Find us on Facebook
Follow our Tweets
Laser Vision Correction
The consultation, similar to a routine eye examination, gives you additional information about laser eye surgery, and enables the optometrist to determine whether laser eye surgery is right for you and your vision needs. This exam can be arranged with our office.
THE LASIK PROCEDURE
What is the Excimer Laser?
Since discovering laser energy and some of its tremendous applications, scientists have been experimenting with laser beams of various wavelengths. A significant break through came in 1982 when it was discovered that a laser beam with special qualities could be produced from a mixture of argon and fluorine gases. This cool beam of light allows the vaporization of tissue with extreme precision and minumum damage to delicate surrounding structures. The Excimer laser that produces this beam of light is so exact that it removes at a rate of less than 0.25 microns at a time (1 micron is one-tenthousandth of a centimeter). These qualities have led to its successful implentation as a valuable microsurgical tool; most notably in the reshaping of the cornea.
Nearsightedness,Farsightedness,Astigmatism & the Lasik prodedure.
LASIK is an acronym for Laser Assisted in Situ Keratomileusis. LASIK is essentially a combination procedure using an instrument known as a microkeratome and the laser surgery (PRK) to correct for focussing problems in the eye. In LASIK a flap is created in the cornea using a special microsurgical blade (microkertome). The excimer laser is then used to remove a microscopic layer of tissue from the deeper layer of the cornea to correct the refractve problem. After the excimer laser reshapes the cornea the flap of tissue created by the microkeratome is then repositioned on the top surface of the eye and adheres strongly after a few minutes without sutures. This is in contrast to surface PRK where the tissue is removed from the surface of the cornea.
How LASIK corrects your focussing problems.
IF YOU ARE MYOPIC (nearsighted) the PRK phase of your LASIK treatment reduces the curvature of you cornea to focus light on to the retina. IF YOU ARE HYPEROPIC (farsighted) the PRK phase of you LASIK treatment increases the curvature of the cornea to focus light on the retina. IF YOU HAVE ASTIGMATISM the PRK phase of you LASIK treatment selectively alters the curvature of the cornea so that the light is focussed at a point on the retina rather than 2 focal lines
Who Qualifies for LASIK?
The first step toward reducing you dependence on corrective eyewear is to make an appointment with the Victoria Corneal Laser Centre or with you current eyecare specialist. This consultation is to ensure that you are a good candidate for treatment and that you understand the benefits and limitations of the LASIK procedure. Potential candidates for LASIK surgery must generally meet the following conditions:
1. 18 years of older;
2. Have stable vision for at least 1 year prior to the time of surgery;
3. Have a full eye examination to rule out conditions that may contraindicate LASIK surgery;
4. Have a refractive problem within the range of effective treatment;
5. Be fully informed of the benefits and possible complications following LASIK surgery;
6. Not currently taking certain medications which maybe containdications to LASIK surgery (notably Accutane &Aminodarone.
Lasik- The surgical experience:
1. We recommend that you take a mild sedative (Ativan) before the surgery to help you relax. Eye drops are not instilled until you recline on the laser chair.
2. You will be asked to recline on the laser chair and are positioned under the laser microscope. Your other eye will be covered with a patch. A special sterilizing solution and local anaesthetic drops are irrigated into the eye to be operated on. You will be asked to look at the red flashing light and the lids are separated by a small instrument (a specullum) so that you do not have to worry about blinking. You will not feel anything because of the anaesthetic drops.
3. A suction ring is placed on the eye so that the corneal flap can be made. At this stage your vision will be dark because of the elevated prossure. The flap is made by passing the microkeratome across the flattened cornea. The suction ring is then removed and your vision returns although it is very blurred.
4. The flap is then moved of the cornea and the laser ablation applied to remove a calculated amount of tissue to correct your refractive error.
5. The surgeon will explain to you when the laser is about to start. Usually several short bursts (passes) of laser treatment are given (a total of less than 100 seconds).
6. The eye is irrigated to remove and debris and the flap is then replaced. After about 3 minutes the flap is firmly attached to the underlying cornea.
7. Antibiotic and steroid eye drops are applied and a soft a bandage contact lens may be placed on the eye.
8. Treatment of the second eye (if you decide to have both eyes treated at the same time).
After LASIK
You will remain in the centre for another 30 minutes and are reexamined to ensure everything is satisfactory. At this stage the vision is still blurry, but definitely improved over your pre-op uncorrected vision. You can leave the Centre but do not attempt to drive. You will have some discomfort in the eye but DO NOT RUB YOUR EYE. Use the drops as directed.
