William D. Mosier, MD
Ophthalmology Physician · Fullerton, CA
William D. Mosier, MD is an ophthalmology physician with a practice address in Fullerton, California, and NPI 1063553378, issued on Feb 9, 2007. Check the license (California A41428, as entered in NPPES) on the Medical Board of California; the Medicare figures below come from public CMS files.
- Name
- William D. Mosier
- Credential
- MD
- Primary taxonomy
- Ophthalmology Physician 207W00000X
- License number
- A41428 CA
Self-reported in NPPES; status is on the state search - Practice location
- 265 Laguna RD, Fullerton, CA 92835
- Phone
- (714) 871-2570
- Enumerated
- Feb 9, 2007
- Record last updated
- Apr 11, 2014 (not updated in 12 years: call before relying on the address or phone)
- Fax
- (714) 441-2020
- Medicaid ID
- 00A414280 CA
- Medicare enrollment
- Enrolled (PECOS I20081208000336); accepts Medicare assignment
- Medical or professional school
- University Of California, Irvine, California College Of Medicine, 1983
- Entity
- Type 1 · individual
8 nearest ophthalmology physician records → All 2,899 in California → Look up another NPI →
Also registered at 265 Laguna RD
A shared address usually means a shared clinic or building; it does not show who employs whom.
- Matthew NobeOphthalmology Physician1821313461
Verify William D. Mosier in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMedical Board of California
Search for license A41428Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
3.0 times the Medicare Part D claims of the average ophthalmology physician in 2024
4,503 Medicare Part D claims for 957 beneficiaries, against an average of 1,518 among the 16,459 providers of this specialty who prescribed in Part D. Brand-name drugs were 45% of claims.
Most prescribed
- Latanoprost1,589 claims
- Timolol Maleate632 claims
- Dorzolamide-Timolol615 claims
- Brimonidine Tartrate278 claims
- Lumigan254 claims
- Prednisolone Acetate224 claims
Source: CMS Medicare Part D Prescribers by Provider and Drug, 2024 (data.cms.gov). Part D covers prescriptions for Medicare patients only; drugs with fewer than 11 claims are not published.
The MIPS final score for 2023 (Medicare payment program): 100 of 100
The Merit-based Incentive Payment System score is reported for this clinician. Four categories are weighted into the final score; the average among 454,083 clinicians with a measured score was 83.5.
Source: CMS Quality Payment Program, MIPS performance year 2023; category weights for 2023 (qpp.cms.gov).
Industry payments in 2024: $917.37
50 payments; by number, the most common kind was food and beverage; the largest payer was Abbvie Inc. The 13,221 providers of this specialty with any payment received $4,535.02 on average. Payments are reported by manufacturers, not by the provider, and are not a sign of wrongdoing.
Source: CMS Open Payments, program year 2024 (openpaymentsdata.cms.gov); average among providers of this specialty with at least one payment.
Bills Medicare through one group practice
- William D Mosier MD Inc A Professional Medical CorporationFullerton, CA
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
William D. Mosier among 2,899 ophthalmology physician records in California
William D. Mosier, MD is one of 2,899 ophthalmology physician records with a practice address in California. 79% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2007, is newer than 55% of them.
- NPI issued2007 · 55% of these records are older, 33% newer
- In a Medicare fileYes · 79% of these records are
- In the CMS Doctors and Clinicians fileYes · 66% of these records are
- Graduated1983 · median 2001 among the 1,907 with a school on file
- Record last updated2014 · 67% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207W00000X and a California practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
Ophthalmology Physician providers in California
There are 2,899 ophthalmology physician records in California.
All 2,899 in California → Every provider in Fullerton → Ophthalmology Physician nationwide →
The 8 ophthalmology physician records with the nearest ZIP codes
- J Berbos, M.D.Fullerton, CA 928351467596114
- Matthew Kim, M.D.Fullerton, CA 928351770514465
- Omar Krad, M.D.Fullerton, CA 928351669635132
- Dagny Luong, MDFullerton, CA 928351790044626
- Matthew NobeFullerton, CA 928351821313461
- William Peloquin, M.D.Fullerton, CA 928351932261336
- Leslie Pham, MDFullerton, CA 928351568500411
- Lam Phung, MDFullerton, CA 928351992231682
Common questions
What is William D. Mosier, MD's NPI number?
William D. Mosier, MD's National Provider Identifier (NPI) is 1063553378, issued on Feb 9, 2007. An NPI identifies a provider in billing; it is not a license.
Where is William D. Mosier, MD located?
The NPPES record lists a practice address at 265 Laguna RD, Fullerton, CA, 92835. Phone: (714) 871-2570. Providers update this record themselves, so call before visiting.
How can I verify William D. Mosier, MD's license?
NPPES lists California license number A41428, as entered by the provider. Search the Medical Board of California at https://www.mbc.ca.gov/License-Verification/default.aspx. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.
How much does William D. Mosier, MD prescribe under Medicare Part D?
In 2024, William D. Mosier, MD had 4,503 Medicare Part D claims for 957 beneficiaries; the average among ophthalmology physician prescribers was 1,518. Part D covers Medicare prescriptions only.
What is William D. Mosier, MD's MIPS final score?
The 2023 MIPS final score is 100 of 100. The average among 454,083 clinicians with a measured score was 83.5.
Source: CMS National Plan and Provider Enumeration System (NPPES), file of Aug 9, 2026 (NPPES files on CMS.gov); NUCC Health Care Provider Taxonomy. Medicare files from data.cms.gov. An NPI identifies who bills; it is not a license.
Figures on PlainDoctor are read from the federal files each page names (CMS NPPES, Medicare Part D, MIPS, Open Payments; the HHS-OIG exclusion list only as counts) and from Census population estimates, with the file date shown beside them. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of Aug 9, 2026.