In an ageing population cataract formation is one of the leading causes of blindness. Cataracts are caused by a failure to clear accumulating aggregated proteins in the lens. MicroRNAs are small non-coding transcripts which bind to specific mRNAs acting at the post-transcriptional level to mediate, normally inhibiting, protein production. Specific microRNAs have been implicated in several cellular processes and disease states. Previous studies have reported that miRlet-7b was upregulated in lens epithelial cells from cataracts. In this paper anterior lens capsule samples from patients with age-related cataract and from normal age-matched individuals were analysed and confirmed increased let-7b expression associated with cataract. In a lens epithelial cell line UV light significantly increased let-7b expression, which led to lens cell apoptosis. Specifically, let-7b was shown to target leucine-rich repeat containing protein-coupled receptor-4 (Lgr4), a molecule associated with premature cataract and progressive deterioration with age in knock-out mice. Let-7b inhibition of Lgr4 is involved in apoptosis of lens epithelial cells, a pathway that may offer therapeutic potential.