, these conditions are more likely to occur in patients with high levels of nearsightedness or farsightedness and for patients with larger-than-average pupil size.
The microkeratome and excimer laser are maintained according to manufacturer specifications. Despite this maintenance, the microkeratome or the excimer laser could malfunction, requiring the Procedure to be stopped before completion. In some instances, this could result in a loss of vision, or rescheduling of the Procedure.
Under-correction or Over-correction
The exact removal of tissue performed by the laser is overridden in some cases by the healing response of the eye. While the treatment of your refractive error is designed to completely neutralize your refractive error (unless otherwise discussed with your surgeon) this treatment is aimed at the “average” eye. If your eye tends to heal in a different way from the “average,” your refraction may result in an over- or under-correction of the refractive error. A patient’s tolerance for under-correction or over-correction varies. In the majority of instances, the over- or under-correction can be corrected with glasses, contact lenses or additional surgery. In other instances, it can be permanent and not amenable to surgery because of structural stability issues or the presence of an irregular corneal surface.
Increased Light Sensitivity of the Eye / Fluctuating Vision
Patients may be sensitive to light and glare or find that their visual acuity fluctuates after the Procedure. These conditions are generally temporary and usually go away within one (1) to three (3) months after the Procedure; however, in some cases they could be permanent.
If the surgeon performs the Procedure on each eye on different days, the eyes may not be able to balance and focus properly until the Procedure is performed on both eyes because there will be a power difference between the two eyes.
Infection, Hemorrhage, Blockage, Drug Reactions & Other Complications
Other risks include severe infection that cannot be controlled by antibiotics, hemorrhage, corneal swelling, retinal detachment, venous or arterial blockage, cataracts, drug reaction, or other complications. These complications range from minor, temporary problems to major, permanent conditions, including but not limited to perforation of the cornea, retinal damage, loss of an eye, and partial or total blindness.
The cornea is living tissue. Once tissue has been removed from the cornea during the Procedure, the surface epithelium (“skin”) can thicken to compensate for the change in shape that has occurred. This happens to a variable degree among treated patients, accounting for the reason why some patients have a stable immediate result (minimal epithelial thickening) and others regress (more significant epithelial thickening). Regression is more likely to occur in very nearsighted patients. In some cases, the patient can have another laser surgery to improve distance vision. In other cases where tissue availability for safe laser re-treatment is limited, the regression is corrected with glasses and/or contacts.
Fragility on Impact
For at least three (3) months after the Procedure, the eye should be considered fragile to direct trauma. When participating in sports or other activities involving possible contact with the eye during this period, you should wear protective eyewear. In any event, it is advisable to protect your eyes from direct trauma after the Procedure as much as possible.
A certain amount of corneal tissue must remain under the flap after the laser has achieved tissue removal. This is believed to relate to the long-term stability of the cornea. In rare instances, imprecision in the accuracy of the keratome cut, coupled with inaccuracy of the pre-operative corneal thickness evaluation can result in less tissue being left under the flap than intended. This can have two effects: it can either result in bulging of the cornea thus reversing the intended flattening effect of the treatment, or it can lead to progressive deformity of the cornea with thinning and increasing curvature changes, and the cornea can develop an irregular shape. In more severe instances, the condition of progressive deformation is called ectasia and the patient may need a corneal transplant in order to restore his or her vision. The probability of this occurring with currently employed modern technology is thought to be approximately one in 1,000 to 10,000.
Faulty or Improperly Created Flap
In the LASIK procedure, the corneal flap created may be too thin, too thick, uneven, and too short, may wrinkle, become displaced or may not heal properly. This condition could be temporary, requiring that LASIK be postponed until the surgeon can create a new flap, or could cause permanent damage to the cornea. In addition, there is a risk that the “hinge” of the flap may be cut off from the cornea (also known as a “free flap”). In some instances, the surgeon can still perform the laser treatment, reposition the detached flap on the cornea, place a contact lens bandage on the eye to promote healing, but in some instances he or she may choose to wait to perform laser treatment until after the flap heals. If, however, a “free flap” is lost, the patient could experience permanent corneal damage. If the damage or distortion in vision is severe, a partial or complete corneal transplant may be necessary to restore vision.
Debris under the Flap or Infection under the Flap
Sometimes after the surgeon creates the flap during LASIK, there may be a small amount of debris or tissue under the flap. Debris can result from the instruments used or consist of tear-film oil or floating material. The surgeon may decide in the immediate post-operative period to irrigate beneath the flap to remove this debris. Small amounts of debris can generally be monitored in the clinic without surgical intervention. In most cases, debris that is left behind is cleared in time by the body’s own clearing systems.
Infection, on the surface of, or beneath the flap is a rare event, estimated to occur at a rate of one in 10,000. Infection is managed by starting antibiotic eye drops and in most instances, taking cultures of the cornea. Your surgeon might even need to lift the corneal flap to culture and treat the infection. If the infection results in significant scarring of the cornea, a partial or complete corneal transplant may be necessary to restore vision.
Diffuse Lamellar Keratitis In some cases, patients experience a temporary complication caused by an inflammatory reaction between the flap and the corneal bed of the eye. This condition is called Diffuse Lamellar Keratitis (also known as “DLK”). The exact cause of this complication has not been determined. Patients with DLK may not show any symptoms at all or may experience blurred vision and tearing, which can last from several days, up to several weeks, which can delay the healing process. DLK can generally be treated with topical or oral steroids, with possible need for surgical intervention (the surgeon irrigates beneath the corneal flap).
