Risks and Possible Complications
The vast majority of people who have laser eye surgery performed obtain an excellent result that lives up to their expectations for the procedure. However for some people, the outcome of their surgery does not meet their expectations, and in a few cases the outcome can be disappointing.
Like any other modern surgical procedure, laser eye surgery is not risk free. In order to have realistic expectations as to what you can reasonably expect from laser eye surgery, you must be aware of LASIK eye surgery risks, as well as its potential benefits. In addition to this information, you should read our informed consent document for a more detailed coverage of the risks of laser eye surgery.
With bladeless LASIK, there is only minor discomfort associated with the surgery, and there is very little postoperative discomfort. With ASLA, the actual procedure is usually only mildly uncomfortable. All patients are given a variety of medications to use after surgery, and are given full instructions about their use prior to the operation. It is important to take the pain relief tablets as prescribed as the eye can be quite uncomfortable for the first 72 hours afterwards.
An infection of the cornea is the worst thing that could happen after laser refractive surgery. This is extremely rare and has been reported to occur in about 1 in 5000 cases. Every effort is made to reduce the risk of an infection following refractive surgery. All instruments are thoroughly sterilised before use. Antibiotic eye drops are used both during and after the laser surgery.
Patients are asked to avoid swimming, spa pools, and hot tubs in the first three weeks following laser surgery to avoid infection or contaminants getting in to the eye. Eye make-up should be avoided for three weeks following laser surgery.
Any increased pain, redness, discomfort or discharge that occurs after your first post laser visit should be reported to LVCCC immediately as this may indicate early infection. If an infection occurs it should be treatable; any delay in treatment may result in permanent severe scarring which in turn may cause significant loss of vision.
Many short-sighted people experience glare during the day or night before having laser surgery. After laser surgery, you will usually experience more glare particularly at night, in the early post operative period. This will usually settle over the first few months and after six months you should be back to your normal "pre-laser" level of glare.
For some people however, night glare or a marked reduction in night vision compared to day vision may be a permanent problem after laser surgery. This was more of a problem with early laser systems, which used a narrow laser beam, and with severely myopic patients, where only a small area of the cornea was treated. LVCCC’s lasers use a scanning spot system, which reduces the frequency of this problem, but it can still occur in about 2% of cases.
Corneal Haze and Scarring
Corneal haze and scarring occur only rarely following ASLA, and are more of a problem with large corrections. Following ASLA all patients will find that their vision is quite hazy in the first week or so. This is caused by the normal healing of the eye which occurs after such procedures.
In the next few weeks after this, however, further changes occur in the cornea.
In some cases, the haze may be much more severe and may cause significant visual problems, such as haloes around lights, fuzzy vision or double vision. Even severe haze will usually eventually clear by itself, but in a few cases may require further laser treatment, or may even be permanent and untreatable.
Severe corneal haze is more common after very large corrections, in corneas that have had previous injuries or radial keratotomy, and in people who get thick skin scars (keloid scars) after injury or operations. Modern scanning spot lasers such as the laser at LVCCC are less likely to cause corneal haze.
Undercorrection and Overcorrection
While the excimer laser is very precisely computer-controlled, everyone responds slightly differently to laser treatment. This means that every patient has a chance of being slightly under or over corrected after laser treatment.
Under correction and over correction can occur after any laser procedure. Under correction is more common and small amounts of under correction are usually not a problem and do not significantly degrade distance vision. However if you are significantly under corrected, in most cases you can be retreated. With bladeless LASIK, re-treatments are usually performed at about three months. With ASLA, re-treatments are usually performed after six months.
If you are over corrected, you may be treated with eye drops, the wearing of a soft contact lens for several months, or possibly further laser treatment.
Under and over corrections are more common after large corrections for myopia. As it is easier and more predictable to treat under corrections than over corrections, for large myopic corrections, you may be deliberately under corrected to reduce the risk of an over correction. A re-treatment for the remaining short sight can then be performed once the eye has settled from the initial treatment. Usually one and occasionally two re-treatments are all that are necessary to obtain a satisfactory visual result.
Sometimes, however, it may not be possible to perform a re-treatment to correct any residual refractive error. If the initial treatment has been for a very large refractive error, there may be insufficient corneal thickness remaining to safely re-treat the remaining refractive error. With ASLA this is very uncommon. In this situation, you may have to accept that your short sight cannot be fully corrected.
