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Early Intervention Training Center for Infants and Toddlers With Visual Impairments Module: Visual Conditions and Functional Vision: Early Intervention Issues Session 2: Visual Capacity Handout D: Congenital Structural Abnormalities That May Alter Visual Development EIVI Traning Center. (2003). Congenital structural abnormalities that may alter visual development. Chapel Hill, NC: Early Intervention Training Center for Infants and Toddlers With Visual Development, FPG Child Development Institute, UNC-CH. Name Optic nerve hypoplasia Source Elston (2000) Comments Occurs in the first or early second trimester May be associated with young maternal age, fetal alcohol syndrome, possible maternal diabetes mellitus Children at increased risk of endocrine disturbances Visual acuity may range from light perception to normal acuity Hertle, Schaffer, & Foster (2002) Atypical development of the optic nerve Microphthalmia/ anophthalmia Anophthamia, absence of the eye, or micropthalmia, a very small and typically malformed eye, represent structural abnormalities of the globe Visual Conditions Module 06/04/04 EIVI-FPG Child Development Institute UNC-CH May result from insult at number of developmental stages or from acute exposure to toxins during early development Could be due to failure or late closure of optic fissure Microphthalmia may result in decreased visual acuity, photophobia, fluctuating visual abilities Anophthalmia results in total blindness of affected eye S2 Handout D Page 1 of 2 Early Intervention Training Center for Infants and Toddlers With Visual Impairments Name Colobomas Source Comments Cook, Sulick, Defect occurs at 4 to 5 weeks’ & Wright gestation Failure of parts of the ocular system to (2003) Can affect iris, choroid, retina, and develop due to abnormal fusion of optic nerve optic fissure When optic nerve and/or retina is involved, vision is affected. Isolated iris colobomas may not affect visual acuity. Decreased visual acuity, photophobia, field loss often result from colobomas, depending on area that failed to develop. Congenital cataracts Wright May result from genetic/hereditary (2003) conditions, maternal infection, Clouding or opacity of the lens that systemic diseases produces indistinct image on retina Treatment within the first few weeks of life results in near-normal visual development Developmental abnormalities of the anterior segment (Defective development of structures near the front of the eye—between cornea and vitreous) Hertle, Schaffer, & Foster (2002) Defects in these structures may result in poor vision due to obstruction of light as it passes through the cornea, pupil, or lens Defects in trabeculum (involved in circulation/drainage of fluid in the eyes) can result in primary glaucoma that can cause vision loss Defects of iris (aniridia, coloboma) affect pupil size and can cause atypical visual development References Cook, C., Sulik, K.K., & Wright, K.W. (2003). Embryology. In K.W. Wright & P.H. Spiegel (Eds.), Pediatric ophthalmology and stabismus (2nd ed., pp. 3-38). New York: Springer. Elston, J. (2000). Visual pathway disorders. In A. Moore & S. Lightman (Eds.), Fundamentals of clinical ophthalmology: Paediatric ophthalmology (pp. 223-235). London: BMJ Books. Hertle, R.W., Schaffer D., & Foster, J. (2002). Pediatric eye disease: Color atlas and synopsis. New York: McGraw Hill. Wright, K.W. (2003). Lens abnormalities. In K.W. Wright & P.H. Spiegel (Eds.), Pediatric ophthalmology and strabismus (2nd ed., pp. 450-480). New York: Springer. Visual Conditions Module 06/04/04 EIVI-FPG Child Development Institute UNC-CH S2 Handout D Page 2 of 2