The preponderance of occasional squinters fuse most of the time at near and squint more often at distance than at near. The consequence of this fact is that management of these esotropes, particularly with vision training, is best implemented by capitalizing on the fusion at near --- thus employing optics or training that enhances vision abilities that are already developed.
It is often surprising how much effect on fusion occurs with optical correction of seemingly trivial refractive errors. Commonly correction of 0.5 diopters of astigmatism or anisometropia substantially increases the percent time of fusing for an occasional esotrope. After correcting the refractive error with optimum plus for esotropes, to provide sharp retinal imagery and facilitates sensory and motor fusion, added lens power should be considered.
A plus add for esotropes is a logical second consideration because it facilitates motor fusion and actively reduces the angle of deviation through the AC/A ratio.
When prescribing added lens power, vertical prism should be considered to neutralize any vertical deviation present WHEN THE EYES ARE IN THE FUSED POSITION. Horizontal prism, a passive treatment that permits the eyes to deviate towards the squinting position but reduces the demand on fusional vergence, should be considered next primarily when the esotropia is present more of the time than not. For occasional strabismics who rarely squint, horizontal prisms are less useful than an active treatment.
Occasional esotropes usually do not have much amblyopia; when it is present, occasional occlusion, especially for distance, should next be considered. This passive form of amblyopia treatment is facilitated by an active program of vision training directed at decreasing the commonly present central suppression.
Awareness of diplopia when an ocular deviation is precipitated is an ideal outcome of orthoptic treatment, since it serves as the provocation for a fusional vergence recovery movement. Training of sensory-motor functions logically comes next; training the sensory aspects of fusion (such as stereopsis) typically results in improved motor fusion. If any motor fusion training is necessary, it is needed less for amplitude than for facility of fusional vergence. Optical and orthoptic management of occasional strabismus usually results in functional correction.
Surgery is typically not necessary unless the angle of deviation is large and discomfort is present. Surgery is sometimes performed with an adjustable suture and tends to be conservative to avoid onset of a vertical deviation or noncomitancy. Optical and orthoptic followup can be helpful immediately after surgery.