• IOL optics can exist as different forms; meniscus, plano-convex or most commonly, bi-convex

 

 

 

 

 

 

 

• The optics themselves are immersed in aqueous humour, which has a refractive index of 1.33, so are more curved than a spectacle lens of identical power

 

• The shape of the optic has an effect on:

  • The position of the IOLs principal planes, which in turn... 

    • Defines the lens optical properties and visual axis locations where the optical power is applied 

 

• Optics which are steeper anteriorly or of an equiconvex design are more popular than those that mimic the human crystalline lens (flatter anteriorly).

  • This design has also been known to be associated with dysphotopsia

    • ​DYSPHOTOPSIA: visual disturbance causing haloes around light sources.

 

 

With meniscus lenses: nodal points occur outside the optics

With plano-convex lenses: one nodal point at the lens surface

With biconvex lenses: both occur within the optics, near the more curved area

• The position of the principal planes and points determined by shape of the haptics and optics                            determine the effective power of the intraocular lens that is inserted