Fig.1 Pseudoexotropia in 4,5-month child with positive angle gamma.
Fig.2 Two-month-old children with different appearance of palpebral fissures.
Pseudoexotropia is a condition,on which the eyes are straight ,however they appear to be outward deviation. In a very young children wide interpupillary distance are frequent. Such a state may simulate divergent strabismus. Often we observed the abnormality of the eyeballs structure(ectopia maculae in retinopathy of prematurity) or its placement in the orbits or changes in the eye protective apparatus. Fig2. Pseudoexotropia present, when the visual axis (connecting fixing object with the fovea) is different (near the nose) then the optic axis ( the line running through the center of cornea and pupil). The angle at which these axes crossed is called gamma angle. Fig. 1.
Exophoria is a latent tendency for the eyes to deviate. Deviation of the visual axis results from the fusion interruption, which is not able to maintain binocular vision any longer.Fig.3,4.
Factors predisposing to decompensated exophoria are listed below:
transient cover of one eye
emotional or physical shock
fatigue or asthenia ( severe infections)
Fig.3Exophopia .Note the deviation the left eye during cover-test.
Fig .4The same patient with exophoria. Note the straight eyes during binocular fixation