Microphthalmia is much more common than anophthalmia and is defined by the presence of a small eye with axial length that is at least 2 standard deviations below the mean axial length for age. Microphthalmic eyes vary in size depending on the severity of the defect. Most infants with a unilateral small orbit (Fig 3-1) and no visible eye actually have a microphthalmic globe. The defect may be isolated, or it may occur with a constellation of abnormalities as part of a well-defined syndrome. Because multiple genetic mutations have been reported in anophthalmia/microphthalmia, microphthalmia is considered a developmental phenotype that results from several different genetic rearrangements.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.