A. The Talmud (Brochos 13b) relates that Rebi Yehuda Hanossi would place his hand over his eyes when reciting the first pasuk of the shema. Rosh (ibid.) and Shulchan Aruch (O.H. 51: 5) explain that the reason is to avoid being disturbed by what one sees and to maintain concentration on the shema.

Kaf Hachaim (ibid. 22) maintains that there is no fault in just closing one’s eyes, although many disagree.

Od Yosef Chai (Vaero) writes that the tradition is that at night one closes his eyes with the right hand, while in the morning, one covers his head and upper face with the talis and then he places his right hand over the talis covering his eyes with both. He notes that although the Arizal omitted the above, it is the accepted tradition to do it. See similar in Divrei Benayahu (O.H. 4: 2).

Meor Yisroel (Brrchos 15b) quotes a minhag to cover ones eyes with both hands, placing them in a specific way that creates the name Shakai.

Horav Shlomo Miller’s Shlit’a opinion is that one should follow the minhag of the community where he davens.