Link – http://kidshealth.org/teen/diseases_conditions/sight/visual_impairment.html#
- Amblyopia (pronounced: am-blee-oh-pee-uh) is reduced vision in an eye caused by lack of use of that eye in early childhood. Some conditions cause a child’s eyes to send different messages to the brain (for example, one eye might focus better than the other). The brain may then turn off or suppress images from the weaker eye and vision from that eye then stops developing normally. This is also known as a “lazy eye.” Strabismus (misaligned or crossed eyes) is a common cause of amblyopia, since the brain will start to ignore messages sent by one of the misaligned eyes.
- Cataracts are cloudy areas in part or all of the lens of the eye. In people without cataracts, the lens is crystal clear and allows light to pass through and focus on the retina. Cataracts prevent light from easily passing through the lens, and this causes loss of vision. Cataracts often form slowly and usually affect people in their 60s and 70s, but sometimes babies are born with congenital cataracts. Symptoms include double vision, cloudy or blurry vision, difficulty seeing in poorly lit spaces, and colors that seem faded.
- Diabetic retinopathy (pronounced: reh-ton-ah-pa-thee) occurs when the tiny blood vessels in the retina are damaged due to diabetes. People with retinopathy may not have any problems seeing at first. But if the condition gets worse, they can become blind. Teens who have diabetes should be sure to get regular eye exams because there are no early warning signs for this condition. To help prevent retinopathy, people with diabetes should also avoid smoking, keep their blood pressure under control, and keep their blood sugar at an even level.
- Glaucoma is an increase in pressure inside the eye. The increased pressure impairs vision by damaging the optic nerve. Glaucoma is mostly seen in older adults, although babies may be born with the condition and children and teens can sometimes develop it as well.
- Macular degeneration (pronounced: mah-kyoo-lur dih-jeh-nuh-ray-shun) is a gradual and progressive deterioration of the macula, the most sensitive region of the retina. The condition leads to progressive loss of central vision (the ability to see fine details directly in front). Macular degeneration is often age related (it occurs in older people, especially older than 60), but sometimes it can occur in younger people. Excessive exposure to sunlight and smoking can increase the risk for age-related macular degeneration. Symptoms may include increased difficulty reading or watching TV, or distorted vision in which straight lines appear wavy or objects look larger or smaller than normal.
- Trachoma (pronounced: truh-ko-muh) occurs when a very contagious microorganism called Chlamydia trachomatis causes inflammation in the eye. It’s often found in poor rural countries that have overcrowded living conditions and limited access to water and sanitation. Blindness due to trachoma has been virtually eliminated from the USA.