These days private ophthalmologist is treating patients as chicken,when patients come with diminition of vision with earlier cataract even if normal vision after refractive error correction, many ophthalmologist advise for surgery because it is easier to operate early immature cataract by phaco-emulsification &  you might visit other ophthalmologist next time so they  want to catch patient by any means, so visit some reputed institution to confirm whether he can carry with eyeglasses or he really needs surgery,with regards Dr Arjun kr Singh Patna

Hello I think your father should undergo retina examination. KINDLY share his vision also. If possible,share his medical records so that I may guide you better REGARDS

You should get thorough examination of the eyes. He may be having some retina problem which should be diagnosed and treated