The epithelium is the surface layer of cells that protects the cornea as the “skin” over the stromal layer of the cornea. If the epithelium is cut or removed, it generally grows back. In LASIK, the surgeon creates a flap, consisting of epithelium and stroma, and holds the flap back while performing the Procedure. The epithelium in some people is not as well attached to the underlying stroma; such eyes are at increased risk for epithelial scratches
or epithelial sliding, especially as the flap-maker is passing over the corneal surface to create the flap. In some cases, we can identify eyes at risk and advise about the increased risks associated with surgery. There are, however, rare patients where there are no pre-operative clues. In addition, older patients are more likely to have areas of weakened “skin” or slips during flap creation. In such instances, the surgeon places a bandage contact lens over the cornea at the end of the LASIK to assist in healing and to reduce discomfort. Patients who experience an epithelial slide or abrasion or erosion may experience a longer recovery period and may be at risk for complications including infection, inflammation, recurrent erosions, flap wrinkles or epithelial in-growth. The surgeon may postpone and reschedule LASIK until the eye heals, or he/she may choose to not treat the second eye at the same session following a severe slide or erosion on the first eye.
Epithelial in-growth is a condition in which epithelial cells from the surface of the cornea grow under the edge of the flap. If the cells continue to grow, they can affect the underlying tissue causing astigmatism, flap edge thinning and reduction of vision. This condition is generally treated by medication and observation, although further surgery to remove the epithelial cells from the interface may be necessary.
Dry eye is a common, but generally temporary, complication arising from LASIK or PRK. This condition can usually be treated with lubricating eye drops and occasionally with temporary inserts or “plugs” that prevent the normal drainage of tears into the nose. Dry eye generally improves within a few months after surgery, but in some instances can continue for longer periods of time, and may require long-term use of lubricant drops and permanent plugs. Patients who have dry eyes prior to LASIK or PRK are likely to experience dry eyes after the Procedure.
When the suction ring is applied to the eye during the flap-making process, the pressure in the eye increases significantly and many patients will notice that the light will dim or go out completely in the eye. When the suction ring is removed, the vision is restored to the eye within a few seconds. There is a remote risk that when the suction ring interrupts the blood supply to the eye, permanent damage to the retina and loss of vision can result. This possible occurrence has a theoretical probability of less than one in 1,000,000.
Microscopic Corneal Surface Irregularities
Microscopic irregularities on the surface of the cornea can cause slight vision loss.
Excessive Corneal Haze
Although corneal haze is part of the normal healing process, and gradually subsides with little or no permanent effect on vision, if the haze is excessive or does not go away, the patient may need additional treatment.
Elevated IOP (Intraocular Pressure)
Because a steroid drop is used post-operatively to control the healing response, some patients may experience a rise in their intraocular pressure (IOP). You will need to be monitored and may require an additional medication to control the pressure until you have completed your prescribed steroid medication.
In our experience, we have had a high success rate with our patients in only one refractive treatment. However, due to each individual’s prescription level and unique physiology, an additional treatment or enhancement, may be required. A patient may be a candidate for a LASIK retreatment or enhancement procedure. The patient must generally wait a minimum of at least three (3) months after LASIK and six (6) months after PRK to have an additional treatment. The patient must have adequate corneal tissue and stable vision, and meet other conditions as outlined in the Coal Harbour Eye Centre Re-treatment Policy. Results cannot be predetermined or guaranteed.
There are currently two methods used for retreatment. One involves re-lifting the flap created from the first surgery and reshaping the underlying corneal tissue. The second involves making a new flap. Both methods involve all the risks of LASIK.
Our goal is to help you achieve a life free from the dependence on glasses or contacts. It should be noted, however, that all patients eventually require the need for reading glasses as part of the unrelated and natural aging process of the eye.
I. Cataracts, Amblyopia, Strabismus, Presbyopia
The Procedure does not correct vision defects that do not arise from refractive errors, such as cataracts, amblyopia, strabismus or presbyopia. Patients with such conditions may be subject to additional risks and additional side effects and should discuss their condition with the surgeon and optometrist before deciding whether to have the procedure.
Cataract is a condition that, if not treated, can cause reduced vision, correctable by cataract surgery. LASIK or PRK will not prevent cataracts, nor will it reverse the effect of a cataract that is beginning to appear.
Amblyopia is a medical condition that develops in early childhood in which a person who has reduced vision in one eye relies on the other eye to focus. LASIK or PRK will not reduce or eliminate amblyopia. It will not improve the vision in the amblyopic eye. If the patient experiences side effects or complications from the Procedure in the eye that is able to focus, he or she could experience a loss of vision because that eye would no longer be able to compensate for the other.
Strabismus is an eye disorder caused by a weakness in the eye muscles in which the eyes may not be aligned properly. LASIK or PRK will not correct, reduce, eliminate or prevent strabismus. Patients with strabismus may develop double vision as a result of or as a side effect of the Procedure
As we age, the crystalline lens of the eye may lose its ability to accommodate to nearby objects. This condition, known as presbyopia, usually begins around the age of 40, and can most often be comfortably corrected through the use of reading glasses.
It is our hope to address some of the initial questions you may have about the procedure within this brochure. However, nothing can take the place of a consultation with an eye care professional at Coal Harbour Eye Centre to determine whether or not laser vision correction will best suit your particular needs or goals. For information on surgical fees and financing contact our refractive counselors. At Coal Harbour Eye Centre we are here to provide you with the answers you need and the level of service you deserve.