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Edit this profileAt a glance
- 1910 S 1St St, Mcallen, TX 78503
About Dr. Grannum
Errol O. Grannum, MD is a healthcare provider in Mcallen, TX specializing in ophthalmology. Errol trained at Yale University School of Medicine, graduating in 1989. Medicare claims data shows Errol provided 1,546 services to 1,046 patients. The services billed most often include established patient problem focused exam of visual system, measurement of corneal pressure, and exam of visual field with extended testing. This provider record is associated with NPI 1508897935.
Factual summary compiled by Guide.md from public records; not written by this provider.
Education & Training
Specialty
Credentials & Licensing
Medicare information
Exactly as CMS reports it (National Downloadable File, Opt-Out Affidavits, Order & Referring). Not an insurance directory; confirm coverage with the office.
Contact Information
- (956) 687-3937
- Email not available
Is this your home address or personal number? Hide it
Practice Locations
1910 S 1ST ST
Mcallen, TX 78503
Conditions Commonly Evaluated or Treated
Within Ophthalmology generally. Availability varies by clinician, training and location — this profile has not been claimed, so nothing here is a personal claim by the provider.
Conditions
Eye injury and cancer
Inflammation, neurologic, and orbit
Most searched conditions
Cornea and external eye
Eyelid and tear drainage
Refractive and focusing
- Astigmatism
- Eye misalignment (strabismus)
- Farsightedness
- Lazy eye (amblyopia)
- Nearsightedness
- Presbyopia
Retina and vitreous
Eye injuries
Retina & vitreous
Procedures & services
Cataract and lens
- Cataract surgery with lens implant
- Laser-assisted cataract surgery
- Intraocular lens exchange
- YAG laser capsulotomy
Cornea and refractive
Emergency and minor
- Corneal rust-ring removal
- Removal of an eye foreign body
- Repair of an eye or eyelid laceration
- Repair of ruptured globe
Examination and imaging
- Eye ultrasound
- Slit-lamp examination
- Visual-field testing
- Corneal topography
- Fluorescein angiography
Eyelid, tear duct, and muscle
- Chalazion removal
- Ectropion repair
- Eyelid surgery
- Tear-duct probing
- Drooping-eyelid repair
- Entropion repair
- Eye-muscle surgery
- Tear-duct bypass surgery
Glaucoma
- Cyclophotocoagulation
- Trabeculectomy
- Glaucoma drainage-device implantation
- Laser peripheral iridotomy
- Minimally invasive glaucoma surgery
- Selective laser trabeculoplasty
Retina
Most searched procedures
Corneal procedures
Eye diagnostics
Eye injuries
Eyelid surgery
Laser eye surgery
Laser procedures
Laser vision correction
Refractive surgery
Tear duct & Orbit
Procedures Most Often Billed to Medicare
1,546 services · 1,046 patients · 12 distinct codes
| Procedure | Type | Code | Services | Compared with peers |
|---|---|---|---|---|
| Creation of eye fluid drainage tracts in iris using a laser, per session | Procedure | 66761 |
38 | More often than most peers in Ophthalmology |
| Laser repair to improve eye fluid flow | Procedure | 65855 |
30 | As often as other peers in Ophthalmology |
| Removal of eyelashes using forceps | Procedure | 67820 |
25 | As often as other peers in Ophthalmology |
| Ultrasound scan of cornea to determine thickness | Imaging | 76514 |
19 | Less often than most peers in Ophthalmology |
| Established patient problem focused exam of visual system | Treatment | 92012 |
610 | More often than most peers in Ophthalmology |
| Measurement of corneal pressure | Treatment | 92145 |
280 | More often than most peers in Ophthalmology |
| Exam of visual field with extended testing | Treatment | 92083 |
160 | More often than most peers in Ophthalmology |
| Exam of the internal drainage system of eye | Treatment | 92020 |
123 | More often than most peers in Ophthalmology |
| Imaging of optic nerve | Treatment | 92133 |
120 | As often as other peers in Ophthalmology |
| Photography of the retina | Treatment | 92250 |
60 | As often as other peers in Ophthalmology |
Source: CMS Medicare public data. Shows how often procedures were billed — not quality of care or patient satisfaction.
Related providers
Connections drawn from the registry and from what providers have told us. A link here is not a referral or an endorsement.
Other eye doctors at this location 1
Same specialty, same street address — most likely the same department or group.
Also at this address 4
Providers at the same street address. Each files their own registry entry, so a shared practice often appears under several different names.
Other eye doctors in Mcallen 8
Same specialty, same city.
More connections — 24 related providers in 3 groups
Trained at Yale University School of Medicine 8
Other providers in the same specialty who trained at the same institution.
Class of 1989 at Yale University School of Medicine 8
Providers who graduated from the same medical school in the same year.
Also performs Creation of eye fluid drainage tracts in iris using a laser, per session 8
Providers in TX who bill this service to Medicare most often.
Common questions
What does Dr. Grannum specialize in?
Dr. Grannum is an eye doctor in Mcallen, TX. That is the designation recorded for this NPI in the federal registry, where it is listed as “Ophthalmology”.
NPI registry
Where is Dr. Grannum located?
Dr. Grannum is listed at 1910 S 1St St, Mcallen, TX 78503. Addresses come from the NPI registry and can lag a move, so confirm before travelling.
NPI registry
What is Dr. Grannum's phone number?
The number on file is (956) 687-3937. Contact the office directly to confirm availability and scheduling.
NPI registry
What is the NPI for Dr. Grannum?
Dr. Grannum's National Provider Identifier is 1508897935. It is issued by the Centers for Medicare & Medicaid Services and is unique and permanent — it does not change if they move practice.
NPI registry
Where did Dr. Grannum go to medical school?
Dr. Grannum attended Yale University School of Medicine, graduating in 1989. This comes from the CMS National Downloadable File.
CMS public data
How much experience does Dr. Grannum have?
Dr. Grannum has 37 years experience. Calculated from a graduation year of 1989, reported in the CMS National Downloadable File.
CMS public data
What does Dr. Grannum do most often?
According to Medicare billing data, Dr. Grannum performs procedures including creation of eye fluid drainage tracts in iris using a laser, per session, laser repair to improve eye fluid flow and removal of eyelashes using forceps; reads or performs imaging such as ultrasound scan of cornea to determine thickness; provides treatments such as established patient problem focused exam of visual system and measurement of corneal pressure, alongside routine visits and testing. This reflects Medicare patients only and is billing volume, not a measure of quality.
Medicare claims
Is Dr. Grannum's profile verified?
Not yet. This profile is built from public federal data and has not been confirmed by Dr. Grannum. If this is you, claiming it is free.
Guide.md
Guide.md listings do not constitute medical advice or an endorsement.