Provider records sourced from NPPES (CMS National Plan & Provider Enumeration System). Data current as of October 4, 2026.
NPIDirectory

Mark T Duffy, MD

Individual provider Ophthalmology Physician · NPI 1235167537

Mark T Duffy, MD practises Ophthalmology in Green Bay, Wisconsin. Graduated from University of Illinois College of Med (CHI/PEOR/ROCK/Chm-Urb) in 1992, 34 years ago. Practices with Baycare Clinic LLP, a 196-clinician group and accepts Medicare assignment. Licensed in Wisconsin.

Years since qualifying
34
Trained at
University of Illinois College of Med (CHI/PEOR/ROCK/Chm-Urb)
Licensed in
WI
In the registry since
2006
Specialties on file
2
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

2253 W Mason St
Green Bay, WI 54303-4706
Phone: (920) 327-7000
Fax: (920) 327-7005
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Pin is approximate — placed at the ZIP-code centre, not the exact door.

Specialties & licences

Ophthalmic Plastic and Reconstructive Surgery Physician (primary) Taxonomy 207WX0200X · Licence 47208 (WI)
Ophthalmology Physician Taxonomy 207W00000X · Licence 47208 (WI)

Record details

NPI number1235167537
Entity typeIndividual (Type 1)
GenderMale
Credentials MD
Sole proprietorNo
NPI enumeratedJune 28, 2006
Last updated in NPPESApril 21, 2026
Certification dateApril 21, 2026

Medicare enrollment

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

Medicare specialtyOPHTHALMOLOGY
Medical schoolUNIVERSITY OF ILLINOIS COLLEGE OF MED (CHI/PEOR/ROCK/CHM-URB)
Graduated 1992 (34 years in practice)
Group practice Baycare Clinic Llp — 196 clinicians
Accepts Medicare assignment Yes — accepts the Medicare-approved amount

Procedures

From CMS Care Compare, which counts the procedures a clinician billed to Original Medicare and Medicare Advantage over a recent 12-month period. CMS reports a fixed list of common procedures, so this is not everything the clinician does. Counts of 10 or fewer are given as a range, because CMS withholds small numbers.

Melanoma (skin cancer) excision 12 times · 66th percentile

The percentile compares how often this clinician performed the procedure with other clinicians who performed it, as CMS calculates it. It measures volume, not outcomes or skill.

Medicare patients and services, 2024

From the CMS Medicare Physician & Other Practitioners file for calendar year 2024. It counts Original Medicare patients only, so a practice that mostly sees Medicare Advantage or privately insured patients looks smaller here than it is.

Medicare patients413
Services billed 7,408 a service is one billed item, such as a visit, a test or a procedure
Average patient age74

Dollar amounts are not shown. What Medicare pays a practice is gross billings, before staff, premises and tax and including the cost of any drugs it administers, so it is not what a clinician earns.

Practises at

Facilities the CMS Facility Affiliation file lists for this clinician.

  • Aurora Baycare Medical Ctr Hospital · Green Bay, WI

Colleagues at Baycare Clinic LLP

Clinicians the CMS Doctors & Clinicians file lists under the same group practice. CMS counts 196 clinicians in the practice; 11 are shown here.

Other providers in Green Bay