Blepharokymasia

Blepharokymasia, the inability to close one eye while simultaneously keeping the other eye open, while bilateral closure of the eyelids proceeds quite normally. In the normal state, the ability to close or open one eye does not depend on similar movement of the other eye, i.e., there exists a physiological dissociation of these movements. This dissociation is acquired during the first years of life and represents a further step in the development of the muscular apparatus of the eye. However, this property of dissociation of eyelid movements is often absent. Blepharokymasia may manifest in the levator palpebrae muscles as well as in the m. orbicularis on both sides, and may also manifest in only one muscle or on only one side (for example, the ability to close the left eye independently of the right, but not vice versa). Such blepharokymasia depends not on paresis of one or another muscle, but on a defect in the normal dissociation of eyelid movements, which in most cases occurs in children (it may also be observed at any age). According to some authors, different visual acuity in each eye can cause blepharokymasia, in which case the eye that sees worse is more easily closed. Blepharokymasia is also observed in cases where recovery from paralysis of the n. facialis is already occurring. In such cases, patients are able to close both eyes simultaneously, but the ability to close the eyelids on the side of the paralysis is absent. This is explained by the fact that unilateral closure of the eyelids requires greater innervational energy than bilateral closure. Almost all hemiplegics usually observe blepharokymasia at the beginning of the disease (which disappears almost simultaneously with the disappearance of the paralysis of the lower branch of the n. facialis).