If it is possible to collect this nasal discharge, please get it tested to rule out a CSF (cerebro-spinal fluid)  leak. (Routine CSF, glucose  and Beta-2 Transferrin levels). Especially if your runny nose is from one side, or is accompanied by headaches. A simple test is to check whether your nasal secretions cause stiffening of your handkerchief or any soft cloth that you may use to clean your nose (Handkerchief Test or Ring Sign). Sneezing, itchy eyes and nasal blockage will be more in favor of a Perennial Allergic Rhinitis which would respond to anti-allergic medication. It could also be due to Intrinsic or Vasomotor Rhinitis. 

dry burning eyes is because of the age related dryness of the eye. but the runny nose seems to be the non allergic rhinitis it require the biopsy of the mucus of the nose. seeing the age and many favctors like bypass surgery and pacemaker, it is better to just leave it like that if it is not really bothersome