LASIK is a very special technique that has been developed for correcting myopia, hyperopia, and astigmatism, based on the work done by Dr. Jose Barraquer and Dr. Luis Ruiz of Bogota, Columbia. Since 1949, Dr. Barraquer has been working on a procedure to reshape the cornea. The cornea, or clear front part of the eye, is responsible for about 2/3 of the correcting power, or refracting power, of the eye. The cornea is the delicate transparent structure that is altered by LASIK in order to bring the unfocused light rays into focus. Please refer to the diagram "Illustration of the Cornea" for understanding the corneal anatomy. One micron is equal to one one-thoundsandth of a millimeter (.001 mm). One human cell is approximately 10 microns tall. One single human hair is approximately 50 microns thick. The central cornea is approximately 500 microns in thickness. This translates to about one-half of a millimeter (.5 mm). As you can see in the diagram, the surface of the cornea is covered by four to five layers of epithelial cells, generally 40 to 50 microns thick, which protect the front surface of the cornea. The main structure of the cornea is referred to as the stroma, which is made up of approximately 70% water. It also consists of multiple layers of collagen fibers (stromal lamellae) and keratocytes. The term "lamellar surgery" is derived from the stromal portion of the cornea, which is filled with stromal lamellae. The stromal lamellae are actually collagen fibers arranged in a transparent fashion within the stroma itself, analagous to the layers of an onion. The endothelial cells line the inner portion of the cornea and are responsible for keeping the cornea transparent.
Dr. Jose Barraquer of Bogota, Columbia, has been involved in lamellar refractive surgery since 1949. His first work was with keratophakia--that is, steepening the cornea by adding donor lamellar tissue (corneal stromal tissue) to the cornea. Therefore, lamellar refractive surgery has been around for more than forty years. Dr. Barraquer developed a small microkeratome with a tiny blade which rapidly oscillates and acts like a carpenter's plane. This microkeratome was used to correct large degrees of myopia by reshaping the front surface of the eye and has been used for that purpose since 1963. At that time, it was referred to as MKM, or myopic kerato-mileusis. HKM, or hyperopic keratomileusis, was also developed to correct hyperopia. In 1963, an approximate 300 micron cap of corneal tissue was resected with the micro-keratome; it was frozen and then placed on a contact lens lathe, and a curve was carved on the back surface of the corneal cap. After the correcting curve was placed on the corneal cap, it was referred to as the corneal lenticle. The corneal lenticle was immediately thawed, laid back on the corneal bed, and sutured into place. I actually began doing this procedure in 1984.
During LASIK, the surgeon uses the Excimer Laser to recontour the corneal bed. Keep in mind that we still have to create a corneal flap and apply the Excimer Laser to the corneal stromal bed in order to effect the corrective change. In the case of myopia, the cornea is flattened; and in the case of hyperopia, the cornea is steepened. In the case of astigmatism, the steeper meridian of astigmatism is reduced or eliminated or the flatter meridian is steepened, or a combination of both.
We know we have over 40 years of history on lamellar refractive surgery, and over 30 years of MKM, or myopic keratomileusis, for high myopia. The combination of Excimer Laser is relatively new, and on-going clinical studies with the use of Excimer Laser and the microkeratome will be necessary to determine the long-term safety and efficacy of this aspect of the procedure. Excimer Laser Photorefractive Keratectomy (PRK) has been used in clinical trials all over the world, beginning in 1988. It has been used to correct low, moderate, and high degrees of myopia and astigmatism, as well as hyperopia. In general, the Excimer Laser PRK has been applied to the surface of the cornea in clinical trials. Only since 1993 has this been used in combination with the microkeratome to treat the bed underneath the surface rather than treating the surface itself. I have been performing Excimer Laser PRK to the surface of the cornea since January 8, 1992. Results of our clinical trials in Mexico have shown that about 98% of our patients between -1.00 and -6.00 diopters have uncorrected vision of 20/40 or better at 12 months. This means that about 98% of these patients are driving a car now without glasses. Due to the recent advancements in laser technology, we are able to achieve better results in patients with myopia higher than 6 diopters.
