He seems kind of like the Lance McCullers of the Horns.
A scratched retina would require a penetrating injury to the eye.
Retinal tears can happen without penetrating trauma.
Either would represent an ocular emergency.
Corneal abrasion would be more likely and though uncomfortable would not carry the risk of permanent vision loss. They can make it damn difficult to see short term however because of discomfort as the lid slides over the irritation.