Megalocornea Clinical Presentation

Updated: Aug 04, 2015
  • Author: Mark Ventocilla, OD, FAAO; Chief Editor: Hampton Roy, Sr, MD  more...
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Presentation

History

Megalocornea is present from birth.

A family history of megalocornea may be present.

The mother may have slightly enlarged corneas.

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Physical

Findings of simple megalocornea

See the list below:

  • Symmetric

  • Dome-shaped cornea

  • Normal corneal thickness

  • Normal endothelial cell density, usually bilateral

  • Usually good visual acuity

  • With-the-rule astigmatism common

  • Corneal diameter usually 13.0-16.5 mm

  • Corneal thickness normal and stroma clear; may have central mosaic dystrophy (see the image below)

    Central mosaic dystrophy sometimes noted in megalo Central mosaic dystrophy sometimes noted in megalocornea.
  • Limbus sharply demarcated

  • Keratometry usually normal but may be steeper than normal

  • Anterior chamber depth increased

  • Lens-iris diaphragm positioned posteriorly

  • Vitreous length short

  • Intraocular pressure normal

Findings of anterior megalophthalmos

See the list below:

  • Megalocornea

  • Ciliary body band wider than the trabecular meshwork and scleral spur on gonioscopy

  • May have any of the following:

    • Iridodonesis

    • Iris stromal hypoplasia

    • Transillumination defects

    • Phacodonesis

    • Ectopia lentis

    • Cataracts

    • Krukenberg spindles

    • Posterior embryotoxon

    • Excessive mesenchymal tissue in the angle

    • Glaucoma (but not congenital glaucoma)

Findings of congenital glaucoma not found in megalocornea

See the list below:

  • Elevated intraocular pressure

  • Corneal edema and Haab striae

  • Increased axial length

  • Decreased endothelial cell density

  • Flatter cornea

  • Decreased lens thickness

  • Asymmetry

  • Optic disc cupping

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Causes

Megalocornea is inherited as an X-linked recessive trait (90% of cases).

The gene locus for X-linked megalocornea is in band Xq12-q26, most likely band Xq21-q23.

Autosomal dominant, autosomal recessive, and sporadic inheritance have been reported.

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