Why did Carmilla’s eyes go red?

Why did Carmilla’s eyes go red? Having decimated waves of night creatures and still fighting more as she takes on Isaac, she is losing. With blood-red eyes, similar to Dracula’s in his final battle, Carmilla is pushed to her limit and past it.

Having decimated waves of night creatures and still fighting more as she takes on Isaac, she is losing. With blood-red eyes, similar to Dracula’s in his final battle, Carmilla is pushed to her limit and past it.