Bitemporal hemianopsia is a type of partial blindness where vision is missing in the outer half of both the right and left visual fields, caused by lesions or compression affecting the center of the optic chiasm. It results in inability to view the peripheral vision. The most common cause is tumors located at the mid-optic chiasm, such as pituitary adenomas or craniopharyngiomas. Other potential causes include meningiomas or aneurysms of the anterior communicating artery. The detailed anatomy and neurocircuitry of the visual pathway empower understanding of how specific lesions can lead to different visual field deficits.

1. 1
Bitemporal Hemianopsia
Bitemporal hemianopsia (or Bitemporal hemianopia) is the medical description of a type
of partial blindness where vision is missing in the outer half of both the right and left
visual field (the peripheral vision), as shown in Figure 1, and is usually associated with
lesions or compression that affect the center of the optic chiasm.
Bitemporal hemianopsia can be broken down as follows:
bi: involves both left and right visual fields
temporal: involves the temporal (or peripheral) visual field
hemi: involves half of each visual field
anopsia: blindness (formed by a(n) no
+ opsis vision
+ ia)
Figure 1 Normal vision (top) vs. bitemporal hemianopsia
(Source: http://pituitary.ucla.edu/images/site/Visual3.3.jpg)
Each of the human eyes have two visual fields, namely the left (shown as blue color in
Figure 2) and right visual fields (red color in Figure 2). Take the right eye as an
example, the information from the right visual field (red color) falls on the nasal (medial)
hemiretina (the left hemisphere of the right eye). The nasal hemiretina is responsible for
carrying the information along the optic nerve, and crosses to the other side at the optic
chiasm and eventually, the information will reach the left primary visual cortex.
On the other hand, the information from the left visual field (blue color) of the right eye
falls on the temporal hemiretina (the right hemisphere of the right eye, blue color). The
temporal hemiretina is responsible for carrying the information along the optic nerve and
eventually the information will reach the right primary visual cortex.
When there is compression at optic chiasm (site of lesion 2 shown in Figure 2) the
visual information from both nasal hemiretina are affected, leading to inability to view
the peripheral vision, i.e. loss of the right visual field of the right eye and the left visual
field of the left eye.

2. 2
Figure 2
(Source: http://what-when-how.com/wp-content/uploads/2012/04/tmp15F67_thumb1.jpg)

3. Bitemporal hemianopsia most commonly occurs as a result of tumors located at the
mid-optic chiasm. Since the adjacent structure is the
tumors causing compression are pituitary adenomas
craniopharyngiomas. Also another relatively common neoplastic etiology is
meningiomas. An etiology of vascular origin is an aneurysm of the anterior
communicating artery which arise superior to the chiasm, enlarge, and compress it from
above.
(Source: http://nicandjacelyn.files.wordpress.com/201
Personal Reflection
This course has empowered me t
hemianopsia by equipping me with the
neurocircuitry of visual signal flow through the optic tract.
This course also allows me to develop a
neuro-system. Take the example
types of disorders can happen
causing deficits in different parts of
this assignment, bitemporal hemianopsia
chiasm while a lesion at the right optic tract will cause contralateral (left) homonymous
hemianopsia where the left visual
Figure 4 Paris as seen with left homonymous hemianopsi
(Source: http://upload.wikimedia.org/wikipedia/commons/thumb/8/81/Lhvf.png/230px
3
Bitemporal hemianopsia most commonly occurs as a result of tumors located at the
optic chiasm. Since the adjacent structure is the pituitary gland, some common
tumors causing compression are pituitary adenomas (as shown in
craniopharyngiomas. Also another relatively common neoplastic etiology is
meningiomas. An etiology of vascular origin is an aneurysm of the anterior
ch arise superior to the chiasm, enlarge, and compress it from
Figure 3 Pituitary adenoma
http://nicandjacelyn.files.wordpress.com/2012/03/bitemporal-hemianopia.png
has empowered me to analyze and better understand
by equipping me with the knowledge in the visual fields and
l flow through the optic tract.
ws me to develop a sense of awe towards the sophistication
example of visual system, as shown in Figure 2,
happen when lesion occurs at different sites of the neuro
ifferent parts of the visual fields. Like what has been discus
itemporal hemianopsia is caused by a lesion at the center of optic
e a lesion at the right optic tract will cause contralateral (left) homonymous
ianopsia where the left visual field of both eyes will be lost, as shown in
Paris as seen with left homonymous hemianopsia
http://upload.wikimedia.org/wikipedia/commons/thumb/8/81/Lhvf.png/230px
Bitemporal hemianopsia most commonly occurs as a result of tumors located at the
pituitary gland, some common
(as shown in Figure 3) and
craniopharyngiomas. Also another relatively common neoplastic etiology is
meningiomas. An etiology of vascular origin is an aneurysm of the anterior
ch arise superior to the chiasm, enlarge, and compress it from
hemianopia.png)
understand bitemporal
the visual fields and the
sophistication of our
, many different
of the neuro-system
Like what has been discussed in
is caused by a lesion at the center of optic
e a lesion at the right optic tract will cause contralateral (left) homonymous
field of both eyes will be lost, as shown in Figure 4.
a
http://upload.wikimedia.org/wikipedia/commons/thumb/8/81/Lhvf.png/230px-Lhvf.png)

4. 4
I would like to thank Professor Mason and her team for making this course so engaging
for me and I have learned a lot from this course despite my limited background in
biology. Professor Mason’s explanation is very clear and easy to follow. The exercises
in this course are thought provoking and allowed me to appreciate the course materials
better.
References
1. http://en.wikipedia.org/wiki/Bitemporal_hemianopsia
2. https://umem.org/educational_pearls/1055/
3. http://www.gpnotebook.co.uk/simplepage.cfm?ID=1872363522