In the first two years after your initial treatment, re-treatment will not incur any further cost to yourself at LVCCC.
Regression is the normal slight drift back towards short sight that occurs after laser treatment. It occurs as part of the normal healing response after laser treatment, where the epithelium on the surface of the eye and the underlying corneal tissue thickens slightly after laser treatment.
After six months, regression is very unlikely to occur. If your short sight increases again after this period, it is most likely to be due to a natural increase in your normal short sight.
Loss of Sharpness
Following laser treatment, a small percentage of patients experience a loss of sharpness of vision (best corrected visual acuity). This means that with any residual refractive error corrected with glasses or contact lenses, they are still unable to see as clearly as they did with the glasses or contact lenses they had before they had laser treatment, and they may be unable to read the bottom one or two lines of the eye chart.
This problem occurs more commonly after large corrections for short sight. The loss of best corrected visual acuity may be due to corneal haze or scarring, irregular healing of the cornea or decentration of the laser beam during the laser procedure. In most cases this loss of sharpness will improve over a period of 6 to 12 months but in some cases may be permanent.
Many patients find their eyes feel more dry after laser refractive surgery, and they may have to use artificial tears regularly to soothe the eyes. This problem is more common after LASIK than after ASLA. It usually improves over time, often taking several months to do so. In some cases however, the problem may be permanent. If you already have dry eyes or poor tear production prior to laser surgery, then you are more likely to have significant dry eye problems afterwards. This may mean you should avoid laser refractive surgery altogether.
Diffuse lamellar keratitis (DLK)
There may be an inflammation under the LASIK flap termed “sands of the Sahara syndrome”, or “DLK”, which may require lifting the flap and intensive use of eye-drops for a number of days. Most cases involve only mild inflammation and are managed with the use of topical eye-drops only.
Irregular astigmatism may cause reduced quality of vision and spectacles may not be effective in restoring useful clear vision. If wavefront-guided treatment cannot be performed to correct the optical problem then contact lenses may be required. They may be difficult to wear and may not fully restore the quality of vision. Further surgery may then be required.
The corneal epithelium may grow under the flap.
The creation of the LASIK flap and removal of some corneal tissue by the laser may weaken the cornea such that long-term bulging or “ectasia” occurs. To minimise this risk, at LVCCC all treatments must leave at least 300 microns of corneal tissue in the centre and corneal thickness is measured prior to treatment.
This may occur if there is a pre-existing squint or difficulty in balancing the eyes. Occasionally “double vision or a ghost image” may be perceived.
Corneal vascularisation (blood vessels growing into the cornea)
This is very rare after LASIK but may occur if there has been a serious corneal abscess (infection) or where there were pre-existing blood vessels in the cornea.
Corneal ulcer formation
This is very rare and is due to serious post-LASIK infection or inflammation.
Lens implant power and eye pressure measurements
In later life laser refractive surgery, as with any corneal surgery, can make the measurements for the lens implant power needed for cataract surgery more difficult. In addition, the interpretation of the eye pressure (IOP) when assessing possible glaucoma is more involved.
Recurrent corneal erosion (which may cause pain or a foreign body sensation)
This occurs when surface corneal epithelial cells are dislodged at the time of surgery and the surface heals only partially. There may be recurrent episodes of foreign body sensation. This problem can usually be treated successfully.
Ptosis (slight drooping of the upper eyelid)
Inflammation or steroid eye drops, and/or use of an eyelid clip during surgery may potentially cause this rare complication.
There is no evidence that the excimer laser treatment or lifting the LASIK flap is associated with cataract development. However if there are post-LASIK complications that require prolonged use of topical steroid eye-drops, then cataract formation may ensue.
You should also be aware that the eyes may be more susceptible to injury after LASIK without the protective effect afforded by spectacles. Protective eye-wear is recommended for very physical sports (e.g. rugby, martial arts etc.) particularly in the early post-operative period.
You should not rub your eyes in the early period after LASIK and you will be given protective goggles for the first week. Accidental trauma to the LASIK flap may dislodge the flap and require flap reposition or replacement.
The latest technologies such as Wavefront guided LASIK have been shown to deliver the clearest vision and fewest night vision symptoms and are least likely to require a touch-up procedure.