How can we detect cataract disease in our eyes by its signs and symptoms?

Many or none. Everyone is different. I've had pts with very poor vision who says they have no symptoms. Then there are people who have 20/20 vision with symptoms usually the first symptoms are trouble with small prints and glare at night. Next complaint is they can't see the scores or words on tv, followed by not being able to read or see the signs very well when driving or see the numbers on the bus.
Poor vision! Most patient with cataract complain about glare and halos at night when driving. Difficulty reading road signs, difficulty reading fine print, needing more light to read fine print...
By change in vision. Common signs of cataract disease are: 1 - general decrease in vision or change in previously stable eye glass or contact prescription. 2 - difficulty with nighttime tasks (particularly driving) due to glare. Patients often describe this as "halos" around oncoming headlights.