Customized LASIK Procedures
LASIK vision correction surgery has been a great improvement over earlier forms of vision correction surgery. Now it is about to get a whole lot better. Dr. Marguerite B. McDonald of Tulane University calls this new development "super vision," (or '20/10' vision). This new approach is being called CustomLASIK.
Currently, LASIK surgery, in a best-case scenario, can improve one's vision to 20/20, but there can also be some side effects, effects include reduced night vision, haziness, halos, and starbursts. This new technique can improve vision to 20/10 or even 20/8, which is better than 20/20! Beyond "super vision," doctors are also hoping that this new technique will improve night vision and decrease vision problems such as halos, haziness and starbursts.
Here is a brief overview of how this new Custom LASIK approach works:
There is a hierarchy to eye problems, what scientists call higher-order and lower-order aberrations. Many of these problems deal with the shape of the eye. Scientists have known for years that the shape of eyes can cause vision problems and that in order to achieve good vision, eyes should have a certain shape. This is basically what the current LASIK surgery does.
The surgeon measures the cornea's topography, or shape, and uses a precise laser to cut a flap in the cornea and fold it back. Researchers discovered that there was less pain and problems afterwards if they worked on the cornea's subsurface, rather than the outside of the cornea. Then the surgeon uses the laser to change the shape of the cornea's subsurface so it conforms to a standard shape, which has been found to improve vision. If the cornea is curved too steeply (causing nearsightedness) they make it more flat, if it is too flat (causing farsightedness) they make it more curved.
Current LASIK surgery only treats the lower-order aberrations, or smaller problems, with our eyes. Scientists have found that the current surgery techniques can actually increase the higher-order aberrations, which createt more problems. Eyesight is improved to 20/20, but sometimes with reduced night vision, haziness, halos, and starbursts.
The higher-order aberrations deal mainly with how light waves enter the eye and are refracted. Think back to elementary school science and the principle of the prism, the refraction through the eye is similar to the way light refracts through a prism. The refraction scatters light waves and what comes through the other side of the prism is a rainbow, which is not what went through it in the beginning. With vision, the light waves need to come straight through the eye and focus on one spot of the retina. What is needed is a flat plane of glass that will not distort the light waves as they come through the eye, not a prism.
Another way of looking at refraction is like sheets on a bed. When we making a bed, one tries to make the sheets smooth, without any wrinkles. The light rays that enter the eyes come at the eyes as flat sheets, or planes, of light. When they are refracted through the eye's lens, they become wrinkled. The wrinkling of the sheets, or planes of light, causes distortions in what is seen, making it difficult to focus on the images entering the eye.
With the current LASIK technology, doctors measure the outside shape of the cornea and correct it to a standard model of what should improve overall vision. It is a one-size-fits-all approach to improving eyesight. The new step in LASIK surgery not only takes the shape of the eye into account, but also measures the wavefront refraction, or wrinkles in the light, as they travel through the eye's lens. The doctor uses the LASIK surgery to change the shape of the eye to most closely decrease wrinkling or refraction of light as it travels through the eye. This is a customized approach to LASIK surgery.
When not only the outside shape of the eye is taken into account, but also the measurement of the light waves as they pass through the eye, the surgeon can improve eyesight to 20/10 and decrease higher-order aberrations, improving night vision and reducing haziness, halos and starbursts. The Custom LASIK procedure is more precise than the current procedure. The surgeon not only makes the cornea more curved or more flat, but if there is a small divot in the cornea, the surgeon flattens out that area. If there is a small bump, the surgeon flattens just that small bump. It is more customized to each individual eye than the current LASIK procedure which only changes the overall shape.
Scientists researching this new customized approach to LASIK surgery still have a great deal to learn about the overall and long-term effects of wavefront correction. According to EyeWorld magazine, FDA approval of Custom LASIK surgery is about 18 to 24 months away.