Frequently Asked Questions
About: The Wilmer Eye Institute
- What qualifications should I look for in a laser eye surgeon?
- What are the qualifications of Wilmer's laser eye surgeons?
- What is The Wilmer Eye Institute?
- What is a corneal fellowship?
- What types of research are important in improving laser eye surgery?
- Why is it beneficial to have a Wilmer faculty member perform your surgery?
About: Laser Surgery
- What is a refractive error?
- What are the types of refractive errors?
- How is a refractive error measured and what is a diopter?
- How can a refractive error be corrected?
- What are surgical options for correction of myopia (nearsightedness)?
- What are surgical options for correction of astigmatism?
- What are surgical options for correction of hyperopia (farsightedness)?
- How does laser vision correction work?
- What is LASIK?
- What is PRK?
- What is LASEK?
- What are corneal rings?
- What are phakic intraocular lenses?
- Am I a good candidate for refractive surgery?
- Are there contraindications to the surgery?
- Is there a problem if I wear contact lenses?
Laser eye surgery treats the cornea, the clear outer surface of the eye. So at Wilmer, we think a laser surgeon should be a corneal specialist, an expert who routinely performs corneal transplants, treats corneal abrasions and infections, performs corneal healing research, teaches other doctors about the cornea, and handles challenging cornea cases. A laser surgeon who is a corneal specialist will:
- See laser eye surgery as one of several ways to improve your vision-- not the only way.
- Detect subtle corneal conditions that may require caution when considering laser eye surgery.
- Know how the cornea ages and recommend laser eye surgery with your long-term vision health in mind.
- Manage your progress after surgery for best results while continuing to provide data.
At Wilmer, our laser surgeons are board-certified ophthalmologists, fellowship-trained cornea specialists, and full-time faculty members of the Johns Hopkins Wilmer Eye Institute. They are highly trained experts who can help you understand laser vision correction and its impact on your long-term vision health; help you have a safe and successful procedure; and help you maintain good vision health throughout your life. Laser surgery is not the best choice for every patient. Rely on your Wilmer surgeon for information and advice.
The Wilmer Laser Vision Center is the part of The Wilmer Eye Institute that performs laser eye surgery. Established at Johns Hopkins in 1925, the Wilmer Eye Institute has repeatedly been ranked the nation's #1 center for eye care in surveys by U.S. News & World Report magazine. That survey asks the opinions of doctors only, so it is the nation's physicians who have consistently put Wilmer at the top. Wilmer has additionally received the top ranking from Ophthalmology Times, which surveys eye doctors specifically.
The doctors at the Wilmer Eye Institute are part of a very special tradition. In addition to providing world-class care, Wilmer trains more eye experts, and is entrusted to perform more eye research, than any other center, resulting in amazing advances in eye care. When you visit Wilmer today, you will receive care from doctors who are creating new eye treatments based on the very latest research/knowledge available, putting all of Wilmer's long tradition of excellence in the service available of your vision health.
A corneal fellowship is a course of advanced study and practice in all aspects of corneal disease and care. Typically, a physician who is interested in eye care first enrolls in a residency program in ophthalmology. The residency program provides training in all areas of the eye, eye diseases, and eye care, and may enable the physician to become a board-certified ophthalmologist. For ophthalmologists who have a strong interest in one area of the eye, fellowship programs provide a mechanism for advanced specialization in that area, and should involve not only medical and surgical care but also research in advanced topics and the teaching of other doctors. A fellowship is considered the ultimate in training for an eye doctor.
The cornea is the outer surface of the eye and thus is easily subject to a range of problems such as abrasion and other trauma, infection, and inflammation. Of course, corneal surgery may open the cornea to these same challenges. Thus, a major area of corneal research is corneal healing: how to bring the cornea back to full function after a problem occurs or after surgery. A laser surgeon who performs corneal healing research is not only likely to know the latest advances in the field, but also to be highly aware of potential post-operative problems and how to prevent or solve them.
An ophthalmologist who teaches other eye doctors will likely be extremely well versed in the subject. But more than this, a teaching ophthalmologist is likely to be able to explain your vision health, and a plan of action, in terms you can understand.
To refract means to bend. When you have a refractive error, the light rays going into your eye are bent and focused by the cornea and lens in such a way that they are not focused on the retina and thus form a blurred image.
The four major types of refractive error are myopia (nearsightedness), hyperopia (farsightedness), astigmatism, and presbyopia.
The most common refractive error is myopia or nearsightedness, whereby the light rays are focused in front of the retina. In astigmatism, irregular curvature of the cornea and lens results in the image being focused on different planes not coinciding with the retina. Hyperopia or farsightedness occurs when the light rays are not bent enough and the image is focused behind the retina. You can also have a combination of myopic astigmatism or hyperopic astigmatism. Presbyopia is a loss of the elasticity of the naturally occurring crystalline lens whereby individuals cannot focus clearly at close distances and need reading aids. This becomes apparent around the fourth decade of life.
