For Dr. Gulani, vision and vision correction surgery are forms of art. He draws on a variety of technologies and the latest techniques to create a personal plan for each person, and each eye, to improve their natural vision. To ensure each patient clearly understands how their eye works, he compares it to a camera and approaches each patient in an individual way.
Just like a camera, the eye has a viewfinder (called the cornea) a shutter (called the iris) and a lens. Normal, clear vision occurs when light rays pass through them and the image focuses directly on the film (called the retina). When light rays don’t converge and focus directly on the retina, this results in “refractive errors” and blurry vision.
This occurs when the cornea is curved too steep in relation to the length (front to back) of the eye. This bends the light more sharply and makes the image focus in front of the retina, as opposed to directly on it. When this occurs, near objects can be seen clearly, but objects in the distance are blurry. Advanced Lasik surgery treats this refractive problem by slightly flattening the corneal curvature, so the focal point of the image is moved back and directly on the retina.
This is the reverse problem from myopia. In farsightedness, the corneal curvature is too flat, or the eyeball is too short, and the focal point of the image is behind the retina. With farsighted vision, objects in the distance appear clear, while objects close up are blurry. Advanced Lasik surgery corrects this problem by slightly steepening the corneal curvature and increasing the refractive power of your cornea so that the focal point of the image is closer and directly on the retina.
In normal vision, the cornea is more spherical or round, like a basketball. An eye with astigmatism has a cornea that is irregularly shaped, like a football. This prevents images from converging or focusing directly on the retina. Although some parts of the image may focus on the retina, others focus in front of or behind it. Astigmatism causes images to appear blurry or distorted. Astigmatism can occur along with either myopia or hyperopia, or it can occur alone. Advanced Lasik surgery can correct it by modifying the corneal curvature so that images can converge and focus directly on the retina.
Presbyopia is most commonly associated with the need for reading glasses as we age, usually after age 40. It is caused by changes in the lens. As we age, the lens hardens and becomes less flexible, losing the ability to change shape. Like a camera, this causes the eye to lose its power to zoom. Presbyopia can also exist with any of the above vision problems and Dr. Gulani can treat them with his unique approach to laser vision surgery. To learn more about other surgical options visit our page about presbyopia.
The above three refractive errors are called lower order aberrations. They account for about 80% of refractive error and affect how much you can see – that is, how clear your visual field is at all distances.
Our eyes also have small defects called higher order aberrations and these affect how well you see. If you imagine the eyes as being a pair of glasses, they could have smears or bits of dust on them which interfere with otherwise clear vision. This would be analogous to your higher order aberrations.
Examples of higher order aberrations are halos around lights, starbursts, and glare, which cause night vision problems. Until recently these more subtle vision problems have not been treatable by Lasik. But since the advent of Wavefront Lasik technology, they can be diagnosed in detail and treated by Lasik, PRK, Advanced Surface Ablation (ASA), LASEK, epi-Lasik, Intralase, and iLasik.
Since the cornea has the most refractive properties to focus images clearly on your retina, the most common treatment for the above refractive errors is corneal surgery. Nearly all cornea-based refractive surgeries (including all variations of laser vision surgery, such as Lasik, Wavefront Lasik, Custom Lasik, Epi-Lasik, Lasek, PRK, Advanced Surface Ablation (ASA)) focus on re-shaping your cornea to modify how light passes through it to improve your vision.
Dr. Gulani’s comprehensive corneal surgery experience gives his patients added confidence and assurance that they have the right surgery for their specific needs. After he has completed a thorough examination of your eyes, he is able to recommend the best procedure for your particular vision problems to achieve the desired visual outcome.
Your prescription for glasses or contact lenses are documented after a doctor measures your eyes and obtains these readings. Patients have a tendency to remember that they are "20/100" or "20/400," but these numbers simply refer to the line on the eye chart that you are able to read. Doctors use a more precise set of numbers to measure your prescription.
If you look at your prescription, either for glasses or contact lenses, you can get a fairly good idea as to the type of refractive error that you have, as well as its severity. Generally, prescriptions appear as a series of three numbers and might look something like this:
The first number (sphere) indicates the curvature of the cornea. A negative number means that you are nearsighted with a cornea that is too steep. A positive number means that you are farsighted with a cornea that is too flat. The closer the number is to zero, the less severe the prescription.
The second number (cylinder) indicates the amount of astigmatism you have. The further the number is from zero, the more pronounced the astigmatism. A value up to 2.50 is considered moderate; anything above 2.50 may be considered severe. The third number (axis) reflects the orientation of your astigmatism.
If you would like to know more about how our eyes work, and about how Dr. Gulani can give you your best vision, please call or email our office to schedule a personal consultation. We look forward to meeting with you soon.
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