Apex domains cannot have CNAME records.
Question and response
Question
dig medicalvillageoptical.com. NS
Answer
medicalvillageoptical.com. 5 NS ns-1812.awsdns-34.co.uk.
medicalvillageoptical.com. 5 NS ns-1748.awsdns-26.co.uk.
medicalvillageoptical.com. 5 NS ns-145.awsdns-18.com.
medicalvillageoptical.com. 5 NS ns-235.awsdns-29.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0