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Risk factors for esotropia and exotropia
E Chew1, N A Remaley, A Tamboli
1National Eye Institute, National Institutes of Health, Bethesda, Md.
Insights
Low birth weight and maternal smoking during pregnancy are key risk factors for childhood strabismus (esotropia and exotropia). Increased maternal age also elevates the risk of esotropia in children.
Area of Science:
- Ophthalmology
- Pediatric Health
- Epidemiology
Background:
- Strabismus, a common childhood eye misalignment, includes esotropia (inward turning) and exotropia (outward turning).
- Identifying risk factors is crucial for early intervention and prevention strategies.
Purpose of the Study:
- To determine risk factors for esotropia and exotropia in a large cohort of children followed from gestation to age 7.
- To analyze the association of various maternal, socioeconomic, perinatal, and neonatal factors with strabismus development.
Main Methods:
- Prospective cohort study involving 39,227 children enrolled from 1959-1965.
- Data collected via maternal interviews and medical examinations at birth, 4, 8 months, 1 year, and 7 years.
- Multivariable logistic regression used to identify significant risk factors.
Main Results:
- Esotropia occurred in 3.0% and exotropia in 1.2% of children.
- Low birth weight (<1500g) significantly increased odds for esotropia (OR 3.26) and exotropia (OR 4.01).
- Maternal smoking (>2 packs/day) increased odds for esotropia (OR 1.83) and exotropia (OR 2.32). Increased maternal age also correlated with higher esotropia risk.
Conclusions:
- Maternal cigarette smoking and low birth weight are independent, significant risk factors for both esotropia and exotropia.
- Esotropia risk increases with maternal age, particularly for mothers aged 30-34.
- Race influenced esotropia prevalence (higher in whites) but not exotropia.
Objective:
To identify risk factors associated with the two major types of strabismus--esotropia and exotropia--in a cohort of children followed up from gestation to age 7 years.
Design:
Pregnant women were enrolled in the Collaborative Project of the National Institute of Neurological Disorders and Stroke, Bethesda, Md, from 1959 to 1965 at 12 university centers. This large multidisciplinary study was designed to evaluate the developmental consequences of complications during pregnancy and the perinatal period. Data on maternal, socioeconomic, perinatal, and neonatal characteristics were collected from 39,227 children and their mothers by medical examination and interview. Examinations of the children were performed at birth, 4 months, 8 months, 1 year, and 7 years.
Outcome Measures:
The evaluation of the presence of strabismus was performed during follow-up examinations and confirmed at the 7-year follow-up visit. Potential risk factors for strabismus were evaluated from the maternal, socioeconomic, perinatal, and neonatal characteristics.
Results:
Esotropia developed in 1187 children (3.0%), and exotropia developed in 490 children (1.2%). Esotropia was more common in whites (3.9% in whites vs 2.2% in blacks, P < .0001). The occurrence of exotropia was similar in the two races (1.2% in whites and 1.3% in blacks). Results of multivariable logistic regression models showed that the risk of strabismus increased with low birth weight (P < .0001). For infants weighing 1500 g at birth compared with those weighing 4000 g at birth, the odd ratios were 3.26 (95% confidence interval, 2.50 to 4.25) for esotropia and 4.01 (95% confidence interval, 2.77 to 5.80) for exotropia. Maternal cigarette smoking during pregnancy also increased the risk of each type of strabismus (P < .0001). For offspring of mothers who smoked more than two packs of cigarettes per day compared with those whose mothers did not smoke, the odds ratios were 1.83 (95% confidence interval, 1.51 to 2.22) for esotropia and 2.32 (95% confidence interval, 1.72 to 3.13) for exotropia. Maternal age was also a significant risk factor for esotropia (P = .0005). The risk of esotropia increased with increasing age until age 34 years. In particular, the odds ratio for mothers aged 30 to 34 years relative to that for mothers aged 20 to 24 years was 1.43 (95% confidence interval, 1.19 to 1.70).
Conclusions:
Esotropia was more common in whites than in blacks. The occurrence of exotropia was similar in the two races. Maternal cigarette smoking during pregnancy and low birth weight were independent and important risk factors for both esotropia and exotropia. There was an increased risk of esotropia with increasing maternal age.