Low vision refers to a significant visual impairment that cannot be fully corrected with standard glasses, contact lenses, medication, or surgery. This condition impedes individuals' ability to perform everyday activities, such as reading, writing, driving, and recognizing faces.
Low vision is not a disease itself but rather a condition resulting from various underlying eye disorders or health issues. It represents a range of visual limitations that cannot be fully corrected by standard means, emphasizing the need for specialized support and rehabilitation services (Brilliant, 1999). Unlike complete blindness, people with low vision retain some degree of usable sight (National Eye Institute, 2023; American Academy of Ophthalmology, 2023; Mayo Clinic, 2023).
Vision rehabilitation services help people with low vision make the most of what they’ve got. A specialist can help connect you with low vision aids and assistive technology to make your life easier (Mayo Clinic, 2023).
In this article, we will explore the following sections:（You can click the titles below to directly go to the corresponding sections）
- Understanding Low Vision Through Visual Acuity Tests
- Is Low Vision Congenital Or Acquired?
- Types Of Low Vision
- What Do Low Vision People See?
- Causes Of Low Vision
- How Can People With Low Vision Make The Most Of Their Remaining Sight?
Understanding Low Vision Through Visual Acuity Tests
Low vision is defined based on visual acuity and visual field criteria. According to the World Health Organization (WHO), low vision includes a visual acuity of less than 6/18 (20/70) but equal to or better than 3/60 (20/400) in the better eye with the best possible correction. Additionally, a visual field of 20 degrees or less in the better eye is considered a significant impairment (World Health Organization, 2023).
In the U.S., the standard visual acuity test is the Snellen eye chart, which measures the clarity of vision at a distance of 20 feet. A score of 20/70 indicates moderate visual impairment, where vision at 20 feet is comparable to normal vision at 70 feet. A score of 20/200 or worse qualifies as severe low vision. However, low vision is a condition present even when using corrective lenses. Individuals who can improve their vision with glasses, contacts, or surgery do not fall under the low vision category (Cleveland Clinic, 2023).
Is Low Vision Congenital or Acquired?
Low vision can be either congenital or acquired, depending on the timing and nature of the underlying condition.
Congenital Low Vision
Some individuals are born with visual impairments due to genetic factors or developmental issues. Conditions like congenital cataracts, albinism, and Leber congenital amaurosis are examples of congenital causes of low vision (Cleveland Clinic, 2023).
For children and adolescents with congenital low vision, there are targeted treatments and interventions that can help improve their vision or manage their condition:
Surgical Interventions
Some congenital conditions, such as congenital cataracts, can be treated with surgery. Removing the cataract and replacing the lens can significantly improve vision.
Vision Therapy
Vision therapy involves exercises and activities designed to improve visual skills and processing. It can be beneficial for children with specific visual impairments (Watson, 2001).
Assistive Technology
The use of low vision aids, such as magnifiers, screen readers, and other assistive devices, can help children maximize their remaining vision and participate more fully in educational and daily activities (Massof & Lidoff, 2001). The following section will discuss that assistive technology is also applicable to children.
Educational Support
Specialized education programs and resources can help children with low vision learn effectively. This may include the use of Braille, large print materials, and adaptive technologies.
Early Intervention
Early diagnosis and intervention are crucial. Regular eye examinations and prompt treatment of any underlying conditions can prevent further vision loss and support better outcomes (National Eye Institute, 2023).
Acquired Low Vision
This form of low vision develops later in life, often due to age-related diseases, trauma, or systemic conditions like diabetes. Age-related macular degeneration and diabetic retinopathy are common acquired causes (Mayo Clinic, 2023).
Types of Low Vision and What Do Low Vision People See?
Low vision can manifest in various forms, each affecting vision differently. Individuals with low vision experience a range of visual disturbances, varying in severity and nature. The specifics of what they see depend on the underlying cause and extent of their impairment. Common types and symptoms of low vision include:
Central Vision Loss
Difficulty seeing things directly in front, which is common in conditions like age-related macular degeneration. This can make activities like reading and recognizing faces challenging.
Peripheral Vision Loss
Trouble seeing things out of the corner of the eye, often associated with glaucoma. This tunnel vision can affect mobility and navigation.
