I have some experience working in a pharmacy, and as someone who is low-vision, I'll admit there are challenges sometimes, but they're not insurmountable. If it would help, show your mom this post.
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I'm legally blind, and while my reading vision is okay, I basically have severe tunnel vision that makes finding things on counters difficult, especially if it gets moved or if it's small. That being said, I get by just fine with a few extra tools like a magnifying glass, a larger screen for the computer I use, and a tray like you might find at a cafeteria to keep pills from rolling away if one tries to escape.
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If you're counting pills to fill prescription bottles, you should know that some pills are going to be super tiny. For instance, I was on one cholesterol med for a while where each pill was like the size of a single grain of rice. If it would help, see if your employer would be willing to provide or let you bring in a large magnifier with a light to help with tiny pills like that. This can be compounded by having to wear rubber gloves which can reduce your tactile feedback a bit, but it isn't an insurmountable obstacle.
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As for other stuff like reading labels or using the computer to process prescriptions, I'm fairly certain that's something you could do with the right combination of assistive tech suited for your vision. Whether it's one of those cameras hooked up to a TTS program so you can snap a pic of the bottle and have it read to you, or just a CCTV magnifier or whatever works best for your particular eyesight problem.
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One of the things my pharmacy does is pill boxes for nursing homes, where you have to prepare a week's worth of meds for a patient according to the instructions on their pill bottles. When a worker, sight-impaired or not, finishes a box, it has to be inspected by a pharmacist to give the okay, so if you wind up with a similar arrangement, you can tailor your tasks to your capabilities.
Based on my experience, if you can count to ninety, are capable of asking for accommodations when you need them, and are willing to do what it takes to become a certified pharm tech, go for it. So long as they don't expect you to be the one driving to make deliveries to nursing homes or whatever, I think you'll do fine enough. But it's also important to recognize when mistakes happen, and talk with your coworkers to see if you need more or different accommodations or if it was just a flub like sighted people make sometimes when they're tired or stressed or distracted by hearing that one coworker's story about how their cat threw up in the ficus again.
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Best of luck, OP!