Visual loss: Encyclopedia - Visual loss

Visual loss

Visual loss results in the absence of vision where it existed before, which can happen either acutely (i.e. abruptly) or chronically (i.e. over a long period of time). The effects of visual loss can, before the acquisition of alternative adaptations and skills, be devastating; especially when a person's vision disappears over a short period of time.

Visual loss - Acute visual loss

Acute visual loss may be dramatic in presentation, and is almost always alarming to the person experiencing the loss. It may be caused by media opacities, retinal disease, optic nerve disease, visual pathway disorders, or functional disorders, or it may be in fact an acute discovery of chronic visual loss.

Visual loss - Media opacity

Opacities of the clear refractive media of the eye such as the cornea, anterior chamber, lens (anatomy), and vitreous humor may cause acute visual loss as manifested by blurry vision or reduced visual acuity. While pupillary reflexes may be affected, these conditions generally do not cause a relative afferent pupillary defect.

Causes of media opacity include corneal edema, hyphema, cataract and vitreous hemorrhage.

Visual loss - Retinal disease

Retinal diseases may cause sudden visual loss. Because the retina is being affected, there is usually a concomitant relative afferent pupillary defect. Conditions that affect or destroy the retina include retinal detachment; macular disease (e.g., macular degeneration); and retinal vascular occlusions, the most important of which is central retinal artery occlusion.

Visual loss - Optic nerve disease

Diseases which affect the optic nerve may cause acute visual loss. Signs include an abnormal pupillary reflex, with an afferent pupillary defect when the optic nerve disease is unilateral.

The optic nerve can be affected by optic neuritis, retrobulbar neuritis, papillitis, papilledema, ischemic optic neuropathy, and giant cell arteritis.

Visual loss - Visual pathway disorder

Visual pathway disorders are any problems that may impede the visual pathway. Rarely, acute visual loss is caused by homonymous hemianopia and, more rarely, cortical blindness.

Visual loss - Functional disorder

The term functional disorder is now used where hysterical and malingering were historically used. This shift recognizes the inherent inability of the physician to identify the subjective experience of a patient (and thus whether that patient can truly see or not).

See also

• Blindness
• Eye examination
• Low vision
• Visual acuity

Adapted from the Wikipedia article "Visual loss", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki