The eye’s aging and dysfunctional natural lens which hardens and becomes cloudy over time. This process starts in your 40s as a gradual loss in near focus, causing frequent eye strain and headaches, leading to needing reading glasses or bifocals. Over time, your natural lens becomes harder and more cloudy, causing your glasses prescription to change frequently, and other symptoms appear such as night glare and halos as well as overall reduced clarity of your vision