How do you lose peripheral vision

Blurred vision

Blurred vision is the most common symptom affecting the eyes. When doctors talk about blurred vision, they usually mean a decrease in visual acuity or clarity that has gradually developed. Sudden, complete loss of vision in one or both eyes (blindness) is considered something else.

causes

Blurred vision is due to four general mechanisms:

  • Disorders affecting the retina, the light-sensitive part at the back of the eye.

  • The opacity of the normally clear parts of the eye (cornea, lens, and vitreous humor - this is the gelatinous mass that fills the eyeball) that rays of light have to pass before they reach the retina.

  • Disorders that affect the nerve pathways that carry visual signals from the eye to the brain (such as the optic nerve)

  • Impairment of the bundling of light rays on the retina (refraction error)

Look inside the eye

Certain diseases can involve more than one mechanism. For example, refraction can be impaired by early cataracts or by reversible lens swelling caused by poorly controlled diabetes.

Some disorders that cause blurred vision are more likely to cause other symptoms that make people want to see a doctor, such as eye pain and reddening of the eyes (for example, acute corneal diseases such as abrasions, ulcers, herpes simplex keratitis or Herpes zoster ophthalmicus).

Common causes

The most common causes of blurred vision include

What is Astigmatism?

Astigmatism is an irregularity in the curvature of the cornea or lens. This means that the cornea or lens is curved differently in different directions. This difference causes the light to travel on different planes and is then focused differently. For example, it can be that the rays incident in the vertical plane are bundled, but not those in the horizontal plane or vice versa. However, the problem can occur at any level and is often different in each eye. A person with astigmatism will usually see certain lines more clearly (sharper) than others (each eye should be tested separately). Astigmatism can be corrected with prescribed glasses or contact lenses. It is often associated with nearsightedness or farsightedness.

The following diagram shows a standard chart for examining one eye at a time for astigmatism.

Rarer causes

Rare disorders that cause blurred vision are

  • Inherited disorders that affect the optic nerve called hereditary optic neuropathies (such as dominant optic atrophy and Leber hereditary optic neuropathy)

  • Scarring of the cornea due to a lack of vitamin A (rare in developed countries).

Some causes and characteristics of blurred vision

A clouding of the normally transparent structures of the eye

Symptoms that develop gradually

Loss of the ability to differentiate between light and dark (loss of contrast), glare (the recognition of halos and star-shaped rays around light sources)

Often in people with risk factors (such as age or the use of corticosteroids)

Physical examination

Scarring of the cornea after an injury or infection

Usually in people with a previous injury or infection

Physical examination

Disorders affecting the retina

Usually symptoms that set in gradually

Loss of central vision (what the person is looking at directly) to a greater extent than loss of peripheral vision (what is seen out of the corner of the eye).