I would like to refer you to the appendix for a brief discussion of the history and physics of the Excimer Laser and Excimer Laser Photorefractive Keratectomy (PRK).
1. Significant irregular astigmatism and loss of best corrected visual acuity
Irregular astigmatism differs from regular astigmatism in the following way. If one has astigmatism, one is generally born with it. This is regular astigmatism. This procedure does not normally induce regular astigmatism. Regular astigmatism generally refers to the shape of the cornea, in that the cornea is shaped like an oval rather than a sphere. Irregular astigmatism differs from regular astigmatism in that the general shape of the cornea can be spherical; however, surface irregularities are present which can diminish the best corrected visual acuity. Normally, irregular astigmatism does not remain permanently; however, occasionally it can. One must have a perfectly smooth corneal surface in order to have the best corrected visual acuity, especially the smooth surface over the visual axis (line of sight) of the eye. The incidence of significant irregular astigmatism with the hinge, or flap, technique and Excimer Laser to the corneal bed is unknown at this time. However, it could be 1% or higher, depending on the degree of attempted correction. When one develops significant irregular astigmatism, one can lose one, two, or more lines of best corrected visual acuity. One of the major problems of irregular astigmatism is the fact that spectacle correction will not adequately correct the vision. The only way to adequately correct the vision would be with a rigid, gas-permeable contact lens. If the contact lens was not a satisfactory alternative and the irregular astigmatism was severe, then a penetrating keratoplasty, or corneal transplant, may have to be performed. Therefore, permanent, significant irregular astigmatism is difficult to correct surgically once induced. Most people who develop irregular astigmatism following this type of surgery improve over time.
2. Significant incomplete or irregular micro-keratome flap or cap resection (uneven cut).
This rarely occurs, but if it does, the surgeon will normally put the cap or flap down on the bed in its original position and not proceed with the second refractive laser ablation in the corneal bed. Normally no harm is done and the vision returns to preop levels in a few days to a few weeks. The surgery can be postponed for 3 to 6 months and then the flap resection with the microkeratome can be repeated in order to achieve an acceptable flap resection. The most common reason for this incomplete microkeratome resection would be poor suction with the suction ring or a break in suction, for whatever reason, during the micro-keratome pass.
3. Decentration of the Excimer Laser beam
Decentration is rare but could occur. A small amount of decentration is of no consequence, but a large de-centration problem could induce large amounts of astigmatism, both regular and irregular, and decrease one's best corrected visual acuity. The eye tracker can decrease the incidence of this problem.
4. Significant decen-tration of the corneal flap or disc (decentration of corneal resection with microkeratome)
This refers to decentration of the flap or disc following the resection of the corneal flap or disc. This problem is also rare, but if it did occur and the corneal bed were regular and smooth, one still may be able to proceed with the Excimer Laser application to the corneal bed for the refractive ablation step. If this could not safely be done, the surgery would have to be postponed for 3 to 6 months and then start all over again. Usually, no harm is done and the vision returns to the preop level a few days to weeks afterwards.
5. Displaced cap or flap
If the corneal cap or flap is not perfectly aligned at postop day #1, it will need to be repositioned under topical anesthesia. A displaced cap may occur from the following reasons:
6. Lost cap of corneal tissue.
This is an exceedingly rare complication since we are now using the flap or hinge technique. Prior to the hinge technique, the surgeon routinely removed the corneal cap, or disc, completely, perform the Excimer Laser photoablation on the stromal side of the "free" cap instead of the corneal bed, and then place the free corneal cap, or lenticle, back onto the corneal bed without sutures. Occasionally the cap would fall off the eye, and sometimes could not be found. If it were found, it could be placed back on the eye into position, and usually sutured into place. If the lost cap could not be found, then what is called a homoplastic lamellar graft, taken from another person, would be used to replace the original lost cap. This latter procedure sometimes takes several months to heal, but one may do quite well with this technique.
