Andrew Duong, MD
Andrew Duong, MD is an Ophthalmology Physician in San Rafael, CA, registered under NPI 1629711981. 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 901 E ST STE 285, San Rafael, CA 94901. 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 |
|---|---|---|
| A188370 | CA | Ophthalmology Physician primary |
This provider holds licence A188370 issued in CA. A licence number in NPPES reflects what was filed at registration — it does not confirm the licence is still active today.
- Status
- Approved
- Provider type
- Order And Referring Only - Ophthalmology
- PAC ID
- 0749665263
- Enrollment ID
- I20220920002896
Medicare enrolment is recorded as approved under the provider type Order And Referring Only - Ophthalmology. 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.
What Ophthalmology covers
An ophthalmologist has the knowledge and professional skills needed to provide comprehensive eye and vision care. Ophthalmologists are medically trained to diagnose, monitor and medically or surgically treat all ocular and visual disorders. This includes problems affecting the eye and its component structures, the eyelids, the orbit and the visual pathways. In so doing, an ophthalmologist prescribes vision services, including glasses and contact lenses. NUCC Health Care Provider Taxonomy, code 207W00000X
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 | 1629711981 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | Apr 15, 2022 |
| Last updated | Aug 5, 2026 |
| Status | Active |
| Sole proprietor | Yes |
| Gender | Male |
| Credential | MD |
| Practice address |
901 E ST STE 285 San Rafael, CA 94901 (415) 454-5565 |
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 | 6 | 2 | 9 | 7 | 1 | 1 | 9 | 8 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 6 | 4 | 9 | 5 | 1 | 2 | 9 | 7 |
Sum = 69 · next multiple of 10 = 70 · check digit = 1 · actual last digit = 1
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.