Monday, March 21, 2011
Microphthalmia is a condition in which one or both globes (eyeballs) are abnormally small. Microphthalmia is defined as a globe with a total axial length (TAL) that is at least two standard deviations below the mean for age. Severe microphthalmia refers to a globe with a corneal diameter less than 4 mm and a TAL less than 10 mm at birth or less than 12 mm after age one year. Simple microphthalmia refers to an eye that is anatomically intact except for its short TAL. Although the major causes for this disorder are genetic, environmental factors have also been implicated such as exposure to radiation, chemicals, or viruses. Microphthalmia in newborns is sometimes associated with fetal alcohol syndrome or infections during pregnancy, particularly herpes simplex virus, rubella and cytomegalovirus (CMV).