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EYE PHYSICIAN AND SURGEON DIPLOMATE, AMERICAN BOARD OF OPHTHALMOLOGY |
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Guide Topics:
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The only way to know whether or not someone is a good candidate for Laser vision correction is to be examined by a qualified refractive surgeon. We therefore make it easy for someone to schedule an appointment for an evaluation. Simply contact our office and request a evaluation for Laser Vision Correction. If glasses or contact lenses are a burden and reduce enjoyment of daily living, Laser Vision Correction can help treat low to severe nearsightedness as well as astigmatism and hyperopia. You must meet certain requirements to be considered eligible for the LASIK procedure. The following represent a general description of the major criteria:
Additionally, the patient must have realistic expectations about the outcome of the procedure, understanding that complications, as in any surgical procedure, while rare, can result. Every person's situation is unique. In order to assess whether someone is a candidate, he or she must have a complimentary consultation with Dr. Tennen. |
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| Seeing is Believing... | |||||||||
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Today, there is much publicity regarding Laser Vision Correction. Laser Vision Correction consists of two different procedures which use a computerized laser to correct a person's refractive error (nearsightedness, farsightedness or astigmatism). These procedures are PhotoRefractive Keratectomy (PRK) and Laser Assisted In Situ Keratomileusis (LASIK).
Laser Vision Correction is exciting, but it is important that you understand as much as you can about it. A patient who has unrealistic expectations and falls short of them will be the unhappiest patient of all. Although our procedures have a high degree of success, we cannot, and do not, promise you 20/20 vision without eyewear correction. With Laser Vision Correction we can significantly reduce your dependence on glasses and contact lenses, but most patients need glasses for reading eventually and some may even need a thin pair of glasses for critical distance activities. It is best for you to think of this procedure not as eliminating your need for glasses, but reducing your dependence upon them and improving your vision. |
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| How the Eye Functions | |||||||||
The individual components of the eye work in a manner similar to a camera. Each part plays a vital role in providing clear vision. So think of the eye as a camera with the cornea, behaving much like a lens cover. As the eye's main focusing element, the cornea takes widely diverging rays of light and bends them through the pupil, the dark, round opening in the center of the colored iris. The iris and pupil act like the aperture of a camera, together controlling the amount of light that enters the eye.
Next in line is the lens which acts like the lens in a camera, helping to focus light to the back of the eye. Note that the lens is the part which becomes cloudy and is removed during cataract surgery to be replaced by an artificial implant nowadays. The very back of the eye is lined with a layer called the retina which acts very much like thefilm of the camera. The retina is a membrane containing photoreceptor nerve cells that lines the inside back wall of the eye. The photoreceptor nerve cells of the retina change the light rays into electrical impulses and send them through the optic nerve to the brain where an image is perceived. The center 10% of the retina is called the macula. This is responsible for your sharp vision, your reading vision. The peripheral retina is responsible for the peripheral vision. As with the camera, if the "film" is bad in the eye (i.e. the retina), no matter how good the rest of the eye is, you will not get a good picture. The human eye is remarkable. It accommodates to changing lighting conditions and focuses light rays originating from various distances from the eye. When all of the components of the eye function properly, light is converted to impulses and conveyed to the brain where an image is perceived. Clear vision is the result of light rays passing through the cornea, pupil and lens and focusing directly upon the retina. If the cornea is not round or is too steep or too flat in relation to the length of the eye, light rays focus either in front of or behind the retina, resulting in "refractive errors" such as nearsightedness, farsightedness and astigmatism. |
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| The Normal Eye | |||||||||
| In a normally structured eye, the cornea is a rounded curve. Light rays pass through the cornea and the pupil to the lens, which further "refracts" or focuses the light directly on to the retina creating a sharp and clear image. |
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| The Nearsighted (Myopic) Eye | |||||||||
Myopia is the medical term for nearsightedness. This is a condition in which light rays entering the eye are focused in front of the retina instead of directly on it as in the normal eye. Myopia is an inherited condition which usually begins in childhood and stabilizes in the late teens or early twenties. Roughly 25% of the population has this condition, making it the most common cause of refractive error.  The term "myopia" implies that you have trouble seeing in the distance without correction but have no trouble seeing objects that are near in your visual field.A myopic eye has too much focusing power. The extra focusing power is a result of an eyeball that is too long or a cornea that is too steep. The result is that the image we see falls short of the retina and is therefore improperly transmitted to the brain for processing.
