Homonymous hemianopsia

Homonymous hemianopsia
Classification and external resources
File:Lhvf.png Paris as seen with left homonymous hemianopsia
ICD-10	H53.4
ICD-9	368.46

Homonymous hemianopsia, or homonymous hemianopia, is a type of partial blindness resulting in a loss of vision in the same visual field of both eyes.

Causes

It is usually caused by injury to the brain itself such as from stroke or trauma, or as a byproduct of certain surgical procedures and does not indicate a malfunctioning of the eyes themselves. It may also be caused by tumour localised at the occipital lobe in the brain.

Vascular and neoplastic (malignant or benign tumours) lesions of the optic tract, visual cortex or uncal herniation can cause a contralateral homonymous hemianopsia. For example, a person who has a lesion of the right optic tract will no longer see objects on his left side. Similarly, a person who has a stroke to the right occipital lobe will have the same visual field defect, but there will be macular sparing. Thus injury to the right side of the brain will affect the left visual fields of each eye.

A stroke on the right side of the brain, in addition to producing a homonymous hemianopsia, may also lead to the syndrome of hemispatial neglect.

However, the symptom of homonymous hemianopsia isn't necessarily of a lethal cause. For instance, it can constitute the aura phase of migraine.

Effects

Mobility can be difficult for people with homonymous hemianopia. “Patients frequently complain of bumping into obstacles on the side of the field loss, thereby bruising their arms and legs.”³

People with homonymous hemianopia often experience discomfort in crowds. “A patient with this condition may be unaware of what he or she cannot see and frequently bumps into walls, trips over objects or walks into people on the side where the visual field is missing.”⁵

Help With Mobility

Peripheral prism spectacles expand the visual field of patients with hemifield visual defects and significantly improve visual function and mobility.⁴

This lens, called the Peli Lens, is an eyeglass lens incorporating high power prisms creating artificial peripheral vision into the blind field for obstacle avoidance and motion detection. In a paper entitled “Rehabilitation of hemianopia”. the authors suggest that “given the relatively low cost of these lenses, perhaps a test pair of adaptive glasses should be offered to suitable patients on a two month trial basis.“ ² The Peli Lens was developed as a mobility aid for homonymous hemianopia by Dr. Eli Peli of the Schepens Eye Research Institute (SERI), an affiliate of Harvard University ³ and is manufactured by Chadwick Optical, Inc. Dr. Peli’s technique provides a measurable 20º expansion of the visual field while leaving central field unobstructed. More information is available and pictures can be viewed at www.Hemianopia.org. Results of clinical trials using this technique were published in 2008 and reported a 74% patient acceptance rate.⁴

An improved version of the Peli Lens expanding the visual field by 30 degrees is available. Clinical trial results are pending.

Etymology

Homonymous hemianopsia can be broken down as follows:

• Homonymous: having the same name
• hemi: half
• anopsia: blindness

Homonymous hemianopsia is also called Homonymous hemianopia.

See also

• Binasal hemianopsia
• Bitemporal hemianopsia
• British Columbia (Superintendent of Motor Vehicles) v. British Columbia (Council of Human Rights)

References

² Schofield TM, Leff, AP, Rehabilitation of Hemianopia, Current Opinion in Neurology, 2009, 22:36-40

³ Peli E. Field expansion for homonymous hemianopia by optically induced peripheral exotropia. Optom Vis Sci 2000; 77:453-464.

⁴ Bowers AR, Keeney K, Peli E. Community-based trial of a peripheral prism visual field expansion device for hemianopia. Arch Ophthalmol 2008;126:657-664

⁵ Prism Glasses Expand The View For Patients With Hemianopia, Medical News today, 14 May 2008, www.medicalnewstoday.com/articles/107160.php

External links

• Hemianopsia.net

da:Homonym hemianopsi tr:Homonim hemianopsi