Lateral Geniculate Body
The lateral geniculate body (LGB) is a highly organized and layered retinotopic structure; therefore, lesions in this region can cause highly localized visual field defects. A congruous horizontal sectoranopia results from disruption within the vascular distribution of the posterolateral choroidal artery, a branch of the posterior cerebral artery. Loss of the upper and lower homonymous quadrants (also known as quadruple sectoranopia) with preservation of a horizontal wedge occurs with disruption of the anterior choroidal artery, a branch of the middle cerebral artery (Fig 4-30; see also Chapter 1, Fig 1-11). These visual field defects respect the vertical meridian, unlike the uncommon wedge defect observed in glaucoma. Sectoral optic atrophy occurs with LGB lesions, and in rare cases, bilateral LGB lesions cause blindness.
Luco C, Hoppe A, Schweitzer M, Vicuña X, Fantin A. Visual field defects in vascular lesions of the lateral geniculate body. J Neurol Neurosurg Psychiatry. 1992;55(1): 12–15.
Figure 4-30 Visual field defects of the lateral geniculate body (LGB). Automated visual field testing shows (A) a central wedge-shaped homonymous sectoranopia caused by lateral posterior choroidal artery occlusion and (B) a loss of the upper and lower homonymous quadrants, with preservation of the horizontal wedge resulting from occlusion of the anterior choroidal artery.
(Reproduced with permission from Trobe JD. The Neurology of Vision. Contemporary Neurology Series. Oxford: Oxford University Press, 2001:130.)
Excerpted from BCSC 2020-2021 series: Section 5 - Neuro-Ophthalmology. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.