Quick answers
- Does John S. Mastroni accept Medicare assignment?
- Yes. Medicare's clinician data says John S. Mastroni accepts Medicare assignment (the Medicare-approved amount as full payment for covered services), as of October 2, 2026. Ask the office to confirm before your visit.
- How many Medicare patients does John S. Mastroni see?
- In 2024, CMS data shows 2,144 Original Medicare patients and 12,277 services for John S. Mastroni. This counts Original Medicare only and measures volume, not quality.
- What is John S. Mastroni's NPI number?
- 1568420008. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Medicare activity in 2024
Official CMS public-use data for John S. Mastroni, data year 2024 (released May 21, 2026). It covers Original Medicare (fee-for-service) patients only, not Medicare Advantage or other insurance. It shows volume, not quality or outcomes. CMS hides any count of 10 or fewer patients.
| Original Medicare patients | 2,144 |
|---|---|
| Services billed to Medicare | 12,277 |
| Different services or procedures | 42 |
| Participating Medicare provider | Yes |
| Average age of these patients | 76 |
Most frequent services
- Established patient office or other outpatient visit with low level od decision making, if using time, 20 minutes or more (99213)2,032 services
- Established patient office or other outpatient visit with moderate level of decision making, if using time, 30 minutes or more (99214)1,529 services
- Imaging of retina (92134)1,428 services
- Injection of drug into eye (67028)1,004 services
- Imaging of optic nerve (92133)852 services
Chronic conditions among these patients
Share of this clinician’s Original Medicare patients with each condition, as published by CMS (it describes the patients, not the care given).
- High blood pressure68%
- High cholesterol65%
- Arthritis39%
- Diabetes30%
- Chronic kidney disease20%
- Anxiety18%
Hospitals where John S. Mastroni works
Medicare's Facility Affiliation Data lists John S. Mastroni at these hospitals (updated October 2, 2026). Each hospital page shows its address, phone, emergency services, Medicare rating and all its clinicians. Star rating and emergency services: Hospital General Information (CMS), data updated October 26, 2026.
- Mad River Community HospitalArcata, CA · Acute Care Hospital · Medicare rating: 1 of 5 stars · Emergency services: listed by Medicare · CCN 050028
Practice locations
Addresses where John S. Mastroni is enrolled with Medicare (CMS data updated October 2, 2026).
- 2840 Oneil LnEureka, CA 95503 (707) 443‑9777
Specialties
- Ophthalmologyprimary
Other ophthalmologists in Eureka
Clinicians with the same Medicare primary specialty in Eureka, CA — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Medical school | Creighton University School Of Medicine |
| Graduation year | 1989 (37 years since medical school) |
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| NPI (National Provider Identifier) | 1568420008 |
| Corrections | Report an error or suggest an update → |
Most corrections must be made at the source: clinicians update their NPI Registry record (NPPES) and their Medicare enrollment (PECOS); this page follows the next data release.
Sources
- Facility Affiliation Data — Centers for Medicare & Medicaid Services (CMS), data updated October 2, 2026, retrieved October 29, 2026
- Hospital General Information — CMS, data updated October 26, 2026, retrieved November 13, 2026
- National Downloadable File (Doctors and Clinicians) — CMS, data updated October 2, 2026, retrieved October 29, 2026
- Medicare Physician & Other Practitioners - by Provider — CMS, data year 2024, released May 21, 2026; Medicare Physician & Other Practitioners - by Provider and Service
- NPI Registry — U.S. Department of Health and Human Services (NPPES), the clinician’s official record
- Medicare Care Compare — official Medicare tool to look up clinicians