Traditional vs. Custom LASIK
The goal of LASIK is to decrease dependence on corrective lenses.
In people with perfect eyesight, light that passes through the cornea and the lens will come to a clear focus on the retina. In some people, light is bent (refracted) too strongly and comes to a focus before it reaches the retina. In others, the light is not focused strongly enough and would focus behind the retina if it could pass through that non-transparent tissue. A LASIK procedure uses a precise laser to reshape the cornea so that it will bend incoming light correctly for a clear focus.
Diagnosis for LASIK
In any medical procedure, LASIK or otherwise, the effectiveness of your treatment depends on the accuracy of your diagnosis. In the early days of LASIK, diagnosis was done with the same equipment used for determining a glasses prescription. That equipment, called a phoropter, places successive lenses between your eye looking through the aperture and the Snellen eye chart visible inside the phoropter. The eye doctor asks you to read the smallest line of letters that you can see clearly through each lens.
This type of diagnosis enables treatments which correct only the three lower order aberrations:
There are also many higher order aberrations – microscopic defects in the corneal surface. Each one causes a subtle defect in vision such as halos around lights at night or spiky glare around lights. Traditional LASIK surgeries did not treat these vision defects because they did not diagnose them.
A more precise LASIK surgery is Custom LASIK which uses Wavefront technology to diagnose both lower and higher order aberrations. Wavefront diagnosis creates two detailed maps, one for each eye. They are color-coded and show in three dimensions the exact microscopic contours of each cornea.
Your LASIK surgeon bases the treatment for each eye on these two maps. The LASIK system computer which stores your diagnostic data guides the treatment laser, under your eye surgeon’s control, in implementing your individualized treatments. The result is such personalized vision correction that nobody in the world will ever have that same treatment. That is because every human eye is unique in its tiny aberrations.
To correct nearsightedness (myopia), the laser flattens the central corneal surface, reducing the cornea’s refractive power slightly and enabling light to focus on the retina
To correct farsightedness (hyperopia), the laser flattens the peripheral or outer edge of the cornea, causing the central portion to steepen and increase its power of refraction
To correct astigmatism, (blurry vision) the laser reshapes portions of the cornea in a customized plan, making the corneal shape more spherical rather than elliptical.
To correct higher order aberrations, the laser removes very tiny pieces of corneal tissue in addition to what is removed to treat the three lower order aberrations.
The LASIK Procedure Steps
The procedure begins with anesthesia drops to numb and dilate your eyes. You will be awake and alert during the procedure.
- Your eye doctor uses a microkeratome to separate a precisely-calculated layer of the cornea from the front of the eye
- This corneal flap is then folded back to one side while remaining attached during the procedure.
- The excimer laser delivers a programmed number of pulses of cool ultraviolet light to reshape the cornea according to your treatment plan.
- The corneal flap is put back in place. The eye holds the flap in place naturally as it heals, so no stitches are needed.
The entire procedure takes only about 15 minutes per eye.
Immediately after your surgery, you will stay in a recovery room for perhaps an hour or so. Your LASIK surgeon will monitor your recovery and make sure you are ready to go home. Many people are able to see clearly right away, but you may experience slight blurriness for a day or two.
Your vision may continue to improve over the next few months. Make sure you follow your eye surgeon’s post-operative instructions carefully. This is essential to minimize the risk of infection and maximize your vision improvement.
To find an experienced and well-qualified LASIK surgeon in your area, please use the links below.