7. Attempting the corneal flap and ending up with a free corneal disc
At the present time, we are leaving a hinge, creating a corneal flap, when we do the microkeratome resection. We then lay that corneal flap back, exposing the corneal bed. Sometimes, due to various factors and circumstances, the microkeratome will resect the corneal cap completely free rather than leaving the small hinge. If that were to happen, we still could have just as good a result as we could have had with the hinge technique; however, we do run the slight risk of cap decentration or dislocation without sutures. Under those circumstances, we would do the sutureless technique; however, we would tape the eyelids shut until the following day. If the cap did dislodge, we would normally be able to find it, if the lids have been securely closed for that period following surgery. It is unusual for a free corneal disc to occur when we are aiming for the corneal flap.
8. Subconjunctival Hemorrhage (Bloodshot eye)
A subconjunctival hemorrhage may occur secondary to the suction ring that is placed on the eye prior to the microkeratome pass. This certainly is not a serious condition and merely presents as a bloodshot eye on the first postop day. If this happens, the subconjunctival hemorrhage will normally clear over the next couple of weeks and is of no visual consequence. A subconjunctival hemorrhage refers to the presence of small, splotchy, superficial hemorrhages underneath the transparent tissue that covers the white part of the eye, or sclera. Sometimes the splotches can enlarge or spread over the first day or two, but then normally stabilize.
9. Pain
The operation itself is painless. One receives only topical anesthetic drops prior to the procedure. One feels pressure, not pain, while the suction ring is on the eye. One may have a mild to moderate foreign body sensation for a few hours following surgery, but after about 4-6 hours the eye normally feels comfortable. During this period, you may take your appropriately prescribed pain medication for this. It would probably be a good idea to take a nap following surgery. Normally, when you wake up the discomfort is gone.
Remember, this is one of the least painful of all refractive procedures following surgery.
10. Undercorrection
The higher the refractive error, the less accurate is this LASIK operation. It is more accurate in the lower to moderately high refractive errors. Therefore, if one is going to be overcorrected versus undercorrected, it is much better for one to be undercorrected. In other words, it is better to remain a little bit nearsighted versus farsighted. If the residual undercorrection is not that much, then a reoperation, or enhancement, may not be necessary. However, if the undercorrection is excessive, then an enhancement can be done six weeks to three months later.
11. Reoperation (touch-up or enhancement)
It will be quite common to need an enhancement in order to fine-tune the vision correction, especially in the extremely high myopes. This is usually done by lifting the original flap and placing more laser treatment in the bed. Usually, one enhancement takes care of the correction; but, rarely a third surgery could be necessary. Dr. Maddox prefers to lift the flap and reapply laser for the enhancement. It is usually done 36weeks to to 3 months post-op. Generally, it will not be necessary to make a new flap with the microkeratome. Each patient should be mentally prepared for an enhancement procedure, if necessary.
12. Will I be able to wear contact lenses after LASIK?
If you remain partially undercorrected and you choose to wear a contact lens after LASIK, it would be extremely unusual for you not to be able to tolerate a contact lens after LASIK, especially if you could tolerate contact lenses prior to surgery.
13. Overcorrection
Since overcorrection is undesireable, we strive to avoid this condition following LASIK. Actually, one may become temporarily overcorrected initially, but this is usually substantially reduced or gone by the first 2 to 3 months postop. If one has a mild overcorrection that is permanent, this is not usually something that has to be corrected. If one has a significant overcorrection, Dr Maddox prefers to lift the flap at 6 weeks to 3 months and retreat the bed.
14. Glare, starburst, contrast sensitivity problems
Significant night glare could occur in a small percentage of the population; however, the glare is usually not any worse than glare prior to surgery, especially when wearing contact lenses. Night glare could be debilitating, but this would be rare.
One commonly experiences some night glare and halos immediately following LASIK. Normally, by 3 to 9 months post-op, night glare is significantly reduced or eliminated.
