Eyesight can be corrected either with glasses or with things like laser eye surgery. It's changing the focus so light hits the back of your eye without being distorted.
Hearing cannot be corrected or repaired; hearing loss is degenerative and will only get worse. Hearing aids amplify frequencies that the inner ear can't perceive at lower amplitudes, so that the wearer can hear the sound. It's not the same as correcting vision as it's replacing an absence of perception rather than adjusting a distortion.
As has been mentioned above, there are also complicating factors like tinnitus (the brain "making up" sounds where it thinks they are missing, because of the hearing loss) which affect what people can hear.
Gradual reduction in hearing perception over time is natural, as is decline in visual accuity. But not hearing loss.
That's why, I'd suggest, hearing loss beyond a certain point is considered an impairment, just like some vision impairments that cannot be corrected.