Margaret Greven, M.D.
NPI 1821380874 · Ophthalmology Physician · Winston Salem, NC
Enrolled with Medicare as Practitioner - Ophthalmology · source: CMS PECOS Public Provider Enrollment (2026.04.01)
Margaret Greven, M.D. is a Ophthalmology Physician provider in Winston Salem, NC (NPI 1821380874).
Provider details
- NPI number
- 1821380874
- Entity type
- Individual
- Primary specialty
- Ophthalmology PhysicianAllopathic & Osteopathic Physicians
- Credential
- M.D.
- Sex
- Female
- Sole proprietor
- No
- License
- 2017-01126 (NC)
Specialties & taxonomies
Allopathic & Osteopathic Physicians
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure25% of score
15 yrs in NPPES registry
- Profile completeness25% of score
100% of core fields populated
- Practice footprint15% of score
1 documented practice location
- Medicare service volume (vs. specialty peers)25% of score
2,478 Medicare services, 2024 (ranked within specialty)
- Open Payments transparency10% of score
Has Open Payments disclosures (2024)
Medicare volume is ranked against active providers in the same specialty. 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 .
What this provider does (Medicare)
Based on Medicare fee-for-service claims, 2024; not all care is captured.
| Service (HCPCS) | Medicare services | Typical Medicare-allowed (2024) |
|---|---|---|
| Imaging of Retina92134 | 941 | $23 |
| Injection of Drug Into Eye67028 | 573 | $95 |
| Established Patient Office Or Other Outpatient Visit With Low Level OD Decision Making, If Using Time, 20 Minutes Or More99213 | 415 | $61 |
| Imaging of Retina92134 | 214 | $38 |
| Injection of Drug Into Eye67028 | 158 | $116 |
| Established Patient Office Or Other Outpatient Visit With Low Level OD Decision Making, If Using Time, 20 Minutes Or More99213 | 81 | $85 |
What this provider prescribes (Medicare Part D)
Top drugs by Medicare Part D claim volume, 2024 · 11 distinct drugs on file.
| Drug | Part D claims (2024) | Beneficiaries |
|---|---|---|
| Prednisolone Acetate | 110 | 70 |
| Latanoprost | 43 | 18 |
| Dorzolamide Hcl/Timolol Maleatbrand: Dorzolamide-Timolol | 34 | 16 |
| Brimonidine Tartrate | 24 | — |
| Timolol Maleate | 21 | 14 |
| Ketorolac Tromethamine | 17 | — |
| Cyclosporinebrand: Restasis | 16 | — |
Transparency — industry payments
Based on CMS Open Payments, 2024; not all care is captured.
$438 across 3 records (Open Payments 2024)
Open Payments discloses payments and transfers of value (meals, travel, consulting, research, royalties) from drug and device makers to providers. This is a transparency signal, not a verdict — such payments are legal and common, and their presence is neither an endorsement nor a criticism. Source: CMS Open Payments, program year 2024.
Practice location
Mailing address
Registry dates
- Enumerated
- 2011-05-10
- Last updated
- 2022-07-21
Frequently asked questions
- What is Margaret Greven's NPI number?
- Margaret Greven's National Provider Identifier (NPI) is 1821380874, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is Margaret Greven's specialty?
- Margaret Greven is listed in the NPPES registry with a primary specialty of Ophthalmology Physician (Allopathic & Osteopathic Physicians).
- Where is Margaret Greven located?
- Margaret Greven's practice location on file with NPPES is Medical Center Blvd Dept of Ophthalmology, Winston Salem, NC 27157-3216.
- What is Margaret Greven's phone number?
- The practice phone number listed in the NPPES registry for Margaret Greven is (336) 716-4091.
- Does Margaret Greven accept Medicare?
- Margaret Greven is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is Margaret Greven's NPI active?
- Yes — Margaret Greven's NPI (1821380874) is active in the NPPES registry as of the last update on 2022-07-21.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.