|
| Click here to skip straight to Conclusion |
 Is there no end to the variations and types of laser treatment available today in Israel for those of us who wear glasses? Whether it’s LASIK, superLASIK, intraLASIK, PRK, LASEK, or epiLASIK, it’s all extremely confusing even for the most enthusiastic patient who is about to undergo this life changing laser eye surgery. Is any technique really better than any other? How do doctors decide what to recommend, and how do you decide what to choose?
The facts are that thousands around the world continue to undergo what continues to be, in the US at least, the most popular laser operation in medicine. Despite claims of superiority by most laser centres who assure you that their technique is best, the truth is results are superb from almost anywhere using latest generation technology and experienced surgeons. These days unhappy patients are a distinct rarity.
Laser eye surgery for vision correction works by reshaping the curvature of the transparent layer of the eye in front of the pupil, called the cornea. The laser evaporates corneal tissue elegantly and delicately, making it flatter in short sighted (myopic) people and steeper in the long sighted (hyperopic).
Overall there are really just two laser techniques, the difference being where on the cornea the laser is performed-either on the surface, or deeper under a thin flap of corneal tissue.
The first technique which can be called "surface treatment" as the laser affects the surface of the cornea directly, involves the gentle removal of the outer skin-like layer of cells called the epithelium, exposing the tissue below which then receives the laser. After the treatment there is a period of about 2-3 days when the eyes are uncomfortable, tender and watery with blurry vision as the epithelium grows back and the eye surface heals. The original name of this technique is Photorefractive Keratectomy or PRK and is the longest established laser technique with over 26 years follow up, stable long term results and is extremely safe.
ASA. Laser applied directly to surface of the cornea, without any cutting of a flap as in Lasik (see below)
Although first performed in 1987 PRK today is a much better procedure due the very advanced laser technology and more controlled post operative healing and pain relief techniques. Dr Fink refers to the procedure today as ASA (Advanced Surface Ablation)
Epi-Lasik and Lasek are almost the same as PRK except both remove the epithelium in such a way (the former mechanically with a blunt instrument which slides across the eye, the latter with dilute alcohol which chemically loosens the tissue) that it can be replaced again afterwards. Some claim that by replacing the epithelium, recovery is more comfortable and may give better visual results especially with high prescriptions. These claims are controversial and not universally accepted, as tests have shown that the original epithelium tends to dissolve and is in any case replaced by fresh epithelium growing in.
The safety and ultimate vision are the same for all surface techniques- excellent . The main and very rare complication (Dr Fink has had 2 cases in 11 years both of which healed up without any problem). In contrast the chance of developing an infection if you wear contact lenses for many years is considered to be on average about 5 times. Scarring of the cornea can rarely occur with high prescriptions, but this has almost become a thing of the past with newest techniques.
The second group of techniques used in laser vision correction involves cutting the cornea, and raising about 20% of the corneal thickness as a flap on a hinge- and more invasive and complicated procedure. The big advantage is that as the laser treatment is under the flap which is immediately replaced after the laser ablation, and not exposed as in the surface treatments, recovery is much quicker, most seeing well the next day with no discomfort beyond the first few hours. The average cornea is slightly more than half a millimetre thick in the centre (500microns) and the flap is usually between 100-160 microns in thickness, which is folded back on a hinge of uncut cornea (see diagram).
LASIK. Side view of eye with partial thickness corneal flap raised, laser performed on the exposed surface underneath, and flap replaced (figures top to bottom)
Most laser centres use an instrument called a microkeratome, which consists of a sharp oscillating and computerised blade that moves across the eye cutting the flap as it passes. This technique is called LASIK and is the most well known by today's laser candidates. It is also extremely safe, although on the very rare occasions that a problem occurs during laser vision correction treatments, it is usually connected with the flap.
IntraLASIK or Z-Lasik techniques use a special laser (femtosecond laser) to cut the flap (and another laser machine to perform the actual treatment of removing the glasses prescription). Supporters of femtosecond laser claim that it is safer than an oscillating blade, and that it creates more accurate and thinner flaps. Some studies seem to support this, but in fact modern microkeratomes are also extremely safe, can also create thin flaps, and only very rarely cause complications- and even when they do, they rarely cause significant long term problems for the patient. There have been few studies comparing femtosecond laser with modern microkeratomes so the issue is still controversial. Also there have been on rare occasions complications with femtosecond laser flaps also. Femtosecond laser treatments are generally much more expensive.
Some studies have shown that femtosecond laser may potentially give better quality vision afterwards but this is controversial also and moreover the importance of the laser machine that performs the actual vision correction treatment itself is far greater. Femtosecond laser does cause more eye inflammation than regular LASIK (although it settles without any problems usually) and is less comfortable for the patient. In addition the femtosecond laser cut is not as clean as with a sharp blade and requires more manipulation by the surgeon to raise it, but again this is rarely a problem.
Other marketing terms such as super-LASIK, ultra-LASIK and i-Lasik are just that-marketing terms.
The main long term concern with LASIK and femtosecond Laser is that by cutting the cornea, it becomes structurally weaker. In about 1 in several thousand cases, and possibly much more frequently (exact figures are difficult to determine as not all case are reported), after a few years the cornea can start to bulge out (a condition called ectasia) causing severe astigmatism, irreversible damage to vision and even a need for a corneal graft. Most at risk cases of ectasia can be predicted in advance e.g. candidates with thin corneas,younger patients, high prescriptions, and they can safely be offered a ASA surface treatment instead. But some cases occur for no obvious reason.
Conclusion
So what are the considerations when deciding which technique is best for you? Firstly of course any potential candidate needs to be assessed to make sure he is a good candidate for either technique. Some patients only suit surface treatment such as those with thin corneas, which makes the decision easier. In contrast hyperopic (far sighted) candidates (a minority in Israel) tend to have better visual results with Lasik.
For patients who suit both techniques the choice is between two very safe and successful techniques, and both of which give equally superb results. Surface treatment is a simpler operation but healing is slower requiring a few days off work (a small price to pay for the long term safety benefits) and vision takes a little longer to reach a good functioning level (3-5 days usually).
LASIK is a more complicated operation involving the cutting of a flap which is the main source of the rare problems that can occur during the laser vision correction procedure. There is also the issue of the very rare but serious long term problem of ectasia. But with more rapid healing, almost instant results and with little interruption in daily routine it continues to be very popular.
Whilst LASIK continues to be more heavily marketed by the large laser centres as the instant results are very dramatic-a high "WOW" factor-in private practice many more candidates are now seeing the advantages of ASA surface treatment.
Dr Fink will help you decide which treatment is most suitable for you at your clinic appointment.
|
צפו בסרטון אודות ניתוח בלייזר 
