[Topographic relation of dislocated lenses to the ciliary body and vitreous base]

There are three forms of lens dislocation in the posterior segment: intravitreal, prebasal, and intrabasal. The location of the dislocated lens depends on gravity and the condition of the vitreous body. As a rule the dislocated lens lies at the bottom of the vitreous cavity; it may be completely embedded in the vitreous substance or completely outside the vitreous body, or partially within the vitreous base. The topographic relations between dislocated lenses and the vitreous body cannot be determined by ophthalmoscopic examination, but biomicroscopy generally permits an accurate assessment. Biomicroscopic findings are described.