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| The Farsighted (Hyperopic) Eye | |||||||||
| Hyperopia is the medical term for farsightedness. This is a condition in which light rays entering the eye are focused behind the retina instead of directly on it as in the normal eye. Hyperopia is an inherited condition which is present in childhood but does not become apparent to most people until their 30's, when their eye muscles no longer can overcome it. This term implies that near objects are blurred and those in the distance are clear. A hyperopic eye is one with too little focusing power. This results from an eyeball that is too short or a cornea that lacks curvature, or in other words is too flat. The result is that the image being focused wants to focus beyond the retina and is therefore improperly transmitted to the brain for processing resulting in blurred near vision. For all individuals over 40 years of age, the focusing mechanism of the eye weakens. The focusing change (called accommodation)
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| Presbyopia | |||||||||
| Presbyopia is a natural part of the aging process whereby special muscles within the eye weaken and the lens hardens. The result is that the accommodation process (the ability of the eye to alter the shape of the lens thereby intensifying the focusing effect) is inadequate for those objects that are near. Between the ages of 40 and 50 nearsighted individuals move into bifocals and most people who did not need corrective lenses prior to this age move into reading glasses. There is a technique that allows for the fitting of contact lenses to compensate for bifocals. This unique procedure is known as monovision and it serves to provide you with one eye that is dominant for distance vision and one eye that is dominant for near vision. The brain adapts to this setup and many patients have chosen to be free of bifocals and glasses by opting for this procedure. Your candidacy for monovision can be discussed with your Ophthalmologist or contact lens specialist. It is important to note that while Laser Vision Correction may eliminate the need for glasses due to refractive error, it will not eliminate the need for reading glasses due to middle age. A possible alternative is performing Laser Vision Correction on only one eye, thereby achieving monovision as detailed above. |
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| Astigmatism | |||||||||
When an eye is astigmatic it lacks a uniform surface and is thus unable to have one focal point. This asymmetry is due to the cornea being more curved or steeper at one axis than all the others. The astigmatic eye is an irregular curvature of the eye resulting in more than one focal point, preventing a sharp point focus on the retina. The concept is clearer as one considers a normal eye to be shaped like a basketball, while an astigmatic eye is shaped more like a football. Astigmatism is usually found in combination with myopia or hyperopia such that objects may appear blurry in the distance as well as up close.
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| Available Treatments | |||||||||
| Many people, who for years have depended on eye glasses or contact lenses, find them inconvenient, dislike their appearance and find they impose barriers to the freedom of everyday life!
Several treatments are currently available for the correction of myopia (nearsightedness), hyperopia (farsightedness) as well as astigmatism. Each treatment has specific benefits and risks, and different treatments can correct different amounts of your required prescription. |
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| Radial Keratotomy (RK) | |||||||||
| Radial Keratotomy (RK) is a surgical technique for treating mild to moderate levels of nearsightedness that involves the ophthalmologist making a pattern of freehand spoke-like micro-incisions on the cornea with a diamond-edged knife. Variations in the pattern of the micro-incisions can be used to treat astigmatism. RK has been refined and improved over the past 20 years in the U.S., but it is not as precise as the laser procedures. There is approximately a 30-35% chance of needing an enhancement or touch-up procedure to achieve desirable results. Visual recovery is less rapid than with the LASIK procedure, but more rapid than PRK. There is less post-operative discomfort than PRK, but more discomfort than LASIK. Radial Karatotomy however is rarely being done nowadays since the introduction of LASIK. Return to top of page. |
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| Astigmatic Keratotomy (AK) | |||||||||
| When astigmatism is present, very small incisions shaped like an arc can be in the surface of the eye (similar to RK) to correct for the astigmatism. This procedure is often done in conjunction with RK, but is not considered an option anymore with the advent of Laser Vision Correction. Return to top of page. |
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| Current Laser Treatments Include: | |||||||||
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Click HERE to learn more about Laser Vision Correction. |
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| Choosing a Doctor | |||||||||
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Only ophthalmologists (Eye MDs) are permitted to perform Laser Vision Corection. The American Academy of Ophthalmology website (www.eyenet.org) features a list of questions to ask your ophthalmologist prior to Lasik surgery. Ask your surgeon the following questions:
Unlike some of the discount laser eye "mills" who only allow you to see the surgeon for 15 minutes on the day of surgery, Dr. Tennen will thoroughly examine your eyes to determine if you are a good candidate for Laser Vision Correction. She will also answer all of your important questions and address any concerns herself. |
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