Treating a Common Condition with Uncommon Skill
Refractive errors of the eye occur when the eye has difficulty bending and focusing light. Caused by an abnormal shape and texture of the eye, this is a common condition that is sometimes hereditary, though it can also result from eye strain, eye trauma or surgery, an extremely thin cornea or even a disease such as diabetes.
Incidence of Refractive Error
For the best visual acuity, incoming light to the eye should be focused on the retina. Such a perfect eye does not need any eyeglasses. Should the light point of focus be in front or back of the retina, however, that would cause myopia (nearsightedness) or hyperopia (farsightedness), respectively. Myopic eyes need negative (concave) spectacle lenses and hyperopic eyes need positive (convex) spectacle lenses for correction.
Astigmatism is another type of refractive error, in which the power of the cornea varies in different meridians. In other words, the corneal shape appears slightly oval instead of circular.
In the United States, 30-40% of the population have some form of refractive error that needs correction. Refractive error is one of the most common causes of correctable visual impairment.
Amblyopia or Lazy Eye
During infancy and childhood, when growth and development of the eyes, visual pathways and brain occur most dramatically, it is critical that the eyes send a “clear vision” signal to the brain. Many diseases or conditions can affect vision clarity, including refractive error. Significant refractive error can cause “lazy eye” during childhood, due to sending “blurry vision” signals to the developing brain. If not recognized early, that blurry vision will continue for a lifetime, and there is no effective treatment for that. So it is critical for all children to get an eye exam at least once in infancy and again before starting school. The sooner treatment for amblyopia starts, the better the results will be.
For people who need eyeglasses or wear contact lenses, correction of their refractive error can lead to clear vision without contact lenses or eyeglasses that is absolutely amazing. It can significantly improve one’s quality of life.
With the invention of the excimer laser, or 193 nanometer laser, modern refractive surgery came into common use, and terms like LASIK (laser-assisted in situ keratomileusis) and PRK (Photorefractive Keratectomy) entered the refractive surgery vocabulary. This laser works by disconnecting carbon atom covalent bonds and leaves no scar on the cornea. Through screening and several specific tests, our surgical team at Advanced Eye Surgery clinic can determine if refractive surgery is right for you.
In a LASIK procedure, the surgeon must create a flap on the cornea, then apply the laser after the flap is lifted. A new version of LASIK eliminates the need for a blade, and the flap also is created with a laser called a femtosecond laser. This technique sometimes is referred to as all-laser LASIK. In PRK, laser treatment would occur on the surface of the cornea. These two LASIK methods are shown to be safe and efficient for correcting refractive error in good candidates. A decision about the type of laser treatment to be used is typically based on the level of refractive error and the cornea’s shape and thickness.
Healthy young eyes can accommodate, meaning that the thickness and curvature of the crystalline lens inside of the eye can change. It can focus on a faraway object and, for close work, on near objects. Around the ages of 45 to 50, our eyes start losing the ability to accommodate. So, many people in this age range will start to have blurry near vision and would most likely need “reading glasses”. This condition is called presbyopia. Yet there are options to be free of reading glasses, as well.
Multifocal lens implantation, at the time of cataract surgery, is the most popular option. Monovision LASIK performed at the time of cataract surgery is another. There is an approved inlay, called KAMRA, that helps with presbyopia and improves near sight. Another possibility, Presbia Microlens, awaits approval after conclusion of investigational studies. Both KAMRA and Presbia Microlens are implanted in the thickness of the cornea.
Perfecting and Correcting
Refractive error is a common eye condition that, at least for the time-being, should be accepted as a fact of life – especially as we age. The good news is that it can corrected with various treatments and surgical procedures. Our experienced ophthalmologists will be happy to sit down with you and advise you as to the best options for your specific situation.