Low vision refers to a visual impairment that cannot be corrected through pharmaceuticals, surgery, contact lenses or glasses. In most cases, it is characterized by partial sight, such as tunnel vision, blurred vision and blind spots. It can affect people of all ages but is mostly prevalent in older adults. It should not be confused with blindness because unless a blind person, a person with low vision has some useful sight. Outlined below are some of the major causes of low vision.
One of the leading causes of low vision is macular degeneration. This is a disorder that affects the retina. The retina is the light-sensitive lining at the back of the eye where images are focused. This causes the macula to deteriorate, causing blurred vision. It is the leading cause of low vision in people above 60 years and accounts for nearly as half of all low vision cases in adults.
anatomy of the eyeball, functions and structure of the retina
Another leading cause of low vision is Diabetic Retinopathy. According to research, more than 30 percent of people diagnosed with diabetes have some form of diabetic retinopathy. People with diabetes are likely to experience day-to-day changes in their vision or visual functioning as a result of the disease. This is because diabetes causes blood vessels that nourish the linings of the retina to develop abnormal branches that leak. This can interfere with one’s vision and, over time, can cause severe damage to the retina resulting in low vision.
Besides the above-mentioned, cataracts have also been singled out as one of the common causes of low vision. Cataracts appear as a clouding of the lens of the eye which interferes with the amount of light entering the retina, resulting in loss of vision. Common causes include long-term exposure to the sun’s ultraviolet light, aging, inherited disorders, and injury among other things. A cataract can be removed surgically and vision restored.
Glaucoma is also another common cause of low vision. It causes damage to the optic nerve which occurs as a result of increasing internal pressure in the eye because of drainage or flow of fluid within the eye. It can also occur when internal pressure within the eye fails to increase but there is not enough blood flowing to the optic nerve.
The last common cause of low vision is retinal detachment. In this case, the retina detaches from its underlying layer, causing vision impairment. Causes include eye trauma, infection, holes in the retina, and blood vessel disturbance.