laser vision correction
LASIK
Background
Laser vision correction in one form or another has been available for nearly 20 years. The exact techniques have of course evolved enormously over these years. One of the most major advancements was the development of LASIK or Laser in situ keratomileusis first performed in 1989. This technique revolutionised laser vision corrective surgery by providing rapid vision correction with reduced patient downtime compared to earlier PRK surface excimer laser. LASIK itself has continued to evolve so that today we have a computer controlled, highly refined procedure that takes less than ten minutes per eye and produces excellent, stable first day vision.
The LASIK procedure has three essential steps:
- The creation of a thin flap through the top layer of the cornea. This is achieved using a specialised device called a microkeratome. Once created the flap is gently folded over to allow application of the laser treatment.
- The excimer laser will then be locked to the eye and will resculpt the underlying cornea to change the optical focusing power of the eye as desired. This process generally takes around ten to thirty seconds and the entire procedure may require the removal of just a few micrometres of corneal tissue (typically around 1-2 times the width of a human hair).
- The flap is then gently replaced into position and will settle back into normal position without any stitches being required.
Which type of Ablation Profile is best?
There are currently 3 major types of ablation profile performed at the Yorkshire Eye Hospital. All three provide very good results and I will help guide you in choosing the most appropriate treatment profile. The three options are:
Plano-Scan
This refers to the simplest treatment profile which in many cases can still produce excellent vision correction. In this treatment the LASER reshaping is aiming to correct only simpler optical aberrations. For example if your optical prescription is written as -3.5/+1.25*90 then the laser will attempt to correct only the -3.5D of myopia and the +1.25D of astigmatism. This type of LASIK has been used for many years and produces really very predictable results. The nature of the corneal reshaping however can lead to the induction of other more complex optical aberrations after this type of LASIK. For this reason patients with higher optical errors, larger pupils or with known preexisting higher optical aberrations are better suited to one of the two alternative treatment profiles.
Aspheric
This is a more sophisticated treatment profile. The essential advantage is that the corneal reshaping is done in a finer, more selective way resulting in excellent vision correction but without inducing one of the main types of higher optical aberration termed “spherical aberration”. By not inducing this particular aberration patients may experience better dim light visual performance (for example driving at night). This treatment profile is best suited to patients who have larger optical errors, ±larger pupil size in dim light and where there is minimal pre-existing higher order aberrations.
Wavefront Personalised “ZYOPTIX”
Wavefront analysis is a technology first used by astronomers to help refocus blurred images from high powered telescopes. Wavefront assessment known as “aberrometry” is based on the principle that if an eye had no imperfections at all, a single point of light passing to the retina would not scatter and be seen as a tiny single point of light at the retina. However as no optical system is perfect & some light scattering occurs in all eyes. The light scattering patterns are termed the wavefront. Rather like a fingerprint no two eyes will show exactly the same wavefront. Our market leading wavefront analyser is mated to an exceptional Laser platform which includes Iris recognition with high frequency 3 dimensional eye tracking technology to help ensure that laser energy is applied in the most precise way possible. The final result is state of the art customised laser correction that allows reduction of pre existing higher optical aberrations whilst simultaneously minimising the induction of further aberrations after treatment.
Clinical Results of “ZYOPTIX”
Zyoptix personalised wavefront guided LASIK offers the following clinically proven benefits:
- Zyoptix provides excellent quality of vision in all lighting conditions.
- Over 80% of Zyoptix treated patients reported “same or better quality of vision in all light conditions.
- 90.7% reported the same or fewer difficulties with night driving.
- Outstanding visual acuity with 91.3% of patients achieving 20/20 (6/6) vision.
- Zyoptix treated patients reported less problems with night driving, haloes & glare when compared to standard LASIK.
- 97% reported a “marked or extreme improvement in the quality of their vision
- 98.8% of patients treated with Zyoptix were “very satisfied” with their treatment and would recommend it.
Results
