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How the Eye Functions


The cornea and the lens of the eye focus light like a camera lens to form an image on the retina at the back of the eye. The cornea, where the light first enters the front of the eye, provides about two thirds of the eye's focusing power, and the lens inside the eye provides the other third.


Myopic Eye / Profile

Eye following Excimer Laser Correction of Myopia / Profile

Excimer Laser Correction of Myopia - Ablation Depth

Some eyes focus, or refract, the light too much, so the images of distant objects are formed in front of the retina, and the image is blurred. This condition is called nearsightedness, or myopia. Myopia usually starts in childhood and gets progressively worse through adolescence. It usually stops changing by the late teens, but it can sometimes get worse into the mid-twenties. In astigmatism the image is not evenly focused to a single point in front of the retina but the light rays are divided into two parts that focus along two lines with opposite orientations that are different distances from the retina.


Nearsightedness can be corrected by any method that reduces the total refractive power of the eye. Astigmatism correction makes all of the rays of light focus at the same distance so that they all fall right on the retina. Eyeglasses and contact lenses do this by putting in front of the eye "negative" lenses that are thicker at the edge than in the center. LASIK corrects nearsightedness by flattening the central part of the cornea, and it corrects astigmatism by flattening the central cornea by different amounts at different orientations to correct for the uneven focus of the rays of light.


In farsightedness (hyperopia), the image focuses beyond the retina. In our youth, the innate accommodating (focusing) power of the eye often compensates for farsightedness. But, as we age, our eyes become less able to accommodate. For this reason, farsightedness most commonly becomes a problem later in life. Many farsighted eyes do not need correction until the individuals reach their forties or fifties.


Hyperopic Eye/Profile

Excimer laser correction of Hyperopia - Ablation Depth

Farsightedness can be corrected by any method that increases the total refractive power of the eye. Eyeglasses and contact lenses do this by putting in front of the eye "positive" lenses that are thicker in the center than at the edge. LASIK does it by making the central part of the cornea more steeply curved.

During a regular eye examination, your doctor uses lenses to measure your nearsightedness, astigmatism, or farsightedness in units called "diopters" (D). The VISX STAR™ Excimer Laser System is approved for photorefractive keratectomy (PRK) for the reduction or elimination of myopia (nearsightedness) between 0 and -12.0 D with up to -4.0 D of astigmatism, hyperopia (farsightedness) between +1.0 and +6.0 D with no more than 1.0 D refractive astigmatism, and hyperopia (farsightedness) between +0.5 and +5.0 D of sphere at the spectacle plane with refractive astigmatism from +0.5 to +4.0 D with a maximum manifest refraction spherical equivalent (MRSF.) of +6.0 D. The VISX STAR Excimer Laser System is also approved for laser assisted in situ keratomileusis (LASIK) for the reduction or elimination of nearsightedness (0 to -14.0 D) with or without astigmatism ranging from -0.5 D to -5.0 D. Safety and effectiveness data has not been established beyond these limits. PRK and LASIK are elective procedures with alternatives including eyeglasses, contact lenses, and other refractive surgeries.

The Best Proven Technologies

Ophthalmology has advanced tremendously in the last few years. We are committed to remaining on the leading edge of these advancements. 


How often should I visit my ophthalmologist?

​If you have a history of eye disease, we recommend making regular appointments and following up as your ophthalmologist advises. Call now for more information or to schedule an appointment.

​Can I bring a friend with me to my ophthalmologist appointment?

​You are always welcome to bring a friend or family member with you to your appointments.  An extra set of ears is always helpful so you don’t forget any important information your ophthalmologist goes over with you during your appointment. 


How do I know if I should schedule an ophthalmologist appointment?

​If you are having eye discomfort or trouble with your vision, schedule an appointment with your ophthalmologist. Health conditions, like high blood pressure or diabetes, increase your risk for certain diseases. If you have questions or think you might need to see an ophthalmologist, call for more information.


Do your ophthalmologists have tips on how I can protect my eyes?


​Don’t forget to wear protective eyewear during activities like mowing the grass, doing construction work, or playing sports.  If you wear contacts, take steps to prevent eye infections. Wash your hands before handling your contacts or touching your eyes, and be sure to replace them regularly.


When should I arrive at my ophthalmologist appointment?


​We ask that you arrive at your eye appointment fifteen minutes early. That gives you time to fill out any necessary paperwork before your appointment with your doctor. 


What should I bring for my ophthalmologist appointment?


​You will need to bring your insurance information. If you have a referral from your primary care physician, please have that with you if you haven’t already sent it to us. And lastly, bring a list of all medications you are taking.


Can your ophthalmologists perform LASIK? What can I expect?


​One of our most popular procedures at Spectrum Eye Institute is LASIK surgery. An outpatient procedure, LASIK surgery corrects the vision of patients who are nearsighted, farsighted or have astigmatism. Call now for more information or to see if LASIK might be right for you. 


Does your ophthalmologist office offer cosmetic services?


​Though ophthalmologists are known for medically necessary services, we also offer cosmetic procedures and services to help you look and feel your best. We offer Botox Cosmetic treatments that smooth deep wrinkles and crows’ feet around your eyes. Call our offices for more information and to schedule a consultation.





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