Evaluating Eye Crossing Using the Corneal Light Reflex

A 6-month-old girl was referred to a pediatric ophthalmology clinic for evaluation of eye crossing. Her parents noted an inward deviation of the left eye starting at 2 months of age. The eye crossing was most noticeable when the child was looking toward the side. Her examination was notable for prominent medial epicanthal folds (Figure 1). She had full ductions and versions, symmetric corneal light reflexes, and no ocular misalignment by alternate cover testing. The visual acuity and refractive error of each eye were appropriate for her age. The family was reassured of the normal examination findings and advised that the appearance of eye crossing would decrease as her facial features develop. Written informed consent was obtained from the patient's guardian to publish photograph and case details. Pseudostrabismus is an optical illusion created by certain morphological features of the face that make the eyes appear to be misaligned. Prominent medial epicanthal folds can obstruct the white sclera nasally to create a false impression of eye crossing.1Xu T.T. Bothun C.E. Hendricks T.M. Mansukhani S.A. Bothun E.D. Hodge D.O. et al.Pseudostrabismus in the first year of life and the subsequent diagnosis of strabismus.Am J Ophthalmol. 2020; 218: 242-246Abstract Full Text Full Text PDF PubMed Scopus (3) Google Scholar It is important to distinguish pseudostrabismus from true strabismus, which affects approximately 2%-4% of children in the US.2McKean-Cowdin R. Cotter S.A. Tarczy-Hornoch K. Wen G. Kim J. Borchert M. et al.Prevalence of amblyopia or strabismus in Asian and non-hispanic white Preschool children.Ophthalmology. 2013; 120: 2117-2124Abstract Full Text Full Text PDF PubMed Scopus (195) Google Scholar, 3Multi-ethnic Pediatric Eye Disease Study GroupPrevalence of amblyopia and strabismus in African American and Hispanic children ages 6 to 72 months the multi-ethnic pediatric eye disease study.Ophthalmology. 2008; 115: 1229-1236.e1Abstract Full Text Full Text PDF PubMed Scopus (275) Google Scholar, 4Friedman D.S. Repka M.X. Katz J. Giordano L. Ibironke J. Hawse P. et al.Prevalence of amblyopia and strabismus in white and African American children aged 6 through 71 months the Baltimore pediatric eye disease study.Ophthalmology. 2009; 116: 2128-2134.e1-2Abstract Full Text Full Text PDF PubMed Scopus (331) Google Scholar The 2 most common types of strabismus are esotropia (inward turning) and exotropia (outward turning). Ocular misalignment in early childhood may result in amblyopia, poor visual development in the deviating eye. Early detection is essential because untreated amblyopia may result in permanent vision loss.5Wu C. Hunter D.G. Amblyopia: diagnostic and therapeutic options.Am J Ophthalmol. 2006; 141: 175-184Abstract Full Text Full Text PDF PubMed Scopus (124) Google Scholar The corneal light reflex is a simple screening test that can be performed with a penlight and can help distinguish pseudostrabismus from strabismus.6Donahue S.P. Baker C.N. Committee on Practice and Ambulatory Medicine American Academy of Pediatrics Section on Ophthalmology American Academy of Pediatrics Ophthalmology and Strabismus et al.Procedures for the Evaluation of the Visual System by Pediatricians.Pediatrics. 2016; 137Crossref Scopus (72) Google Scholar To perform the test, the examiner should be at eye level, approximately 2 feet away from the child, and hold the penlight midline while observing the position of the corneal light reflex in both eyes. If the eyes are well-aligned, the light reflex should be symmetrically centered in both eyes. However, in children with strabismus, the corneal light reflex will not appear at a symmetric position in each eye. If the child has an inwardly deviated eye, the light reflex will be temporal to the pupillary center, whereas if an eye is outwardly deviated, the light reflex will be nasal to the pupillary center (Figure 2). It is important to consider evaluation by an eye specialist for children suspected of having strabismus, because in some cases it may be difficult to distinguish true strabismus from pseudostrabismus. Intermittent eye crossing can be a normal finding in early infancy. However, constant horizontal strabismus after 4 months of age does not typically resolve spontaneously and warrants referral to a pediatric ophthalmologist.6Donahue S.P. Baker C.N. Committee on Practice and Ambulatory Medicine American Academy of Pediatrics Section on Ophthalmology American Academy of Pediatrics Ophthalmology and Strabismus et al.Procedures for the Evaluation of the Visual System by Pediatricians.Pediatrics. 2016; 137Crossref Scopus (72) Google Scholar In addition, children with suspected new-onset misalignment, abnormal eye movements, and ocular motility restrictions require further evaluation. Finally, some children with pseudostrabismus may develop strabismus later in life, so it is important to continually evaluate ocular alignment and visual development in this population.