How the Eye Works

Aphakic
The word “aphakic” describes an eye that has had its natural crystalline lens removed.

Astigmatism
Astigmatism means that the cornea is not spherical, or round, but rather has a different curvature at different points on the patient's cornea. A nice way to picture astigmatism is to think of an eye being shaped like a football, with the greatest, or steepest, amount of corneal curvature being across the laces and the lesser, or flatter, corneal curvature being across the end to end portion of the football. A normal eye is shaped like a basketball.

When a person has astigmatism the eye bends light in different strengths in different portions of the cornea and distortion and blurred vision is seen. Astigmatism often occurs along with Myopia and hyperopia and can be corrected.

Cataract
A cataract is a clouding of the normally-clear lens in your eye. In a healthy eye, the iris (the colored part of the eye) regulates the amount of light that enters the eye through the pupil. The light passes through the lens, where it is focused onto the retina at the back of the eye. Signals are then sent from the retina to the brain via the optic nerve, where they are translated into the images you see.

An eye with a cataract functions normally except that the lens has grown cloudy. Light enters the eye as usual, but the clouded lens disperses the light, causing the retina to have difficulty transmitting a clear image. Therefore, because the light that the retina receives is patchy, the retina’s transmissions to the brain are also affected, resulting in hazy, blurred vision.

Choroid
The choroid is the spongy middle layer of the eye, located between the sclera and the retina. Filled with blood vessels, the choroid's function is to nourish the outer layers of the retina.

Ciliary Body
The ciliary body is located behind your iris near the lens. The aqueous fluid that fills the front of your eye is made inside the ciliary body. Also, the ciliary body is made up of muscles that allow the eye to focus at different distances by expanding and contracting the crystalline lens.

Conjunctivitis
Conjunctivitis, often called "pink eye," is an inflammation or infection of the membrane that covers the white of the eye and the inside of the eyelid. Most of the time, conjunctivitis is not serious, but it may be contagious and should be diagnosed as quickly as possible. Typical symptoms include redness and swelling of the eye, a feeling of itching or burning, or a release of tears and discharge.

Cornea
The cornea is the "front window of the eye," similar to a watch crystal. Light passes through the cornea being focused, or bent, and then passes through the pupil to be focused a little more by the eye's natural crystalline lens.

The cornea is the part of the eye that is treated in LASIK, PRK and CK. LASIK is essentially a two-step procedure, with the first step being the creation of a thin flap in the cornea. After the flap is made, the cornea is gently reshaped with a laser before the flap is folded back over.

Dry Eye
Dry eye syndrome is one of the most common problems treated by eye physicians. Over 10 million Americans suffer from dry eyes. It is usually caused by a problem with the quality of the tear film that lubricates the eyes, and can be treated with drops or punctal plugs.

Symptoms include:
·  Itching
·  Burning
·  Irritation
·  Redness
·  Blurred vision that improves with blinking
·  Excessive tearing
·  Increased discomfort after periods of reading, watching TV, or working on a computer.

Excimer Laser
The Excimer laser is used to gently reshape the cornea in all LASIK procedures.  Dr. Gelvin wrote the first article published in the Journal of the American Optometric Association on this laser.  This article was published back in 1990.

Hyperopia
Hyperopia, or farsightedness, occurs when the eye does not focus the light rays strong enough, or the eye is too short. This causes the light rays to be aimed at a focal point behind the Retina. Thus, the light rays are out of focus as they are reaching the Hyperopia, and a blurred image is formed. Hyperopic individuals see relatively better at a distance than near, but are often blurred at all distances without glasses or contact lenses.

Intacs
Intacs are two half-rings that reshape the curvature of the cornea from within, enhancing the natural shape of the eye to correct flawed vision. These corneal implants are an alternative to LASIK for people with mild to moderate nearsightedness and limited astigmatism. Intacs can also be effective in helping patients with keratoconus

Iris
The iris is the colored portion of the eye located directly behind the cornea. It controls the amount of light entering the eye by varying the size of the pupillary opening.

Lens
The eye's natural crystalline lens is similar in function to a camera lens, serving to aid in focusing light onto the retina at the back of the eye. Located directly behind the iris and the pupil, the lens flexes and relaxes to aid in the eye's ability to accommodate, or change its focus between far and near. In our 40's, the lens begins to stiffen in a process called presbyopia, at which point bifocals or reading glasses are needed for close work.

Microkeratome
The blade microkeratome is the surgical blade used in traditional LASIK to create a flap in the cornea.  The results are generally excellent with traditional LASIK.

Mono-Focal IOL
Mono-focal implants focus at one main point, and that point can be set at distance, intermediate or near. This implant allows for the sharpest possible vision at its set point.

