Macrophthalmos

Look For First

Increased anteroposterior (axial) length of globe compared to normal fellow eye or reference measurements
Pattern of enlargement: posterior/AP predominant (axial myopia/macrophthalmos) versus diffuse global enlargement (buphthalmos)
Posterior staphyloma or focal contour deformity indicating chronic myopia or structural remodeling
Exclude intraocular mass, enhancement, calcification, or retinal/choroidal detachment that would suggest alternative pathology

Key Image Findings

Axial macrophthalmos presents with predominantly posterior and anteroposterior globe elongation while the anterior segment remains relatively preserved, on both CT (water-attenuation vitreous with no focal lesion) and MRI (T2-bright vitreous without abnormal enhancement).
Posterior staphyloma—a focal outpouching or thinning of the posterior globe—is a characteristic finding in high axial myopia and appears as focal contour deformity posterior to the equator on orthogonal imaging planes.
Buphthalmos (glaucoma-related diffuse enlargement) shows uniform or globally enlarged anterior and posterior segments with possible lens flattening and optic-disc changes, distinguishing it from axial-predominant macrophthalmos.
On MRI, an associated 'floppy' or lax-appearing globe contour may indicate connective-tissue disease (Marfan, Ehlers–Danlos, homocystinuria) and is better appreciated on high-resolution imaging.
CT excels at confirming globe dimensions (bilateral AP and transverse measurements), detecting orbital osseous abnormality such as sphenoid-wing dysplasia (associated with NF1), and excluding occult intraocular calcification or hemorrhage.
MRI provides superior assessment of globe-wall, optic nerve, and orbital soft-tissue pathology; uncomplicated vitreous remains homogeneous T2 bright with normal optic-nerve signal and no retinal detachment or abnormal choroidal pathology.
Ultrasound reliably measures axial length and identifies posterior staphyloma and retinal detachment but is often not the modality on which radiologists first recognize macrophthalmos in cross-sectional imaging.
A discrete intraocular mass, abnormal enhancement, retinal/choroidal detachment, or abnormal vitreous signal indicates an alternative diagnosis (retinoblastoma, hemorrhage, inflammation) rather than simple globe enlargement.

Differential Diagnosis

Buphthalmos (congenital/infantile glaucoma): diffuse global enlargement including anterior segment, lens flattening, optic-disc changes, and usually occurs in infants/young children; axial macrophthalmos has posterior-predominant elongation.
Focal posterior enlargement (posterior staphyloma or coloboma): localized contour deformity rather than uniform globe enlargement; may coexist with myopia but distinguished by focal outpouching rather than global proportional expansion.
Intraocular mass (retinoblastoma, hemangioma, or other lesion): discrete enhancing lesion, calcification, retinal detachment, or abnormal vitreous on contrast-enhanced imaging; globe may appear enlarged due to mass effect rather than true structural enlargement.
Phthisical globe or end-stage glaucoma: small, shrunken globe with calcification and retraction, contrasting with the enlarged globe of macrophthalmos or early buphthalmos.
Unilateral exophthalmos (orbital mass, thyroid eye disease, inflammation): displaces globe anteriorly without inherent globe enlargement; measure globe dimensions to distinguish from true macrophthalmos.
High myopia without macrophthalmos: normal globe size with refractive error; requires correlation with ophthalmologic refraction and comparison imaging to establish true increase in axial dimensions.

Discussion

High axial myopia is the most common cause of macrophthalmos; the chronically elongated globe compensates for refractive error and may show posterior staphyloma as a marker of chronic scleral stretching and remodeling.

Connective-tissue disorders (Marfan syndrome, Ehlers–Danlos syndrome, homocystinuria) predispose to both high myopia and globe distensibility, producing a lax or floppy globe configuration that may be more apparent on MRI.

Congenital and infantile glaucoma produce buphthalmos because the immature, compliant sclera expands diffusely under chronically elevated intraocular pressure; early recognition and management can prevent permanent vision loss and globe sequelae.

In a pediatric patient with buphthalmos or unexplained ocular enlargement, evaluate for syndromic associations: NF1 (sphenoid-wing dysplasia, optic-pathway glioma), Sturge–Weber (ipsilateral leptomeningeal angiomatosis), or anterior-segment dysgenesis syndromes.

Accurate reporting must distinguish the pattern of enlargement (axial-predominant versus diffuse) and exclude concurrent pathology (mass, detachment, hemorrhage) to guide appropriate clinical correlation and ophthalmologic management.

Terminology is inconsistent across sources; descriptive reporting of globe configuration and suspected cause (e.g., 'elongation consistent with high myopia' or 'diffuse enlargement concerning for childhood glaucoma') is more clinically useful than relying on the term alone.

Reporting Pearls

Report the observed pattern of globe enlargement (posterior-predominant versus diffuse), specify anteroposterior and transverse dimensions, exclude intraocular mass or retinal detachment, and note any associated orbital bone or intracranial findings; use descriptive language (e.g., 'posterior-predominant globe elongation consistent with axial myopia/macrophthalmos' or 'diffuse globe enlargement concerning for buphthalmos') rather than the term alone to guide clinical correlation.

Pitfalls

Confusing axial macrophthalmos (posterior-predominant elongation due to high myopia) with buphthalmos (diffuse global enlargement due to elevated intraocular pressure in infancy); measurement of anterior versus posterior segment contribution and clinical history are essential to differentiation.
Attributing apparent globe enlargement to an intraocular process (mass, hemorrhage, detachment) without careful inspection for discrete lesions, abnormal enhancement, or abnormal vitreous signal; a simple enlarged fluid-filled globe should remain homogeneous and nonenhancing.
Missing concurrent pathology such as posterior staphyloma, optic-nerve abnormality, or orbital bone dysplasia by focusing only on globe size; these findings refine diagnosis and direct management.
Overlooking syndromic clues (sphenoid-wing dysplasia, intracranial lesions, cerebral angiomatosis) in a child with buphthalmos; evaluation for associated NF1, Sturge–Weber, or anterior-segment dysgenesis is critical to comprehensive assessment and genetic counseling.

Macrophthalmos

Key Images