Eye Blindness Symptoms
If vision loss develops within minutes to days, it is considered sudden. It may affect single or double eyes, all or part of the field of vision.
Only a small fraction of the visual field is lost (for example, due to a small retinal detachment) may be blurred vision. Other symptoms, such as eye pain, may occur as a result of vision loss.
There are three common causes of sudden loss of vision:
- The turbidity of normal transparent eye structure
- Retinal (photosensitive structure at the back of the eye) abnormal
- Nerve abnormalities (optic nerve and visual pathways) that transmit visual signals from the eye to the brain.
Light is passed through several transparent structures before it is felt by the retina. First, light passes through the cornea (the iris and the clear layer in front of the pupil), then the lens, and then the vitreous (gel-like substance that fills the eyeball).
Most diseases, when they affect the entire eye, cause complete loss of vision, and may also affect only the parts of the eye.
When the visual pathway is damaged
The nerve signals of the left and right eyes are in line with the corresponding optic nerve fibers. The two optic nerves converge at the chiasm.
The nerve signals of the left and right eyes were respectively taken along the corresponding optic nerve fibers.
After convergence at the optic chiasm, the optic nerve fibers were crossed to the opposite side and half were extended to the same side of the brain or hyperopia definition.
Due to this arrangement, the brain receives information through the left and right visual nerves. There are differences in the types of visual fields.
Principles And Causes Of Blindness
Anything that blocks light in the environment from entering the eye or disturbing nerve impulses from the back to the brain can interfere with vision.
Legal blindness means that even after correction by spectacles or contact lenses, the visual or visual clarity of the eye is 20/200 or worse, or the visual field is limited to less than 20 °.
Many people who are considered legally blind can distinguish between shapes and shadows.
Blindness can occur in the following situations:
- Light cannot reach the retina.
- Corneal damage caused by infection, such as keratoconjunctivitis of herpes, or infection caused by long-time contact lenses, causing corneal scarring
- Vitamin A deficiency leads to dry eyes, corneal softening, etc., corneal scarring occurs
- Severe trauma damages the cornea leading to corneal turbid scar formation
- Cataract causes crystal clarity to decrease
- The light does not focus properly on the retina.
- Severe refractive errors, frame glasses or contact lenses cannot be corrected.
- The retina does not sense light properly
- Retinal detachment
- Macular degeneration
- Retinitis pigmentosa