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Release Date: October 31, 2005; Valid for credit through October 31, 2006

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Oct. 31, 2005 — Heavy maternal alcohol use during pregnancy is related to decreased visual acuity in infancy, according to the results of a prospective study reported in the October issue of The Journal of Pediatrics.

"In the early 1970s, Jones and Smith described a syndrome of prenatal growth deficiency, developmental delay, and specific craniofacial dysmorphology, which they termed fetal alcohol syndrome (FAS)," write R. Colin Carter, MD, from Wayne State University School of Medicine in Detroit, Michigan, and colleagues. "Disorders of the eye were noted in the earliest reports of FAS, and case studies have documented numerous ophthalmologic abnormalities."

The investigators examined infant visual acuity in 131 Cape Coloured (mixed ancestry) maternal-infant pairs in Cape Town, South Africa, and they documented drinking patterns by maternal reporting during pregnancy. At 6.5 months after term, grating acuity was assessed with Teller Acuity Cards (TAC), which uses preferential looking to assess if an infant can differentiate black and white stripes from a gray background as the stripe widths decrease.

Greater average daily prenatal alcohol exposure was associated with poorer acuity, as reflected in lower TAC scores. Compared with infants born to younger mothers, infants born to mothers at least 30 years of age at delivery showed a more significant effect of alcohol on acuity. This effect was not mediated by gestational age or birth size, nor could it be attributed to alcohol-related neurocognitive deficits.

"This study linked prenatal alcohol exposure ascertained prospectively to poorer visual acuity in infancy," the authors write. "The results are consistent with clinical and animal evidence of alcohol-related disruption of the visual system."

Study limitations include inability to conduct a complete eye examination, precluding determination of the source of the alcohol-related lower acuity scores.

"These findings suggest that the TAC is a useful tool for screening for adverse effects of prenatal alcohol exposure on acuity," the authors conclude. "Particular attention needs to be given to screening infants born to older mothers, who are at higher risk of damage to the ocular system from their mothers' alcohol use during pregnancy. An in-depth ophthalmologic evaluation of the infants in this study during childhood is necessary to determine the nature of the visual abnormalities associated with fetal alcohol exposure and the degree to which the screening information from the TAC is indicative of these deficits."

The National Institute on Alcohol Abuse and Alcoholism, the National Institutes of Health Office of Research on Minority Health, the Foundation for Alcohol Related Research in Cape Town, South Africa; and the Joseph Young, Sr., Fund from the State of Michigan have disclosed that they supported this study.

J Pediatr. 2005;147:473-479

Learning Objectives for This Educational Activity

• Describe the effect of prenatal alcohol exposure on visual acuity in infants.
• Describe the roles of maternal age, gestational age, and birth size on the effect of prenatal alcohol exposure on visual acuity in infants.

Clinical Context

Infants exposed to alcohol in utero can develop FAS with features of growth deficiency, developmental delay, craniofacial dysmorphic features, and ophthalmologic abnormalities, including reduced visual acuity. Factors that potentially influence visual acuity include growth, gestational age, poor attention or developmental disabilities, and maternal age. For example, reduced visual acuity might be a result of developmental delay affecting the child's ability to perform the task or inattention to the task. Studies by Jacobson and colleagues, one published in the May 12, 1994, issue of the Journal of Pediatrics and the other in the April 1994 issue of Alcoholism, Clinical and Experimental Research, reported an association between prenatal alcohol exposure and reduced birth size and gestation; it is possible that impaired fetal and postnatal growth play a role in the effect of alcohol exposure on visual acuity. In previous case studies, each successive child exposed to alcohol in utero was more severely affected than a previous child, which was possibly because of increased maternal age.

According to an article by Jacobson and colleagues in the 2002 issue of Alcoholism, Clinical and Experimental Research, the authors stated that they would conduct a future prospective study to evaluate the effects of heavy prenatal alcohol exposure on neurobehavioral development in a population with high prevalence of FAS: the Cape Coloured population of mixed white European, Malaysian, Khoi, and black African ancestry in the Western Cape Province of South Africa.

