Quick answers
- Where does Martin Williamson see patients?
- Medicare's clinician data lists 2 practice locations, including Decorah, IA and Pr Du Chien, WI. Call before your visit to confirm the address.
- What is Martin Williamson's specialty?
- Medicare lists Optometry as the primary specialty.
- Does Martin Williamson accept Medicare assignment?
- Yes. Medicare's clinician data says Martin Williamson accepts Medicare assignment (the Medicare-approved amount as full payment for covered services), as of 2026-10-02. Ask the office to confirm before your visit.
- What is the phone number for Martin Williamson?
- (563) 382-3140, as listed in official Medicare / NPI Registry data.
- What is Martin Williamson's NPI number?
- 1740778646. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Practice locations
Addresses where Martin Williamson is enrolled with Medicare (CMS data updated 2026-10-02).
- 1830 State Hwy 9Decorah, IA 52101 (563) 382‑3140
- 610 E Taylor StPr Du Chien, WI 53821 (608) 326‑6466
Group practices
Medicare enrollment lists Martin Williamson as a member of this group (CMS data updated 2026-10-02).
- Gundersen Clinic Ltd418 clinicians in the group
Specialties
- Optometryprimary
Other optometrists in Decorah
Clinicians with the same Medicare primary specialty in Decorah, IA — not a recommendation.
Clinician information
| Graduation year | 2018 |
|---|---|
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| NPI (National Provider Identifier) | 1740778646 |
| Corrections | Report an error or suggest an update → |
Most corrections must be made at the source: clinicians update their NPI Registry record (NPPES) and their Medicare enrollment (PECOS); this page follows the next data release.
Sources
- National Downloadable File (Doctors and Clinicians) — CMS, data updated 2026-10-02, retrieved 2026-10-29
- NPI Registry — U.S. Department of Health and Human Services (NPPES), the clinician’s official record
- Medicare Care Compare — official Medicare tool to look up clinicians