Night Blindness
Poor vision in low-light conditions, which can occur with retinitis pigmentosa.
(Netrajyot Eye Clinic, n.d.)
Blurred Vision
Everything appears out of focus, typical in cataracts. Objects may appear out of focus at any distance.
Hazy Vision
Objects seem to be covered with a film or glare, often seen in corneal scarring or severe dry eyes.
(Healthline, n.d.)
Reduced Contrast Sensitivity
Difficulty distinguishing between objects of similar colors.
(Singapore National Eye Centre, n.d.)
Glare and Light Sensitivity
Bright lights can cause discomfort or obscure vision (American Academy of Ophthalmology, 2023; All About Vision, 2023).
These visual challenges necessitate tailored interventions and support to improve the quality of life for individuals with low vision.
Causes of Low Vision
Low vision can result from various eye conditions and diseases, including:
Age-Related Macular Degeneration (AMD)
A leading cause of low vision in older adults, characterized by the deterioration of the central part of the retina.
Glaucoma
Increased pressure in the eye can damage the optic nerve, leading to peripheral vision loss.
Diabetic Retinopathy
High blood sugar levels can damage the blood vessels in the retina, resulting in vision impairment.
Cataracts
Clouding of the eye's lens can significantly blur vision.
Retinitis Pigmentosa
A genetic disorder that affects the retina and can lead to tunnel vision and night blindness.
Traumatic Injuries
Physical damage to the eye or optic nerve can cause irreversible vision loss (All About Vision, 2023; Cleveland Clinic, 2023; Brilliant, 1999).
Infectious Diseases
Conditions such as trachoma and onchocerciasis are significant causes of low vision in developing countries (World Health Organization, 2023).
Uncorrected Refractive Errors
Conditions like myopia, hyperopia, and astigmatism, if left uncorrected, can contribute to low vision (Bourne et al., 2023).
This video from Northwestern Medicine is divided into two parts and can help you understand what people with these vision problems see. Click to watch:（then click the full-screen button in the lower right corner of the video, or press the "f" key on your keyboard, to watch the video for a better view.）
Understanding the specific cause of low vision is crucial for effective management and treatment (Goodrich & Kirby, 2001).
How Can People with Low Vision Make the Most of Their Remaining Sight?
Maximizing the use of remaining vision involves a combination of strategies and resources. Effective management and support are crucial for helping individuals with low vision maintain their independence and improve their quality of life. The following interventions and tools can be particularly beneficial:
Use of Assistive Devices
Magnifiers, telescopic glasses, and electronic reading aids can enhance visual capabilities, making it easier to read, write, and perform other tasks.
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Acesight VR | A VR headset designed for enhanced visual experiences. |
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Environmental Modifications
Improving lighting, using high-contrast colors for better visibility, and reducing glare can significantly improve the usability of remaining vision. Simple changes like using brighter bulbs or arranging furniture to avoid shadows can make a big difference (National Eye Institute, 2023).
Vision Rehabilitation
Specialized training programs can teach individuals how to utilize their residual vision effectively and adapt to their visual limitations. This may include orientation and mobility training to improve navigation skills (Scheiman & Scheiman, 2007).
Technology
Screen readers, voice-activated assistants, and apps designed for low vision users can facilitate daily activities such as reading, shopping, and communicating. These technologies can be tailored to individual needs and preferences (Optometrists.org, 2023).
Adaptive Techniques
Learning new ways to perform tasks, such as using tactile markers and organizational systems to identify items, can help individuals manage their daily routines more efficiently. For example, using raised dots on appliances can help distinguish different settings by touch (Cleveland Clinic, 2023)
Exercise
Regular physical activity can improve overall health and well-being, which in turn can positively impact vision health. Safe and enjoyable exercise routines tailored for people with low vision can be found here: Safe and Enjoyable Exercise for People with Low Vision.
Medical treatment and regular eye examinations are also important for managing underlying conditions like glaucoma or diabetic retinopathy, which can help slow the progression of vision loss (American Academy of Ophthalmology, 2023)
By leveraging these resources and techniques, individuals with low vision can make the most of their remaining sight and maintain a high quality of life.
