Quick answers
- Does Walter F. Nieves accept Medicare assignment?
- Yes. Medicare's clinician data says Walter F. Nieves 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 Walter F. Nieves see?
- In 2024, CMS data shows 24 Original Medicare patients and 70 services for Walter F. Nieves. This counts Original Medicare only and measures volume, not quality.
- What is Walter F. Nieves's NPI number?
- 1225007453. 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 Walter F. Nieves, 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 | 24 |
|---|---|
| Services billed to Medicare | 70 |
| Different services or procedures | 16 |
| Participating Medicare provider | Yes |
| Average age of these patients | 75 |
Most frequent services
- Established patient problem focused exam of visual system (92012)25 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 cholesterol75%
- High blood pressure67%
- Diabetes54%
Practice locations
Addresses where Walter F. Nieves is enrolled with Medicare (CMS data updated October 2, 2026).
- 3285 Ave MilitarIsabela, PR 00662 (787) 830‑5784
Specialties
- Ophthalmologyprimary
Other ophthalmologists in Puerto Rico
Clinicians with the same Medicare primary specialty in Puerto Rico — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Medical school | University Of Puerto Rico School Of Medicine |
| Graduation year | 1994 (32 years since medical school) |
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| NPI (National Provider Identifier) | 1225007453 |
| 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
- 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