Type 2 · Organization ✓ Active NPI ✓ Valid NPI checksum

M. Patrick Day, Od, A Professional Corporation

Optometrist in Clinton, OK · enumerated 2008 · authorized official Marshall Day, Co-Owner/Optometrist.

Data current as of Jul 13, 2026 · sourced from CMS NPPES

National Provider Identifier

1902083280

Verified

See something wrong? Report a correction

Registry record

Entity type Organization (Type 2)

Legal business name M. Patrick Day, Od, A Professional Corporation

Other name <Unavail>

Practice address 565 S 30th St, Clinton, OK, 73601

Phone (580) 323-5421

Fax (866) 585-2957

Enumeration date Jan 29, 2008

Last updated in NPPES Sep 27, 2023

Taxonomy & classification

152W00000X Optometrist Eye and Vision Services Providers · License 918 (OK) Primary

332H00000X Eyewear Supplier Suppliers Secondary

Authorized official

Name Marshall Day

Title Co-Owner/Optometrist

Phone (580) 323-5421

What is an NPI number?

A National Provider Identifier (NPI) is a unique 10-digit number that CMS assigns to every U.S. healthcare provider and organization under HIPAA. Type 1 NPIs identify individual providers; Type 2 NPIs identify organizations. The NPI appears on insurance claims, prescriptions, and credentialing paperwork, and never changes, even if the provider moves or changes specialty.

Read the full guide → Validate an NPI →

Frequently asked questions

What is a Type 2 NPI?

A Type 2 NPI identifies an organization (group practice, hospital, pharmacy, lab), while Type 1 NPIs identify individual providers. Organizations bill under their Type 2 NPI.

What type of organization is M. Patrick Day, Od, A Professional Corporation?

M. Patrick Day, Od, A Professional Corporation is registered in NPPES as a Optometrist (its primary provider taxonomy).

Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2023-09-27.