What is low vision?

 Low vision is a vision problem that makes it hard to do everyday activities. It can’t be fixed with glasses, contact lenses, or other standard treatments like medicine or surgery. In the practice of eye care “LOW VISION” has a specific meaning as defined by WHO.

 “A person with low vision is one who has impairment of visual functioning even after treatment and/or standard refractive correction, and has a visual acuity of less than 6/18 to light perception, or a visual field of less than 10 degree from the point of fixation, but who uses, or is potentially able to use, vision for planning and/or execution of a task.

 Under this definition persons who would benefit from low vision care also exist among those who are currently categorized as blind.

You may have low vision if you can’t see well enough to do things like:

  • Read
  • Drive
  • Recognize people’s faces
  • Tell colors apart
  • See your television or computer screen clearly.

 What are the types of low vision?

 The type of low vision that you have depends on the disease or condition that caused your low vision. The most common types of low vision are: 

  • Central vision loss (not being able to see things in the center of your vision)
  • Peripheral vision loss (not being able to see things out of the corners of your eyes)
  • Night blindness (not being able to see in low light)
  • Blurry or hazy vision

The table for low vision criteria and category is given below:

What causes low vision?

 Many different eye conditions can cause low vision, but the most common causes are:

  • Age-related macular degeneration (AMD)
  • Cataracts
  • Diabetic retinopathy (a condition that can cause vision loss in people with diabetes)
  • Glaucoma

 Low vision is more common in older adults because many of the diseases that can cause it are more common in older adults. Aging doesn’t cause low vision on its own.

Eye and brain injuries and certain genetic disorders can also cause low vision.

 What are some of the causes of Low Vision in children?

 Low vision can be the result of childhood conditions such as albinism, pediatric cataracts, pediatric glaucoma, nystagmus, and retinal and optic nerve abnormalities.



 Near visual acuity levels, in Point system, before and after the use of low vision aids. Using low vision aids was associated with a marked increase in number of patients who could discern N8 point font size or better, and a decrease in the number of patients who could only discern N48 point font size or larger fonts as shown in figure:



How will my eye doctor check for low vision?

 Your doctor can check for low vision as part of a dilated eye exam. The exam is simple and painless. Your doctor will ask you to read letters that are up close and far away, and will check whether you can see things in the center and at the edges of your vision. 

 Then, they will give you some eye drops to dilate (widen) your pupil and check for other eye problems — including conditions that could cause low vision.

 What’s the treatment for low vision?

 Unfortunately, low vision is usually permanent. Eyeglasses, medicine, and surgery can’t usually cure low vision — but sometimes they can improve vision, help you do everyday activities more easily, or keep your vision from getting worse. 

Treatment options will depend on the specific eye condition that caused your low vision. Ask your doctor if there are any treatments that could improve your vision or help protect your remaining vision.

After provision of low vision aids, there was a significant increase in the number of patients who could discern N8 print and better. Twenty seven patients (57%) could discern N8 print and better. Thirty-one patients (66%) at presentation could only discern N32 or larger print, this number markedly decreased to only 2 patients (4%) after use of LVAs. Results of improvement in near visual acuity are detailed in Table given below:

 Many people would consider losing their eyesight one of the worst losses they could endure. While most of us will not suffer from complete blindness, millions currently live with some form of visual impairment.

 According to the National Eye Institute (NEI), older adults represent the majority of the visually impaired population in the United States. While vision loss later in life is common, it can be particularly difficult for seniors to accept and adapt to as other senses like hearing, smell and taste also tend to weaken with age. Use the following tips to ensure an aging loved one properly cares for their eyes and takes advantage of all resources at their disposal to help them remain active in spite of vision loss.


Keeping an Eye on Visual Health

One of the first steps to leading a safe and active life with impaired vision is understanding the degree and underlying cause of this loss.

 The American Academy of Ophthalmology recommends individuals age 65 and older get a dilated medical eye exam every year or two, or as recommended by their ophthalmologist. During a routine eye exam, the ophthalmologist will evaluate a patient’s eyesight and assess the overall health and function of both eyes. Screening for new or worsening eye conditions and maintaining a current prescription for eyeglasses and/or contacts are crucial for optimal visual function at any age.

 For most people, vision loss is a very gradual process, so seniors (and their family members) may not be aware of how compromised their eyesight has become.

 “Many older adults believe that there is no way they can cope with this loss, since it affects almost all aspects of daily life,” Rogers explains. “But, caregivers and persons with visual impairment need to know that there is hope, and life, after vision loss.”

 How can I make the most of my remaining sight?

 If you have low vision, you can find ways to make the most of your vision and keep doing the things you love to do.

If your vision loss is minor, you may be able to make small changes to help yourself see better. You can do things like:

  • Use brighter lights at home or work
  • Wear anti-glare sunglasses
  • Use a magnifying lens for reading and other up-close activities .

 If your vision loss is getting in the way of everyday activities, ask your eye doctor about vision rehabilitation. A specialist can help you learn how to live with your vision loss. This can include things like:

  • Training on how to use a magnifying device for reading .
  • Guidance for setting up your home so you can move around easily
  • Sharing resources to help you cope with your vision loss
  • Watch these videos about how people live with low vision.




The telescopic system (TS) or telescope is an optical instrument that improves the resolution of an object by increasing the size of the image projected on the retina, making it closer.

