John S. Mastroni, MD
Ophthalmology Physician · Eureka, CA
John S. Mastroni, MD is an ophthalmology physician with a practice address in Eureka, California, and NPI 1568420008, issued on May 3, 2006. Check the license (California G76915, as entered in NPPES) on the Medical Board of California; the Medicare figures below come from public CMS files.
- Name
- John S. Mastroni
- Credential
- MD
- Primary taxonomy
- Ophthalmology Physician 207W00000X
- License number
- G76915 CA
Self-reported in NPPES; status is on the state search - Practice location
- 2840 Oneil Lane, Eureka, CA 95503
- Phone
- (707) 443-9777
- Enumerated
- May 3, 2006
- Record last updated
- Jul 13, 2026
- Fax
- (707) 445-1003
- Medicaid ID
- 00G769150 CA
- Medicare enrollment
- Enrolled (PECOS I20090909000181); accepts Medicare assignment
- Medical or professional school
- Creighton University School Of Medicine, 1989
- Entity
- Type 1 · individual
8 nearest ophthalmology physician records → All 2,899 in California → Look up another NPI →
Also registered at 2840 Oneil Lane
A shared address usually means a shared clinic or building; it does not show who employs whom.
- Gregory Gibb, MDOphthalmology Physician1467410829
Verify John S. Mastroni in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMedical Board of California
Search for license G76915Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
3.7 times the Medicare Part D claims of the average ophthalmology physician in 2024
5,628 Medicare Part D claims for 840 beneficiaries, against an average of 1,518 among the 16,459 providers of this specialty who prescribed in Part D. Brand-name drugs were 39% of claims.
Most prescribed
- Latanoprost1,752 claims
- Brimonidine Tartrate619 claims
- Timolol Maleate515 claims
- Dorzolamide-Timolol475 claims
- Dorzolamide Hcl398 claims
- Lumigan300 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.
John S. Mastroni among 2,899 ophthalmology physician records in California
John S. Mastroni, 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 2006, is newer than 9% of them.
- NPI issued2006 · 9% of these records are older, 45% newer
- In a Medicare fileYes · 79% of these records are
- In the CMS Doctors and Clinicians fileYes · 66% of these records are
- Graduated1989 · median 2001 among the 1,907 with a school on file
- Record last updated2026 · 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 Eureka → Ophthalmology Physician nationwide →
The 8 ophthalmology physician records with the nearest ZIP codes
- Gregory Gibb, MDEureka, CA 955031467410829
- Christopher Lin, MD, FACSEureka, CA 955031811982291
- Angus Stewart, M.D.Eureka, CA 955031497084933
- Louise Minor, PHD, MDEureka, CA 955011740289081
- Michael Mizoguchi, M.D.Eureka, CA 955011861418808
- Stephen Tanaka, M.D.Union City, CA 954871790863553
- David Davis, MDArcata, CA 955211588682918
- Erik Jansson, MDArcata, CA 955211659338788
Common questions
What is John S. Mastroni, MD's NPI number?
John S. Mastroni, MD's National Provider Identifier (NPI) is 1568420008, issued on May 3, 2006. An NPI identifies a provider in billing; it is not a license.
Where is John S. Mastroni, MD located?
The NPPES record lists a practice address at 2840 Oneil Lane, Eureka, CA, 95503. Phone: (707) 443-9777. Providers update this record themselves, so call before visiting.
How can I verify John S. Mastroni, MD's license?
NPPES lists California license number G76915, 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 John S. Mastroni, MD prescribe under Medicare Part D?
In 2024, John S. Mastroni, MD had 5,628 Medicare Part D claims for 840 beneficiaries; the average among ophthalmology physician prescribers was 1,518. Part D covers Medicare prescriptions only.
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.