Lens

Looks like

A clear, flexible disc about 10 mm across and 4 mm thick, hanging just behind the iris.

What it does

Focuses light on the retina and changes shape to see near objects.

Keeping it well

Stiffens from the mid-40s (reading glasses) and clouds with age as cataract; sunglasses and not smoking slow it, and surgery replaces it.

Its parts

• Right lens
• Left lens

Related conditions

• Blepharitis & styes
• Cataract
• Conjunctivitis
• Hyperthyroidism & Graves' disease
• Keratitis (corneal infection and ulcer)
• Keratoconus
• Marfan syndrome & connective tissue disorders
• Presbyopia
• Retinal detachment
• Retinoblastoma
• Short and long sight (refractive error)
• Sjögren's disease
• Squint & lazy eye
• Uveitis & iritis