A cataract is a cloudiness or opacity in the lens. A cataract is not a film, growth, or tumor. The lens is normally clear and allows light to pass through it. When a cataract forms, light cannot easily pass through it and this affects vision. The position of the opacity, and the degree of opaqueness affect the amount of sight lost, the degree of light sensitivity, and the need for surgical removal. Some types of cataracts develop rapidly, while others progress more slowly. Cataracts are not affected by the amount the eyes are used.
Functional Implications: Light sensitivity, vision is cloudy or hazy, colors are dull.
Diabetic Retinopathy results from changes in the walls of the blood vessels. These vessels fail to nourish the retina properly. In the early stage, called background diabetic retinopathy, central vision may gradually decrease due to small hemorrhages or leaks near the macula. In the later stage, called proliferative diabetic retinopathy, new vessels grow and hemorrhage excessively. These new vessels are very leaky and blood leaks into the vitreous gel which clouds or blurs vision. Material can form around these leaks which can pull on the retina and cause rapid destruction–or an eventual detached retina.
Functional Implications: Blurred or spotty vision with blind spots, floaters; both near and distant vision can be affected. Often have difficulty with driving, reading, and/or color identification.
Glaucoma is characterized by the pressure of the fluids inside the eyeball being too high. There are many types of glaucoma. Open Angle Glaucoma occurs when the meshwork is clogged and the angle widens. Closed Angle Glaucoma is the shrinkage or closing of the angle resulting from the cornea adhering to the iris, or the lens pressing against the iris. Pressure kills nerves in the optic disc. This damage first affects side vision and later can affect central vision.
Eye Pressure Range:
12 – 18 = normal
20 = need exam to determine damage
20+ = increased chance of damage
30+ = definite damage
40+ = very painful
Functional Implications: Open Angle Glaucoma is chronic, usually inherited, and the most common type of glaucoma. It slowly steals visual function with no symptoms of pain or blurred vision. Closed Angle Glaucoma is acute and the most serious type of glaucoma. There is a rapid rise in pressure with symptoms of severe pain, sensitivity to light, and cloudiness in vision.
Macular Degeneration, commonly referred to as Mac D or MD, affects central vision, is often age related, and is a progressive condition. It is often the result of changes in the blood vessel supply to the macula–the critical area of the retina that is responsible for fine detail/focal vision. There are two types of Macular Degeneration, wet and dry. In the early stage only one eye may be affected, but eventually it progresses to the other eye. This may happen in a matter of months or may take years. The Wet type is a much greater threat to vision loss. Wet MD is associated with a more sudden loss of vision due to leakage or bleeding under the macula. The area of fluid accumulation or bleeding eventually develop into a dense mass of scar tissue, resulting in permanent loss of central vision.
Functional Implications: A person’s ability to identify small detail is lost and surrounding objects appear to be out of focus. A person can learn to use this side/peripheral vision to identify large objects (eccentric viewing). Macular degeneration does not result in total vision loss.
Optical aids and additional lighting are often used successfully for reading.
A separation between the inner and outer layers of the retina that is most often caused by a hole or a tear in the retina.
Functional Implications: The sudden appearance of blind spots or bright flashes of light, or the appearance of a shadow in the side vision or “a shade coming down” may be symptoms of a detached retina. Immediate examination by an ophthalmologist is crucial. Total blindness results if the retina detaches completely.
Retinitis Pigmentosa, commonly referred to as RP, is a progressive condition which initially results in reduced peripheral vision. Fields gradually become smaller and lead to eventual loss of central vision. Retinitis Pigmentosa (RP) is an inherited disease. There are many forms and varying degrees of severity.
Functional Implications: Tunnel vision, night blindness. Difficulty identifying large objects and moving through the environment due to reduced fields. Amber lenses are used to enhance contrast. Magnification is not normally recommended. Eventual progression to total vision loss.