'optometrical' ultimately originates from Greek, specifically from the elements 'optos' meaning 'seen' or 'eye' and 'metron' meaning 'measure', via New Latin/modern English formations such as 'optometry'.

'optometrical' developed from New Latin/modern English 'optometry' (19th century), itself formed from Greek roots 'optos' + 'metron'; the adjective arose by adding the English adjectival suffix '-ical' to the noun form.

Initially associated with the idea of 'measuring the eye' ('measuring sight'), it evolved into the adjectival sense 'relating to the profession or practice of examining eyes and correcting vision'.