I'm 39 and was just diagnosed with polymialgia rheumatica and hortons disease, i was told its rare for my age but how likely am i to go blind?

Giant cell arteritis: Best way to diagnose is with temporal artery biopsy. If biopsy is positive treatment with oral Prednisone to make sure sed rate returns to normal level. Prednisone is then gradually tapered while sed rate is monitored. Following this protocol the chance of going blind in one or both eyes would be highly unlikely. See a neuro-ophthalmologist if you are unsure you are getting proper treatment.

Small risk: Vision loss in giant cell arteritis is small but definitive and irreversible. Emergent treatment is essential if visual symptoms occur, whether blurry, decreasing, double vision, acute headache , temple pain, jaw pain or cramping with chewing, scalp tenderness an others b.