Refractive Surgery San Francisco

Recent advances in Refractive surgery are designed to permanently reduce or eliminate the need for corrective eyewear to see objects clearly. Today, more than 3 million corneal refractive procedures are performed worldwide each year. Presently, more than 100 million patients wear contact lenses for correction of their refractive errors.

To better understand refractive surgeries, one should understand how a perfectly normal eye (20/20) focuses light and what are different types of refractive errors? Let us first understand the main components of eye.

Anatomy of the Eye

Cornea: It is the transparent front wall of the eye. Cornea is one of the most critical components of the eye and is the “window” of your eye, just like the anterior window of your camera. Cornea works to refract light rays from the object viewed so that they focus on the retina at the back of your eye. Refractive errors occur when the cornea fails to focus light rays precisely on the retina. Cornea is the tissue which is reshaped during laser surgery.
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Iris: The iris is the colored portion of the eye. It is similar to the aperture of a camera. The iris regulates the amount of light entering the eye.

Pupil: The adjustable opening at the center of the iris that allows varying amounts of light to enter the eye. Dilation drops used by your eye doctor increase the size of the pupil so that the internal health of your eye can be evaluated.

Lens: The lens focuses the light entering through the pupil, directing it to the retina. The curvature of the lens adjusts to focus at different distances.

Optic Nerve: The optic nerve is similar to the cable that connects your video camera to the VCR. The image seen in the eye is transported to brain where the image is processed. The optic nerve head is the portion of the optic nerve that is seen by an experienced eye care professional to evaluate for eye diseases such as glaucoma, papilledema (increase pressure in the brain), and optic neuritis.

Retina: It is a nerve layer at the back of your eye that senses light and sends images to your brain. The retina is similar to the film in a camera. This is where the picture seen by the eye is converted to electrical signals and then transported to the brain via the optic nerve. The retina is made of cells called rods and cones. Rods are primarily used to aid with night and peripheral vision, while cones are designed to aid with color vision and crisp 20/20 vision.

Macula: The macula is a small area located at the posterior portion of the retina. It is comprised of cones and functions in crisp 20/20 vision. Diseases that affect this area can cause a decrease in vision. Disease processes such as macular degeneration, retinal detachments, diabetes, and hypertension can potentially cause blindness.

Sclera: The sclera is the white portion of the eye. It is comprised of tough connective tissue that gives the eye its shape.

Conjunctiva: It is a very thin layer covering the sclera. This layer carries blood vessels and very importantly it contributes to the innermost layer of a healthy tear film. Conditions affecting this layer such as surgery, infection etc. can affect your tear film.

Muscles: Ocular muscle alignment is critical in developing sharp three-dimensional vision. During a routine eye exam, an eye care professional evaluates the integrity of the muscles and the nerves which supply them. Muscle imbalance can cause lazy eye if it is not corrected during childhood.