When you read a prescription, a minus sign means nearsightedness and a plus sign means farsightedness. The first number in the prescription indicates the amount of myopia or hyperopia you have. If there are numbers written in the next two columns, these indicate the amount of astigmatism, if any, and the axis where it is present. The unit to measure a refractive error is called a diopter or D. For example, if your prescription says -2 or -2D or -2 sph or -2 sphere, it means that you are nearsighted and require 2 diopters of correction. A diopter is a unit of measurement related to the focal length of an optical system including the human eye. The larger the diopter the shorter the focal length.
The standard method for correction of any refractive error is glasses or contact lenses. A newer correction available is Corneal Refractive Therapy (CRT), available from Wilmer's optometrists at Green Spring Station, which uses special contact lenses that mold the cornea. There are also several types of surgical options depending on the type of refractive error; some options use lasers, some do not.
The most common surgical procedures are the excimer-laser-based procedures called LASIK (laser assisted in-situ keratomileusis) and photorefractive keratectomy (PRK); in addition our surgeons perform corneal rings and intraocular lense implants.
If the astigmatism is combined with myopia or hyperopia, the surgeon can correct astigmatism using LASIK or PRK. If the astigmatism is not combined with myopia or hyperopia, non-laser incisional methods such as astigmatic keratotomy (AK) may be used.
Wavefront-guided LASIK and LASEK are approved for correction of farsightedness.
Laser vision correction changes the curvature of the cornea, one of the structures of the eye that focuses light on the retina. If the eye is too large or the cornea's curvature too great, light focuses improperly and distant objects appear blurred. This is called nearsightedness or myopia. If the cornea's curvature is too flat, close objects appear blurred. This is called farsightedness or hyperopia. With the laser we can reshape the contour of the cornea by sculpting extremely small amounts of corneal tissue. The four types of laser treatment we use are called Wavefront-guided LASIK, LASIK, PRK and LASEK.
|LASIK, or laser-assisted in-situ keratomileusis, combines delicate surgical procedures and laser treatment. First we surgically create a "flap" of corneal tissue less than a third the thickness of a human hair, and lift the flap to one side. We then apply laser energy to reshape the cornea according to carefully calculated measurements. When treating nearsightedness, we use the laser to decrease the cornea's relative curvature. When treating farsightedness, we increase the cornea's relative curvature. We then reposition the corneal flap. A naturally-adhering bandage, the flap helps to improve results and speed recovery. LASIK may be used for nearsightedness, nearsightedness plus astigmatism, farsightedness, and farsightedness plus astigmatism.|
|In PRK, or photorefractive keratectomy, we apply the laser directly to the cornea according to carefully calculated measurements, without creating a flap. For nearsightedness we decrease the relative curvature; for farsightedness we increase the relative curvature. At the conclusion of the procedure we place a transparent "bandage" contact lens over the cornea to promote healing. PRK is presently used to treat nearsightedness, nearsightedness plus astigmatism, farsightedness, and farsightedness plus astigmatism.|
|In LASEK, or laser epithelial keratomileusis, we surgically treat the outermost layer of the cornea to create and move aside a sheet of cells a third the thickness of a LASIK flap (see "The LASIK treatment"). We then apply the laser to reshape the cornea. For nearsightedness we decrease the relative curvature; for farsightedness we increase the relative curvature. At the conclusion of the procedure we replace the sheet of cells and cover the cornea with a transparent "bandage" contact lens to promote healing. LASEK is presently used to treat nearsightedness, nearsightedness plus astigmatism, farsightedness, and farsightedness plus astigmatism. LASEK is reserved for patients who have thin corneas, are at risk of occupational damage to the eye, are reluctant to have a LASIK flap, or have corneal disease that precludes the LASIK procedure.|
|In the corneal ring segment treatment, we make an incision in the side of the cornea, place a tiny plastic ring inside the cornea to flatten its curvature, then close the incision. The ring treats mild nearsightedness and mild astigmatism in patients with very thin corneas, and may be used to treat a disorder called keratoconus. The rings are not visible to the patient or to others, and may be removed if necessary.|
|The phakic intraocular lens, which has recently been FDA approved is a non-laser treatment. In the intraocular lens treatment we make an incision in the side of the cornea, place an artificial lens between the iris and the eye's natural lens, then close the incision. The treatment is a potential alternative for patients whose refractive error is outside that treated by LASIK-higher nearsightedness and farsightedness. The lens is not visible to the patient or to others, and may be removed if necessary.|
You should be at least be 21 years of age to ensure stable vision, and should not have scars in the cornea or any autoimmune diseases. A complete evaluation by a specially trained Wilmer optometrist, together with a Wilmer laser surgeon, is required to determine if you are a candidate. The evaluation lasts 1 - 2 hours and includes a complete dilated eye exam, refraction, and corneal topography exam.
There are certain medications that should be discontinued prior to surgery. Persons who are pregnant or nursing should postpone their surgery until their hormonal status is back to normal. People with certain corneal conditions such as keratoconus should be excluded prior to surgery.
You should discontinue contact lens wear prior to your evaluation. Long-term contact lens wear can cause reversible surface changes in the cornea also known as corneal warpage. Soft contact lenses should therefore be removed at least two weeks prior and hard or rigid gas-permeable lenses at least three weeks prior to the evaluation.