Criteria for Cataract Surgery

I am in Southern California and one of the criteria for Cataract surgery is Reduced visual acuity. Does anyone know what that means as far as number?

re: Criteria for Cataract Surgery

The main indication for cataract surgery is when a person’s visual function no longer meets his or her needs and cataract extraction will provide improved vision. This level of visual impairment is subjective and differs considerably among individuals. Nevertheless, insurance carriers typically choose 20/40 Snellen visual acuity as the threshold for cataract surgery