Conclusion
Low vision, a condition affecting millions of people worldwide, encompasses a range of visual impairments that significantly impact daily activities. Understanding that low vision is not a single disease but rather a result of various underlying conditions highlights the importance of personalized care and targeted interventions. Through the use of assistive devices, environmental modifications, vision rehabilitation, technology, and adaptive techniques, individuals with low vision can enhance their remaining vision and improve their overall quality of life. Early diagnosis and ongoing medical care are crucial for managing low vision and preventing further deterioration. With the right support and resources, those with low vision can lead fulfilling and independent lives.
FAQs
What is the difference between low vision and blindness?
Low vision refers to significant visual impairment that cannot be corrected with standard means, but some usable vision remains. Blindness is a complete or near-complete lack of vision.
Can low vision be prevented?
Some causes of low vision, such as diabetic retinopathy, can be managed and potentially prevented with proper medical care and lifestyle adjustments. Regular eye examinations are crucial for early detection and management.
Are there technologies available to help people with low vision?
Yes, various assistive technologies, such as magnifiers, screen readers, and specialized lighting, are available to help individuals with low vision perform daily tasks more effectively.
References
- American Academy of Ophthalmology. (2023). Understanding Low Vision. Retrieved from https://www.aao.org
- All About Vision. (2023). Low Vision: Definition, Causes, Treatment. Retrieved from https://www.allaboutvision.com
- Bourne, R. R. A., et al. (2023). Global prevalence of vision impairment and blindness. The Lancet Global Health, 11(1), e88-e98. https://pubmed.ncbi.nlm.nih.gov/29550169/
- Brilliant, R. L. (1999). Essential Concepts in Low Vision Rehabilitation. Butterworth-Heinemann. ISBN: 978-0-75060-537-7.
- Cleveland Clinic. (2023). Low Vision: Causes, Characteristics, Treatment & Prevention. Retrieved from https://my.clevelandclinic.org
- Goodrich, G. L., & Kirby, J. N. (Eds.). (2001). Visual Impairment in the Schools (3rd ed.). Charles C Thomas Publisher. ISBN: 978-0-39807-382-2.
- Healthline. (n.d.). Hazy vision: Causes, symptoms, and treatment. Healthline. https://www.healthline.com/health/hazy-vision
- Massof, R. W., & Lidoff, L. (Eds.). (2001). Low Vision Rehabilitation: Caring for the Whole Person. American Foundation for the Blind. ISBN: 978-0-89128-379-9.
- Mayo Clinic. (2023). Low Vision. Retrieved from https://www.mayoclinic.org
- National Eye Institute. (2023). Facts About Low Vision. Retrieved from https://www.nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/low-vision
- Netrajyot Eye Clinic. (n.d.). Night blindness (nyctalopia): Illuminate your path to clearer nights. Netrajyot Eye Clinic. https://netrajyot.com/night-blindness-nyctalopia-illuminate-your-path-to-clearer-nights/
- Optometrists.org. (2023). What is Low Vision? Retrieved from https://www.optometrists.org
- Scheiman, M., & Scheiman, M. (2007). Low Vision Rehabilitation: A Practical Guide for Occupational Therapists. Slack Incorporated. ISBN: 978-1-55642-740-8.
- Singapore National Eye Centre. (n.d.). Low vision: Common symptoms, contrast sensitivity, and glare. Singapore National Eye Centre. https://www.snec.com.sg/patient-care/specialties-and-services/clinics-centres/low-vision-common-symptoms-contrast-sensitivity-and-glare
- Watson, G. R. (2001). Low Vision in the Geriatric Population: Rehabilitation and Management. Slack Incorporated. ISBN: 978-1-55642-452-0.
- World Health Organization. (2023). Global Initiative for the Elimination of Avoidable Blindness. Retrieved from https://www.who.int/blindness/causes/priority/en/index3.html
- Zoomax. (2023). Safe and Enjoyable Exercise for People with Low Vision. Retrieved from https://www.zoomax.com/low-vision-information/safe-and-enjoyable-exercise-for-people-with-low-vision/
