Clearview Eye and Laser Medical Center

The first step in a LASIK surgery is creation of a corneal flap. The cornea is the clear front part of the eye, and has several layers. Vision correction is done on the stromal layer, which means that the top layer, the epithelium, must be somehow moved out of the way to give access to the stroma beneath it. This is accomplished by creating a hinged flap, folding it aside for the treatment, then folding it back in place. It then heals by itself, and in the process provides a protective cover for the treated area beneath it.

Not everybody can have LASIK. The cornea must be thick enough, and not too steep.

• If you are extremely nearsighted, your corneas are very steep, and could be too steep for safe flap creation
• If you happen to have corneas which are too thin, there’s a risk that the microkeratome could create a flap that’s too thick for your eyes.

In both cases, you could be a good candidate for Intralase, also called Bladeless LASIK. IntraLase uses no microkeratome or any type of blade at all. Instead, it uses a second laser to create the flap. It's a very fast pulsed laser, called a femtosecond laser because its pulses last a femtosecond – a quadrillionth of a second.

Because it's bladeless and uses this laser instead, Bladeless LASIK can be offered to many more people than traditional LASIK can. With each of its femtosecond pulses, the laser creates a microscopic bubble beneath the corneal surface, at a predetermined depth. As it moves back and forth over the planned treatment area, it creates a continuous area of these bubbles, where it has vaporized microscopic fragments of corneal tissue.

Now the surface flap can be easily lifted, since the bubbles have broken the cell connections. Precise planning is key here. That's why the WaveScan wavefront system is so valuable to us. If you have been told that you're not a good candidate for LASIK, please contact us for a free consultation.

Cornea is the name of the clear front part of the eye, through which we can see the person’s colored iris and the black pupil. It’s curved and translucent. All curved and translucent objects accept light rays and bend them as they pass through it.

The cornea bends light entering the eye. That light continues on through the eye's lens, which is another curved, translucent object and bends it more. If it's a 20/20 eye, those light rays will now focus clearly on the retina, the “camera film” at the back of the eye.

Refractive therapy (surgery) works on the cornea's curvature. Refraction is the technical term for bending of light.

• In a farsighted eye, the cornea is too flat
• In a nearsighted eye, the cornea is too steep
• In an astigmatic eye, the cornea is football-shaped instead of round

So LASIK and other refractive therapies use a laser to subtly change the cornea's shape by vaporizing microscopically tiny pieces. This is done according to a minutely worked-out treatment plan.

At Clearview Eye and Laser Medical Center in San Diego, California, we use a computerized diagnostic system called the WaveScan wavefront system. It makes a colored three-dimensional map of each eye. We use those two maps to develop an exact treatment plan for each eye.

When the cornea's curvature is subtly changed in the correct ways for you, your vision is suddenly far clearer, and usually our patients are able to discard their glasses or contact lenses.

A cataract is not a film over the eye, which is a misconception floating around. It's a clouding of part of the eye's lens, and the only way to treat it is by cataract surgery.

The lens sits behind the iris and bends light rays as they enter the eye. Those light rays have already been bent by the cornea (front clear part of the eye). In a 20/20 eye, by the time light has passed through the cornea and the lens, it focuses precisely on the retina, and you see clear images.

When the lens forms cataracts, they might be anywhere on the lens. If they're near the edges, you may have no symptoms for quite a long time. If they're near the center, they’ll give symptoms quite early on. They'll cause a blurriness or clouding of the center part of whatever you're looking at. That's because they are preventing light rays from focusing on the retina. Instead, the light is scattered by the cataract, and doesn't focus at all. Light passing through the parts of the lens without any cataract do focus. Therefore, vision is partly clear and partly clouded.

Because of this scattering of light, the most typical symptoms of cataracts are:

• Poor night vision
• Increased light sensitivity (glare)
• Double vision in one eye
• Dimming of colors
• Need for a brighter light when reading

Cataract surgery is the removal of the entire lens, and its replacement with an artificial lens called an intraocular lens (IOL). At Clearview Eye and Laser Medical Center in San Diego, California, we offer four kinds of IOLs. The most advanced and sophisticated is Tecnis.

If you are in your 40s or 50s and have recently started needing reading glasses, but can see clearly in the distance, you are not farsighted. You have presbyopia. At first they seem to be the same, since they both allow clear vision in the distance but require glasses for close-up objects.

But they have different causes, which makes them totally different conditions from the perspective of an ophthalmologist. Farsightedness is caused by the shape of the cornea, and is an inborn condition, whereas presbyopia is caused by increasing rigidity in the lens associated with getting older. You can have 20/20 eyes but also have presbyopia.

The two conditions do have this in common: that a change in how the affected eye bends light rays will increase clarity of vision.

Our eyes bend incoming light twice: first by the cornea, then by the lens.

• LASIK changes the shape of the cornea, which corrects farsightedness.
• The shape of the lens cannot be changed. So to correct presbyopia, it must be removed altogether, and an artificial lens implanted. These are known as Intraocular Lenses (IOLs). We offer three IOLs: Crystalens, ReSTOR, and ReZoom.

• LASIK
• PRK
• IntraLase
• Presbyopia
• Implantable Contact Lenses
• Intacs
• Cataracts
• BOTOX®

Previous Posts

• LASIK 101
• LASIK For Astigmatism
• Preparing for LASIK surgery
• What to expect at a LASIK consult
• Iris registration and LASIK
• Affordable options for LASIK
• Is LASIK possible after implantable contact lens s...
• How long is recovery from implantable contact lens...
• How long do implantable contact lens last?
• Are there different types of implantable lenses?

Archives

• May 2007
• October 2007
• November 2007
• December 2007
• January 2008
• February 2008
• March 2008
• April 2008