An individual is defined as having ‘low vision’ if their vision loss interferes with their ability to do the things they want to do. It is also defined as fully corrected vision which is insufficient to do what you want to do.
There are many eye conditions and diseases, including macular degeneration, cataracts, diabetic retinopathy and glaucoma, that can lead to vision loss. Some of these conditions can lead to total blindness if not treated early. However, when treated early, rarely do these diseases lead to total blindness as the vast majority of people affected by vision loss still retain some residual and useful vision.
Those living with low vision, or varying degrees of legal blindness, usually try to maximize their sight as much as possible with visual aids.
To understand blindness and other types of vision loss, it’s vital to first understand how the eye works.
How the Eye Works
There are four main parts of the eye that help it function:
- Cornea and lens – these are found at the front of the eye. They focus light entering the eye, allowing you to form an image on the retina.
- Retina – a neural layer found at the back of the eye that detects light and color, and converts these into electrical signals.
- Optic nerve – This transmits electrical signals from the retina to the brain for interpretation, allowing us to comprehend the information delivered by the eye.
When one of these components is affected, damaged or has degenerated over time, blindness or low vision may occur.
Understanding the Different Types of Vision Loss
Vision Loss is an umbrella term that describes the partial or total loss of vision. Below are some terms to describe the various types of vision loss:
Low vision is when a person’s vision loss interferes with their ability to do the things they want to do. Moreover, the person has a visual acuity of 20/70 or lower that can’t be improved, even with glasses or contact lenses.
Legally blind is when a person has vision of 20/200 or lower. They aren’t considered legally blind if conventional visual aids such as glasses, contact lenses or surgery can correct a person’s vision to better than 20/200.
Totally blind is when a person has a complete loss of sight.
Depending on the type of low vision you have, different parts of the eye will be affected.
Common types of low vision include:
- Loss of central vision – there is a blind spot or spots in the center of your vision.
- Loss of peripheral vision – you cannot see anything above/below eye level or to either side. However, your central vision is intact.
- Blurred vision – objects, far and near, are out of focus.
- Hazy vision – your field of vision appears covered with a film or a sheer curtain.
- Night blindness – difficulty seeing at night or in low-lit places.
What Eye Conditions and Diseases May Cause Severe Vision Loss?
For many patients, the difference between experiencing some vision loss and total or near-total blindness is early diagnosis and treatment. This is especially true for eye diseases that typically don’t present with symptoms until irreversible vision loss has occurred.
Common eye conditions and diseases that can cause vision loss, including blindness, include:
Cataracts cause the eye’s natural lens to become less transparent, resulting in cloudy or misty vision. During cataract surgery, your eye doctor removes the clouded lens and replaces it with an artificial one. If left untreated, cataracts can eventually cause blindness.
Glaucoma refers to a group of eye conditions that damage your optic nerve, usually due to a buildup of fluid pressure in the eye, often affecting your peripheral vision. Unfortunately, glaucoma is permanent, and there is no cure. However, it’s often possible to minimize vision loss through early detection and treatment.
In macular degeneration, which is a condition usually related to aging, the retina (the macula) begins to deteriorate and affect central vision. Early diagnosis and treatment is the key to preventing vision loss. Although there is no cure, anti-VEGF medications and laser eye surgery can reduce the potential for greater vision loss in the wet form of AMD.
Diabetic retinopathy (DR) is a complication of diabetes where the blood vessels that nourish the retina are damaged by high blood sugar levels. In its earlier stages, DR doesn’t have any noticeable symptoms. Eventually, the patient experiences blurred vision and eye pain and vision loss.
To prevent or manage diabetic retinopathy, patients need to gain control of their blood sugar levels, cholesterol and blood pressure. Treatment options include laser eye surgery, medication injections or surgery to remove scar tissue or blood from the retina.
How We Can Help
People with low vision or partial vision can benefit from a variety of visual aids and devices to maximize their vision. When vision loss interferes with the tasks you want to do, a low vision evaluation is highly recommended. We at Chism Low Vision Institute have extensive experience in helping those with vision loss regain their abilities.
We understand the importance of living a comfortable, high-quality, and joyful life, no matter your visual limitation. That’s why we assess our low vision patients carefully and provide them with low vision glasses, devices, and aids that improve their lives and enable them to do the activities they enjoy.
Whether you are struggling with driving, reading, watching TV, seeing faces or anything else, Dr. Larry M. Chism will recommend the best low vision aids and devices for you.
Chism Low Vision Institute serves patients from Abilene, Austin, Fort Worth, and Georgetown, all throughout Texas.