Tunnel vision [Gun barrel vision, tubular vision]

Tunnel vision [Gun barrel vision, tubular vision]: Excerpt from Nursing: Interpreting Signs and Symptoms

Resulting from severe constriction of the visual field that leaves only a small central area of sight, tunnel vision is typically described as the sensation of looking through a tunnel or gun barrel. It may be unilateral or bilateral and usually develops gradually. (See Comparing tunnel vision with normal vision.) This abnormality results from chronic open-angle glaucoma and advanced retinal degeneration. Tunnel vision may also result from laser photocoagulation therapy, which aims to correct retinal detachment. Also a common complaint of malingerers, tunnel vision can be verified or discounted by visual field examination performed by an ophthalmologist.

History and physical examination

Ask the patient when he first noticed a loss of peripheral vision, and have him describe the progression of vision loss. Ask him to describe in detail exactly what and how far he can see peripherally. Explore the patient's personal and family history for ocular problems, especially progressive blindness that began at an early age.

To rule out malingering, observe the patient as he walks. A patient with severely limited peripheral vision typically bumps into objects (and may even have bruises), whereas the malingerer manages to avoid them.

If your examination findings suggest tunnel vision, refer the patient to an ophthalmologist for further evaluation.

Medical causes

Chronic open-angle glaucoma.With chronic open-angle glaucoma, bilateral tunnel vision occurs late and slowly progresses to complete blindness. Other late findings include mild eye pain, halo vision, and reduced visual acuity (especially at night) that isn't correctable with glasses.

Retinal pigmentary degeneration.Retinal pigmentary degeneration disorders, a group of hereditary disorders such as retinitis pigmentosa, produces an annular scotoma that progresses concentrically, causing tunnel vision and eventually resulting in complete blindness, usually by age 50. Impaired night vision, the earliest symptom, typically appears during the first or second decade of life. An ophthalmoscopic examination may reveal narrowed retinal blood vessels and a pale optic disk.

Nursing considerations

▪ To protect the patient from injury, remove all potentially dangerous objects and orient him to his surroundings.

▪ Prepare the patient for diagnostic procedures, such as tonometry, perimeter examination, and visual field testing.

Patient teaching

▪ Explain the underlying disorder and treatment plan.

▪ Because vision impairment is frightening, reassure the patient, and clearly explain diagnostic procedures.

▪ Teach the patient how to compensate for tunnel vision to avoid bumping into objects.

Pictures

Book Source Details

• Book Title: Nursing: Interpreting Signs and Symptoms
• Author(s): Springhouse
• Year of Publication: 2007
• Copyright Details: Nursing: Interpreting Signs and Symptoms, Copyright © 2007 Lippincott Williams & Wilkins.

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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.

More About This Book: Title: Nursing: Interpreting Signs and Symptoms Authors: Springhouse Publisher: Lippincott Williams & Wilkins Copyright: 2007 ISBN: 1-58255-668-7

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