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

Mark A Greiner, MD

Individual provider Student in an Organized Health Care Education/Training Program · NPI 1194992958

Mark A Greiner, MD practises Ophthalmology in Iowa City, Iowa. Graduated from University of California, Davis School of Medicine in 2007, 19 years ago. Practices with State University of Iowa, a 1,885-clinician group and accepts Medicare assignment. Licensed in Iowa.

Years since qualifying
19
Trained at
University of California, Davis School of Medicine
Licensed in
IA
In the registry since
2008
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

Student / training record This NPI belongs to someone enrolled in a health care training programme. It carries no licence and no practice of its own, so no address or phone number is published for it.

Iowa City, IA

No coordinates on file. Search this address in Google Maps

Specialties & licences

Ophthalmology Physician (primary) Taxonomy 207W00000X · Licence 40489 (IA)
Student in an Organized Health Care Education/Training Program Taxonomy 390200000X

Record details

NPI number1194992958
Entity typeIndividual (Type 1)
GenderMale
Credentials MD
Sole proprietorNo
NPI enumeratedMay 12, 2008
Last updated in NPPESAugust 16, 2012

Medicare enrollment

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

Medicare specialtyOPHTHALMOLOGY
Medical schoolUNIVERSITY OF CALIFORNIA, DAVIS SCHOOL OF MEDICINE
Graduated 2007 (19 years in practice)
Group practice State University Of Iowa — 1885 clinicians
Accepts Medicare assignment Yes — accepts the Medicare-approved amount
Practice locations2 on file with Medicare

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.

Cataract surgery 76 times · 70th 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 patients604
Services billed 2,175 a service is one billed item, such as a visit, a test or a procedure
Average patient age75

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.

Colleagues at State University of Iowa

Clinicians the CMS Doctors & Clinicians file lists under the same group practice. CMS counts 1885 clinicians in the practice; 12 are shown here.

Other providers in Iowa City