Could you tell me what's the common symptoms that suggest you need a cataract surgery ?

Several: Blurred vision. Glare at night. Halos around lights. Starbust effect.

Here are a few: Decreased vision even with glasses affecting the ability to do basic daily activities like read, watch tv etc. Haloes and glare around lights at night to the point of interfering with night driving is a common problem too.

Glare, halos, VA: The eyeMD can see a cataract at the microscope (slit lamp) when pt is dilated. Surgery usually recommended when vision (or glare test)