Millions of Americans experience low vision as a result of common ocular diseases. It is also common to hear people use the term “legally blind” without an understanding of what it truly means. Understanding the causes of low vision, and knowing what it means to be legally blind, allows the individuals affected and the people around them to make adjustments to minimize the impact of these visual impairments on their everyday lives.

According to the World Health Organization (WHO), low vision is defined as a visual acuity of 20/60 to 20/200, and less than 20 degrees of peripheral vision in the best seeing eye with the best possible correction. Those who are unable to achieve better than 20/200 vision or 10 degrees of peripheral vision with the best glasses, contact lenses, or other traditional methods are considered to be legally blind. Individuals who have poor vision without glasses or contact lenses but see well with them, are not actually legally blind.

Adults over 50 are most commonly affected by reduced vision, as they are more prone to advanced ocular diseases. These di-seases include macular degeneration, glaucoma, diabetes, and sometimes cataracts. As these conditions progress later in life, they start to affect one’s ability to read, drive, use the computer, see the television, and even recognize familiar faces. Once these daily activities are impaired, a person’s quality of life can suffer.

Causes and types of low vision

Eye and brain injuries, as well as certain genetic conditions, can cause sudden reduced vision. This is especially true in younger individuals. Reduced vision in older people tends to develop gradually with chronic, progressive diseases. Many times, there are no alerting symptoms until you have lost significant vision, which is why doctors encourage annual comprehensive eye exams.

Age-Related Macular Degeneration

Central vision loss can be caused by advanced age-related macular degeneration (AMD). The macula is the light-sensitive area of the retina that is responsible for seeing the details of objects directly in front of you. AMD is a leading cause of low vision and affects the ability to read, write, and see people’s faces.

There are two types of AMD with varying levels that progress slowly over time. Dry AMD tends to be less visually significant, as most people do not notice much vision loss until later in this stage. While eye vitamins are recommended to slow progression of AMD, there is no cure at this time.

As the disease advances, many will start to notice straight lines becoming wavy or central visual distortion. This is much more common in wet AMD, where there is a more significant impact to vision. In this type, patients notice more central vision missing, trouble with low lighting, and a dampening of colors. There are ocular injections to help treat this stage of the condition, but once vision is permanently lost, it cannot be restored.

AMD is more common in people over the age of 50, those who have a family history, Caucasians, and smokers (including former smokers). To reduce the risk of AMD, patients are encouraged to adopt a healthy lifestyle with the cessation of smoking, increasing green leafy vegetable intake, regular exercise, and the use of UV protection when outdoors.

Glaucoma

There are a variety of types of glaucoma – all of which can lead to peripheral vision loss if not managed and treated in time. Open-angle glaucoma is the most common type in the United States and is a very slowly progressing condition that causes damage to the optic nerve. Glaucoma also typically presents with no symptoms until the disease becomes advanced.

African-Americans and Hispanics have an increased risk of glaucoma. Its true cause is unclear. There is often an association with elevated intraocular pressure, but this is not always the case.

The treatment usually consists of drops to lower eye pressure, laser treatments, and surgical procedures to help drain fluid out of the eye more efficiently. Since glaucoma can lead to blindness, early detection is key.

Diabetes

Another condition that does not have any symptoms in the early stages is diabetic retinopathy. Everyone who has difficulty controlling blood glucose is at risk for this disease. The blood vessels in the retina (the light-sensitive part of the eye) begin to leak, which can be damaging to those sensitive layers in the back of the eye. More than half of individuals with diabetes will develop this condition. The longer you have had the disease, the higher your risk.

There is treatment for advanced stages to stabilize the condition. Sometimes eye injections, laser treatment, and eye surgery are needed. Unfortunately, once the retina has been damaged and vision is lost, it often cannot be regained. To reduce your chances of diabetic retinopathy, it is important to maintain a healthy lifestyle with diet and regular exercise.

Adapting and Accepting Low Vision

Vision loss and blindness can be very distressing, especially when one is used to having fairly good vision. Partial vision loss is often harder to adapt to than total loss. In addition to the visual changes, people also have to cope with a loss of independence. It is normal to experience an initial period of denial, followed by depression, and final-ly acceptance. This happens at different times and at different extents of severity for everyone. No one should have to deal with this alone. In addition to seeing a low vision specialist, patients also need to consider counseling and support groups.

Having reduced vision means that you have to find new ways to enjoy doing the things you love. Low vision specialists are available to help maximize one’s remaining sight. While they cannot reverse the damage that has already been done, they can offer visual aids such as magnified devices in addition to glasses or contact lenses.

To make daily tasks easier for those with milder vision loss, I recommend:

– Better illumination/ lighting that can be angled directly on the page;
– Hand-held or stand magnifiers;
– High magnified reading glasses;
– Filtered glasses to reduce glare.

For more advanced vision loss, it may require additional options including: large print texts/books or audio books; changing text size/contrast on smart phones and computers; telescopes; electronic readers; and an occupational therapist to offer guidance on how to set up your home safely.