  1. Telescope for distant view: A telescope enables greater participation in daily and social activities such as watching television and reading white boards, street signs, house and building numbers, billboards, and menu boards.
  2. Telescopes for distance, near, and middle distance:

Galilean Telescope

The Galilean telescope is a simple system consisting of 2 lenses:

Objective lens: convex (plus) lens, closest to the object

Ocular lens: minus lens, closest to the eye

The distance between the 2 lenses is determined by the difference in their focal lengths. The image produced is real and erect. It’s lighter, shorter, and cheaper than the Keplerian type, thus the first-choice prescription for children.


 Nonoptical aids are visual aids that do not use magnifying lenses to improve visual function. They can improve the other visual aid’s function or can even replace optical aids. They enhance visual function by:

  • Linear magnification
  • Lighting control
  • Enhanced contrast
  • Reduction of glare
  • Improving physical comfort (accessories)


Natural light is the adequate lighting for most low-vision children; however, artificial light allows better control of illumination. Incandescent light of 60–75 watts is preferred because it provides a more continuous spectrum than fluorescent light, but might be harder to find, particularly in the United States where some states have banned incandescent lighting. Fluorescent light emphasizes the “cooler” blue spectrum, which can intensify glare. Everyone, even those without low vision, should avoid single-tube fluorescent lamps without a diffuser because they are intermittent, and can cause eyestrain and inhibition of accommodation.


The light should be shone directly on the reading material, avoiding reflective surfaces. The focus should be placed at shoulder height corresponding to the better-seeing eye, forming a 45‑degree angle with the visual axis. When using natural light, the child should sit with their back to the window or on the side leading to the best lighting and visualization.


A typoscope, caps or visors, side shields, and/or polarizing lenses should be prescribed to control the reflection of light. A typoscope can also be used as a guide to reading, writing, and signature in cases of large defects of visual field.

Light-filtering lenses are useful and frequently prescribed. They should filter ultraviolet radiation below 400 nm, minimizing the loss of VA and color discrimination. It is important to consider comfort; protection from ultraviolet, infrared, and visible light; increased contrast; and glare reduction.


Several factors should be considered when choosing a filter: lens color, optical density, polarization, and spectrum of protection. The filters can be adapted in glasses, clip-ons, or contact lenses.


Different filters can be prescribed for different situations, paying close attention to the goals to be achieved, levels of lighting, cost, and especially the individual preference.


Enhanced Contrast and Reduction of Glare

Lighting control is of great importance to enhance contrast and reduce glare. The type, position, and intensity of the light source should be monitored. Absorptive lenses in yellow for low-light environments and amber for more intense lighting are good prescription options. It is also important to support daily activities with aids such as black felt-tipped pen, bold lines, and contrasting colors.

For a better acceptance and adaptation to the optical aid, physical comfort is key. An inclined board set at a 45‑degree angle can be of help.


Electronic Assistive technology is an interdisciplinary field of knowledge comprising products, resources, methodologies, strategies, practices, and services that promote functionality for visually impaired people with regard to autonomy, quality of life, and social inclusion. High-tech aids are increasingly of benefit to people with low vision.


Electronic devices include video magnifier systems, closed-circuit televisions, Bluetooth connections to smart projectors, large-print computer programs such as Zoom Text, screen readers such as Virtual Vision and Jaws, and computer tablets.


Electronic devices can be very helpful in moderately or severely visually impaired children and in children who do not respond to other proposed aid. A computer and a tablet can be a good option for a multihandicapped child.


Different electronic devices are currently available:


Video Magnifier System


A video magnifier system consists of a monitor and a camera that projects the enlarged image on the screen. Advantages are higher reading speed (2.5 times) and greater working distance (3 times) when compared to other aids. The larger working distance makes it easy to use for writing, drawing, or painting. It provides additional visual field, brightness, contrast, and polarity control, making it the choice for diseases with low contrast and glare. It allows magnification of 2 to 60 times and binocular vision. It can be fixed or portable, black and white or color, mouse or tray, and fixed-focus or autofocus, allowing objects to be seen at various distances.


 Video magnifier system:

A video magnifier system requires coordination and training, but it is the only aid that effectively improves contrast and residual vision and it is well indicated for:

  • Greater working distance
  • Prolonged and less tiring reading
  • Allows contrast to be reversed
  • Glare
  • Large visual-field defects (less than 5 degree)


 Video Magnifiers:

These electronic devices make printed pages and pictures look bigger. The cheapest available “video magnifiers” are the smartphones and tablets that allow you to increase contrast and font size of texts.




Telescopes may be attached to eyeglasses or be like binoculars, and are used to see objects or signs far away.


Stand Magnifiers:


These magnifiers are placed away from your eye, on the object you are trying to read. The handheld versions are also available for reading, and these usually have built-in lights. In case you have a tremor or arthritis, stand magnifiers are best suited for you.


Magnifying Spectacles:


Magnifying spectacles are worn like eyeglasses, and help you see better for tasks like reading, threading a needle, stitching etc. These are hands-free magnifiers, allowing you to work with your hands.





Low vision aids are potential methods of improving the residual vision in low vision patients. In the background of the high and increasing prevalence of low vision and poor awareness about low vision aids among them, efforts are necessary to rehabilitate them with affordable and accessible low vision services.




For further reading references are given below:









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