The family of a beloved great-grandmother from Brooklyn is convinced that the 9/11 terror attacks destroyed her health, essentially killing her — and now they hope to use revamped rules to make it official.

Gloria Knight, a then-72-year-old retired bartender, went to Worth Street the morning of Sept. 11, 2001, to get a new pair of eyeglasses when the planes hit.

She breathed in dust and smoke while fleeing on foot to the Manhattan Bridge — where she had a heart attack and collapsed.

“She told me she was trying to walk home to Brooklyn when she felt chest pain and had difficulty breathing,’’ said Michael Sean Weinstock, a volunteer EMT and attorney who treated Knight after she fell.

Weinstock is now repping the family in its fight for her status as a 9/11 victim. Knight died in 2004 at 75. Such a move could reimburse Knight’s family for her health-care costs and also give them a minimum $250,000 payout.

The first application to have Knight certified was rejected because she was physically outside the current designated impact zone when the towers fell.

Relatives say they will re-apply to the September 11th Victim Compensation Fund again next month in the hopes of being approved, given that the agency is expanding the impact zone.