Complex sentence: Trifocals, patented in 1827 by John Isaac Hawkins, are eyeglasses where the lenses have 3 regions to correct for distance, intermediate (arm's length), and near vision.
Split into simpler sentences: Trifocals, patented in 1827 by John Isaac Hawkins, are eyeglasses where the lenses have 3 regions to correct. These regions are distance, intermediate (arm's length), and near vision.