William Sierra, M.D.
NPI 1275552796 · Ophthalmology Physician · Los Angeles, CA
Enrolled with Medicare as Practitioner - Ophthalmology · source: CMS PECOS Public Provider Enrollment (2026.04.01)
William Sierra, M.D. is a Ophthalmology Physician provider in Los Angeles, CA (NPI 1275552796).
Provider details
- NPI number
- 1275552796
- Entity type
- Individual
- Primary specialty
- Ophthalmology PhysicianAllopathic & Osteopathic Physicians
- Credential
- M.D.
- Sex
- Male
- Sole proprietor
- No
- License
- G32593 (CA)
Specialties & taxonomies
Allopathic & Osteopathic Physicians
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure38% of score
19 yrs in NPPES registry
- Profile completeness38% of score
100% of core fields populated
- Practice footprint23% of score
1 documented practice location
Signals a provider has no public data for (e.g. Medicare claims) are left out of the score entirely — never counted as zero — so providers without that data are not penalized. See the full formula and weights in our methodology.
Practice location
Mailing address
Registry dates
- Enumerated
- 2006-07-18
- Last updated
- 2016-08-23
Frequently asked questions
- What is William Sierra's NPI number?
- William Sierra's National Provider Identifier (NPI) is 1275552796, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is William Sierra's specialty?
- William Sierra is listed in the NPPES registry with a primary specialty of Ophthalmology Physician (Allopathic & Osteopathic Physicians).
- Where is William Sierra located?
- William Sierra's practice location on file with NPPES is 4754 E Cesar E Chavez Ave, Los Angeles, CA 90022-1234.
- What is William Sierra's phone number?
- The practice phone number listed in the NPPES registry for William Sierra is (323) 909-0041.
- Does William Sierra accept Medicare?
- William Sierra is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is William Sierra's NPI active?
- Yes — William Sierra's NPI (1275552796) is active in the NPPES registry as of the last update on 2016-08-23.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.