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Edit this profileAt a glance
- 33 Riddell St, Greenfield, MA 01301
About Dr. Warren
Based in Greenfield, MA, John F. Warren, MD is listed in the NPI registry under ophthalmology. John graduated from Stanford University School of Medicine in 1997. According to Medicare claims data, John cared for 2,714 Medicare patients across 3,913 services. The services billed most often include measurement of corneal curvature and depth of eye, removal of cataract with insertion of prosthetic lens, and imaging of retina. NPI 1386634400 identifies this record in the national registry.
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
- (413) 774-7016
- Email not available
Practice Locations
33 RIDDELL ST
Greenfield, MA 01301
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
- Chemical injury to the eye
- Foreign body in the eye
- Hyphema
- Open-globe eye injury
Inflammation, neurologic, and orbit
- Optic neuritis
- Optic neuropathy
- Orbital cellulitis
- Thyroid eye disease
- Uveitis
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
- Epiretinal membrane
- Retinal detachment
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
- Endothelial corneal transplant
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
- Macular hole surgery
- Pneumatic retinopexy
- Retinal laser treatment
- Scleral buckle surgery
- Vitrectomy
Most searched procedures
- Cataract surgery
- Eye exam
- LASIK
- Retina surgery
Corneal procedures
- Amniotic Membrane Eye Graft
Eye diagnostics
Eye injuries
- Eye Scratch Laceration Repair
- Foreign Object Removal from Eye
Eyelid surgery
Laser eye surgery
- Laser Floater Removal
Laser procedures
- Laser Treatment for Retinal Tear
Laser vision correction
- SMILE Eye Surgery
Refractive surgery
- Clear Lens Exchange
- Implantable Contact Lenses
Tear duct & Orbit
- Orbital Decompression Surgery
- Tear Duct Plugs
Procedures Most Often Billed to Medicare
3,913 services · 2,714 patients · 15 distinct codes
| Procedure | Type | Code | Services | Compared with peers |
|---|---|---|---|---|
| Removal of cataract with insertion of prosthetic lens | Procedure | 66984 |
619 | More than most peers in Ophthalmology |
| Insertion of drug delivery implant into tear duct of eye | Procedure | 68841 |
213 | More often than most peers in Ophthalmology |
| Removal of recurring cataract in lens capsule using a laser | Procedure | 66821 |
72 | More often than most peers in Ophthalmology |
| Extracapsular removal of cataract with insertion of artificial lens and insertion of drainage device in front chamber of eye | Procedure | 66991 |
45 | More often than most peers in Ophthalmology |
| Complex removal of cataract with insertion of prosthetic lens | Procedure | 66982 |
40 | More often than most peers in Ophthalmology |
| Measurement of corneal curvature and depth of eye | Treatment | 92136 |
987 | More than most peers in Ophthalmology |
| Imaging of retina | Treatment | 92134 |
542 | More often than most peers in Ophthalmology |
| Established patient complete exam of visual system | Treatment | 92014 |
538 | More often than most peers in Ophthalmology |
| Ct scan of cornea | Treatment | 92025 |
333 | More than most peers in Ophthalmology |
| Established patient problem focused exam of visual system | Treatment | 92012 |
136 | 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.
Related specialists at this location 6
Clinically related specialties at the same address — the people this provider most likely works alongside.
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.
More connections — 23 related providers in 3 groups
Trained at Stanford University School of Medicine 8
Other providers in the same specialty who trained at the same institution.
Class of 1997 at Stanford University School of Medicine 8
Providers who graduated from the same medical school in the same year.
Also performs Removal of cataract with insertion of prosthetic lens 7
Providers in MA who bill this service to Medicare most often.
Common questions
What kind of doctor is Dr. Warren?
Dr. Warren is an eye doctor in Greenfield, MA. That is the designation recorded for this NPI in the federal registry, where it is listed as “Ophthalmology”.
NPI registry
What is Dr. Warren's address?
Dr. Warren is listed at 33 Riddell St, Greenfield, MA 01301. Addresses come from the NPI registry and can lag a move, so confirm before travelling.
NPI registry
How can I make an appointment with Dr. Warren?
The number on file is (413) 774-7016. Contact the office directly to confirm availability and scheduling.
NPI registry
What is Dr. Warren's NPI number?
Dr. Warren's National Provider Identifier is 1386634400. 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. Warren train?
Dr. Warren attended Stanford University School of Medicine, graduating in 1997. This comes from the CMS National Downloadable File.
CMS public data
How long has Dr. Warren been practicing?
Dr. Warren has 29 years experience. Calculated from a graduation year of 1997, reported in the CMS National Downloadable File.
CMS public data
What procedures does Dr. Warren perform?
According to Medicare billing data, Dr. Warren performs procedures including removal of cataract with insertion of prosthetic lens, insertion of drug delivery implant into tear duct of eye and removal of recurring cataract in lens capsule using a laser; provides treatments such as measurement of corneal curvature and depth of eye and imaging of retina, alongside routine visits and testing. This reflects Medicare patients only and is billing volume, not a measure of quality.
Medicare claims
Has Dr. Warren confirmed this information?
Not yet. This profile is built from public federal data and has not been confirmed by Dr. Warren. If this is you, claiming it is free.
Guide.md
Guide.md listings do not constitute medical advice or an endorsement.