Epicanthal folds are present to some degree in most infants and children during the first few years of life (Figure 18 A, B). These skin folds can create an illusion of esotropia. Parents think one eye turns in because no ‘white’ can be seen medially, especially in the adducted eye in lateral versions. Two techniques can be used to relieve parental concern regarding pseudoesotropia from epicanthus. First, the examiner demonstrates the centered pupillary reflexes with a muscle light. Second, the examiner carefully pulls the skin forward over the bridge of the nose to demonstrate the ‘straightening’ effect of exposing the medial conjunctiva or ‘white of the eye’ (Figure 19). It is still a good rule for the ophthalmologist presented with an obvious case of pseudostrabismus to carry out a complete eye examination, including cycloplegic refraction and retinal examination. A medial skin fold sweeping upward from below is called epicanthus inversus (Figure 20).
A Epicanthal folds obscure the nasal conjunctiva in both patients, giving the appearance of esotropia. However, the light reflex is centered in the pupil in each case. This reflex indicates the presence of parallel pupillary axes and, therefore, straight eyes or absence of manifest strabismus. Cover testing must be performed eventually to confirm the presence of parallel visual axes because a large angle kappa* could hide a small manifest esodeviation.
B Epicanthal folds are present, but the displaced pupillary reflex in the right eye confirms the presence of a right esotropia.
*Angle kappa is the angle formed by the pupillary axis and the visual axis. A positive angle kappa is present when the visual axis is nasal to the pupillary axis. This simulates exotropia and is common. A negative angle kappa is present when the visual axis is temporal to the pupillary axis. This simulates esotropia and is much less common than positive angle kappa.
A Centered pupillary light reflex
B The ‘straightening’ effect of exposing more ‘white’ nasally. (This is shown in an older patient because it is difficult to photograph the younger child where the test is more effective.)
A skin fold originating below and sweeping upward is called epicanthus inversus. This deformity is frequently associated with blepharophimosis and ptosis. These three deformities, which may be combined with telecanthus, cause significant disfigurement and present a formidable therapeutic challenge.
Telecanthus, which is an increased interorbital distance, may be confused with epicanthus (Figure 21). Normally, the intercanthal distance is about one half the pupillary distance. Intercanthal separation in excess of this suggests true telecanthus, but this diagnosis must be confirmed by radiologic evaluation demonstrating a bony abnormality. Other midline facial abnormalities, especially clefting of a facial structure in the presence of telecanthus, should raise the suspicion of defects at the base of the skull including encephalocele. These patients also may have optic nerve anomalies ranging from hypoplasia to morning glory disk or even may be missing a medial rectus muscle.
A This patient demonstrates telecanthus with an interorbital dimension clearly more than one-half the interpupillary distance and also an exotropia.
B This patient with telecanthus also has prominent epicanthal folds.