We've developed this handbook to help our patients become better informed about the entire process of laser vision correction. We hope you find it helpful and informative.
Dr. Booth received his medical degree from the University of California: San Diego and his bachelor of science from Stanford University.
Dr. Booth completed his residency in ophthalmology at Shiley Eye Center, University of California: San Diego. He did his internship at St. Vincent Hospital in Indianapolis, Indiana. He is fellowship trained in cataract and refractive surgery from Baylor University in Houston, Texas. In addition to refractive surgery, Dr. Booth provides comprehensive medical and surgical ophthalmology services.
What is refractive surgery?
Refractive surgery includes several surgical procedures designed to eliminate or reduce the need for glasses or contact lenses. All refractive and laser surgeries work by
reshaping the cornea, or clear front part of the eye, so that light traveling through it is properly focused onto the retina located in the back of the eye. These procedures (e.g. LASIK and PRK) correct refractive errors by changing the focus of the eye.
History of refractive surgery
Ophthalmic surgeons have been performing refractive surgery for the treatment of myopia (nearsightedness), hyperopia (farsightedness), and astigmatism (irregular shaped cornea) for approximately 100 years, but the past decades have produced rapid change and growth by means of refined techniques and the emergence of laser vision correction surgery.
The excimer laser was developed originally to etch computer chips; ophthalmologists began later using the excimer laser successfully for refractive surgery techniques to remove very precise amounts of tissue from the cornea. Excimer lasers revolutionized refractive surgery by providing a degree of safety and precision that was previously unattainable with other techniques.
REFRACTIVE ERRORS
The shape of your eye determines how well your vision can focus. Light rays enter the eye through the clear cornea, passing through the pupil and the lens. In a normal eye the light rays are focused onto the retina, a light-sensitive tissue lining the back of the eye. Signals from the retina are sent through the optic nerve to the brain where they are interpreted as the images we see. Refractive errors exist because the curvature of the eye is mismatched to the length of the eye and light rays cannot focus properly on the retina.
HOW THE EYE WORKS
Sharp vision depends on many factors. The parts of the eye work together to refract (bend) and focus light rays. For normal vision, light must focus on the retina. If the cornea or the eyeball as a whole is not the right shape, light doesn't focus correctly, and vision is blurry. Common focusing problems include myopia, hyperopia, and
astigmatism.
Myopia (nearsightedness) is the most common refractive error, affecting more than one in four people in North America. Myopic patients see close objects more clearly, the distant objects are blurry or even indistinguishable. Myopia occurs when the eye is too long or the cornea is too steep. As a result, light rays entering the eye fall in front of the retina instead of directly onto it.
Hyperopia (farsightedness) patients can focus on more distant objects, but near objects appear blurry. Hyperopia occurs when the eye is shorter than normal or the cornea is too flat. As a result, light rays are not focused by the time they reached the retina. In young people, the natural lens can sometimes correct the focus in hyperopic eyes by changing its shape. With aging, the natural lens loses this ability.
Astigmatism occurs when the curvature of the cornea and sometimes the lens is steeper in one direction than the other: like a football or the back of a spoon. Almost everyone has some degree of astigmatism, but for some the uneven curvature causes light rays to focus on many points in the eye and distort both close and far vision.
Presbyopia is the age-related loss of close-up focusing ability. When we are young, our eye’s lens is soft and flexible and can change shape easily, allowing the eye to focus on objects both close and far away. As people enter their 40s the lens becomes less flexible and is unable to focus on close-up objects.
DR. BOOTH'S EXCIMER LASER PROCEDURES
Computer-controlled excimer lasers can sculpt the cornea into a new shape. Dr. Booth uses an FDA approved laser. The laser has an eye tracking device that follows even slight eye movements during the procedure.
Combinations of high-tech surgical tools are used to prepare and treat the cornea. The excimer laser produces a concentrated beam of cool, ultraviolet (UV) light. Each pulse of this laser can remove a tiny portion of corneal tissue. The excimer laser is so accurate that it can cut a notch in human hair. It generates no heat and is gentle to tissue.
With LASIK surgery a femtosecond laser is used to create a corneal flap. It makes an extremely precise, thin cut, resulting in a corneal flap that is typically about 1/10 to 2/10 of a millimeter thick.
