Mark Larson, MD
Mark Larson, MD is a Glaucoma Specialist (Ophthalmology) Physician in Greenfield, WI, registered under NPI 1831651868. This provider registers 2 separate taxonomy codes, which usually means they practise across more than one recognised specialty.
Getting there
The practice address on file is 4600 W LOOMIS RD STE 310, Greenfield, WI 53220. We have not yet mapped what surrounds this office — parking, transit, and nearby pharmacies are added as our data collection reaches each location.
Credentials and Medicare
| Licence | State | Specialty |
|---|---|---|
| 84144-20 | WI | Glaucoma Specialist (Ophthalmology)… primary |
| 73841 | MN | Ophthalmology Physician |
Licences are recorded in 2 states: WI, MN. Providers licensed in several states often practise near a state border or deliver telehealth across state lines.
- Status
- Approved
- Provider type
- Practitioner - Ophthalmology
- PAC ID
- 4082037999
Medicare enrolment is recorded as approved under the provider type Practitioner - Ophthalmology. This means the provider is enrolled to bill Medicare, though it does not tell you whether they are currently accepting new Medicare patients. Call the office to confirm.
Licensed in 2 states
This provider holds licences in 2 states: Minnesota and Wisconsin. The practice address on file is in Greenfield, WI, but a licence in another state usually means they see patients there too — either at a second location or by telehealth. If the address above is far from you, it is worth calling to ask whether they practise closer to where you live.
- Licence
- 84144-20
- Specialty
- Glaucoma Specialist (Ophthalmology)…
Licence numbers are self-reported to NPPES at registration. They do not confirm a licence is currently active, in good standing, or valid for the specialty shown — only the state board can tell you that, which is why we link to each one.
What Glaucoma Specialist covers
An ophthalmologist who specializes in the treatment of glaucoma and other disorders related to increased intraocular pressure and optic nerve damage. This specialty involves the medical and surgical treatment of these conditions. NUCC Health Care Provider Taxonomy, code 207WX0009X
All registered taxonomy codes
This provider registers 2 taxonomy codes. The primary code is what appears on most claims; the others record additional recognised specialties.
| Code | Specialty | Licence | State | |
|---|---|---|---|---|
| 207WX0009X | Glaucoma Specialist (Ophthalmology) Physician Glaucoma Specialist | 84144-20 | WI | primary |
| 207W00000X | Ophthalmology Physician | 73841 | MN |
The taxonomy records how the provider classifies their own practice. It does not confirm which conditions they currently treat, whether they are accepting new patients, or which insurance they take — call the office for that.
Full NPPES record
An NPI-1 identifies a single person. It stays with the clinician for life, even if they move practice or change state, which is why the address on file can lag behind where they actually work today.
| NPI | 1831651868 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | Mar 31, 2019 |
| Last updated | Sep 10, 2024 |
| Status | Active |
| Sole proprietor | No |
| Credential | MD |
| Practice address |
4600 W LOOMIS RD STE 310 Greenfield, WI 53220 (414) 281-0424 Fax (414) 281-0959 |
Number check
How the check works, step by step
Every NPI carries a Luhn check digit — the same scheme used on credit cards. CMS prefixes the number with 80840 before computing it, which marks it as a US health identifier.
| Digit | 8 | 0 | 8 | 4 | 0 | 1 | 8 | 3 | 1 | 6 | 5 | 1 | 8 | 6 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 8 | 6 | 1 | 3 | 5 | 2 | 8 | 3 |
Sum = 62 · next multiple of 10 = 70 · check digit = 8 · actual last digit = 8
A valid check digit only means the number is well-formed. It does not mean the provider is licensed, active, or in good standing — those are separate questions answered by the sections above.