Mark Barsamian, DO
Mark Barsamian, DO is a Retina Specialist (Ophthalmology) Physician in Hopedale, MA, registered under NPI 1821204207. NPPES records them as a sole proprietor, meaning the practice is not incorporated as a separate legal entity.
Getting there
The practice address on file is 54 HOPEDALE ST STE 1, Hopedale, MA 01747. 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 |
|---|---|---|
| 243559 | MA | Retina Specialist (Ophthalmology)… primary |
| DO00851 | RI | Retina Specialist (Ophthalmology)… |
Licences are recorded in 2 states: MA, RI. 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
- 3375638265
Enrolled in Medicare 2 times, across 2 states:
| State | Enrollment ID | Provider type |
|---|---|---|
| Massachusetts | I20100712000006 | Practitioner - Ophthalmology |
| Rhode Island | I20170310000448 | Practitioner - Ophthalmology |
Medicare enrolment is recorded as approved under the provider type Practitioner - Ophthalmology. There are 2 separate enrolment records across 2 states (MA, RI). Multiple enrolments usually mean the provider bills Medicare from more than one practice location, or has kept an earlier enrolment after moving. Each record carries its own enrolment ID, listed above. Being enrolled means the provider can bill Medicare; 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: Massachusetts and Rhode Island. The practice address on file is in Hopedale, MA, 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
- 243559
- Specialty
- Retina Specialist (Ophthalmology)…
- Licence
- DO00851
- Specialty
- Retina 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 Retina Specialist covers
An ophthalmologist who specializes in the diagnosis and treatment of vitreoretinal diseases. NUCC Health Care Provider Taxonomy, code 207WX0107X
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 | |
|---|---|---|---|---|
| 207WX0107X | Retina Specialist (Ophthalmology) Physician Retina Specialist | 243559 | MA | primary |
| 207WX0107X | Retina Specialist (Ophthalmology) Physician Retina Specialist | DO00851 | RI |
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 | 1821204207 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | May 15, 2007 |
| Last updated | Jan 29, 2026 |
| Status | Active |
| Sole proprietor | Yes |
| Credential | DO |
| Practice address |
54 HOPEDALE ST STE 1 Hopedale, MA 01747 (774) 396-6905 Fax (810) 202-7533 |
| Mailing address |
8 NOTTINGHAM RD Westborough, MA 01581 |
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 | 2 | 1 | 2 | 0 | 4 | 2 | 0 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 8 | 4 | 1 | 4 | 0 | 8 | 2 | 0 |
Sum = 53 · next multiple of 10 = 60 · check digit = 7 · actual last digit = 7
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.