Partial or complete lens dislocation (subluxation) may be hereditary or due to trauma.

Hereditary Lens Dislocation

Hereditary lens dislocation is usually bilateral and may be an isolated familial anomaly or due to inherited connective tissue disorder such as homocystinuria, Marfan syndrome, or Weill-Marchesani syndrome.

A partially dislocated lens may be complicated by cataract formation. If that is the case, the cataract may have to be removed, but there is a significant risk of vitreous loss, predisposing to retinal detachment. If the lens is free in the vitreous, it may lead in later life to the development of glaucoma of a type that responds poorly to treatment. If dislocation is partial and the lens is clear, the visual prognosis is good.

Traumatic Lens Dislocation

Partial or complete traumatic lens dislocation may occur following a contusion injury such as a blow to the eye with a fist. If the dislocation is partial, there may be no visual symptoms; but if the lens is floating in the vitreous, the patient will have significantly blurred vision. Iridodonesis, a quivering of the iris when the patient moves the eye, is a common sign of lens dislocation and is due to the lack of lens support. This is present both in partially and in completely dislocated lenses but is more marked in the latter.

Uveitis and glaucoma are common complications of dislocated lens, particularly if dislocation is complete. If there are no complications, dislocated lenses are best left untreated. If uveitis or uncontrollable glaucoma occurs, lens extraction may need to be done despite the poor results possible from this operation. For completely dislocated lenses, the technique of choice is pars plana lensectomy or phacofragmentation, depending on the density of cataract. Some partially dislocated (subluxed) lenses are amenable to phacoemulsification with various adaptations, such as capsular tension rings or support hooks.