The world's local bank
HEALTHNET
LASIK: Am I suitable for LASIK?
(Posted on 1 May 2008)
Eyeglasses have become part of fashion in recent years, but wearing eyeglasses due to sight problems may lead to a host of annoyances. With its increasing accessibility, laser refractive surgery has become an option for more and more people in Hong Kong to improve eyesight and avoid the nuisance caused to daily life. However, is laser refractive surgery safe? To what should we pay attention?
Laser-Assisted in situ Keratomileusis (LASIK) is the most common type of laser refractive surgery for correcting short-sightedness, long-sightedness and astigmatism. LASIK mainly consists of two steps: flap cutting and ablation of the cornea. A thin flap is first created on the cornea. Then the inner corneal tissue is ablated to modify the curvature of the cornea.
Please visit an ophthalmology centre for a preliminary check-up on whether laser refractive surgery is suitable to you. The most important items include the degree of short-sightedness, long-sightedness or astigmatism, as well as the thickness of the cornea. A minimum thickness of 450 microns is required and this figure varies with the degree of correction. A certain corneal thickness is needed to correct every 100 degrees of short-sightedness. The range of correctability by laser refractive surgery depends upon the corneal thickness, usually up to a maximum of 1,200 degrees for short-sightedness and 600 for long-sightedness and astigmatism.
Source: Quality HealthCare Medical Services
- Is anyone eligible for laser refractive surgery? By what criteria should we select a laser refractive surgery centre?
- Does laser refractive surgery cause any pain? To what should we pay special attention before and after the operation?
- Is LASIK safe?
- How long should we rest after the surgery? How can we confirm if the operation is successful?
- What kind of food is beneficial to the eyes?
- How to protect children eye visions?
- Chemoprophylaxis of Bacterial Meningitis
Is anyone eligible for laser refractive surgery? By what criteria should we select a laser refractive surgery centre?
Basically, anyone aged above 18 with good health and stable eyesight over the past year (no change in the degree of short-sightedness, long-sightedness or astigmatism) is eligible for laser refractive surgery. Eyesight is stabilised only around the age of 21 or 22, so younger persons are not eligible for the procedure.
Laser refractive surgery has no upper age cap, but check-up is mandatory as the prevalence of other eye diseases increases with age. Moreover, patients of lupus erythematosus, rheumatoid arthritis, keratitis, keratoconus, glaucoma or advanced cataract are not eligible for the operation. Therefore, you must report to the ophthalmologist your health conditions in detail for a comprehensive and safe evaluation.
If you decide to undergo laser refractive surgery, the next issue would be how to locate a reliable ophthalmology centre. Besides opinions from your doctors and friends, you may look for a reputable centre on the Internet. Accredited laser refractive clinics are run by doctors with professional qualifications in ophthalmology. Pay attention to their professional licence. Moreover, these centres may provide different consultation periods, ranging from six-month, one-year to even lifelong follow-up services.
Does laser refractive surgery cause any pain? To what should we pay special attention before and after the operation?
Laser refractive surgery takes only 2-3 minutes and is basically painless. The doctor would give anaesthetics and oral sedatives to ease the eye discomfort. Watery eyes or dry eyes, and eye irritation may follow the operation. These symptoms normally subside on the following day. Daily activities can be resumed in one or two days. Besides, some may experience dry eyes within the next month, in which case the doctor would proscribe suitable medication and artificial tears to reduce such discomfort. You must comply with the instructions given by the doctor before and after the procedure to protect your eyes.
Stop wearing contact lenses before laser refractive surgery:
- Soft lens users should stop wearing them one week before the operation.
- Hard lens users should stop wearing them two weeks before the operation.
Protect your eyes after laser refractive surgery:
- Apply eye drops as instructed by the doctor.
- Avoid any contact of soap, shampoo or water with the eyes.
- Do not rub or touch your eyes.
- Wear sunglasses with UV protection when going outdoor to reduce any irritation to the cornea.
- Do not wear any eye makeup for a week following the operation.
- Avoid high-impact sports such as basketball and football, as well as water sports such as swimming and water skiing for four weeks following the operation.
Is LASIK safe?
According to reports by the Consumer Council, some patients suffer from double vision after laser refractive surgery? Is the procedure safe? Will there be any side-effects?
As estimated by the American Society of Cataract and Refractive Surgery, LASIK operation did not work for about 2-3% out of more than 1 million patients annually. Statistics by the Food and Drug Administration (FDA) revealed that, six months following the procedure, 28% of the patients suffered from insufficient tears, 16% blurred vision, 18% difficulty to drive at night and some even experienced long-term eye pain.
According to experts, dry eyes are the most common problem after the surgery and usually disappear after three to six months. Bear in mind that surgery carries a certain risk. Improper postoperative care may lead to complications and side-effects, including corneal flap irregularities, wrinkles and dislocations, epithelial ingrowth, infections and ulcers. Nevertheless, laser refractive technology has matured in the last 10 years such that the risk of complications and side-effects is as low as 1% with proper care of the wound. By medical statistics, the risk of vision worsening after the surgery is under 0.1%, and no cases of blindness have been caused by the procedure to date. Most side-effects can be tackled, and the risk of permanent damage to eyesight is minimal.
