Typically diagnosed clinically by the finding of lens opacity on direct ophthalmic exam
Precise classification (nuclear, cortical, posterior sub-capsular) may be done by ophthalmologist
If the patient has risk factors for diabetes or HIV/AIDS, consider appropriate diagnostic tests
Precise classification (nuclear, cortical, posterior sub-capsular) may be done by ophthalmologist
Cataracts
Painful
Red eye 
Arteritic anterior ischemic optic neuropathy
Ocular palsy
Optic neuritis
Papilledema
Temporal arteritis†