Errol Grannum, MD
NPI 1508897935 · Ophthalmology Physician · Mcallen, TX
Enrolled with Medicare as Practitioner - Ophthalmology · source: CMS PECOS Public Provider Enrollment (2026.04.01)
Errol Grannum, MD is a Ophthalmology Physician provider in Mcallen, TX (NPI 1508897935).
Provider details
- NPI number
- 1508897935
- Entity type
- Individual
- Primary specialty
- Ophthalmology PhysicianAllopathic & Osteopathic Physicians
- Credential
- MD
- Sex
- Male
- Sole proprietor
- Yes
- License
- K5972 (TX)
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
19 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
1,546 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) |
|---|---|---|
| Established Patient Problem Focused Exam of Visual System92012 | 610 | $79 |
| Measurement of Corneal Pressure92145 | 280 | $11 |
| Exam of Visual Field With Extended Testing92083 | 160 | $56 |
| Exam of the Internal Drainage System of Eye92020 | 123 | $24 |
| Imaging of Optic Nerve92133 | 120 | $30 |
| New Patient Office Or Other Outpatient Visit With Moderate Level of Medical Decision Making, If Using Time, 45 Minutes Or More99204 | 69 | $150 |
| Photography of the Retina |
What this provider prescribes (Medicare Part D)
Top drugs by Medicare Part D claim volume, 2024 · 33 distinct drugs on file.
| Drug | Part D claims (2024) | Beneficiaries |
|---|---|---|
| Latanoprost | 2,675 | 566 |
| Brimonidine Tartrate | 805 | 213 |
| Erythromycin Basebrand: Erythromycin | 706 | 326 |
| Brimonidine Tartrate/Timololbrand: Brimonidine Tartrate-Timolol | 626 | 187 |
| Timolol Maleate | 600 | 155 |
| Dorzolamide Hcl/Timolol Maleatbrand: Dorzolamide-Timolol | 569 | 146 |
| Dorzolamide Hcl | 382 | 100 |
Transparency — industry payments
Based on CMS Open Payments, 2024; not all care is captured.
$475 across 23 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
- 2006-07-05
- Last updated
- 2007-07-08
Frequently asked questions
- What is Errol Grannum's NPI number?
- Errol Grannum's National Provider Identifier (NPI) is 1508897935, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is Errol Grannum's specialty?
- Errol Grannum is listed in the NPPES registry with a primary specialty of Ophthalmology Physician (Allopathic & Osteopathic Physicians).
- Where is Errol Grannum located?
- Errol Grannum's practice location on file with NPPES is 1910 S 1st St, Mcallen, TX 78503-1255.
- What is Errol Grannum's phone number?
- The practice phone number listed in the NPPES registry for Errol Grannum is (956) 687-3937.
- Does Errol Grannum accept Medicare?
- Errol Grannum is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is Errol Grannum's NPI active?
- Yes — Errol Grannum's NPI (1508897935) is active in the NPPES registry as of the last update on 2007-07-08.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.