One may experience glare and star burst without glasses at night following surgery if a significant residual refractive error remains. The glare can be reduced merely by using a light pair of prescription glasses when driving at night.
Those individuals who have very large and dilated pupils at night will complain more about night glare, halos, etc. than those who have small or moderately dilated pupils at night.The new laser system allows for a larger optical zone treatment diameter, thus reducing nighttime glare and halo problems. The pupil size will be carefully evaluated prior to surgery.
15. Sands of the Sahara
Occassionally, one may develop excessive inflammation between the flap and corneal bed. This is usually eliminated with the use of potent and frequent steroid eye drops. Occassionally, the flap has to be raised, the inner side of the flap and surface of the bed have to be cleaned, and the flap has to be repositioned in order to prevent corneal melt and irregular astigmatism.
16. Epithelium in the interface (between the corneal flap, or disc, and corneal bed)
Possibly 2 or 3% of the time, the corneal epithelium may be found to be present in the interface. The corneal epithelium consist of 4 or 5 cell layers that normally cover the surface of the cornea and protect it. For example, if the corneal flap has a loose edge, say the first day postop, the epithelium may choose to grow under the flap in that particular area and cause problems with vision and stability of the corneal flap. The flap will become loose and can induce significant amounts of astigmatism. This epithelium can be 20 to 70 microns thick. Therefore, we know that epithelial ingrowth can be significant, and we must repair the edge defect and rid the epithelium from underneath the flap. This can usually be done quite easily under topical anesthetic drops; however, if this is not easily fixed, then the flap may have to be lifted up to give access to the epithelial cells, and be vigorously cleaned. Afterwards, the flap is either repositioned without sutures or with temporary sutures. This will usually take care of the problem, but if it doesn't, the procedure can be repeated until the epithelium is eradicated from beneath the flap. Sometimes there is a localized island of epithelium under the flap that is tiny, and we just observe it and do nothing unless it grows to 2 mm or larger, and then we would remove it. If we left it and allowed it to continue to grow, it could cause a localized corneal melt problem anterior, or in front of, the epithelial island, or plaque. Normally, the epithelium under the flap is more of a nuisance than anything else; and we can generally remove it without it growing back.
17. Particulate matter under the cap or flap
We sometimes see particulate matter, or tiny filaments in the interface, but they are usually of no consequence. At the time of surgery, we try to remove it; however, if we see them at the slit lamp biomicroscope the next day, we can either leave them or remove them at that time. Occasionally, we see a small amount of blood in the interface. If this occurs, it would come from prior long-term contact lens wearers where tiny superficial blood vessels have grown into the superficial peripheral corneal area. This is of no consequence and will disappear in a few weeks.
18. Mechanical failure of the microkeratome or Excimer Laser
If either the micro-keratome or the Excimer Laser malfunctioned, surgery would have to be temporarily postponed.
19. Infection
Infection is exceedingly rare after LASIK in general. If one did develop a bacterial infection after LASIK, it most likely could be cured by antibiotic drops. However, if the infection is not discovered until the late stages, one may have to remove the cap or flap and cure the infection and then have a homoplastic corneal cap later on (donor corneal material). The infection could permanently scar the corneal bed and necessitate a corneal transplant. It could also enter the eye and cause loss of the eye, but this would be extremely rare with LASIK.
20. Poor exposure
This is often due to narrow eyelids and/or small orbit with a small eye. Also, deep-set eyes are not as easily accessible. Therefore, if the eye does not protrude enough for the suction ring, an injection around the eye, of balanced salt solution or anesthetic solution, may have to be given in order to expose the eye enough for the surgery. This is rarely done. Sometimes a lateral canthotomy needs to be done in order to widen palpebral fissure area. This is done with a light injection of anesthetic at the lateral corner of the eyelid. Two tiny snips are carried out on the lateral canthal area (the lateral portion of the corner of the lids where the upper and lower lids meet). This also is rarely done.
