Amblyopia (lazy eye)
Amblyopia, commonly referred to as lazy eye, is actually the visual deficiency of one or both of a patient’s eyes due to a lack of clarity during the visual development period of a child. This normally occurs during the period in life when the mind and body decides on which nerve connections are needed and which are useless. Due to an inability to see or a reduction in vision the mind decides that the fine visual synapses aren’t necessary and discards them, which can result in permanent visual reduction regardless of glasses, contact lens, or surgical correction. If caught early enough as a child, this disorder can possibly be avoided. The persons most prone or likely to suffer from this disorder are those whose eyes develop differently from one another, where one eye is much weaker or stronger than the other. This difference in focusing ability can cause one eye to be used more often than the other. Other times, the eyes are misaligned, causing one eye to “shut off” to avoid double vision. Regardless of the cause, the result is a weakened or amblyopic eye.
As light enters the eye it is concentrated by the cornea and the lens into a fixed single image on the retina in order to appreciate it. Sometimes the corneal development ends with it having an irregularly shape. This irregularity in the cornea can distort that image resulting in it being focused on two different areas of the retina. This is known as astigmatism. For the cornea to bend light correctly, it should be dome-shaped, like a basketball. Astigmatic corneas are shaped more like a football. This causes a distorted view when looking at objects which are close-up and far away.
The cause of astigmatism is unknown. Astigmatism is often associated with myopia or hyperopia, and it usually is present from birth, but can increase throughout life. It may be hereditary, or it may be caused by factors such as pressure on the cornea, incorrect posture, or increased use of the eyes for “near work.”
Mild astigmatism usually does not need to be corrected, unless it is irregular astigmatism. Eyeglasses, contact lenses, or refractive surgery can correct moderate to high degrees of astigmatism.
Computer Vision Syndrome
Computer Vision Syndrome (CVS) affects 75% of computer users. It is a series of symptoms related to extended periods of computer usage. Don’t worry, there is no cause for panic, measures can be taken to relieve it.
Symptoms: CVS can appear as a variety of symptoms such as: headaches, eye strain, neck and back aches, sensitivity to light, blurred vision, double vision, and irritated eyes.
Risk Factors: Any computer user can develop CVS. Your vision, your computer, and the environment where you use your computer are all factors which can lead to CVS.
Emmetropia is present when the light rays entering the eye are focused directly on the retina of a relaxed eye. Emmetropia is the medical term for 20/20 vision, or the vision of a person that needs no corrective lenses, contact lenses, or reading glasses. Emmetropia occurs as a result of the ocular structures developing in unison, through a process called emmetropization, where the optical power perfectly focusing an image on the retina. Any deviation from that normal development or growth process results in a refractive error. A person who develops a refractive error can be considered non-emmetropic, which is known as ametropia. With ametropia, the focal point of the eye is some distance in front of or behind the retina. The following vision conditions are types of ametropia.
Hyperopia is more commonly known as farsightedness. As the name suggests, people with farsightedness are able to focus on objects that are further away, but have difficulty focusing on objects which are very close. This is either because the eyeball is shorter than normal or the lens is weaker than it needs to be, which prevents the crystalline lens in the eye from focusing correctly on the retina. About a fourth of the population is farsighted. Hyperopia if left unchecked can lead to chronic anterior chamber angle closer, which if significant can lead to a more serious condition, Chronic Glaucoma, later in life.
A family history of hyperopia is a risk factor for developing hyperopia. Just about everyone is born with hyperopia but most outgrow the condition by going through emmetropization, as their eyes develop. So those with significant amounts of hyperopia can be thought of as those who never went through emmetropization, the proper eye growth and development.
Myopia is the medical term for what most people call nearsightedness. It is a condition where you can see objects clearly only when they are closer, but when objects are further away you can’t focus on them. Myopia usually develops in early childhood, though it sometimes develops in early adulthood. In rare cases, myopia can lead to more serious conditions such as retinal detachment.
Myopia is considered a genetic disorder. If your parents are nearsighted, you are at greater risk of also being nearsighted. Another risk factor is ‘near work’ – work involving fine detail or focusing on close objects.
Myopia can be accommodated and sometimes corrected with eyeglasses or contact lenses. Sometimes myopia continues to gradually worsen throughout life, a condition known as myopic creep. Myopia can also be corrected by LASIK surgery.
Presbyopia is the inability to focus on near objects, through your best distance correction, that gradually worsens as you age. The onset of presbyopia usually begins when people hit their early to mid 40s. These people tend to first notice that it is more difficult to read or use the computer when it is closer to them and have to either pull it back or back away from it to read. Bifocals or reading glasses are ways to remedy this condition.
Presbyopia is a natural consequence of the aging process. There is no cure, though researchers are constantly looking for one. Even if a someone has never had vision problems before, he can still develop presbyopia. It may seem to occur suddenly, but it actually occurs over a long period of time. Symptoms include having to hold things at arm’s length to see them clearly, eye strain, fatigue, and headaches from near work.