What visual field pattern is characteristic of glaucoma?

Glaucoma characteristically produces arcuate defects that follow the path of retinal nerve fiber bundles, curving from the blind spot around fixation. Early glaucoma often starts as a nasal step (asymmetry across the nasal horizontal meridian) or paracentral scotomas that can progress to full arcuate scotomas. These defects respect the horizontal midline because nerve fiber bundles do not cross the nasal raphe.

What does a bitemporal hemianopia indicate?

Bitemporal hemianopia, where the outer (temporal) visual field is lost in both eyes, is the classic sign of optic chiasm compression. The most common cause is a pituitary tumor pressing on the chiasm from below, damaging the crossing nasal retinal nerve fibers. Other causes include craniopharyngiomas, meningiomas, and aneurysms near the chiasm.

How do you tell where along the visual pathway the damage is?

The pattern of field loss localizes the damage: monocular defects suggest pre-chiasmal (retina or optic nerve) lesions; bitemporal defects indicate chiasmal lesions; and homonymous defects (same side affected in both eyes) point to post-chiasmal damage. The more congruent (identical) a homonymous defect appears between the two eyes, the more posterior the lesion is along the visual pathway.

Visual Field Defect Patterns: Scotomas, Hemianopias, and More

Understanding Visual Field Defects

Visual field defects are areas of reduced or absent vision within the field of view. Their pattern and location provide critical diagnostic information because different types of damage at different points along the visual pathway produce characteristic and predictable field loss patterns. Recognizing these patterns is a core skill for ophthalmic professionals.

Types of Visual Field Defects

Scotoma

A scotoma is a localized area of reduced or absent vision surrounded by areas of normal or relatively better vision. Scotomas can be:

Absolute: Complete blindness in the affected area
Relative: Reduced but not absent sensitivity
Central: Affecting the fixation point (macular disease)
Paracentral: Adjacent to fixation
Peripheral: In the outer visual field

The physiological blind spot is a normal scotoma located approximately 15 degrees temporal to fixation, corresponding to the optic nerve head where there are no photoreceptors.

Arcuate Defect

An arcuate defect follows the arc of the retinal nerve fiber layer, curving from the blind spot around fixation in a bow or crescent shape. This pattern is the hallmark of glaucoma because glaucomatous damage affects nerve fiber bundles that follow these arcuate paths. Early glaucomatous field loss often appears as a nasal step (asymmetry of sensitivity across the nasal horizontal meridian) that can progress to a full arcuate scotoma.

Arcuate defects respect the horizontal midline (the nasal raphe) because superior and inferior nerve fiber bundles do not cross this boundary. A field defect that crosses the horizontal midline is unlikely to be glaucomatous and suggests a different etiology.

Altitudinal Defect

An altitudinal defect involves loss of the entire upper or lower half of the visual field, with the boundary following the horizontal midline. Common causes include:

Anterior ischemic optic neuropathy (AION): Often produces an inferior altitudinal defect
Branch retinal artery occlusion: Produces an altitudinal defect corresponding to the affected retinal area
Advanced glaucoma: Can produce an altitudinal-like pattern from coalescence of arcuate defects

Hemianopia

A hemianopia is loss of half the visual field. The type depends on which half is affected and whether it involves one or both eyes:

Homonymous hemianopia: Loss of the same side (right or left) in both eyes. Caused by post-chiasmal lesions (optic tract, lateral geniculate body, optic radiations, or occipital cortex). A right homonymous hemianopia means the right half of the visual field is lost in both eyes, indicating damage on the left side of the brain.
Bitemporal hemianopia: Loss of the temporal (outer) field in both eyes. This is the classic pattern of a pituitary lesion or other mass compressing the optic chiasm.

Bitemporal hemianopia is a high-priority finding. If you identify this pattern on a visual field test, notify the doctor promptly because it often indicates a pituitary tumor or other chiasmal compression requiring neuroimaging.

Quadrantanopia

A quadrantanopia is loss of one quadrant (one-quarter) of the visual field. It localizes the lesion more precisely along the post-chiasmal pathway:

Superior quadrantanopia: Suggests a temporal lobe lesion (Meyer's loop)
Inferior quadrantanopia: Suggests a parietal lobe lesion

Localizing Defects Along the Visual Pathway

Defect Pattern	Likely Location of Damage	Common Cause
Central scotoma	Macula or optic nerve	Macular degeneration, optic neuritis
Arcuate defect	Retinal nerve fiber layer	Glaucoma
Altitudinal defect	Optic nerve or retinal vessels	AION, branch artery occlusion
Bitemporal hemianopia	Optic chiasm	Pituitary tumor
Homonymous hemianopia	Post-chiasmal (tract to cortex)	Stroke, tumor, trauma
Homonymous quadrantanopia	Optic radiations	Temporal or parietal lobe lesion

Confusing homonymous and heteronymous hemianopias. Homonymous means the same side is affected in both eyes (right or left), indicating post-chiasmal damage. Heteronymous (like bitemporal) means opposite sides are affected, indicating chiasmal damage. The distinction is critical for localization.

Key Takeaways

Visual field defect patterns directly correlate with the anatomical location of damage along the visual pathway
Arcuate defects respect the horizontal midline and are the hallmark of glaucoma
Bitemporal hemianopia indicates optic chiasm compression, most commonly from a pituitary lesion
Homonymous hemianopia indicates post-chiasmal damage on the opposite side of the brain
Altitudinal defects suggest optic nerve or retinal vascular pathology