Cormac McCarthy's novel "The Road" portrays a bleak post-apocalyptic world, where the environment is marked by an overwhelming sense of desolation and hopelessness. The imagery of darkness and grayness signifies the bleakness of existence, with the nights being characterized as incredibly dark and the days lacking color or vibrancy. This atmosphere reflects the emotional and psychological struggles of the characters as they navigate through their grim reality.

The quote conveys a profound sense of despair, suggesting that each passing day feels more lifeless than the last, similar to the gradual loss of sight caused by glaucoma. McCarthy effectively communicates the sense of loss and the relentless decay of the world around the characters, emphasizing the struggles they endure in a ravaged landscape devoid of hope and warmth.