21. Perforation of the globe and/or retrobulbar hemmorrhage
This is extraordinarily rare, since we do not routinely use a retrobulbar or peribulbar injection to anesthetize the eye. We routinely use topical anesthetic drops. The only time we might do an injection around the eye would be if the eye would not give us good exposure. In other words, if the eye did not naturally protrude enough for application of the suction ring and microkeratone. If this were the case, then 4 to 5 cc of balanced salt solution or local anesthetic solution could be injected around the eye in order to achieve better exposure. This is normally a benign, painless procedure; but, only rarely, this could cause a sight-threatening problem such as perforation of the globe or hemmorrhage behind the eye with possible permanent loss of vision, partial or complete. If we were to do a retrobulbar or peribulbar injection, there is a small risk that the injection fluid used could infiltrate up under the conjunctiva or transparent tissue that surrounds the sclera, or white part of the eye. This is not a dangerous problem in and of itself; but it can interfere with good suction by the suction ring. Therefore, if this occurred, the operation would have to be delayed about an hour or so, or completely postponed in order for the chemosis, or swelling, of the conjunctiva to recede. Also, Surface PRK could be substituted for LASIK under these circumstances.
22. Loss of endothelial cells
The endothelial cells line the inside of the transparent cornea. They play an important role in keeping the cornea transparent. Without these cells, the cornea would become opaque, or lose its transparency. LASIK itself has not been shown to cause any significant endothelial cell loss or damage over the years. Also, Excimer Laser to the corneal bed has thus far not been shown to be harmful to the endothelial cells. Further studies are underway to determine any such longterm effects.
23. Persistent corneal epithelial defect with foreign body sensation and a prolonged healing period and prolonged irritation
Normally, the epithelium covers over the corneal flap edge within 24 hours following LASIK. However, there are those rare cases that may take a bit longer. For the first few weeks post-op, the eye may feel "dry" and you may use non-preserved artificial tear drops as frequently as needed. Even more rare is a persistent localized area of the cornea that causes a foreign body sensation; infrequently this has to be treated in order for it to clear.
24. Cataract formation
Cataract formation has not been a problem with LASIK. The Excimer Laser is an ultraviolet laser with a wave length of 193 nanometers. The maximal penetration is only 1 to 3 microns; hence, it is not believed to cause cataract formation.
25. Corneal Ectasia (excessive structural weakness of the cornea.)
It is believed that one should be left with around 250 microns of corneal bed (excluding the corneal flap) after the LASIK procedure in order to avoid corneal ectasia or loss of structural integrity of the corneal bed. If one leaves a corneal bed less than 250 microns, this may cause the cornea to bow forward ("pseudo-keratoconus") where one would most likely need a corneal transplant. Very careful calculations and ultrasonic pachymetric measurements are made in order to avoid this complication.
26. Temporary Glaucoma or increased intraocular pressure
Temporary glaucoma or increased intraocular pressure has not been a problem with LASIK, especially since drops are only used for approximately 1 week following surgery.
27. Transient iritis (inflam-mation inside the eye)
Usually less than 1% of patients develop iritis during the epithelialization period following LASIK. The iritis normally clears with topical corticosteroid drops, or intramuscular injection of a systemic corticosteroid.
28. Temporary Fluctuation of Vision
This phenomenon may occur during the first few days following LASIK. Once the eye stabilizes, which is usually 1 to 3 months, the fluctuation normally disappears. Longterm fluctuation of vision has not been a problem with LASIK, unless one has a "dry eye".
29. Ptosis or droopy eyelid (usually temporary)
It is felt that use of potent corticosteroids is the most common cause for ptosis, and it usually tends to be reversible. It could be caused from the lid speculum, or from post-op lid edema or swelling. It would be rare to have a permanently droopy eyelid following LASIK. If one developed a permanent droopy eyelid, surgical correction of this condition may be necessary.
30. Dry Eye
There are a number of patients who have undergone LASIK who complain of a dry eye feeling for a few weeks to months following this refractive surgery. We do recommend that these patients use a non-preserved artificial tear drop as often as needed to relieve this sensation.
