Superior homonymous quadrantanopia

Loss of the upper quarter of the visual field on the same side in both eyes, nicknamed ‘pie in the sky’ and also spelled quadrantanopsia.

After a complete lesion of the right Meyer’s loop: left superior homonymous quadrantanopia. Fields as the patient sees them, central 30° with rings at 10° and 20°. Hatched areas are lost, and the dark ovals are the normal blind spots.

Lesion site: Meyer’s loop, temporal lobe
Left eye loses: Upper temporal quadrant, 25% of the plotted field
Right eye loses: Upper nasal quadrant, 25% of the plotted field
Pattern: Homonymous: the same half in both eyes, so the lesion is behind the chiasm
Lost to both eyes at once: 25% of the central 30°
Fibers cut: 2 of the 8 fiber groups the model draws

Try in: Visual Field Defects Explorer →

Put the lesion on the right Meyer’s loop to see the two lower-retina fibers cut.

Which lesion causes a superior quadrantanopia?

A lesion of Meyer’s loop in the temporal lobe on the opposite side. The loop carries the fibers from the lower half of each retina, which see the upper field, forward around the temporal horn of the lateral ventricle, so cutting it takes the upper quarter of the opposite half of the field from both eyes.

Why the upper quarter

The optic radiation leaves the lateral geniculate nucleus in two streams, divided by retinal level. The lens inverts the image, so the lower retina sees the upper field, and its fibers take the long route through the temporal lobe; the upper retina’s fibers, which see the lower field, run back through the parietal lobe instead. A temporal lobe lesion catches the first stream alone.

After a right-sided lesion the left eye loses its upper temporal quarter and the right eye its upper nasal quarter, which sit on the same side of the two charts.

The fiber groups cut by a complete lesion of the right Meyer’s loop
Fibers from	See	Cross at the chiasm	Then run in
Left eye, nasal retina, lower half	Upper temporal quarter	Yes	Right optic tract, then Meyer’s loop
Right eye, temporal retina, lower half	Upper nasal quarter	No	Right optic tract, then Meyer’s loop

2 of the 8 fiber groups the model draws are cut; the other 6 reach the cortex.

Usual causes

Temporal lobe tumors, abscesses and strokes. It is also a familiar result of anterior temporal lobectomy for epilepsy.

Telling it apart

Its parietal counterpart is the inferior quadrantanopia, ‘pie on the floor’. A larger lesion that reaches the whole radiation gives a complete homonymous hemianopia. Defects this far back are more congruous than tract defects, because fibers from matching points of the two retinae now lie together, and the pupils react normally.

Left-sided and right-sided lesions

The same site on the other side gives the mirror image, named for the half of the field it takes.

The defect from a complete lesion at this site on each side
Lesion	Defect	Left eye loses	Right eye loses
Left Meyer’s loop	Right superior homonymous quadrantanopia	upper nasal quadrant	upper temporal quadrant
Right Meyer’s loop	Left superior homonymous quadrantanopia	upper temporal quadrant	upper nasal quadrant

Tools for the visual pathway

Visualiser · Biology Visual Field Defects Explorer Place a lesion anywhere from optic nerve to visual cortex and see each eye’s field loss, named and explained. Visualiser · Biology Blind Spot Mapper Watch a dot vanish, as Mariotte’s paper did in 1668, then map your own blind spot in degrees and see it as the optic disc on the retina. Visualiser · Biology Brain Explorer 101 brain structures, gyri to ventricles, separable.

Visual Field Defects Explorer puts a lesion anywhere on the pathway and draws every fiber it cuts.
Blind Spot Mapper maps your own blind spot, the dark oval in each chart, in degrees.
Brain Explorer has the optic nerves, chiasm, tracts and geniculate bodies as 3D models.

Sources: Kandel, Principles of Neural Science, 6th edition, chapter 22, for the pathway and its lesions; Purves, Neuroscience, 6th edition, chapter 12, for the pathway and its lesions; Kupfer, Chumbley and Downer, Journal of Anatomy 1967;101:393, for the 53 percent of optic nerve fibers that cross at the chiasm. A teaching diagram of complete lesions: real fields are read with the history, the other eye, the optic discs and imaging.