According to the Manitoba Association of Optometrists, and under PHIA, your request for your prescription must be made in writing. I would suggest that if you haven't requested it in writing, you do that first.
"Access to Personal Health Records
Manitoba's Personal Health Information Act provides that patients have a right to examine and receive a copy of their personal health information kept by their optometrist. The original copy of the records must be retained by the optometry practice, but a copy can be made for you if you wish.
To examine and receive a copy of your records, the request must be made in writing, must be signed by you, and must include your name, address and Personal Health I.D. No. If you wish to authorize another person to examine and receive a copy of your records, this should be included in your signed request.
The Personal Health Information Act also provides that a reasonable fee can be charged for providing this information."
(from
https://www.optometrists.mb.ca/patients/eye-exams )