This sample population was used to conduct the current prospective, longitudinal study to evaluate the effects of heavy prenatal alcohol exposure on visual acuity at age 6.5 months in a population with a high prevalence of FAS.

Study Highlights

• Pregnant women were enrolled in the heavy-drinking group if they averaged at least 1 oz of absolute alcohol (AA) per day or at least 2 incidents of binge drinking (at least 5 standard drinks on 1 occasion) per month during the first trimester. Alternating enrollees were pregnant women who drank less than 0.5 oz of AA per day, did not binge drink, and had gestation within 2 weeks of previously recruited heavy-drinking women. Exclusion criteria for women included age younger than 18 years, diabetes, epilepsy, or cardiac conditions requiring treatment, and Muslim practices prohibiting alcohol. Exclusion criteria for infants were major chromosomal anomalies, neural tube defects, multiple births, and seizures.
• At recruitment, drinking history was taken for a 2-week period at time of conception and any drinking increase. At follow-up antenatal visit, drinking history was taken for previous 2 weeks and any increase. At 1-month postpartum visit, drinking history was taken for 2 weeks of latter part of pregnancy. The 6 measures of alcohol use were average AA per day at conception and during pregnancy, AA per occasion at conception and during pregnancy, and drinking days per week at conception and during pregnancy.
• Among the mothers, 18.3% completed high school, 30.5% were at least 30 years old, 35.9% were primiparous, 93% breast-fed their infants, 11% met Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, criteria for alcohol abuse, 22.9% met criteria for dependence, 70.2% reported smoking cigarettes, and 10.7% reported marijuana use.
• Of 131 infants, 46.6% were born to heavy-drinking women and 53.4% to low level-drinkers, 18.3% were preterm, 19.1% were low birth weight, 44% were girls, and 16.8% infants met criteria for FAS. Weight, length, head circumference, and Fagan Test of Infant Intelligence (FTII) were measured at 6.5 months. FTII assesses visual recognition memory and information processing speed. Visual acuity was evaluated by the TAC resolution acuity test at age 6.5 months, corrected for prematurity. 12.2% were below the fifth percentile for visual acuity. 27.3% of infants with FAS had TAC scores below the fifth percentile vs 9.3% of infants without FAS (P < .005). Alcohol exposure during pregnancy was significantly related to decreased birth weight and size at 6.5 months, but not to gestational age.
• Poorer acuity at 6.5 months was associated with higher average daily alcohol consumption at conception (Pearson r = -0.21; P < .01) and during pregnancy (r = -0.23; P < .01). Poorer acuity was also associated with number of drinking days per week at conception (r = -0.23; P < .01) and during pregnancy (r = -0.26; P < .01). The number of drinks per occasion was not related to acuity, but infants of mothers who binge drink were more likely to have poorer acuity (P < .005). Effects of pregnancy drinking on acuity were dose dependent with drinking average of at least 0.5 oz per day (P < .05).
• The relation of pregnancy drinking (AA/day during pregnancy) to visual acuity was not significantly changed when controlling for gestational age, birth size, 6.5-month size, and FTII results. In infants of mothers aged older than 30 years, there was an association between acuity and AA per day at conception (r = -0.33; P <.05) and during pregnancy (r = -0.40; P < .01) and number of drinking days per week at conception (r = -0.35; P < .05) and during pregnancy (r = -0.43; P < .01). Mothers aged older than 30 years did not drink larger amounts of alcohol.
• The authors comment that eye examinations would help in determining specific reasons for reduced visual acuity and the usefulness of TAC in screening for visual deficits.

Pearls for Practice

• Greater average daily prenatal alcohol exposure is related to poorer visual acuity screening scores in infants at 6.5 months.
• The effect of prenatal alcohol exposure on visual acuity is significant primarily for infants whose mothers are at least age 30 years old vs mothers younger than age 30 years. Gestational age and birth size do not influence the effect of alcohol exposure on acuity.

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Penny Murata, MD
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