Other / Other / MRI

Glaucoma

Glaucoma is a progressive optic neuropathy causing vision loss and blindness, detected either as an incidental finding during routine eye examination or when patients present with acute symptoms like eye pain, halos, or decreased vision, particularly in closed-angle glaucoma. Open-angle glaucoma (Most common glaucoma type) The drainage angle between the iris and cornea is open, but aqueous fluid drains poorly through the trabecular meshwork. This usually causes a slow, often painless rise in eye pressure and gradual optic-nerve damage. Angle-closure glaucoma The peripheral iris blocks the drainage angle, preventing aqueous fluid from exiting the eye. Pressure may rise gradually in chronic cases or suddenly and severely in acute angle closure.

Key Images

Congenital Glaucoma

Acquired Glaucoma

Glaucoma (open and closed)

Glaucoma

Severe glaucoma

Macrophthalmia due to glaucoma

Glaucoma Valeves

Congenital glaucoma

Look For First
  • Optic nerve thinning and decreased optic nerve diameter on axial MRI sequences
  • Optic chiasm atrophy with loss of height indicating axonal density loss
  • Increased axial diameter of the ocular globe in advanced cases
Key Image Findings
  • Decreased optic nerve diameter and thinning on MRI, reflecting axonal loss from glaucomatous neuropathy.
  • Optic chiasm atrophy with loss of height on MRI T2 and contrast-enhanced sequences, indicating chronic axonal density loss.
  • Increased axial diameter of the ocular globe may be identified in advanced glaucomatous disease.
  • In early and mild-to-moderate disease, MRI findings may be unremarkable or subtle, requiring high-quality thin-section imaging for detection.
  • Open-angle glaucoma demonstrates axonal loss pathology despite potentially normal or only mildly elevated intraocular pressure.
  • Closed-angle glaucoma is associated with rapid intraocular pressure elevation due to impaired aqueous humor drainage, occurring in populations with narrow angles (more common in Asian populations).
Differential Diagnosis
  • Compressive lesion of the optic pathway (pituitary adenoma, meningioma, craniopharyngioma): distinguished by mass effect, enhancement pattern, and involvement of adjacent structures rather than primary optic nerve atrophy.
  • Traumatic optic neuropathy: distinguished by history of orbital trauma and acute clinical presentation rather than insidious progressive vision loss.
  • Leber hereditary optic neuropathy: distinguished by younger age of onset, mitochondrial inheritance pattern, and bilateral symmetric optic nerve involvement.
  • Non-arteritic anterior ischemic optic neuropathy: distinguished by acute painless vision loss, optic disc edema acutely, and segmental rather than diffuse optic nerve changes.
  • Demyelinating optic neuritis: distinguished by acute presentation, white matter disease on brain MRI, and younger patient population.
  • Chronic papilledema from idiopathic intracranial hypertension: distinguished by elevated cerebrospinal fluid opening pressure, empty sella, and bilateral optic disc swelling.
Discussion

Glaucoma pathology involves axonal loss and neuropathy, with open-angle glaucoma affecting ~90% of glaucoma patients in White and Black populations but only presenting with symptoms late in disease when optic nerve damage is advanced.

Closed-angle glaucoma, more common in Asian populations and female patients, presents acutely with elevated intraocular pressure causing sudden pain, halos, and vision loss requiring emergent treatment.

Normal-tension glaucoma is a clinically important variant in which optic nerve damage occurs despite normal intraocular pressures, making diagnosis dependent on structural and functional assessment rather than pressure alone.

MRI findings of optic nerve thinning and chiasm atrophy are markers of chronic glaucomatous damage, reflecting the degree of axonal loss and can help confirm diagnosis in advanced cases.

Risk factors including age, race (Black patients 3x higher for open-angle glaucoma), diabetes, hypertension, and family history guide screening and patient counseling.

Early-stage glaucoma often shows minimal or no MRI abnormalities, emphasizing the importance of clinical examination, visual field testing, and intraocular pressure measurement for early detection before structural changes become evident on imaging.

Reporting Pearls

When reporting suspected glaucoma on MRI, specifically measure and document optic nerve cross-sectional diameter on axial T2 sequences and describe any chiasmal atrophy or loss of height; compare to prior studies when available and note that even subtle thinning of the optic nerve can represent significant axonal loss in the glaucomatous process.

Pitfalls
  • Over-interpreting normal optic nerve size as exclusion of glaucoma, since early and moderate glaucoma often shows minimal MRI changes and requires functional testing (visual fields, optical coherence tomography) for diagnosis.
  • Mistaking mild optic nerve caliber variation or normal anatomic asymmetry for glaucomatous atrophy without clinical correlation and comparison to contralateral nerve and prior studies.
  • Attributing optic chiasm atrophy to glaucoma when other etiologies (compression, demyelination, previous inflammation) may be responsible; clinical history and associated imaging features are essential.
  • Failing to recognize that most cases of glaucoma will appear unremarkable on MRI, especially in early stages, leading to false reassurance when imaging is used as a screening tool rather than confirmatory test.
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