Provider records sourced from NPPES (CMS National Plan & Provider Enumeration System). Data current as of August 10, 2026.
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Errol Olwyn Grannum, MD

Individual provider Ophthalmology Physician · NPI 1508897935

Errol Olwyn Grannum, MD is an Ophthalmology in McAllen, Texas. Graduated from Yale University School of Medicine in 1989, 37 years ago. Practices with Alexander P. Sudarshan MD PA, a 7-clinician group and accepts Medicare assignment. Licensed in Texas.

Years since qualifying
37
Trained at
Yale University School of Medicine
Licensed in
TX
In the registry since
2006
What do these letters mean?
MD — Doctor of Medicine
A physician who completed allopathic medical school.

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Practice location Address checks out

1910 S 1st St
McAllen, TX 78503-1255
Phone: (956) 687-3937
Fax: (956) 687-3938
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Pin is approximate — placed at the ZIP-code centre, not the exact door.

Specialties & licences

Ophthalmology Physician (primary) Taxonomy 207W00000X · Licence K5972 (TX)

Record details

NPI number1508897935
Entity typeIndividual (Type 1)
GenderMale
Credentials MD
Sole proprietorYes
NPI enumeratedJuly 5, 2006
Last updated in NPPESJuly 8, 2007

Medicare enrollment

From the CMS Doctors & Clinicians file — this clinician is enrolled in Medicare.

Medicare specialtyOPHTHALMOLOGY
Medical schoolYALE UNIVERSITY SCHOOL OF MEDICINE
Graduated 1989 (37 years in practice)
Group practice Alexander P. Sudarshan Md Pa — 7 clinicians
Accepts Medicare assignment Yes — accepts the Medicare-approved amount
Practice locations2 on file with Medicare

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