Aside from cataracts, there are 2 other types of lens abnormalities: changes to lens shape and changes to lens position/size. Conditions that result in these changes are reviewed on this page.
Ectopia Lentis
Ectopia lentis is the dislocation of the lens and it can be acquired or congenital. Changes in lens position distort the refraction of light and decrease visual acuity. Anterior dislocation in particular can obstruct the normal flow of aqueous and result in glaucoma.
Congenital Causes
- Familial ectopia lentis - superotemporal displacement
- Marfan’s syndrome - Superotemporal displacement
- Homocystinuria - Inferonasal displacement
- Weill-Marchesani syndrome - Anterior inferior displacement
The exam will focus on testing the direction of displacement and the associated congenital conditions. Acquired cases are mainly due to trauma.
Congenital aphakia is the complete absence of the lens. It is caused by a FOX3 gene mutation.
Management
- Minor displacement can be managed with contact lenses and spectacles
- Major displacements are managed with lensectomy
Lenticonus/globus
Abnormal lumpy protrusion of the lens surface. It causes abnormal distortion of light
Lenticonus
- A conal protrusion
- Anterior lenticonus (anterior lens) is associated with Alport's syndrome
- Posterior lenticonus (posterior lens) is associated with Lowe’s syndrome
Alport’s syndrome is a disorder of type 4 collagen
Lentiglobus
- A hemispherical protrusion
- Retroillumination using a slit-lamp shows a classic oil droplet sign
