To be able to see sharply again – without glasses or contact lenses – that is what LASIK promises. LASIK (laser in situ keratomileusis) is a laser eye surgery procedure performed since 1990. The goal is the correction of optical refractive errors. LASIK is in demand: in Germany alone, the number of laser eye surgeries amounts to more than 100,000 annually – and the trend is rising. The German Association of Specialty Clinics for Eye Laser and Refractive Surgery even expects an annual increase in LASIK surgeries by an average of seven percent by 2015. There’s no question about it: LASIK is booming; LASIK is currently considered the go-to procedure for refractive surgery.
What is LASIK?
Schematic diagram for LASIK eye surgery. Click to enlarge. Unlike eyeglasses or contact lenses, which are merely “aids” to correct an existing vision problem, LASIK addresses the root of the evil: the vision problem itself. LASIK is considered an effective eye surgery procedure for myopia, hyperopia and astigmatism. The limits of correction are: -10 diopters for nearsightedness, +4 diopters for farsightedness and 5 diopters for astigmatism. However, these limits are not to be understood as rigid: In addition to country- and clinic-specific peculiarities, laser-specific constellations can also shift these limits, so that ultimately one or two diopters more or less can be the result. The most important prerequisite for LASIK is a certain thickness of the cornea. The residual thickness remaining after the operation must not be less than 250 µm. If this is not guaranteed, the operation must not be performed. Another contraindication, according to which LASIK treatment is prohibited, concerns chronic progressive corneal diseases. The same applies to eye diseases such as glaucoma and cataract. General diseases – for example, autoimmune diseases – also prohibit LASIK surgery.
Function, effect, and goals
LASIK is a type of eye surgery in which part of the cornea is removed – and it is largely painless: After administration of anesthetic eye drops and their effect has occurred, the operation also begins. With the help of a precision scalpel, a microkeratome, the so-called flap – that is a small lid – is created on the corneal surface. For this purpose, the upper pain-sensitive layer of the cornea is opened by means of a very thin incision on one outer side. This allows the layer underneath to be exposed and cornea to be selectively removed at various points. The laser performs the latter: In the micrometer range, the laser beam models the corneal tissue and thus gives the cornea exactly the right curvature. The flap is then folded back into its original position. After only a few minutes, the outpatient procedure is over, and the patient can go home – provided with instructions for his behavior in the following days. Sharp vision should return shortly after the procedure – at least in the ideal case. Of course, the regeneration of the flap in particular must be allowed some time, which is why eye rubbing and the like must be strictly avoided. And: In the first nights after treatment, an eye patch is an absolute must anyway, as are eye drops.
Risks, side effects and dangers
Although foreign body sensations when blinking or dry eyes as well as glare in sunlight and at night are frequent side effects after LASIK surgery, they disappear after three months at the latest in 95 percent of patients. Only less than one percent of all LASIK patients experience complications during surgery. These usually relate to the flap. Last but not least, in addition to individual influencing factors and the number of dioptres to be corrected, the experience of the surgeon performing the operation and the technique used also play a decisive role in the success of LASIK treatment. Risks also arise from the LASIK procedure itself: For example, preparation of the flap can lead to severing of corneal nerves. Epithelial cells can also grow under the flap, causing opacities. In the worst case, the flap can also tear off – especially after sports accidents. However, these are absolute exceptions. The most serious problem, however, concerns the structural weakening of the cornea after tissue reduction. However, trained doctors and modern equipment largely minimize these weaknesses of the LASIK procedure.The results of LASIK are apparently satisfactory overall, as evidenced by patients’ statements: 90 percent of patients are satisfied after their LASIK treatment – that’s what an American study says. However, even LASIK is not free of risks and possible complications, and here the opinions and assessments of ophthalmologists and other experts sometimes differ. The weighing of risks and benefits is a constant source of controversy among experts. So far, no results are available on possible LASIK late effects: This is due to the fact that LASIK operations have only been performed since 1990. Last but not least, there are discussions about the medical necessity of LASIK: Some experts see it more as a “lifestyle surgery”. In addition, many patients apparently do not take LASIK seriously enough: They do not really regard it as an operation, which it nevertheless is. All the more importantly a proper and professional clearing-up of the patients seems, so that at the end the visible quality of life can become also reality – as with 90 per cent of the patients: The visual acuity after LASIK surgery with modern devices is a maximum of 0.5 diopters above or below the target value envisaged. An apparently calculable risk – as the sharp look then reveals later.
