Quadrantanopia

Quadrantanopia (also spelled quadrantanopsia) is loss of one quarter of the visual field - and, crucially, the same quarter is missing in both eyes. That combination of features makes it one of the most location-specific findings in vision. Because the missing piece is homonymous and respects the vertical midline, it places the problem behind the optic chiasm, in the visual pathways of the brain, rather than in either eye. For the wider map of how field-loss shapes localize the lesion, see our overview of visual field defects; this page focuses on the quarter-field pattern itself.

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A Quarter of the World, Missing in Both Eyes

Two midlines define this finding. The visual world is split left from right down a vertical midline and top from bottom across a horizontal one. A quadrantanopia respects both: the loss is confined to a single corner - upper-left, upper-right, lower-left, or lower-right - and stops at right angles where those two lines cross. And it is homonymous, meaning the same corner of the world is missing for each eye (for example, the upper-right quarter in both the right and the left eye).

That homonymous quality is what proves the problem is behind the chiasm. In front of the chiasm, each eye's pathway is independent, so damage there affects only one eye. Once the fibers from the two eyes have mixed and re-sorted by left-versus-right at the chiasm and beyond, a single lesion takes the matching piece out of both eyes at once. So a homonymous quarter is the brain's fingerprint.

"Pie in the Sky" Versus "Pie on the Floor"

Behind the chiasm, the fibers carrying vision fan out into the optic radiations on their way to the back of the brain - and they split into an upper and a lower stream that travel through different lobes. This split is why a quadrantanopia is so informative.

• "Pie in the sky" (superior quadrantanopia) - the lower fibers loop forward into the temporal lobe along a curve called Meyer's loop, and they carry the upper field. A lesion there - often a temporal-lobe stroke or tumor - removes an upper quarter of vision, a wedge that sits up in the sky.
• "Pie on the floor" (inferior quadrantanopia) - the upper fibers run more directly back through the parietal lobe and carry the lower field, so a parietal lesion drops a lower quarter onto the floor.

A simple memory aid: Temporal lobe takes the Top of vision; the Parietal lobe takes the lower, Pedestrian-level field. The crossover - top fibers below, bottom fibers above - trips people up, so it is worth pausing on: the lobe that is hit and the part of the field that disappears are vertically opposite.

Congruity: How Matched Are the Two Eyes?

The two eyes' quarters are rarely identical to the millimeter, and how identical they are adds a second layer of localization. Congruity describes how closely the defect in one eye matches the other. The farther back along the pathway the lesion sits, the more congruous (better matched) the two eyes become, because the fibers serving corresponding points from each eye lie closer together as they approach the visual cortex. A highly congruous quadrant points toward the back of the brain near the occipital cortex; a more lopsided, incongruous one points farther forward, toward the optic radiations or tract. It is a detail the field test can capture that the patient would never notice.

Why a Quadrantanopia Means a Brain Workup

This is the point that surprises people most: a quadrantanopia is found by an eye test but is fundamentally a brain problem. Nothing is wrong with the retina, the lens, or the optic nerve. The eyes are faithfully sending their images backward; the loss happens where the brain assembles them. That reframing changes the entire evaluation. Instead of retinal imaging and pressure checks, the workup turns to the brain.

• MRI of the brain is the central test - it locates the lesion in the temporal or parietal lobe and usually reveals the cause.
• A visual field test documents and measures the quadrant, confirms it is homonymous, and tracks change over time.
• If a stroke is found, the evaluation extends to its source - vascular imaging, cardiac evaluation, and risk-factor assessment - to prevent the next one.

What Damages the Optic Radiations

The list of causes is essentially the list of things that injure brain tissue in the temporal and parietal lobes:

• Stroke - the leading cause, from either the middle cerebral or posterior cerebral artery territory depending on which part of the radiations is involved.
• Brain tumors - primary tumors or metastases pressing on or infiltrating the radiations.
• Trauma - traumatic brain injury or, occasionally, a complication of intracranial surgery.
• Demyelination - a plaque of multiple sclerosis sitting in the radiations.
• Other - a brain abscess, a hemorrhage, or a vascular malformation.

The cause matters enormously for what happens next, which is exactly why the imaging is not optional.

When It Comes On Suddenly: BE-FAST and 911

How fast the defect appeared is the single most important piece of history. A quadrantanopia that develops gradually over weeks to months suggests something like a tumor and is worked up urgently but not as a 911 event. A quadrantanopia that appears suddenly is a stroke until proven otherwise.

Quadrantanopia Versus an Altitudinal Defect

A quadrantanopia is sometimes confused with an altitudinal defect, since both remove a chunk of field, but they tell opposite stories:

In short, a quarter missing in both eyes is a brain finding, while a horizontal half missing in one eye is an eye (nerve or retina) finding. The shape and the one-eye-versus-both question settle it.

Rehabilitation and Reading Strategies

A quadrantanopia is permanent in many cases, though some spontaneous recovery can occur, most of it within the first few months. Even when the field does not return, people can function well with training and a few adjustments.

• Scanning training teaches deliberate eye and head movements into the blind quarter, so hazards are not missed - the single most useful adaptation for getting around safely.
• Reading strategies matter when the blind quarter falls on the side you read toward. A right-sided defect makes it hard to find the next word; a left-sided one makes it hard to find the start of the next line. A line guide or ruler, holding text at an angle, and (for some) audiobooks all help.
• Daily life is easier with good, even lighting and conscious awareness of the affected corner when navigating stairs (inferior defects) or reaching for things overhead (superior defects).
• Driving depends on local rules; some jurisdictions permit driving with a quadrantanopia and others do not, and an on-road or occupational-therapy driving evaluation is often the fairest way to judge. Our guide to driving with vision changes walks through the considerations.

Frequently Asked Questions

Is a quadrantanopia less serious than a hemianopia?

Not necessarily - it is more about where than how bad. A quadrant defect localizes to the temporal or parietal radiations, while a homonymous hemianopia suggests a larger or more posterior lesion. Both deserve a careful workup to find and treat the cause; the size of the missing area does not, by itself, tell you how dangerous the underlying problem is.

Why didn't I notice a whole quarter of my vision was gone?

The brain is very good at filling in, and the seeing parts of each eye cover for the missing quarter, so a quadrant loss often goes unnoticed until it causes bumping into door frames, missing words while reading, or near-misses while driving. This is exactly why formal field testing exists - it finds losses the basic eye chart misses entirely.

Can a quadrantanopia get better?

Sometimes. Some defects recover partially, usually in the first few months, especially when swelling around a stroke or treated tumor settles. Even when the field itself does not return, scanning therapy and practical adaptations meaningfully improve day-to-day function.

My eye exam was normal but I have a quadrantanopia - how?

Because the problem is not in the eye. The retina, lens, and optic nerve can all be perfectly healthy while the loss sits in the optic radiations or visual cortex, where the brain processes the image. That is why the next step is brain imaging rather than more eye tests.

References

1. StatPearls (NIH). Homonymous Hemianopsia.
2. Zhang X, Kedar S, Lynn MJ, Newman NJ, Biousse V. Homonymous hemianopias: clinical-anatomic correlations in 904 cases. Neurology. 2006;66(6):906-910.