Tunnel Vision: What It Is and What Peripheral Vision Is

Tunnel vision is a condition in which a person loses the ability to see peripherally and sees only what falls within the central area of the retina, the inner lining of the eye. Simply put, the world narrows to a small circle directly in front of the face. Below we explain which diseases cause this sign and when an ophthalmologist — a doctor who treats eye diseases — is needed.

What tunnel vision is

With tunnel vision, everything at the edges of the visual field drops out of the picture, and only the central zone remains. A person has difficulty navigating in space: they do not notice objects to the side and may bump into furniture or a passerby. The condition can be transient, for example during a sudden rush of blood away from the head — this happens to pilots and cosmonauts under high g-forces — or chronic, when the cause is glaucoma or retinal degeneration.

Peripheral vision: what it is responsible for

Peripheral vision is the ability to notice objects not at the point where the gaze is directed, but at the edges of the visual field. It does not provide sharpness, but it warns of danger from the side and helps a person walk freely along the street and around a room. In tunnel vision, it is precisely this part of the visual field that is affected, while central, sharpest vision is preserved longer, so a person may not notice the narrowing for a long time.

Causes of visual field narrowing

Various causes are named, and not all of them are ocular:

• glaucoma — damage to the optic nerve, most often due to increased pressure inside the eye, and pigmentary retinal degeneration;
• cataract — clouding of the lens, the eye's natural lens;
• migraine with aura — a headache attack preceded by visual images;
• a sharp drop in blood pressure, major blood loss, oxygen deprivation;
• pituitary tumors and mercury poisoning.

Narrowing of the visual field also occurs in stroke and transient cerebrovascular accident, brain tumor, retinal detachment, and inflammation of the optic nerve; some medications also affect vision. Glaucoma has its own risk conditions: age over 50, the disease in a brother, sister, or parent, myopia, hyperopia, diabetes.

How loss of side vision manifests

The first sign is difficulty seeing objects on one side or the other. In glaucoma, vision is initially normal, but over time poor vision in the dark, blind spots, and loss of vision to the side appear; both eyes are affected, although one may be affected more severely. Blind spots, or scotomas, are dark areas in which nothing can be seen. In retinal detachment, a person feels as if a curtain is descending from the side.

How the visual field is tested

The doctor checks visual acuity, eye movements, pupils, retina, and pressure inside the eye. Examination with a dilated pupil, slit-lamp examination, measurement of intraocular pressure, and visual field testing are used: in a special way, it is determined which areas around the center a person notices. Glaucoma is often found during a routine check before complaints appear, and then the patient is referred to an ophthalmologist. Vision should be checked at least once every two years, and after age 65 — every year.

When to see an ophthalmologist

A complete eye examination is needed if it is difficult to see objects to the side, difficult to see at night or read, vision gradually loses sharpness, it is difficult to distinguish colors, and also in diabetes or a hereditary predisposition to it.

Tunnel vision by itself is not a reason to call an ambulance. Numbers 103 and 112 are needed if vision has partially or completely disappeared at least temporarily, double vision has appeared at least temporarily, there is a sensation of a curtain or blind from the side, above, or below, blind spots or distortions have suddenly appeared, vision has become blurred together with pain and redness of the eye, and also in case of sudden severe eye pain, rainbow-colored halos around light, nausea, and headache.

This material is for reference: it explains what the terms "tunnel vision" and "peripheral vision" mean, but does not replace consultation with a doctor who will examine the eye and identify the cause.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer