Perhaps Harry discovers that his loss of glasses is part of a magical curse and he has to break it to get them back and restore his vision.
A fanfiction could start with Harry's glasses being stolen by a mischievous house - elf. Harry starts to squint to see in his classes, which causes some problems. For instance, in Potions class, he misreads the instructions and creates a minor explosion. He spends the day trying to find the house - elf and his glasses. Along the way, he meets some other characters who help him in unexpected ways. By the end of the day, he gets his glasses back and has learned a valuable lesson about not taking his eyesight for granted.
He could misidentify something important. For example, he might think an approaching friendly ship is an enemy vessel because he can't see clearly. This could lead to a lot of chaos and misunderstanding among his comrades on the ship.
One possibility in this fanfiction could be that Harry's wish for his glasses was a part of a much larger plot. The glasses could be the key to unlocking an ancient magic. When he wished for them, it set in motion a series of events. The glasses might start to glow and lead Harry to a hidden chamber. Inside, he discovers a prophecy that was meant only for those who could find it with the help of the special glasses. This would make the glasses not just an accessory, but a crucial element in the fight against evil.
In the fanfiction, when Harry Potter loses his glasses, it could lead to some really interesting character development. For example, his friends might have to step up and protect him more. Also, it could be a chance for him to discover new magical ways to improve his vision without the glasses, perhaps a spell or a potion that he has to search for.
He might end up in a place where he can't see clearly without his glasses and struggles to find his way. For example, he could be in a dark forest where he stumbles around, trying to figure out where he is and how to get back. Without his glasses, his magical abilities might also be affected in some way, like his spell - casting accuracy.
Maybe it's a fanfiction set in an alternate magical universe. Here, Draco might have a more complex role in Harry's kidnapping, and the glasses issue adds an extra layer of drama.
Another reason might be related to a new magical artifact or potion. Harry might have come across something that had an unforeseen effect on his glasses. It could be that a new charmed item he was using interacted with his glasses and caused them to disappear.
In the fanfiction, if Harry Potter's glasses were confiscated, he would be at a huge disadvantage. His ability to observe his surroundings, which is crucial in the wizarding world full of hidden passages and magical creatures, would be severely hampered. Without his glasses, he might not be able to recognize friends or foes quickly. Also, during Quidditch, he wouldn't be able to see the Snitch clearly, and his team could lose the game.
One possible fanfiction could be about Harry having trouble with his glasses after a spell goes wrong. He has to squint constantly to see clearly, and this leads to some comical situations at Hogwarts. For example, he mistakes a cat for a Kneazle during Care of Magical Creatures class.
Well, it could be that Harry's glasses are actually in the possession of a dark wizard who wants to disrupt Harry's life. Without his glasses, Harry would struggle to see clearly and defend himself. However, with the help of his friends, he might be able to track down the dark wizard and retrieve his glasses. This could lead to an epic battle or a series of clever magical maneuvers to outwit the enemy.