Possible Complications:
Studies to date indicate that there are very few complications following LASIK. Complications Related to the Microkeratome:
Incomplete cuts. If this happens, the procedure usually is aborted and rescheduled for 2 months later.
Free flap.Usually this is not a serious problem as the flap can be replaced on the cornea and will adhere. Sometimes sutures are necessary to hold the flap in position for a few days.
Perforation of the flap. If suction fails during the pass, the flap may be cut irregularly.The procedure is usually canceled and rescheduled.
Perforation of the cornea with lens and vitreous involvement. This may occur if the keratome has been incorrectly assembled.
Interface debris. This may require a second procedure to clean out the debris.
Epithelial ingrowth. Occasionally following LASIK the epithelium (skin layer) may grow between the flap and stroma.
Infection can occur in the interface. If organisms are present, they will be relatively procected from antibiotics.
Persistent folds of wrinkles in the flap may be associated with loss of BCVA (best corrected visual acuity) and irregular astigmatism.
Decentration of the flap
Complications Related to the Excimer Ablation: As in surface Photorefractive Keratectomy, many complication may occur.
Decentration, Haze, Regression,Overcorrection & Undercorrection For a more detailed look at these complications see complications sections of the surface PRK literature.
All of the above compications can be retreated by lifting the flap again of by cutting another flap and retreating.
The benefits of LASIK Surgery.
If all goes well at the procedure, LASIK has the following advantages:
1. Rapid recovery of good vision. The epithelium is relatively untouched in the visual axis.
2. Minimal discomfort lasting only for 1 day.
3. Less tendency of haze formation than in surface PRK.
4. Less tendency to regress.
5. Reduced frequency of post-op eye drops.
6. Reduced frequency of follow up visits.
A patient who has had a successful LASIK procedure appreciates these advantages.
THE PRK PROCEDURE
Nearsightedness, Farsightedness, Astigmatism & Surface PRK
By reshaping the cornea, the Excimer laser can correct such refractive visual problems as myopia(nearsightedness), hyperopia (farsightedness), and astigmatism. At present, these refractive errors are usually corrected by means of glasses or contact lenses. For people who prefer not to or cannot wear glasses or contact lenses for various reasons, several types of surgical procedures are available. The Excimer laser has made possible the procedure known as Photorefractive Keratectomy (PRK). In surface PRK the outer most layer of the cornea (the epithelum) is first removed so that the laser can vaporize a microscopic amount of tissue from the cornea to correct the particular refractive problem.
How surface PRK corrects your focusing problems.
If your focusing problem is myopia (nearsightedness) surface PRK focuses the light on the retina by reducing the curvature on your cornea. If your focussing problem is hyperopia (farsightedness) surface PRK focuses light on the retina by increasing the curvature on your cornea. If you have astigmatism surface PRK selectively alters the curvature of the cornea to render it more spherical so that there is 1 focal point on the retina rather than 2 of more focal lines.
Who Qualifies for surface PRK?
Persons with myopia (nearsightedness) with or without astigmatism,and those with moderate amounts of hyperopia with or without astigmatism can benefit tremendously from surface PRK. The first step toward reducing of eliminallting your dependence on corrective eyewear is to make an appointment with the Victoria Corneal Laser Center or with your current eyecare specialist. This consultation is to ensure you are a good candidate for treatment and that you understand the benefits and limitations of the surface PRK procedures.
Potential candidates for surface PRK Same as LASIK
Surface PRK- the surgical experience.
When you arrive for refractive surgery, you probably are experiencing a mixture of excitement and apprehension. The Staff at VCLC understand how you feel. We do everything possible to make sure that all your questions are answered before, during, and after the procedure. Your visit will not be rushed and you will be told exactly what is happening at each stage of the procedure.We want you to have a pleasant experience and the best possible result.
1 We recommend that you take a mild sedative. (Ativane) before the surgery to help you relax. Local anaethetic eye drops and non-steroidal antiinflammatory eye drops will be instilled into the eyes.You will again be examined by the surgeon and the centre of the treatment area will be marked on the cornea using a round tipped instrument. It is very important that the centre of the treated area is exactly identified.The position of this mark is confirmed on a corneal topographical map.
2 You will need to recline on the laser chair and when you are comfortable, you will be positioned under the laser. A soft pillow is molded around your head so that you need not worry about moving. You will notice a flashing red light and will be asked to fixate on this with the eye that will be having the treatment. The other eye will be covered by an eye patch to avoid confusion. Do not be concerned if the flashing light becomes obscure or disappears (as it will) during the procedure.The centration mark ensures that the surgeon is aware of the position of the eye.Just keep looking straight ahead. A small instrument (a speculum) is used to separate the lids so that you do not have to worry about blinking. You will not feel this because of the anaesthetic drops.
