Health @ Heart
Vision correction surgery
What is vision correction surgery?
Vision correction or refractive 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 eyewears. 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 3 procedures mentioned above will not correct Presbyopia. Those undergoing any of those vision correction surgery 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, one of the top eye centers in the United States, provided to me by my daughter, Emily Chua-Greenlee, M.D., a senior Ophthalmology resident there, 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.
What is the cost for Refractive Surgery?
The package fee is about $1,800 per eye for LASIK and PRK, and $2,000 per eye for Intacs. This includes the hospital and physician charges and follow-up visits for one year.
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 nearsightedess (-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.
(The main objective of this column is to educate and inspire people to live a healthier lifestyle to prevent illnesses and disabilities, and achieve a happier and more productive life. Any diagnosis, recommendation or treatment in our article are general medical information and not intended to be applicable or appropriate for anyone. This column is not a substitute for your physician, who knows your condition well and who is your best ally when it comes to your health.)
Dr. Philip S. Chua is Cardiac Surgeon Emeritus based in Northwest Indiana and Las Vegas, Nevada, and is the Chairman of Cardiovascular Surgery of the Cebu Doctors' University Hospital in Cebu City. He is also the Vice-President for Far East Operations of the Cardiovascular Hospitals of America, a hospital builder in Wichita, Kansas. His email address is scalpelpen@gmail.com