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Eye Care Articles

Outcome Statistics

For many patients, the most important question after refractive surgery is "Can I See 20/20?"

The answer to that is not as simple as it might seem. A good result for one patient might indeed be 20/20 vision. However, the procedure shouldn't be deemed a failure if you don't achieve 20/20 vision after LASIK. The American Academy of Ophthalmology (AAO) reports that seven out of 10 patients achieve 20/20 vision, but 20/20 does not always mean perfect vision.

While visual acuity (20/20, 20/40, etc.) is a useful clinical test of vision, it is not the only measurement of vision. For example, eye charts do not assess sensitivity to different shades of gray, how your vision is affected at night or in dim light, or how effectively your eyes change and maintain focus. LASIK cannot provide perfect vision every time for every patient.

Success depends upon a number of factors: the laser system used, the patient's physiology and last, but not least, the skill of the surgeon. Even successful surgery seems to be defined differently by doctors and patients.

The American Society of Cataract and Refractive Surgery represents about 9,000 eye surgeons nationwide. It estimated that 97 percent of LASIK surgeries are successful -- meaning, the patient "achieves a visual outcome that meets their goals and expectations and allows them to be free of glasses and contact lenses for all or most of their activities."

FDA experts put the dissatisfaction numbers much higher. As recently as Aug. 1, 2002, members of the FDA's Ophthalmic Devices Panel put the number of unsatisfied or extremely unsatisfied patients at approximately 10 percent for a variety of laser-based refractive surgeries. They also expect 20 percent, or one person in five, to lose "low contrast acuity" -- that is, they will be able to see less on an eye chart.

As a result, reliable and quantifiable statistics are difficult to come by. The Food and Drug Administration is perhaps the best source and most authoritative source for statistics but those vary by the types of laser systems.

Complications and Side Effects

Most patients are very pleased with the results of their refractive surgery. However, like any other medical procedure, there are risks involved. That's why it is important for you to understand the limitations and possible complications of refractive surgery.

Before undergoing a refractive procedure, you should carefully weigh the risks and benefits based on your own personal value system, and try to avoid being influenced by friends that have had the procedure or doctors encouraging you to do so.

  • Some patients lose vision. Some patients lose lines of vision on the vision chart that cannot be corrected with glasses, contact lenses, or surgery as a result of treatment.
  • Some patients develop debilitating visual symptoms. Some patients develop glare, halos, and/or double vision that can seriously affect nighttime vision. Even with good vision on the vision chart, some patients do not see as well in situations of low contrast, such as at night or in fog, after treatment as compared to before treatment.
  • You may be under treated or over treated. Only a certain percent of patients achieve 20/20 vision without glasses or contacts. You may require additional treatment, but additional treatment may not be possible. You may still need glasses or contact lenses after surgery. This may be true even if you only required a very weak prescription before surgery. If you used reading glasses before surgery, you may still need reading glasses after surgery.
  • Some patients may develop severe dry eye syndrome. As a result of surgery, your eye may not be able to produce enough tears to keep the eye moist and comfortable. Dry eye not only causes discomfort, but can reduce visual quality due to intermittent blurring and other visual symptoms. This condition may be permanent. Intensive drop therapy and use of plugs or other procedures may be required.
  • Results are generally not as good in patients with very large refractive errors of any type. You should discuss your expectations with your doctor and realize that you may still require glasses or contacts after the surgery.
  • For some farsighted patients, results may diminish with age. If you are farsighted, the level of improved vision you experience after surgery may decrease with age.
  • Long-term data is not available. LASIK is a relatively new technology. The first laser was approved for LASIK eye surgery in 1998. Therefore, the long-term safety and effectiveness of LASIK surgery is not known.