3 The surgeon will explain to you when the laser is about to start. The treatment consists of the following short stages:
a) Epithelium Removal (25 seconds). This is the stage where the eye is prepared for the laser correction. In this first stage you may be startled by the loud noise of the laser. Try to maintain fixation on the red flashing light. Any remaining epithelial cells are gently removed using a moist sponge.
b) Stroma Removal: This is the phase that is actually correcting your refractive error.In this stage the refraction is corrected by removing a calculated amount of tissue. Usually several short bursts(passes) of laser treatment are given (a total of less than 100 seconds).
c) Bandage Contact Lens Placement: A soft protective contact lens is placed jon the cornea and the speculum is removed. The total time from the speculum insertion to the contact lens insertion is usually less than 7 minutes.
d) Treatment of second eye.
4 Application of post treatment eye drops. You will be reexamined by the surgeon to conflirm the position of the contact lens.
After surface PRK
At this stage the vision is still blurry although patients who were originally very myopic may notice an improvement. You are now able to leave the Centre, but you should not attempt to drive yourself. You will be given a post-op kit containing the medications you require in the post-op period. You should go straight to home or lodging and rest with both eyes closed in a quiet room. You may take sleeping pill (Dalmane) or tylenol #3. All the eye drops should be instilled 4 times a day, but leave 1 minute between each drop to avoid floating the contact off the cornea. Use the lubricating drops as required if the eye feels irritated. If the contact lens does become displaced, you will experience significant discomfort.Do not attempt to replace the contact lens yourself, but phone the surgeon or eye care specialist (whose phone number will be on your post-op instruction list) and arrangements will be made to reinsert a new contact lens.
Possible Complications:
Studies to date indicate that there are very few complications following surface PRK.
Infections: The cornea is at risk of infection if the epithelium (skin layer) is unhealed. The epithelium typically takes 2-3 days to heal for myopic patients and 5-7 day in hyperopic patients. VCLC feels that it is imperative that the cornea be examined each day until the contact lens is removed and the epithelium is healed.
Fluctuation of Vision: In the early post-op period after removal of the contact lens, fluctuation of vision may be noticed by approximately 40% of all surface PRK patients for up to 8 weeks post treatment.
Undercorrection: Undercorrection may be apparent two weeks after PRK.Regression may occur at any time up to one year post PRK but most commonly between one and four months post PRK. This is corrected with and enhancement procedure.
Overcorrection: Occasional overcorrections do occur for no apparent reason. If persistent, overcorrections can be retreated hyperopic PRK or Holmium Laser Thermo Keratoplasty.
Persistent Halos:In young patients, the pupil may dilate wider than 6 mm leading to halos or rings around lights, particularly oncoming car headlights at night. In our experience, we have never had a patient who found glare disabling. Most patients describe similar symptoms before PRK when they wore contact lenses or glasses.
Decentration: Significant decentration is very unusual using the VCLC technique of dotting the center of the pupil to enhance treatment centration.
Delayed Epithelial Healing: With the VCLC technique of partial laser epithelial removal followed by we and dry polishing of the Bowmans layer, the epithelium usually has regenerated and closed the defect in 48-72 hours.We have not yet had a myopic patient whose epithelium did not heal in 4 days.
Haze superficial, post-op corneal haze can develop. This haze occurs most frequently in an eye requiring a high degree of correction. In most cases,this haze does not interfere with vision, but it can contribute to glare from bright lights at night. Corneal haze usually fades and disappears within 6 months following surface PRK but may persist longer and in rare cases never completely vanishes. If haze persists an enhancement procedure may be required to reduce of eliminate it.
Benefits of surface PRK surgery.
The surface PRK treatment offers many benefits:
1 Precision-The Excimer Laser beam and the mechanical devices used are regulated both by computer and by your surgeon, resulting in a beam which is more predictable than a hand held surgical knife.
2 Versatility-The Excimer Laser is a versatile instrument that makes possible a variety of surgical patterns for safely correcting refractive error.
3 Preservation of corneal strength-There is no measurable weakening of the cornea and no known increased suseptibility to injury following surface PRK.
4 Efficiency- The actual surgical time is short, 30 to 120 seconds.
5 Results- Studies have demonstrated that 96% of patients treated for myopia (nearsightedness) with surface PRK obtain 20/40 or better uncorrected vision. With 20/40 vision they can legally drive without glasses or contact lenses.
