Refractive surgery aims to reduce or eliminate a person’s dependence on corrective lenses. In most patients the surgery will remove the need for glasses or contact lenses. However surgery does not guarantee perfect vision. Most people who undergo this type of surgery are happy they did. In one survey of patients who have had LASIK, 97% said they would recommend the procedure to their friends. How well and how quickly your vision improves depends on various factors including how your cornea heals and the severity of your prescription. Most patients do achieve 20/20 (or 6/6) vision or are within 1 or 2 lines of this on the eye chart. In order to drive without glasses you need a visual acuity of 6/12 which is 3 lines above the 6/6 line.
Understanding the procedure and having realistic expectations will help you make the right decision about refractive eye surgery.
Refractive Eye Surgery or Contact lenses …?
Each has it pros and cons. Let’s take a look at some of these:
Cost - surgery involves paying a relatively large lump sum, but it is almost always a once off cost. Contact lenses are an on-going expense. Laser eye surgery may in fact work out cheaper in the long term.
Convenience - surgery wins here – no question.
Effectiveness - both can be equally effective. Soft contact lenses work extremely well, especially if you have minimal astigmatism.
Contacts do have the advantage in that you can easily change the strength of your lenses should your prescription change over time. Enhancements can be done after surgery, even years later, but this is not quite as simple as changing your contacts.
Presbyopia - neither contact lenses, nor laser eye surgery can correct presbyopia adequately (unless you opt for monovision). Either way you will need reading glasses in your 40’s.
Safety - both contact lenses and LASIK are considered safe hence the popularity of both means of vision correction. But each does have some small amount of risk. In a recent study researcher’s reviewed several studies of complications from both contact lenses and LASIK surgery concluded that LASIK may actually be the safer option in the long run.They calculated the risk of significant loss of vision at 1 in 10,000 (0.01%) with LASIK surgery. Compare that to contact lens wearers who have approximately a 1 in 100 (1.0%) risk of developing a serious contact lens-related eye infection over 30 years of use. They also have about a 1 in 2,000 (0.05%) chance of significant vision loss as a result of a contact lens-related eye infection over the same period.
LASIK and your fears
These are things that may go through you mind when you first consider laser refractive surgery:
"I am afraid that something might happen"
"I am worried about the long-term effects”
"I am waiting until the technique is perfected"
"What if I move when they are doing the laser?"
"What if ......?"
We hear these questions all the time. These fears can keep many potentially good candidates away. We think that it is normal to have some reservations whenever you have surgery. For many people it is fear of the unknown. We like all our patients to be well informed. We like you to know the risks and the things we do to minimise the risks. This gives you the confidence to make the right decision.
Probably 20% of people are not suitable for LASIK or PRK. The criteria for inclusion or exclusion are now well established after years of experience and clinical studies. We perform an extensive preoperative exam on all patients.
On the day of the procedure you will be a little nervous. Your eyes are sensitive and nobody likes to have their eyes touched. Some people fear the possibility of pain during LASIK, especially as the procedure is done while they are fully conscious. A little sedation helps. We will talk you through the procedure. Numbing drops are used and although you may feel some pressure or mild discomfort, LASIK is usually pain free. The whole thing is over very quickly.
Some people fear the safety of the laser beam itself. The laser beam remodels your eye quickly, usually in 10-15 seconds and the specific wavelength of the laser light has been chosen because it is cold light and does not penetrate beyond a few layers of your cornea. Some people fear that the laser may be placed in the wrong position if they blink or move there eye. You will be unable to blink during the procedure and the tracking system follows eye movement to ensure correct placement of the laser.
Some patients are still fearful of having to watch the entire LASIK procedure. In actual fact you do not see what is going on apart from blurry movements. The eye not being operated on is covered, and the eye being operated on is to some extent blinded by all the lights above you. When the flap is being created you may feel a little pressure and during this period your vision will blank out completely
LASIK Complications and Safety
Before undertaking any surgical procedure it is important to understand the associated risks and limitations. Refractive surgery is not trivial surgery, and attention should be given to understanding this aspect of the surgery. We understand the concerns you have for your eyes and hold your safety in our highest regard.
The chance of having a serious vision-threatening complication is rare due to surgeon experience and the sophisticated equipment used. Although most patients are very pleased with the results of their refractive surgery, every patient should weigh the chance of experiencing complications against the potential benefits the procedure can provide.
Remember that wearing contact lenses has its own set of risks. You may not have been told about these when you first got your lenses, but infections do occur with contacts and these do sometimes cause vision reducing scarring of the cornea. Almost everything you do in life has some degree of risk and taking this into account helps put things in perspective.
Results of clinical studies indicate the chances of having a serious complication from a laser vision correction procedure is much less than 1%. Many of these complications can be treated and few people have severe visual loss as a result.
