Indhaha qeybta danbe ee (retina) marka ay toos ugu gudbin iftiinka.
Waa cilad ku timaadda leexinta iftiinka isha, taas oo keenta in sawirku si sax ah ugu dhicin retina-da, sidaa darteedna araggu noqdo daciif ama qalloocan. Waxaa ka mid ah myopia, hyperopia, iyo astigmatism.