New pediatric risk factors for amblyopia: strabismic versus refractive.

PURPOSE: To assess the role of risk factors for amblyopia, such as family history and neonatal background, for the prediction of either strabismic amblyopia or refractive amblyopia.

METHODS: In this retrospective case-control model, the study population included all children born at the Hospital de Braga during 1997-2012 (3 to 18 years old) with ophthalmologic consultation in 2014. Data collection was performed from the clinical database and through telephone questionnaire surveys.

RESULTS: A total of 298 (50%) controls and 298 (50%) cases (120 [40.3%] strabismic amblyopia and 178 [59.7%] refractive amblyopia) were analyzed. A significantly lower birthweight was detected in patients with strabismic amblyopia (mean 2,961 g [95% confidence interval (CI) 2,827-3,096]) compared to controls (mean 3,198 g [95% CI 3,125-3,271]) (p = 0.002). Five-minute Apgar was significantly lower in patients with strabismic amblyopia (mean 9.57 [95% CI 9.37-9.77]) than in controls (mean 9.83 [95% CI 9.77-9.90]) (p = 0.004) or patients with refractive amblyopia (mean 9.79 [95% CI 9.69-9.89]) (p = 0.031). Family history of either amblyopia or strabismus was associated with amblyopia (χ2 [2, n = 562] = 12.66; p = 0.002; Cramer V = 0.150; χ2 [2, n = 561] = 11.0; p = 0.004; Cramer V = 0.140), but was significantly more associated with strabismic amblyopia (p = 0.0023 and p = 0.0032) than with refractive amblyopia (p = 0.48 and p = 0.015, respectively). Multinomial logistic regression model explained 50.8% of the variance in amblyopia development. Low 5-minute Apgar had a relevant odds ratio (OR) for either strabismic amblyopia (OR 3.44; p = 0.066) or refractive amblyopia (OR 3.30; p = 0.077).

CONCLUSIONS: This division in amblyopia subtypes gives a new perspective of the risk factors for amblyopia, with family history and some obstetrician/neonatal outcomes appearing to be more relevant in strabismic amblyopia. Educating health care providers to recognize these risk factors can result in an early ophthalmologic referral.