A common phrase in the world of ophthalmology is “low vision.”
Used to describe individuals whose eyesight deficiencies cannot be corrected by eyeglasses, it is estimated that 285 million people around the world are living with blindness or visual impairments.
Understanding what low vision is, what causes it, and what can be done to mitigate it is important.
What is low vision?
Low vision is a condition that can be caused by eye disease, in which visual acuity is 20/70 or poorer in the better-seeing eye and cannot be corrected or improved with regular eyeglasses, surgery or medical intervention. Most surveys and studies indicate that the majority of people in the United States with vision loss are adults who are not totally blind; instead, they have low vision.
Vision is made up of two parts — acuity and contrast sensitivity. Acuity is the ability to see detail in small or distant objects. The classic eye chart in your optometrist’s office measures acuity. The smaller row of letters you can read, the higher your visual acuity.
Contrast sensitivity is your ability to distinguish an object from its background. The more subtle distinctions in colors or shades you can observe, the higher your contrast sensitivity.
How is low vision different from blindness?
These are important, because the general belief that all blind people — or those with low vision or vision impairment — see only blackness is incorrect. In fact, fewer than 1 percent of those with blindness have no light perception, says Dr. Nicole Ross of the NECO Center for Eye Care Commonwealth and the New England Eye Low Vision Clinic at Perkins School for the Blind.
Ross, who specializes in low vision rehabilitation, says the number of individuals diagnosed with low vision continues to grow.
“We are seeing a major shift over time,” she says. “As people are living longer, we are seeing vision impairment become more prevalent.”
Put into perspective, the number of people in the U.S. who are blind or visually impaired is expected to double to more than 8 million in the next three decades, according to a study by Dr. Rohit Varma, Director at Southern California Eye Institute.
What causes low vision?
Some of the most common causes of low vision include age-related macular degeneration, diabetes and glaucoma. Low vision may also result from cancer of the eye, albinism, brain injury, Cortical/Cerebral Visual Impairment, or inherited genetic disorders of the eye such as retinitis pigmentosa and Leber congenital amaurosis.
The work at the Low Vision Clinic and at Perkins itself always involves working with the patient or student to maximize whatever vision remains, and provide the individual with whatever equipment and/or strategies they need to live their lives.
“Our goal is always to improve a person’s functional ability, customized to each individual’s needs,” Ross said. “The eye is a fragile organ. But we always say, there is always something we can do. We can help make the world adaptable. It is so important for people with low vision to have partners and resources.”
If an adult is diagnosed with age-related vision impairment due to macular degeneration, diabetes, or glaucoma, Ross said the strategy is along the lines of “rehabilitation, in which we help them to learn to do things differently.” If a person is born with low vision due to genetic variation, like retinitis pigmentosa, “we use habilitation, in which we teach them to meet their milestones, like walking for example, with support and tools.”
Why does it matter?
Visual impairment is one of the most prevalent disabilities among children under 18, yet they remain disproportionately underserved both in the classroom and in their communities. While many people are beginning to understand the spectrum of blindness, there is still work that needs to be done to counter common misconceptions and advocate for a more accessible world. To start, continue reading up on vision impairment and share your knowledge with friends.
Visit the New England Eye Low Vision Clinic at Perkins for information on services available and to schedule an appointment.