Multi-Focal Implant
Multi-focal implants allow focusing to occur at multiple distances by using light that enters in different parts of the eye to focus at different distances. This renewed focus sometimes comes with some degree of loss of sharpness at a particular distance.

Myopia
People who are myopic, or nearsighted, can see objects close at hand more clearly than far away objects. This occurs because the retina and the lens focus light too strongly, or the eye is too long, causing the light rays to come to focus before hitting the retina. By the time the light rays reach the retina they are out of focus and blurry.

Myopia is very common and affects roughly one of four people in America.

Optic Nerve
The optic nerve is a bundle of over one million nerve fibers that connect the retina to the brain. Light travels through the cornea, the pupil, and the lens and is focused onto the retina at the back of the eye. The visual messages then travel along the optic nerve to the brain, where they are translated into the images you see.

Phacoemulsification
Phacoemulsification is a process that uses ultrasound to break the eye's natural crystalline lens into pieces for removal through a small incision. Used in cataract surgery and refractive lensectomy, the doctor will begin by making a small incision in order to remove the natural lens. The incision is made either at the far edge of the cornea or in the sclera (the white of the eye), and is also used for the placement of the new implant.

Phakic
A phakic intraocular lens implant is an artificial lens that is placed inside the eye without removing the eye’s natural crystalline lens. The word “phakic” refers to an eye that still contains the natural lens – in other words, a normal eye is phakic, and remains so after having a phakic IOL implanted because the eye’s natural lens is not removed. Phakic implant surgery is generally considered less invasive than cataract surgery. The prevalent type of phakic implant is the Verisyse lens.

Photorefractive Keratectomy (PRK)
Like LASIK, Photorefractive Keratectomy (PRK) uses a cool pulsing Excimer laser to reshape the cornea.
·  Rather than touching the tissue underneath the cornea, however, it shapes the surface of the cornea itself.
·  Because all adjustments are made on the surface of the eye, the whole procedure is always entirely bladeless, and doesn’t require creating any flaps. This allows for incredible accuracy and minimal need for additional correction.

Presbyopia
As we age, our eyes gradually begin to lose the ability to accommodate, or to quickly change their focus from far to near. Known as presbyopia, this condition occurs because the eye's natural crystalline lens slowly becomes larger and less flexible over time. The lens, by contracting and expanding, plays a major role in the eye's ability to focus, so this aging process often results in a loss of sharp near vision since the larger lens cannot contract to an acceptable size.

Pupil
The pupil is the adjustable opening at the center of the Pupil that allows varying amounts of light to enter the eye.

Refractive Error
For many people the focusing power of the eye combined with the length of the eye does not allow the light rays to come to a pinpoint focus on the retina. In these patients, the light rays focus either in front of, or behind, the retina and thus a blurred image is seen. Vision can be brought into focus with glasses, contact lenses, or refractive surgery.

Refractive Lens Exchange
There are two main reasons that the eye’s natural lens is removed: either the patient is farsighted and requires an artificial lens for improved focusing, or the patient’s natural lens has developed a cataract and is blocking sharp vision. Refractive lens exchange is a procedure nearly identical to cataract surgery, in which the impaired natural lens is replaced with an artificial one. But with this procedure, unlike cataracts, the eye’s natural lens is clear, so its replacement usually serves to correct either farsightedness or focusing difficulties.

Retina

The retina is a thin structure in the back of the eye that captures the image of light and processes it to be sent to the brain for the interpretation of what we are seeing. When the light comes to a pinpoint focus on the retina, signals are sent from the retina to the brain via the optic nerve, where they are translated into the images you see.

Sclera
The sclera is the white outer layer of the eyeball. It combines with the cornea to protect the entire eyeball. It is also where incisions are often made for implant procedures as part of a process called phacoemulsification.

Verisyse
The Verisyse Phakic IOL is designed to treat patients who are extremely nearsighted, and for whom LASIK may not be a viable option. The Verisyse lens acts like a contact lens that is implanted in front of the iris to improve your vision. And unlike cataract surgery and some other implant procedures, the eye’s natural crystalline lens is left in the eye, allowing your focus to easily adjust between objects that are far and near.

Vitreous
The vitreous is a clear, gelatinous mass that fills the rear two-thirds of the eyeball, between the lens and the retina.

YAG Laser Capsulotomy
After cataract surgery, your vision can become cloudy, like it was when you had a cataract. But it isn't a new cataract; instead, the posterior capsule, which holds the lens in place, becomes cloudy and may blur your vision. This is called an after-cataract, and can develop months or even years after your surgery. Unlike a cataract, an after-cataract is treated with a laser. In a painless out-patient procedure called YAG laser capsulotomy, your doctor uses a laser beam to make a tiny hole in the posterior capusule to let light pass through.

Zonules
The zonules are a series of fine fibers that connect the crystalline lens to the ciliary body. The function of the zonules is to hold the lens in place in the eye.