Strabismic amblyopia.

NOTWITHSTANDING the vast literature, a complete and satisfactory definition of the clinical picture of amblyopia in strabismus has not yet been produced, and some symptoms are often confused with those of other forms of functional amblyopia. Bangerter (1953) and many other authors embrace in the term " amblyopia ex anopsia" the amblyopia observed in anisometropia, in high ametropia, and in nystagmus, as well as the true strabismic amblyopia. There are, however, certain clinical symptoms which seem to be characteristic of strabismic amblyopia, and the treatment of these symptoms by pleoptics appears to be fundamental for the recovery of the visual acuity in the amblyopic eye and, following this, for the final cure of the squint. In persons affected by concomitant squint, particularly in its convergent form, the amblyopia is not limited to the functional reduction of the vision of one eye, but is accompanied by other symptoms which are no less important in prognosis and in choice of therapy. Apart from the deficiency in the perception of shape (the morphoscopic acuity of vom Hofe, 1930), the existence of which needs further confirmation, the phenomena which have recently attracted attention are the deficiency offixation in the amblyopic eye, and the so-called difficulty of separation. To these symptoms must be added the lack of motor coordination observed in amblyopic persons when they try to localize a point in space by following the lead of the amblyopic eye. This disturbance has been pointed out by a few authors, but has not yet been studied sufficiently, although some of the pleoptic exercises described by Bangerter seem to be based on the re-education of the motor coordination. The most important discoveries regarding fixation deficiency are of very recent date, and it is now generally agreed that eccentric fixation may occur in strabismic amblyopia, as suggested by von Graefe in 1881. Apart from those cases with a fixed and constant eccentric fixation, there are many others in which the fixation is unstable (Ehrich, 1955, 1956, 1958; Brook and Givner, 1952; Urist, 1955; Lazich, 1948); moreover recent researches in electro-oculography (Mackensen, 1957; von Noorden and Burian, 1958) have demonstrated the instability of fixation in amblyopic eyes. B6hme (1957) and Pouliquen (1958) describe motor disturbances in amblyopia leading to a difficulty in fixation in abduction and to differences