How long should we rest after the surgery? How can we confirm if the operation is successful?
Hong Kong is a busy, efficiency-savvy society. Most of us may be concerned if we can resume work immediately after the surgery. Basically, you may return to duty the next day. Watery eyes would persist for three hours following the operation, and eye discomfort is common due to the effects of anaesthetics. These conditions normally recede on the next day only. Therefore, patients may go home after the operation to give yourself and your eyes some well-deserved rest. Of course, if you do not feel any discomfort or cannot afford a break, you may return to work.
Some may experience dry eyes for a month after the surgery, and then the uneasiness would fade gradually. In case of serious discomfort, please consult your doctor for a detailed check-up. Generally speaking, normal eyesight is restored largely on the next day and completely in around three months, in which case the procedure is regarded as a success.
What kind of food is beneficial to the eyes?
According to various research and clinical experiments, food with antioxidant vitamins is beneficial to the well-being of eye cells and tissues. Researchers have found that antioxidant vitamins A, C and E are closely related to the health of the eyes, and these vitamins could help prevent cataract and macular diseases.
Vitamin A (β carotene): Vitamin A can prevent night blindness. Carrot, sweet potato, mango, pumpkin, almond, spinach, cantaloupe, green pepper and cod liver oil are recommended.
Vitamin C: Vitamin C is vital to the protection of eyesight and helpful for the prevention and amelioration of glaucoma. Citrus fruit and juice, papaya, red and green pepper, tomato juice, strawberry, mango, broccoli and cauliflower are recommended.
Vitamin E: Vitamin E is a potent antioxidant. Nuts (like pecan, almond, cashew, peanut and sunflower seed), vegetable oils (like olive oil, soybean oil, peanut oil and sunflower oil), mango, wheat germ and egg are recommended.
Calcium: Calcium helps relieve tension of the eyes. Beans and green vegetables are recommended. Such dishes as pork soup or sweet and sour pork can enrich the calcium content as well.
Zinc: Researchers have found that zinc deficiency may lead to macular degeneration. Wheat, nuts, oyster, shellfish, fish, shrimp and other seafood are recommended.
How to protect children eye visions?
The eyes are our window to the world. Loss of sight is equal to the loss of light. Protection of the eyes must begin from childhood. Make sure your children know how to look after their eyes. Below are some tips for the kids:
- Where children read and learn must be well lit. Anglepoise lamp is a good option.
- TV set must be placed at least 1.5m from children. Brightness should be adjusted: excessive brightness irritates the eyes while excessive dimness causes fatigue.
- Do eye massage after viewing TV to soothe fatigue.
- Do not let your children gaze at the screen for too long. Whether they are watching TV, working with computer or reading, remind them to look into the distance for 10 seconds every 10 minutes and rest for at least 10-15 minutes every hour.
- Take your children to qualified opticians for annual check-up.
- Prepare food rich in vitamin A for your children.
Chemoprophylaxis of Bacterial Meningitis
Meningitis is the most common type of central nervous system (CNS) infection which can be caused by various pathogens, including bacteria, viruses, fungi, and parasites.
Examples of causative microorganisms of bacterial meningitis are group B streptococci (Streptococcus agalactiae), Escherichia coli, Listeria monocytogenes, Haemophilus influenzae, Streptococcus pneumoniae, and Neisseria meningitidis etc.
Bacterial meningitis typically presents with the classic triad of fever, neck stiffness, and altered mental status. Other symptoms include headache, photophobia, nausea and vomiting, rash, and seizures. As the disease progresses, life-threatening complication such as septicaemia may occur.
People in close contact with patients with meningitis caused by N. meningitidis or H. influenzae are at increased risk of contracting the disease. Other types of bacterial meningitis such as those caused by S. pneumoniae are considered to be less transmissible between people. Both N. meningitidis and H. influenzae colonize mucosal surfaces of nasopharynx and are transmitted through direct contact with large droplet respiratory secretions from the patients or asymptomatic carriers.
Chemoprophylaxis for close contacts of patients with meningitis caused by N. meningitides and H. influenzae is therefore recommended to eradicate the nasopharyngeal carriage of bacteria.
Ideally, chemoprophylaxis should be instituted within 24 hours of exposure, while administering chemoprophylaxis 14 days or more after identification of the index case is probably of limited value. The first-line regimen for chemoprophylaxis is rifampicin orally with a recommended dosage of 10mg/kg every 12 hours or 600mg every 12 hours in adults for 2 days (meningococcal); or 20mg/kg once daily for children over 1 month old or 600mg once daily for adults for 4 days (Haemophilus).
Alternative chemoprophylaxis regimen that have been shown to be effective for reducing nasopharyngeal carriage of N. meningitidis are ceftriaxone 250mg or 125mg intramuscularly in adults and children, respectively, and ciprofloxacin 500mg orally as a single dose in adults. Rifampicin should not be recommended for pregnant women and ceftriaxone should be given as alternative.
Source: Hong Kong and Drug Education Resources Centre, The Society of Hospital Pharmacists of Hong Kong