Many side effects and risks are due to the varied healing processes of individual people. Below we have listed some of the possible side effects and complications, but this does not include all possibilities.
Possible side effects
Dry eyes: Some people do experience dryness after surgery. Usually this is temporary and resolves spontaneously after a few weeks. It can be usually be relieved by using lubricating eye drops (artificial tears) and taking Omega 3 oil capsules orally (1 gram twice daily). Others may need temporary plugs inserted in their tear ducts to conserve natural tears. This is painless and is done in the consulting rooms. Dry eyes are more common in patients going through menopause and if taking certain medications. It can rarely last for months to years.
Reduced low-light vision: Some patients may not see as well in reduced light conditions. These patients may be aware of halos, starbursts or glare around lights. Some people report this even before surgery with their glasses or contacts. These symptoms do improve over a few months. If you do a lot of night driving you should discuss this possible side effect with the doctor prior to having the procedure.
Over-correction or under-correction: In more than 95% of patients the final prescription will be between 0 and ±0.75. In this range you would usually be happy with your vision. In 2 - 5% of patients the prescription may be out of this range and an enhancement (re- treatment) may need to be considered. Enhancements are more commonly required if you have a high prescription to start with. There are many elements that can contribute to the laser treatment not giving the expected result. These include environmental factors and patient factors, such as the accuracy of the subjective refraction (the glasses test) done prior to surgery, as well as age and individual corneal healing factors. We control as many of these factors as possible to get consistent results.
Decrease in best corrected vision: Occasionally (2%), some patients will not see as sharply as they did prior to surgery, even if corrected with glasses. In many cases the sharpness returns after several months as the cornea heals and the brain adjusts and adapts.
Difficulty wearing contact lenses: Most patients never need to wear contact lenses and should you need to it is almost always possible. However there are some patients who do not tolerate contact lenses as well as they did before.
Flap complications: In LASIK the corneal flap is cut by an instrument called a microkeratome. This is a sophisticated and high precision instrument that is calibrated to cut the flap with the thickness of about 1/10 mm. Flap complication occur in less than 1% of cases and include incomplete and irregular flaps and flaps that may be too thin . Should this occur, the laser reshaping may not be done as it may be better to allow the flap to heal for a few months and then recut the flap or perform PRK. Other flap complications include misalignment or wrinkling of the flap, inflammation of the flap (called diffuse lamellar keratitis), irregular astigmatism due to an irregular corneal surface or the growth of epithelial cells beneath the flap (epithelial in-growth).
Infection: Infection can occur after any surgical procedure. Antibiotic drops are used to minimise this risk and the risk is indeed very low (about 1 in 5000). If caught early most infections can be treated successfully and the vision may not be affected. The risk of corneal scarring with severe loss of vision is about 1 in 30 000.
Corneal haze: This is a rare complication after PRK (1 in 2000). These days we use a drug called Mitomycin on the cornea during the procedure which has almost eliminated the risk of haze. It PRK patients it is also helpful to wear sunglasses when outside for the first few months, and to take Vitamin C 1000 mg per day for a few months.
Instability of the cornea (ectasia): If the cornea is weakened through the removal of too much tissue during LASIK, or if the collagen fibres in your cornea are weaker than normal, the centre of the cornea may bulge making the eye surface irregular and resulting in poor quality vision. At your pre-operative assessment, your surgeon will take measurements to ensure that 250 microns depth of corneal tissue remains untouched following LASIK, as this is generally accepted as a safe level. Most often we more conservative and leave much more tissue than this. Rarely ectasia can occur even if these guidelines have been strictly followed. This can be due to a weakness in the collagen fibres that make up the cornea, and we cannot always detect this prior to surgery. If you had to develop ectasia there is a procedure called cornea collagen crosslinking that can be performed to strengthen the cornea and stabilise the cornea.
Does LASIK increase the risk of retinal detachment? Detachment of the retina more commonly occurs in short-sighted people. Can having LASIK increase your risk?We are not absolutely sure but most probably not. The suction applied by the microkeratome during flap creation can puts tension on the vitreous and retina, and theoretically could increase the risk. A study done by Dr J Fernando Arevalo and presented in 2009 reported no apparent causal relationship between LASIK and retinal detachment. Over 11,500 eyes were examined retrospectively and the incidence of retinal detachment was found to be lower than the general population. In another study presented by Dr Vincenzo Pucci MD in 2003, laser refractive surgery for high myopia did not appear to increase the risk of retinal detachment. His series comprised 2,809 eyes of 1,477 patients who had undergone either LASIK or PRK for the correction of myopia or myopic astigmatism up to -13 diopters over a 10 year period.These studies support the conclusion that the retinal detachments after excimer laser surgery for the treatment of high myopia is not increased.