Patient Friendly Version: Altitudinal Visual Field Defects: Why the Pattern Matters
Updated: Aug 27
When a patient loses part of their vision, the pattern of that vision loss can tell us a lot about where the problem is coming from. One of the most important patterns eye doctors look for is an altitudinal visual field defect.
An altitudinal defect means the patient is missing the top half or bottom half of their visual field. In many cases, this type of defect respects the horizontal midline, meaning the missing area stops at the horizontal dividing line of vision rather than crossing through it.
This pattern is important because visual field defects caused by problems inside the eye or optic nerve often behave differently than defects caused by problems in the brain.
What Is an Altitudinal Visual Field Defect?
An altitudinal visual field defect is vision loss that affects either the upper or lower portion of the visual field.
For example, a patient may say:
“I can see straight ahead, but the bottom half of my vision is missing.”
Or:
“It feels like a curtain is blocking the top part of my vision.”
On visual field testing, this can show up as a defect that stays mostly above or below the horizontal midline.
This is different from some brain-related visual field defects, which often split vision along the vertical midline.
The Big Rule: Eye Problems Often Respect the Horizontal Midline
One helpful clinical rule is:
Problems in the eye, retina, retinal nerve fiber layer, or optic nerve often respect the horizontal midline.
This happens because the retinal nerve fibers are organized in a way that separates the superior and inferior retina. Diseases that damage these nerve fiber bundles may create defects that stop at the horizontal meridian.
Common examples include:
Glaucoma
Ischemic optic neuropathy
Branch retinal artery occlusion
Branch retinal vein occlusion
Optic nerve drusen
Retinal detachment
Papilledema
Other optic nerve diseases
Altitudinal defects are especially associated with ischemic optic neuropathy and retinal vascular disease, but glaucoma can also create nerve fiber layer defects that respect the horizontal midline.
Brain Problems Often Respect the Vertical Midline
Another helpful rule is:
Problems behind the optic chiasm, meaning farther back in the brain’s visual pathway, often respect the vertical midline.
This is because visual information from the right and left sides of the world is separated as it travels through the optic chiasm, optic tracts, optic radiations, and occipital lobe.
Brain-related visual field defects may include:
Right or left homonymous hemianopia
Right or left superior quadrantanopia
Right or left inferior quadrantanopia
Bitemporal visual field loss from optic chiasm compression
For example, a stroke affecting the left side of the visual pathway may cause loss of the right side of vision in both eyes. These post-chiasmal visual pathway lesions typically create homonymous defects, meaning the same side of vision is affected in both eyes.
A pituitary tumor pressing on the optic chiasm can cause a bitemporal visual field defect, where the outer side of vision is lost in both eyes.
Horizontal vs Vertical Midline: A Simple Way to Think About It
Imagine the visual field like a window divided by two lines:
One line goes left to right.That is the horizontal midline.
One line goes up and down.That is the vertical midline.
When a defect respects the horizontal midline, we often think about problems in the:
Retina
Retinal nerve fiber layer
Optic nerve
When a defect respects the vertical midline, we often think about problems in the:
Optic chiasm
Optic tract
Optic radiations
Occipital lobe
Brain visual pathway
This rule is not perfect, but it is one of the most useful clues in visual field interpretation.
Why Altitudinal Defects Can Be Urgent
A new altitudinal visual field defect should never be ignored.
Sudden upper or lower field loss can occur with conditions that need urgent evaluation, including:
Anterior ischemic optic neuropathy
Giant cell arteritis
Branch retinal artery occlusion
Retinal detachment
Stroke or neuro-ophthalmic disease
In older patients, a sudden altitudinal defect raises concern for ischemic optic neuropathy. If symptoms such as scalp tenderness, jaw pain, temple pain, fever, weight loss, or fatigue are present, doctors must also consider giant cell arteritis, which can threaten vision in both eyes.
Branch retinal artery occlusions may also create altitudinal or sectoral defects, and they can be associated with vascular risk factors involving the carotid arteries, heart, or circulation.
What Patients May Notice
Patients with an altitudinal visual field defect may describe:
Missing top or bottom vision
A shadow or curtain in one part of vision
Trouble seeing steps, curbs, or the floor
Difficulty reading if the defect involves central vision
Bumping into objects above or below
Vision loss in one eye
Sudden or gradual change in peripheral vision
Some patients do not notice the defect at first, especially if the other eye is compensating. This is one reason visual field testing is so important.
How Eye Doctors Evaluate It
When an altitudinal defect is suspected, the eye exam may include:
Visual acuity testing
Pupil testing
Eye pressure measurement
Dilated retinal exam
Optic nerve evaluation
OCT of the optic nerve and retina
Visual field testing
Retinal imaging
Blood pressure and vascular risk review
Referral for bloodwork, imaging, neurology, or retina care when needed
The goal is to determine whether the problem is coming from the eye, the optic nerve, or the brain.
Clinical Pearl: The Midline Tells a Story
A helpful way to remember this:
Eye and optic nerve disease often respects the horizontal midline.
Brain and chiasmal disease often respects the vertical midline.
So when an eye doctor looks at a visual field, they are not just asking, “Where is the vision missing?”
They are asking:
What pattern does the defect follow, and what does that pattern tell us about the location of the problem?
That pattern can help guide the next step, whether that means monitoring glaucoma, evaluating the retina, treating optic nerve disease, or ordering urgent neurologic testing.
When to Seek Care
Patients should seek urgent eye care if they notice:
Sudden loss of upper or lower vision
A curtain, shadow, or missing area of vision
Vision loss in one eye
New double vision
New severe headache
Jaw pain or scalp tenderness
Weakness, numbness, trouble speaking, or stroke-like symptoms
Visual field defects can be subtle, but they can also be the first sign of something serious.
Comments