LASIK (laser-assisted in situ keratomileusis) surgery was first approved for use in the United States in 1995 and remains one of the most popular vision correction procedures. It involves making a thin flap in the cor
LASIK (laser-assisted in situ keratomileusis) surgery was first approved for use in the United States in 1995 and remains one of the most popular vision correction procedures. It involves making a thin flap in the cornea and reshaping of the corneal surface.
For patients whose corneas are too thin or who have other conditions, surgeons use laser treatments to the outer layer of cells on the cornea. These are called PRK (photorefractive keratectomy), LASEK (laser epithelial keratomileusis) or Epi-LASIK surgery.
Patients can see near objects clearly but things at a distance are blurred. Myopia usually results when the eye is too large or elongated, which causes light entering the eye to focus before reaching the retina.
Patients have good distance vision but close-up objects appear blurred. Hyperopia is due to the eye being smaller than normal, causing light entering the eye from close-in objects to come into focus too far behind the retina.
This can impair both near and far vision. It occurs when the cornea and eye lens is oval in shape instead of round, which lets light focus on several points on the retina instead of one, causing blurring. Astigmatism often occurs with myopia or hyperopia.
Presbyopia (aging eyes)
Most patients begin to experience “old-eyes” in their 40s, a function of natural aging as the eye lens hardens and loses the flexibility to focus on close-up objects.
For patients with extreme nearsightedness, thin corneas or other conditions, surgeons can implant an intraocular lens. Implantable lenses are also being developed for patients with farsightedness and astigmatism.
A cataract is a clouding of the transparent dome-shaped surface of the eye that prevents light from reaching the retina. It results in blurred vision, glare and halos around objects. There are three types of cataracts:
- Nuclear cataracts form in the nucleus or center of the lens, usually as a patient ages.
- Cortical cataracts form in the cortex, outside the eye lens. Over time, this cataract extends from the outside to the inside of the lens. They are common in diabetic patients.
- Subcapsular cataracts form at the back of the lens. This type of cataract is common in diabetics, people taking steroid medication and those who are farsighted or have retinitis pigmentosa.
It isn’t known why cataracts form. But some common risk factors include ultraviolet light exposure, diabetes, steroid medication, cigarette smoking and heavy alcohol consumption.
Small or slowly developing cataracts can be countered with prescription glasses or bifocals and avoiding activity such as driving at night. Patients whose cataracts impair visual function often have surgery to replace the natural lens with a soft plastic intraocular lens (IOL).
This microsurgery, involving tiny incisions, is performed in an outpatient ambulatory surgery center. In most cases, the procedure is completed painlessly in less than 20 minutes. Most patients find their vision improved immediately after the surgery.
Macular degeneration, or age-related macular degeneration (AMD), is a disease that gradually destroys the macula, the part of the eye that is responsible for central visual acuity.
A leading cause of vision loss in Americans age 60 and older, AMD causes no pain and, in some cases, advances so slowly that people notice little change. In other patients, the disease progresses quickly and may lead to a loss of vision in both eyes. It occurs in two forms:
- In dry AMD, the macula’s light-sensitive cells break down slowly, causing a gradual blurring of central vision. Over time, as less of the macula functions, central vision is lost in the affected eye.
- In wet AMD, abnormal blood vessels behind the retina start to grow under the macula. These vessels tend to be fragile and often leak blood and fluid, which pushes the macula from its position at the back of the eye and results in rapid loss of central vision.
An early symptom of wet AMD is that straight lines appear wavy. In dry AMD, the most common symptom is slightly blurred vision, difficulty recognizing faces, reading and performing other tasks. The central vision