31. Decompensated Eye Muscle Imbalance (Rare)
Decompensated eye muscle imbalance is rare after LASIK. If one has had a prior history of a crossed eye, but now is straight, this could recur after LASIK treatment, especially if there is a substantial imbalance in the refractive error between the two eyes. Once both eyes are balanced by equal or similar refractive errors, they usually will straighten out. Rarely surgery has to be performed to correct this muscle imbalance.
32. Vascular Occlusion
When the suction ring is applied to the eye prior to the keretectomy, the intraocular pressure is raised to 65mm Hg or greater. This pressure occludes the central retinal artery of the eye and prevents one from seeing until after the keratome pass and release of the suction ring pressure. It would be extremely rare for this pressure to cause damage to the eye. Only a few cases of this have been reported on a world wide basis. I have never seen this happen.
33. Mutagenesis (Cancer)
There have been no reported cases of mutagenesis. Since the Excimer Laser 193 nanometer wave length penetrates only about 1 to 3 microns at the most, it is felt that it does not penetrate deep enough to affect the nucleus of the cell. Animal studies have not indicated any problem with mutagenesis as a result of Excimer Laser photoablation.
34. Retinal radiation effect from the Excimer Laser
Since the 193 nanometer wave length does not penetrate more than 1 to 3 microns, no damage to the retina or other intraocular structure has ever been reported. Some of the ultraviolet fluorescence, other than the 193 nanometer, in the 300 to 400 nanometer range is present to a certain degree; however the exposure during LASIK is no more than that received by the eye when one is walking outside for a few minutes on a bright, sunny day. The retina is the photoreceptor cell lining of the inside of the eye that receives and transmits light energy back to the visual cortex in the brain.
35. Induced regular astigmatism
Significant amounts of astigmatism induced after LASIK are unusual, and it would be rare to be clinically significant. Regular astigmatism occurs when the cornea is shaped like an oval rather than a sphere and requires a special cylindrical lens or contact lens to correct it. Significant amounts of induced regular astigmatism can be reduced or eliminated with a diamond blade or with the Excimer Laser.
We have gone over the most important risks and complications. Even though a serious side effect is unlikely to occur, the remote possibility exists. We believe that the long track record for myopic keratomileusis (MKM) has stood the test of time since 1963. With the recent technological breakthrough on the microkeratome in conjunction with the excimer laser since 1991, it appears that this has made the procedure more accurate, safer, and less complicated for the surgeon to perform. So far, there have been several million of these cases done with impressive results.
(Note to ladies preparing for LASIK surgery: please discontinue application of eye makeup for at least one day prior to the date of surgery. Be sure to clean makeup from the base of the lashes or lid margins, both upper and lower lids. Generally, you may resume eye lid makeup, preferably with new cosmetics, 7 days after surgery has taken place and the eye is comfortable. Be very gentle in applying your eye makeup and be sure not to bump your eye during the process. Use extreme caution with curling irons, makeup brushes, and hair or deodorant spray.)
If your evaluation exam proves that you qualify for surgery, we will discuss surgical options with you. If you have the LASIK surgery on one eye, you may wish to have the second eye done several days to weeks later. When the first operated eye is comfortable and sees well, and both the doctor and the patient are satisfied, then evaluation for LASIK surgery on the second eye can be considered.
However, more and more cases of bilateral LASIK are being performed. Patients are opting for both eyes to be done on the same day for obvious reasons. If you desire both eyes to be done on the same day, discuss this with your referring doctor or with Dr. Maddox.
However, if it is determined that you are not a good candidate for the LASIK surgery, you will be given an explanation as to the reasons why you are not a good candidate. It may be recommended that you postpone your refractive surgery until further developments take place with LASIK. You may want to consider an alternative method of refractive surgery, or stay with your glasses or contact lenses for the time being.
