Gregory Tesluk, MD
Gregory Tesluk, MD is an Ophthalmology Physician in Modesto, CA, registered under NPI 1255351755. This provider registers 2 separate taxonomy codes, which usually means they practise across more than one recognised specialty. 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 400 E ORANGEBURG AVE STE 2, Modesto, CA 95350. 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 |
|---|---|---|
| C41824 | CA | Ophthalmic Technician/Technologist |
| C418240 | CA | Ophthalmology Physician primary |
This provider holds licence C41824 issued in CA. A licence number in NPPES reflects what was filed at registration — it does not confirm the licence is still active today.
This NPI does not appear in the PECOS Medicare enrolment file. Providers who do not bill Medicare — or who bill only through a group's enrolment — will not appear here. It is not a sign of any problem with the registration.
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
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 | |
|---|---|---|---|---|
| 156FX1100X | Ophthalmic Technician/Technologist Ophthalmic | C41824 | CA | |
| 207W00000X | Ophthalmology Physician | C418240 | CA | primary |
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 | 1255351755 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | Jul 20, 2006 |
| Last updated | Sep 11, 2025 |
| Status | Active |
| Sole proprietor | Yes |
| Gender | Male |
| Credential | MD |
| Practice address |
400 E ORANGEBURG AVE STE 2 Modesto, CA 95350 (209) 526-3000 Fax (209) 526-3133 |
| Mailing address |
3424 WYCLIFFE DR Modesto, CA 95355 |
| Other identifiers |
00C418240
· Medicaid (CA) |
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 | 2 | 5 | 5 | 3 | 5 | 1 | 7 | 5 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 2 | 1 | 5 | 6 | 5 | 2 | 7 | 1 |
Sum = 55 · next multiple of 10 = 60 · check digit = 5 · actual last digit = 5
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.