Four eyes is derogatory, 'the girl in the glasses' is not, nor is the black person, the white male, the female with the crutches, the boy with the black hair, the Englishman, the lady in the red dress. They are visual descriptors, there is absolutely nothing wrong with using a visual descriptor...
Can we call tall people tall, or short people short? Can i call a woman a woman? Can i be called a man? Can i say someone is athletically built?
Some statements are just true. No matter how PC you want to be.