1. Computerized Topographical Analysis (Video Keratography)
This is a very sophisticated, computerized, high-tech analysis machine that will record in detail the corneal topography (over approximately 6,000 points on the corneal surface), so that we may be able to see exactly what the corneal shape is prior to surgery and be able to follow that corneal shape after surgery to determine the impact of LASIK on the cornea.
2. Pupil Diameter
3. Pachymetry
Pachymetry will be measured to determine the thickness of the cornea. This measurement will also be done during surgery to determine the flap thickness and the thickness of the corneal bed.
4. Tonometry
Tonometry is taken to determine the intraocular pressure both preoperatively and postoperatively.
5. Endothelial Cell Count (ECC) (on selected patients)
This is a technique employed to determine the number of endothelial cells present on the back of the cornea, as well as the health of the endothelial cells. These measurements may be followed periodically after LASIK. Endothelial cells are responsible for corneal clarity and appropriate hydration of the cornea.
6. Contrast Sensitivity Analysis
This is a contrast sensitivity test that may be done prior to and following the Excimer Laser surgery. Contrast sensitivity measures the ability of the eye to distinguish images under varying degrees of lighting.
7. Horizontal Diameter of the Cornea
8. Eye Dominance
9.Refraction on the Automated Refractometer
10. Tear Test to Rule Out Dry Eye.
11. Complete Eye Exam
12. Others
Prior to surgery, you will be administered a mild sedative; then, your cornea will be marked with a dye mark at the 6 and 12 o'clock meridians. Next, you will be positioned under the microscope, and asked to fixate (concentrate) on a blinking red light. The unoperated eye will be taped shut. Make sure you do not squeeze your unoperated eye shut, because it will affect your ability to hold your operated eye steady. Just act as though the unoperated eye that is taped shut is open. Try to use both eyes together, and this will steady the operated eye.
The eye will be anesthetized with topical anesthetic, an eye drape will be placed over the lashes and lid margins, and an eyelid speculum will be placed between the eyelids in order to hold them open during the procedure.
You will once again be asked to concentrate on the red fixation light under the microscope, and the corneal flap dye marks will be applied. Next, a suction ring will be placed and centered on the eye, and suction will be applied. At this time, you will feel pressure, but no pain. While the suction ring is in place, it will be normal for you not to be able to see out of the eye while the suction is on. Once the suction is released, vision then returns to the eye. It is best to be as relaxed as possible and try not to move your eyes while the suction ring is in place. The suction ring has a tiny groove and track on it for the microkeratome to drive across. Next, the microkeratome will be placed into position onto the suction ring track and groove, and is then driven across 90% of the cornea, resecting approximately 160 microns of cornea tissue, creating a corneal flap, and then is reversed off the suction ring. It is important to realize that when the microkeratome is traveling across the cornea, there is a normal buzzing sound to the keratome itself. It is critical that this buzzing noise does not startle you and cause you to jump or squeeze your eyes while it is passing across the cornea. Once the corneal flap is made, it is hinged back, away from the corneal bed, and the Excimer Laser is then applied to the bed of the cornea or stromal interface in order to correct the refractive error.
Prior to doing the Excimer Laser, you will be asked to fixate on the red blinking fixation light only. Once the Excimer Laser begins, you will perceive this as a mild buzzing sound, and you may smell the odor of the molecules of protein being vaporized from the corneal bed. When fixating on the green light inside of the red ring during the laser treatment, you may see the green light become somewhat blurry, and this would be normal. If during the Excimer Laser treatment, you inadvertently move your eye, the laser beam eye tracking system will take over and will follow small eye movements. Once the Excimer Laser treatment is completed, the corneal flap will be put back into position over the corneal bed, without sutures in most cases. It takes approximately 20 to 30 seconds for the corneal flap to seal itself securely to the corneal bed. A clear plastic shield will be placed over the eye until the next day.
