It is an inadequate, long, and sustained contraction of the ciliary muscle and can originate, either as a functional disorder or in an iatrogenic way, for example, when glaucomatous-young patients are treated with para-sympathomimetics (miotics). It can appear in patients with hyper-excitability of the accommodation center, which especially in young people, can be psychogenic.
Treatment: If the cause is discovered, treat it. Relieve symptoms, using a spectacle that improves your distant visual acuity, never leaving permanently and only for specific tasks. Perhaps the most important is visual reeducation, at the proprioceptive level and visual therapy, it is the best of all therapeutic approaches. Optometric phototherapy, called Syntonic, can work very well, since the lack of harmony of the autonomic nervous system is a constant in this problem.