Just like a fingerprint, each person's vision is unique to their eyes. Until recent advancements in technology, doctors were only able to use standard measurement techniques to correct vision. Essentially, the same prescription was used to design glasses, contact lenses or a laser vision treatment procedure.
In 2003, refractive surgery experienced an exciting development when the US Food and Drug Administration (FDA) granted approval for custom laser vision correction, also known as custom LASIK. A fundamental change in the way LASIK surgery is done, this procedure measures and corrects the focusing imperfections unique to each person's vision.
How custom LASIK works
Custom laser technology was originally developed for use in sophisticated telescopes to reduce distortions, allowing distant objects in space to be seen more clearly. In preparation for custom LASIK, a patient looks into an instrument which uses the same technology (called "wavefront") to measure light as it travels through their eyes. As the light waves travel through their eye's optical system, any distortions are measured.
Light which passed through the patient's eyes is compared to light passing through an ideal eye. A three dimensional map or "optical fingerprint" of the patients eyes is created from the comparison.
The map of the ideal or perfect eye has a flat surface. Real eyes, however, have "wavy" maps like the image at the right. Wavy maps provide information about the unique optical imperfections (aberrations) in the patient's eyes. This information is transferred to a computer that guides the laser during the custom LASIK procedure.
Benefits of Custom LASIK
How much you see depends on what lower-order aberrations you have; lower-order aberrations are also called refractive errors and include myopia, hyperopia and astigmatism. Traditional LASIK treats these lower-order aberrations. Conventional LASIK is based on a patient's eyeglass prescription and does not include the measurements of the eye that wavefront technology provides.
How well you see depends on what higher-order aberrations you have; higher-order aberrations are irregularities other than refractive errors, and can cause such problems as decreased contrast sensitivity or night vision, glare, shadows and halos. Higher-order aberrations do not always affect vision.
Custom LASIK treats both lower- and higher-order aberrations. 20/20 is commonly referred to as "perfect" vision. But, with custom LASIK vision correction, individuals have the potential to see even better than 20/20. In several studies, six months after receiving a custom LASIK procedure more than 70% percent of patients tested saw 20/16 or better. In a custom LASIK trial conducted by the FDA, 98% of patients achieved 20/20 vision or better, without glasses or contacts.
Are you a good candidate?
According to the FDA, you must be at least 18 years old and your glasses or contact lens prescription must be stable for at least 1 year. Stability is defined as a change of 0.5 diopter or less in your prescription over the last year. You cannot be pregnant or nursing; you cannot have collagen vascular disease and you cannot be taking certain medications. In general, over 95% of people that wear glasses or contacts are good candidates. If you've been considering laser vision correction and you meet the above criteria, check with your eye doctor for more information.