Under no circumstances jump or squeeze your eye. It is critically important that you remember during the operation to relax completely your shoulders, your neck, your chin. Do not clench your hands or make your hands into fists and squeeze them. Doing so can detract from your steadiness. It is best to relax your hands, your legs, your feet. Do not chew gum during the procedure. Do not cross your legs. I will be reminding you about these things throughout the treatment session. The entire procedure usually takes less than 20 minutes to perform.
As we have said, the operation itself is really not painful, and there is usually nothing more than pressure that is felt during the operation. Following surgery, it is unusual to have severe pain, but a prescription for pain medication will be given to you, just in case. Usually, the first day the eye may have a slight foreign body sensation, and nothing more. Sometimes the eye waters, and you may be light-sensitive for a couple of days. It is not unusual, for the first month, to have some mild glare problems at night; but that usually disappears or is significantly reduced over time. Vision may be surprisingly good on the first day postop; however, if it is not, we ask that you not worry about this. Sometimes it takes a few weeks before the vision really gets sharp. Normally, you can see and function quite well without glasses the first post-op day.
It may take at least 1 to 3 months for the operated eye to stabilize and be able to achieve the desired excellent vision. Remember, with high myopia, astigmatism, or hyperopia, one will have a greater chance that an enhancement will be necessary in order to fine-tune the vision. enhancements are usually done from 6 weeks to 3 months postop.
Normally the first day of surgery you will not be required to put drops into the eye; however, you will start the following day. Your drop regimen will be given to you prior to surgery. Normally we don't have to use the drops longer than 1 week. Vision is usually stable at one month, but can change slightly between 1 and 3 months. Stability of vision is affected by the dryness of the eyes--i.e., the dryer the eye, the longer it takes for the vision to stabilize.
The second eye may be operated on when the first eye recovers and sees well. When the visual result is satisfactory and the eye is completely comfortable, one may consider having the second eye treated in order to balance both eyes. This time period between the treatments of each eye may be as little as a few days to as long as a few weeks. However, LASIK on both eyes the same day can be done if desired. You will need to discuss this with Dr. Maddox.
You will need to sleep with a protective shield over the eye while sleeping or napping. This must be done for at least 1 week following surgery. You should not swim for at least 2 weeks, and try not to get the eye wet while bathing or showering for at least a week. One of the things you really don't want to do is rub the eye, especially the first 3 months following the surgery. It probably is not a very good idea for any of us to rub our eye, whether we have had surgery or not. Be extremely cautious about deodorant spray, hair spray, paint, and any other kinds of sprays. The mist from the spray can get on the cornea and cause irritation.
Your eyes may be imbalanced following the surgery if only eye is done. You can wear a contact lens on the unoperated eye until the operated eye gets well in order to balance the eyes. Or, if you prefer, you can wear your glasses, but when you want to read or drive , you will have to patch the operated eye and use the unoperated eye until the operated eye is comfortable and can see well; please realize that you will have todo this for a few weeks if only one eye is done. In most cases, one cannot comfortably balance both eyes together with glasses if one eye is nearsighted and the other eye has been corrected with LASIK. In addition, some individuals who choose this method of dealing with the imbalance prefer using no glasses at all after the operated eye recovers good vision if they are well under 40 years of age. If one is in the presbyopic age group (over 40) and chooses to wear a contact lens on the unoperated eye while the operated eye recovers, one will most likely need reading glasses or bifocals to be worn over the unoperated eye during the recovery phase with or without the contact lens. The imbalance problem is one of the main reasons we prefer to do bilateral laser surgery. Please be prepared to have some blurry vision out of the operated eye for a few weeks.
It is imperative that you see us, or your own eye doctor, if you have been referred, for your recommended post-operative follow-up visits. In these cases, we recommend that you be seen at 1 week, 1 month, 3 months, 6 months and 1 year. Please note that the cost of eyedrops is not included in the surgery fee. You will be responsible for the cost of all postoperative medications.
We advise that you do not drive an automobile until the eyes are comfortable and you can see well enough. Many people are able to go back to work the next day because their vision is adequate to function at work and they are comfortable. Under these circumstances, it would be okay to return to work the next day after surgery.
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