Halo vision
Halo vision: Excerpt from Professional Guide to Signs & Symptoms (Fifth Edition)
Halo vision refers to seeing rainbowlike colored rings around lights or bright objects. The rainbowlike effect can be explained by this physical principle: As light passes through water (in the eye, through tears or the cells of various anteretinal media), it breaks up into spectral colors.
Halo vision usually develops suddenly; its duration depends on the causative disorder. This symptom may occur in disorders associated with excessive tearing and corneal epithelial edema. Among these causes, the most common and significant is acute angle-closure glaucoma, which can lead to blindness. In this ophthalmic emergency, increased intraocular pressure (IOP) forces fluid into corneal tissues anterior to Bowman’s membrane, causing edema. Halo vision is also an early symptom of cataracts, resulting from dispersion of light by abnormal lens opacity.
Nonpathologic causes of excessive tearing associated with halo vision include poorly fitted or overworn contact lenses, emotional extremes, and exposure to intense light, as in snow blindness.
History and physical examination
First, ask the patient how long he has been seeing halos around lights and when he usually sees them. Patients with glaucoma usually see halos in the morning, when IOP is most elevated. Ask the patient if light bothers his eyes. Does he have eye pain? If so, have him describe it. Remember that halos associated with excruciating eye pain or a severe headache may point to acute angle-closure glaucoma, an ocular emergency. Note a history of glaucoma or cataracts.
Next, examine the patient’s eyes, noting conjunctival injection, excessive tearing, and lens changes. Examine pupil size, shape, and response to light. Then test visual acuity by performing an ophthalmoscopic examination.
Medical causes
Cataract
Halo vision may be an early symptom of painless, progressive cataract formation. The glare of headlights may blind the patient, making nighttime driving impossible. Other features include blurred vision, impaired visual acuity, and lens opacity, all of which develop gradually.
Corneal endothelial dystrophy
Typically, halo vision is a late symptom of this disorder, which may also cause impaired visual acuity.
Glaucoma
Halo vision characterizes all types of glaucoma. Acute angle-closure glaucoma—an ophthalmic emergency—also causes blurred vision, followed by a severe headache or excruciating pain in and around the affected eye. Examination reveals a moderately dilated fixed pupil that doesn’t respond to light, conjunctival injection, a cloudy cornea, impaired visual acuity and, possibly, nausea and vomiting.
Chronic angle-closure glaucoma usually produces no symptoms until pain and blindness occur in advanced disease. Sometimes, halos and blurred vision develop slowly.
In chronic open-angle glaucoma, halo vision is a late symptom that’s accompanied by mild eye ache, peripheral vision loss, and impaired visual acuity.
Special considerations
To help minimize halo vision, remind the patient not to look directly at bright lights.
Pediatric pointers
Halo vision in a child usually results from congenital cataracts or glaucoma. In a young child, limited verbal ability may make halo vision difficult to assess.
Geriatric pointers
Primary glaucoma, the most common cause of halo vision, is more common in older patients.
Book Source Details
- Book Title: Professional Guide to Signs & Symptoms (Fifth Edition)
- Author(s): Springhouse
- Year of Publication: 2006
- Copyright Details: Professional Guide to Signs & Symptoms (Fifth Edition), Copyright © 2006 Lippincott Williams & Wilkins.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
» Next page: Costovertebral angle tenderness (Professional Guide to Signs & Symptoms (Fifth Edition))
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