Crystalline Lens (Background + Presbyopia)

Lens

Refractive surface that helps focus light

Thickens, becomes less transparent, loses ability to flex (lose accommodation) with age

Pt will complain of blur, glare, and halos

Capsule

Thick basement membrane

Left in cataract Sx

Anterior capsule epithelium

Metabolically active cells that form new lens fibers throughout life

Fibers are never shed and compact with age

Cortex

Loosely packed younger fibers

Nucleus

Tightly packed, oldest fibers

Zonules

Aid in accommodation and hold lens in place

Pathology in the capsule will lead to…

Posterior capsular opacification

Pathology in the subcapsular region will lead to…

Anterior and posterior subcapsular cataracts

Anterior is less common

Pathology in the cortex will lead to…

Cortical cataracts

Pathology in the nucleus will lead to…

Nuclear sclerosis

Pathology in the zonules will lead to…

Ectopia lentis

Presbyopia

Lens loses ability to flex → Can’t see at near

Lens flexibility

Begins around 10 and progresses throughout life

All flexibility is lost around 65

Tx for presbyopia

Bifocals

+2.50D for 40cm working distance