Optometry is a health care profession concerned with eyes and related structures, as well as vision, visual systems, and vision information processing in humans. Optometry is one of three eye care professions, the others being ophthalmology (which is a branch of surgery) and orthoptics (a sub-specialty of ophthalmology primarily dealing with strabismus). Optometric history is tied to the development of vision science (related areas of medicine, microbiology, neurology, physiology, psychology, etc.), optics, optical aids, optical instruments, imaging techniques, and other eye care professions. Behavioral optometry is a related area of non-strabismus vision therapy that some optometrists practice. Generally, ophthalmologists and orthoptists do not practice this.