- by Dr H Janhavi
- 1 Shares
- Jan 31 2018
What is Low Vision?
It is defined as a loss of sight that cannot be corrected with prescription eyeglasses, contact lenses, or surgery. It does not include complete blindness because there is still some sight left. The Academy of Ophthalmology divides low vision into two categories based on the vision in your best eye:
Partially sighted: Your vision is between 20/40 and 20/200 with conventional prescription lenses.
Legally Blind: When vision is not better than 20/200 with conventional correction then it is termed as Legally Blind.
The World Health Organisation uses the following classifications of visual impairment:
- 20/30 to 20/60, this is considered mild vision loss or near-normal vision.
- 20/70 to 20/160, this is considered moderate visual impairment or moderate low vision.
- 20/200 to 20/400, this is considered severe visual impairment or severe low vision.
- 20/500 to 20/1000, this is considered profound visual impairment.
- Less than 20/1000, this is considered near-total visual impairment.
- No light perception, this is considered total visual impairment or total blindness.
Types of Low Vision
- Loss of central vision: Blind spot in the centre of your field of vision.
- Loss of Peripheral vision: When you cannot see anything to either side or above or below eye level.
- Night Blindness: When you cannot see properly in poorly lit places.
- Blurred Vision: When objects are out of focus whether near or far.
- Hazy Vision: When entire field of vision seems to be covered with a film or glare.
Causes of low vision
It can be because of injuries and age is also one of the factors. Other possible causes include:
- Cancer of the eye
- Eye trauma
- Brain injury
The doctor will take an eye exam. He will use lighting, magnifiers, and special charts to test your visual acuity, depth perception, and visual fields.
Low vision is permanent but some sight disorders, like diabetic retinopathy can be treated to restore or maintain vision. However, there are some products which can help:
- Telescopic glasses
- Lenses that filter light
- Magnifying glasses
- Handheld and freestanding magnifiers
- Reading prisms
- Closed-circuit television
It can be prevented for patients with diabetes but if it is caused by cataracts, it cannot be reversed.
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