[Functional treatment of strabismus: theoretical bases--practical rules].

Functional treatment of strabismus is no longer empirical, but has currently a scientific basis. To disperse the "doubts" surrounding functional treatment, it appeared necessary to situate it more clearly within its true framework, that of functional re-education in general. Indeed, although the terrain differs adults with a lesion and children whose binocular function is poorly or only partially developed - in both cases: - functional recovery is the result of changes within the central nervous system, changes which are possible due to the plasticity of the central nervous system. These modifications occur very slowly, sometimes over a period of years. - The crucial condition for success of treatment remains the same: the patient must participate actively, this being all the more essential in that recovery will take a long time. Although strabismus treatment must obviously consider physiological parameters (triad), psychological parameters are just as important, and as well as purely technical problems, other factors must also be taken into account: subject's motivation, length of treatment, communication with the doctor and medical team, attitude of the patient's family. This type of therapy is only justified as long as strabismus is considered to be a dysfunction of binocularity (this however, does not exclude surgery in some cases, and the operation is an integral part of the treatment). Functional treatment of strabismus is therefore difficult and disconcerting for the practising ophthalmologist. Disconcerting in that it differs radically from other types of eye therapy (medical or surgical); difficult in that the restraint it imposes is often in contradiction with the permissive society we live in. One of the main obstacles to be overcome is perhaps our own judgement as ophthalmologists; our opinion of the nature of strabismus, the possibility of a cure, to which must be added the application of the right technique, patient participation, etc. This study attempts to situate strabismus within the general framework of functional re-education, employing different authors' opinions of basic notions of neurophysiology relating to nervous plasticity and their application in cases of cortical lesions in adults. In Part II we shall outline why and how we have opted for functional re-education. The reasons why and the manner in which functional re-education was chosen are then outlined.