====== Optic radiation ======
{{ https://upload.wikimedia.org/wikipedia/commons/d/d0/ERP_-_optic_cabling.jpg?400}}

The optic [[radiation]] (OR) is a [[white matter]] [[bundle]] with a very complex [[anatomy]]. Its anterior component bends sharply around the tip of the [[temporal horn]], forming the [[Meyers Loop]]
((Bertani GA, Bertulli L, Scola E, Cristofori AD, Zavanone M, Triulzi F, Rampini
PM, Carrabba GG. Optic Radiation Diffusion Tensor Imaging Tractography: an
Alternative and Simple Technique for the Accurate Detection of Meyer's Loop.
World Neurosurg. 2018 May 29. pii: S1878-8750(18)31084-2. doi:
10.1016/j.wneu.2018.05.131. [Epub ahead of print] PubMed PMID: 29857218.
)).

===== Definition =====

The optic radiation (also known as the geniculocalcarine tract, the geniculostriate pathway, and posterior thalamic radiation) are axons from the neurons in the [[lateral geniculate nucleus]] to the primary [[visual cortex]]. 

====Blood supply====
The optic radiation receives blood through deep branches of the [[middle cerebral artery]] and [[posterior cerebral artery]].

They carry visual information through two divisions (called Upper and Lower division) to the visual cortex (also called striate cortex) along the [[calcarine fissure]]. There is one such tract on each side of the brain. If a lesion only exists in one optic radiation, the consequence is called [[quadrantanopia]].



The optic radiation can be accurately delineated by tractography and propagated onto postoperative images. The technique is fast enough to propagate accurate preoperative tractography onto intraoperative scans acquired during neurosurgery, with the potential to reduce the risk of visual field deficit (VFD)
((Winston GP, Daga P, Stretton J, Modat M, Symms MR, McEvoy AW, Ourselin S,
Duncan JS. Optic radiation tractography and vision in anterior temporal lobe
resection. Ann Neurol. 2012 Mar;71(3):334-41. doi: 10.1002/ana.22619. PubMed
PMID: 22451201; PubMed Central PMCID: PMC3698700.
)).

====Importance====
[[Visual field defect]]s (VFDs) due to [[optic radiation]] (OR) injury are a common complication of temporal lobe surgery. 

Sparing optic radiations can be of paramount importance during [[epilepsy surgery]] of the [[temporal lobe]]. The anatomical heterogeneity of the [[Meyers loop]] of the optic radiations could be assessed by means of diffusion tensor tractography.

The [[posterior interhemispheric transprecuneus gyrus approach]] is one of the surgical routes that has been suggested to reach the [[atrium]] of the [[lateral ventricle]]. It has the advantage of avoiding the disruption of the [[optic radiation]]s; however, it has a narrow working area that at times makes the execution of this approach rather challenging. 

A modification of the approach that might create a better surgical angle and a wider corridor by accessing the atrium from the contralateral side after transection of the falx, named this new approach the "posterior interhemispheric transfalx transprecuneus approach."
((Wang S, Salma A, Ammirati M. Posterior interhemispheric transfalx
transprecuneus approach to the atrium of the lateral ventricle: a cadaveric
study. J Neurosurg. 2010 Nov;113(5):949-54. doi: 10.3171/2010.1.JNS091169. Epub
2010 Feb 12. PubMed PMID: 20151777.)).

===== Dorsal loop of the optic radiation =====

[[Dorsal loop of the optic radiation]].