Understanding Vision

In order to understand vision, one must have a basic understanding of the structures of the eye.

The Nonefront surface of the eyeball is known as the cornea. It is a clear dome that serves as the window into the eye. The major functions of the cornea are to allow light to pass into the eye and to help focus that light.

The iris is the colored part of the eye and it lies just beneath the clear cornea. It works like the shutter of a camera and its main function is to regulate the amount of light that enters the eye. It has a central hole in it known as the pupil, and by changing the size of the pupil, the iris can vary the amount of light that passes into it.

Just behind the iris is another structure that assists the cornea in focusing light. It is known as the crystalline lens or just simply the lens of the eye. In tandem with the cornea, the lens is responsible for helping to focus the light that enters the eye. Just like a camera lens, the natural lens of the eye must be perfectly clear in order to transmit a clear image into the eye.

The vitreous gel is the substance that makes up the majority of the volume of the eyeball. Its main purpose is to provide structural support and to help transmit light to the back of the eye.

The retina is a very thin tissue that lines the inside surface of the back eye wall, much like wallpaper lines the inside wall of a room. Its function is quite similar to that of camera film. In other words, the retina is responsible for sensing the light that enters the eye. Whereas the cornea and lens help to focus the light from a distant object, the retina senses this light and converts it into a tiny electrical impulse.

After the retina has detected the light and turned it into an impulse, this impulse is then transferred to the optic nerve. Much like a telephone cable carries information as an electrical impulse, the optic nerve transmits visual information to the brain where the visual images are processed and ultimately “seen”.

Any impairment along this pathway from the cornea, through the pupil, lens and vitreous, to the retina and ultimately optic nerve and into the brain, can result in an impairment in vision.

Through detailed examinations combined with the latest in diagnostic and treatment modalities, the doctors of Stasior Eye Care can successfully identify and treat problems that can occur anywhere along the visual pathway, thereby improving the functioning of the eye and ultimately the quality of the visual experience.

Myopia (Nearsightedness)

Nearsighted individuals typically have problems seeing well at a distance and are forced to wear glasses or contact lenses. The nearsighted eye is usually longer than a normal eye, and its cornea may also be steeper. Therefore, when light passes through the cornea and lens, it is focused in front of the retina. This will make distant images appear blurred. There are several refractive surgery solutions available to correct nearly all levels of nearsightedness.

Hyperopia (Farsightedness)

Farsighted individuals typically develop problems reading up close before the age of 40. The farsighted eye is usually slightly shorter than a normal eye and may have a flatter cornea. Thus, the light of distant objects focuses behind the retina unless the natural lens can compensate fully. Near objects require even greater focusing power to be seen clearly and therefore, blur more easily. LASIK, Refractive Lens Exchange and contact lenses are a few of the options available to correct farsightedness.


Asymmetric steepening of the cornea or natural lens causes light to be focused unevenly, which is the main optical problem in astigmatism. To individuals with uncorrected astigmatism, images may look blurry or shadowed. Astigmatism can accompany any form of refractive error and is very common. Astigmatism can be corrected with glasses, contact lenses, corneal relaxing incisions, laser vision correction, and special implant lenses.


Presbyopia is a condition that typically becomes noticeable for most people around age 45. In children and young adults, the lens inside the eye can easily focus on distant and near objects. With age, the lens loses its ability to focus adequately. Although presbyopia is not completely understood, it is thought that the lens and its supporting structures lose the ability to make the lens longer during close vision effort. To compensate, affected individuals usually find that holding reading material further away makes the image clearer. Ultimately, aids such as reading glasses are typically needed by the mid-forties. Besides glasses, presbyopia can be dealt with in a number of ways. Options include: monovision and multifocal contact lenses, monovision laser vision correction, and new presbyopia correcting implant lenses.