LASIK
LASIK stands for Laser In Situ Keratomileusis. It's a technique for reshaping corneal tissue. First a femtosecond laser creates a thin flap in the cornea. Next an excimer laser changes the underlying cornea into a new shape to correct the refractive error. The flap is then repositioned and adheres on its own without sutures. LASIK can be used to correct hyperopia, myopia, and astigmatism.
PRK
PRK stands for photorefractive keratectomy. In PRK, the epithelium, the outer layer of cells covering the cornea is removed and the excimer laser sculpts the cornea to correct the refractive error. A bandage contact lens is usually placed on the eye following the procedure to speed the epithelial healing process, which usually takes 4 to 5 days. Because PRK sculpts the outer surface of the cornea, patients experience some
discomfort usually lasting up to 3-5 days after surgery. PRK is sometimes recommended instead of LASIK, because it does not create a flap in the cornea and may be a better option for people have thinner corneas or whose occupation makes it more dangerous to have a flap.
COMPARING LASIK and PRK
LASIK and PRK are both surgical techniques that use precise excimer laser energy to alter the refractive status of the eye. The difference between these procedures concerns where the excimer laser energy is applied.
LASIK consists of first making a corneal flap with a femtosecond laser. After the flap is created, the excimer laser removes small amounts of underlying tissue from the exposed cornea. Following the laser treatment, the flap is carefully repositioned to complete the surgery.
PRK consists of mechanical removal of surface cells on the cornea (called the
epithelium), followed by use of the excimer laser to remove small amounts of tissue from the front of the cornea.
The primary difference is that the tissue removal is done either under a flap with LASIK or on the surface of the cornea with PRK.
What are the advantages of LASIK?
• There is little or no discomfort typically both during and after the operation. • Recovery of vision is generally very rapid, and many people have useful vision
within one day of surgery.
• Retreatment by lifting a previously made flap may be done 3 to 12 months after the initial surgery. In other words, if a second surgery is needed, typically a second flap does not need to be cut on the cornea.
What are the disadvantages of LASIK?
• Because LASIK involves creating a flap, the surgery involves deeper layers of the cornea. This could excessively weaken corneas of patients whose corneas are too thin. If the flap is irregular, your quality of vision may be greatly reduced. Other flap related complications (e.g. folds in the flap, incomplete flap, or free flap) may occur which limit your post-operative outcome and best visual acuity.
• The creation of the flap also cuts corneal nerves and can increase dry eye symptoms in patients who are predisposed to this problem.
• Cost: because a femtosecond laser carries an additional cost due to the extra laser used, LASIK costs more than PRK.
What are the advantages of PRK?
• PRK avoids the use of the femtosecond laser to make the LASIK flap. This leaves a greater portion of the cornea untouched by the surgery, which is important in patients who have thin corneas.
• In addition, there appears to be more rapid recovery of the function of the corneal nerves, which minimizes the amount of dryness that can be present following the procedure.
• PRK may also provide an extra margin of safety in a patient whose corneas have an unusual shape; this advantage is again due to leaving more of the cornea untouched by the surgery.
• If eye trauma occurs after surgery, there is less risk of complication with PRK than with LASIK. The LASIK flap, in rare instances, can become elevated or partially dislodged if the eye is struck. This problem is obviously avoided with PRK because there is no flap. In PRK, the trauma may cause a surface abrasion, but without a flap the abrasion would be the same as in an eye that had not undergone any laser surgery.
What are the disadvantages of PRK?
• For the first several days following PRK, there can be mild to moderate eye discomfort because it takes time for the healing of the corneal surface. Depending on the rate of recovery of vision, patients can usually drive and return to work about 4 to 5 days after PRK surgery.
• Visual acuity generally takes longer to stabilize after PRK compared to LASIK. Generally 2 to 4 weeks of fluctuating vision is expected, sometimes more.
• As in LASIK, if the outcome of the original procedure does not meet your and our expectations, retreatment can be performed. This would essentially be the same process as the original surgery.
• PRK patients are usually required to take steroid drops for up to four months after surgery; the purpose of these drops is to minimize the risk of the
development of haze in the cornea. A mild amount of haze is common, and this is not noticed by the patient typically. The purpose of the steroid drops is to help prevent the development of any haze that might be noticeable to the patient.
