New pediatric risk factors for amblyopia: strabismic versus refractive



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.


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.


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).


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.

Post author correction


Article Subject: Paediatric ophthalmology



Sandra Guimaraes, Maria Vieira, Tatiana Queirós, Andreia Soares, Patrício Costa, Eduardo Silva

Article History


Financial support: No financial support was received for this submission.
Conflict of interest: None of the authors has conflict of interest with this submission.

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  •  Department of Ophthalmology, Hospital de Braga, Braga - Portugal
  •  Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga - Portugal
  •  ICVS/3Bs, PT Government Associate Laboratory, Braga/Guimarães - Portugal
  •  School of Medicine, University of Minho, Braga - Portugal
  •  Clinical Academic Center-Braga, Braga - Portugal
  •  Department of Ophthalmology, Centro Cirurgico de Coimbra, Coimbra - Portugal
  •  IBILI, Faculty of Medicine, University of Coimbra, Coimbra - Portugal
  •  Department of Ophthalmology, CHLN, Lisbon - Portugal
  •  Sandra Guimaraes and Maria Vieira contributed equally to this work.

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