The front neck shaping is worked with decreases and increases (see photo below and page 2 of pattern). Sweater has optional crochet edging around neck, cuffs and hem. This sweater is a wardrobe staple worth having in more than one color, and it is a fast knit! (from pattern description) Also available on Craftsy.
However, ptosis of the upper eyelid can be a symptom of several health conditions, including diabetes, diseases of the nervous system such as myasthenia gravis, or damage to the third cranial nerve that controls the eyelids. Myasthenia gravis is a serious autoimmune neuromuscular disease that results in nerve weakness.
I am sorry to hear that your left eyelid seems to be drooping, and that it is bothering you. Ptosis (the medical term for drooping of the eyelid) can be caused by many different things. Some of them serious, some of them benign.