Other Refractive Surgery Procedures
Multifocal intraocular lenses are used to treat nearsightedness (myopia), farsightedness (hyperopia), and the inability to focus at near with advanced age (presbyopia). These lenses enable your eye to regain its focusing and refractive ability.
Refractive lens exchange (RLE)
Refractive lens exchange (RLE) is most often used to treat moderate to high degrees of farsightedness and in patients who are not ideal candidates for LASIK or PRK. This is a non-laser procedure in which the natural, clear lens of the eye is removed and replaced with an artificial intraocular lens (IOL). As with multifocal IOLs, the cornea is not reshaped in the RLE procedure.
Monovision
Monovision is a refractive surgery technique for people with presbyopia. While there are laser refractive surgeries such as LASIK and PRK to reduce nearsightedness and
farsightedness, these procedures do not help correct presbyopia. The technique uses laser refractive surgery to enable one eye to focus up close while the other eye is left to focus at distance. Having the eyes configured for different focusing distances can reduce or eliminate the need for eyeglasses or contact lenses. It may seem difficult to get used to at first but after the monovision procedure, your brain is frequently able to adjust to the different focusing ability of your eyes. A preoperative trial with contact lenses is often useful to see if a patient will adapt to the intended refractive outcome.
Limbal Relaxing Incisions (LRI)
Limbal Relaxing Incisions (LRI), also known as peripheral corneal relaxing incisions (PCRI), can be used to help reduce or eliminate astigmatism in the cornea. LRIs are incisions that are placed on the far peripheral aspect of the cornea near the limbus resulting in a cornea that has less astigmatism, thus improving uncorrected vision.
The procedure can be completed after numbing the eye with anesthetic drops. There is usually minimal postoperative discomfort. Furthermore, the cornea is usually stable within a week, indicating that visual fluctuations have typically resolved by that time interval. The procedure can be most effective in patients whose primary refractive error is astigmatism.
Are You A Good Candidate For Refractive Surgery?
To be a good candidate for refractive surgery, you must meet the physical, health, and age criteria for the particular surgery. Before choosing refractive surgery, you should fully understand the procedure and be aware of the risks and possible side effects. General guidelines include:
• 20 years of age or older • healthy eyes
• stable glasses prescription or contact lens prescription for at least the past year • vision within the correctable range for a given procedure
What You Should Consider
Refractive surgery may not be for you if you: • do not have stable vision
• have a vision problem that is severe
• have a condition that slows healing or increases your risk of infection • are taking certain medications
Risks
As with all procedures, laser vision correction is not without risks and side effects. Your eyes may receive an over-treatment or an under-treatment resulting in blurry vision. In some cases, this can be improved by performing additional laser treatment that is usually done at least three months after the initial procedure.
Laser vision correction, like all surgical procedures, may result in a number of other complications, most of which are rare. These include infection, scarring, loss of vision, flap complications in the event of LASIK, corneal haze, and the need for further surgery including laser surgery or corneal transplant. Any of these, if they are significant, may require the use of glasses or contact lenses to maximize your
potential vision in the future. In rare instances, as with any surgical procedure on or near the eye, vision may be permanently reduced as a result of complication; fortunately, these occurrences with laser vision correction are rare. Generally these occur with much less than 1% frequency; it is important, however, to realize that even though the risks are low, there is no such thing as a risk-free, guaranteed surgery for any condition.
Vision For The Future
Your vision is precious. If you choose refractive surgery, you'll need to see Dr. Booth and his eye care team for follow-up visits. These visits are necessary to help assure that you are able to obtain the best possible outcome with your surgery. You also will be responsible for taking good care of your eyes to preserve the gains you've made from surgery. Administration of eyedrops at home is critical to effective recovery after surgery. Certain restrictions such as not wearing eye makeup or limiting swimming for two weeks after surgery are important to maximizing your visual acuity.
Payment Options
The eye examination and consultation fee is $200. If Dr. Booth determines that you're a candidate for refractive surgery and you choose to proceed, the consultation fee of $200 will be deducted from the surgical fee. The cost of laser vision correction varies according to the specific procedure that is performed. The cost will include the initial laser vision correction surgery as well as one year of follow-up visits.
