What is refractive surgery?
Refractive or vision correction surgery is an operation on the eyes to correct error of refraction, like nearsightedness, farsightedness and astigmatism, to eliminate the use of prescription eyeglasses or contact lenses.
What are the various procedures available today?
The advent of Excimer laser in 1988 ushered in a new revolutionary era in vision correction. It provided added lifestyle choices made possible by the freedom from, or dependence on, prescription eyewear. That important technological advance resulted in major treatment modalities not possible before then. The three popular procedures for refractive surgery today are LASIK (Laser Assisted In-Situ Keratomileusis or Laser Vision Correction), PRK (Photorefractive Keratectomy) and Intacs (Corneal Ring Segments) implants.
What is Excimer laser?
Excimer laser is a computer-controlled ultraviolet beam of light that reshapes the cornea (outer window of the eye), resulting in the light focusing more directly on the retina at the back of the eye. Excimer laser gives out a cool or nonthermal (not hot) light beam, making it ideal for corneal surgery, eliminating the possibility of thermal burns to the surrounding tissues. Each laser pulse is so accurate it achieves disruption and removal of the molecular tissue bonds between the corneal cells up to 0.25 micons (or 0.00004 of an inch), which improves the vision. Usually, only about 50 microns of tissue (about half the thickness of human hair) are removed to achieve the correct amount of vision correction.
What does each procedure involve?
In LASIK, a thin layer of the corneal (outer covering) stroma is fashioned using a microkeratome (cutting) instrument and this tissue is set back in place after the laser procedure is done. LASIK reshapes the corneal tissue underneath the surface of the cornea, while PRK uses laser to remove the epithelium, a thin protective “skin” on top that covers the cornea, before the actual corrective treatment is performed. For Intacs, two tiny incisions and tunnels are made on the outer edges of the cornea and the Intacs (half-moon or C-shaped) ring segment is implanted in each tunnels and a suture is placed.
What are Intacs?
Intacs are two mini half rings, made of biocompatible plastic that has been safely used for about five decades in cataract operations and in contact lenses. Intacs permanently corrects error of refraction when placed within the outer edges of the eyes as described above.
What are the benefits of these procedures?
The corrective surgery decreases or eliminates the dependence on glasses or contact lenses, increases safety while indulging in outdoor or sports activities, provides more convenience, improves vision 24 hours a day, and in some people, it may improve self-esteem, the look, or satisfy vanity.
Is general anesthesia used for this?
No, only topical anesthesia is used for these procedures. Eye drops to numb the eyes are instilled prior to the surgery. This is enough to prevent the patient from feeling any pain during the operation.
Does this correct aging vision?
Error of refraction in the elderly, usually starting from age 40, is called Presbyopia. The three procedures mentioned above will not correct Presbyopia. Those undergoing any of these vision correction surgery procedures will still need reading glasses.
Are there potential risks and side-effects?
Just like any surgery, these vision correction procedures have possible risks and side effects. Following the surgery around 5 to 25% of patients will have some haziness of vision that is aggravated at night. It peaks at 8 to 12 weeks after treatment and in almost all of the cases, this problem resolves with eye drops and the natural healing process. Some patients may notice halos or glare when looking at bright lights or at night. A few of them may feel increased intraoccular pressure, and many will experience some discomfort that is relieved by home pain killers like acetaminophen (Tylenol). Infection is rare but possible. It is best to discuss all the details about the recommended procedure, advantages and disadvantages, timing and sequence of surgery, possible risks and complications with your Ophthalmologist performing the procedure.
Can this procedure be done on a pregnant woman?
Because of the nature of the procedure, these laser-assisted procedures may NOT be done during pregnancy, until three months after delivery and breastfeeding. After the procedure, the patient should wait 6 months before becoming pregnant.
How effective are these procedures?
The statistics from the Department of Ophthalmology and Visual Sciences of the University of Iowa Hospital in Clinics (6th on the Top Ten list of Best Hospitals in America), according to Assistant Clinical Professor Emily C. Greenlee, M.D., show that their results at UIHC provided 95% of eyes treated improved 20/40 vision, the legal driving limits in most states, following the procedure. One half to 2/3 of the patients obtained a 20/20 vision (normal without prescription eyeglasses) after the surgery.
Who are candidates for this vision correction?
Those age 18 or older, with otherwise healthy eyes, with mild to moderate nearsightedness (-1.00 to –14.0 dopsters), farsightedness (+1.50 to +4.00 diopters) and astigmatism are good candidates for LASIK or PRK. For Intacs, the best patients are those with nearsightedness (-1.00 to –3.00 dopters). These procedures will provide better vision without eyeglasses or contacts, but none of them will give perfect vision. A realistic expectation is very essential with this refractory surgery.
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Philip S. Chua, MD, FACS, FPCS, Cardiac Surgeon Emeritus in Northwest Indiana and chairman of cardiac surgery from 1997 to 2010 at Cebu Doctors University Hospital, where he holds the title of Physician Emeritus in Surgery, is based in Las Vegas, Nevada. He is a Fellow of the American College of Surgeons, the Philippine College of Surgeons, and the Denton A. Cooley Cardiovascular Surgical Society. He is the chairman of the Filipino United Network – USA, a 501(c)(3) humanitarian foundation in the United States. Email:[email protected]. Please visit www.xlibris.com and search for the book, Let’s Stop “Killing” Our Children which contains a compilation of articles from this column.
