American Medical Association Family Medical Guide - American Medical Association [747]
Secondary Tumors
Cancer cells can spread through the bloodstream or the lymphatic system from a tumor in one area of the body to form a tumor in another part of the body, including in the eye.
Symptoms
If a so-called secondary tumor grows behind the eyeball, it can cause the eyes to bulge. The effects of a tumor on a person’s vision can vary, depending on where in the eye the tumor is located, how fast the tumor is growing, and whether one or both eyes are affected. If a tumor grows inside the eye, it can cause blurred vision.
Treatment
A secondary tumor is treated separately from a primary tumor. A doctor may prescribe chemotherapy (see page 23) or radiation therapy (see page 23) to block the growth of or destroy a secondary tumor in the eye. Any loss of vision that occurs before treatment may be permanent.
Color Vision Deficiency
Color vision deficiency (also called color blindness) is a vision disorder in which a person sees colors differently than other people see them or has difficulty distinguishing shades of some colors. The disorder occurs when malfunctioning receptor cells for color in the retina (the light-sensitive membrane lining the back of the eye) transmit incorrect information about color to the brain.
Color vision deficiency is a common disorder that is usually inherited. Although women can carry the gene for the common form of color vision deficiency and pass it on to their children, men are more often affected by the disorder; about 8 percent of men in the United States have color vision deficiency. Difficulty distinguishing colors can develop when normal age-related changes in the lens of the eye cause it to darken, impairing a person’s ability to see differences between some colors. The disorder can also result from a disease or injury that damages the eye or the optic nerve, or from degeneration of the retina or the optic nerve.
Symptoms
The symptoms of color vision deficiency can range from difficulty seeing the difference between shades of the same color to an inability to see all colors. Although the severity of color vision deficiency varies from one person to another, most people who have the disorder have a mild deficiency and have difficulty distinguishing shades of red and green.
Diagnosis and Treatment
A diagnosis of color vision deficiency is based on the symptoms, your family health history, and the results of color vision tests. Although there is no cure for color vision deficiency, your ophthalmologist can recommend steps you can take to deal with the problem, such as learning to recognize colors by brightness or location. For example, to read traffic signals, you remember that the red light is on the top and the green light is on the bottom. Some people who have difficulty distinguishing shades of red and green may benefit from using tinted prescription glasses.
Other Eye Disorders
The two bony sockets in the skull that contain the eyeballs are called the orbits. The eyeballs are supported in the orbits by soft tissue. Sometimes an underlying disease or condition, such as Graves’ disease or a tumor behind the eyeball, causes one or both eyeballs to bulge forward in the orbits. In some cases, an infection that has spread to the soft tissue of the orbit from the sinuses or from a nearby boil causes inflammation that makes the eyeballs bulge forward. Muscles attached to the outside of each eyeball and to the inside back portion of each orbit give the eyes movement. If these