Presbyopia

Presbyopia is when the eye loses its natural focussing ability due to age. The eye's inner lens loses its elasticity and results in difficulty reading.  It typically occurs in early to mid 40's. Common symptoms include headaches, and having to hold reading material further than usual. This is corrected with reading glasses, or if a distance prescription is also present, bifocal (or progressive: no-line-bifocal) lenses.