NPI registry status
Active
2026 NPPES data Ophthalmology Physician NPI 1407903180 MD
Verify on CMS → Thom Thomassen, MD
Ophthalmology Physician in Janesville, Wisconsin.
This profile is drawn from the federal National Provider Identifier Registry (CMS NPPES), which lists more than 7 million U.S. healthcare providers - including 22,082 in Ophthalmology Physician, and covers specialty classification, practice address, and Medicare Part D prescribing data when reported. According to CMS, every field reflects the provider's official federal registration, see our methodology.
Federal data, no proprietary rating.
We show these CMS records as-is - no composite score, no star rating, no editorial opinion layered on top.
Prescribing volume
302
Medicare Part D claims · 66 beneficiaries · Ophthalmology Physician avg: 1K
Generic prescribing
54%
generic claims · 46% brand-name · higher generic rates reduce patient out-of-pocket costs
Source: CMS Medicare Part D Prescriber Public Use File, 2023
Compiled from official public sources by the PlainDoctor editorial team.
What the federal data shows
Thom Thomassen, MD filed 302 Medicare Part D claims in 2023 as a Ophthalmology Physician in Janesville, Wisconsin, prescribing 54% generic.
- 302
- Part D claims, 2023
- 54%
- generic prescribing
- Likely
- board-certified (heuristic)
Every figure on this page comes straight from federal CMS records (NPPES, Medicare Part D, MIPS, Open Payments) - no proprietary rating or editorial opinion is applied.
Thom Thomassen, MD's Medicare Part D volume vs every U.S. prescriber
Total Medicare Part D claims, 2023, across all CMS prescribers nationally
302 Top 43% higher than 57% of 1,370,886 prescribers
Each bar is a band; taller bars hold more prescribers. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count, share, and where it sits relative to this entry.
Source CMS Medicare Part D Prescriber Public Use File · 2023
✓
Board certification likely (heuristic, not verified)
Thom Thomassen, MD practices in an ABMS-board-eligible specialty and shows active CMS Medicare participation + 1 hospital affiliation - signals consistent with board-certified status. For verified board certification, see CertificationMatters.org (the official ABMS public lookup).
What does the federal data show about Thom Thomassen, MD?
Quality data not reportedPrimary specialty
Ophthalmology Physician
Medicare Part D claims
302 79% vs specialty avg
Specialty distribution in Wisconsin
How Ophthalmology Physician compares to other specialties among Wisconsin providers
Board certification
Not published by CMS
CMS does not publish a per-provider board-certification field in NPPES. PlainDoctor does not have a reliable per-specialty certification rate to show for Ophthalmology Physician. Verify directly:
How MIPS and board certification work
The Merit-based Incentive Payment System (MIPS) scores providers 0–100 across four performance categories: Quality, Cost, Promoting Interoperability, and Improvement Activities, weighted under 42 CFR §414.1380. Reporting is voluntary for many small practices, so absence of a MIPS score is not a quality signal.
Board certification through an ABMS or AOA member board signals voluntary post-licensure examination plus continuous Maintenance of Certification cycles. Verify any individual provider's status through certificationmatters.org (ABMS) or osteopathic.org (AOA).
Thom Thomassen, MD appears in the CMS NPPES registry as an Ophthalmology Physician provider holding MD credentials at 3524 E MILWAUKEE ST, Janesville, WI, 53546, with a listed phone of (608) 756-7100. NPI 1407903180 was issued on 01/04/2007.
Medicare Part D records for calendar year 2023 show 302 prescription claims written by this provider, covering 66 Medicare beneficiaries and totaling roughly $70K in drug spend, split 46% brand-name and 54% generic by claim count.
Ophthalmology Physician is a mid-sized specialty nationwide, with 22,082 enrolled providers across 56 states and an average of 1,420 Part D claims per prescriber, so the context for interpreting these metrics differs meaningfully from a primary-care baseline.
Important: PlainDoctor is a directory of publicly available government data, not medical advice, a malpractice database, or a quality rating. Inclusion here does not imply a recommendation, and absence of complaints or sanctions on this page does not mean none exist, always verify credentials through the NPPES NPI Registry, your state medical board, and the ABMS or AOA before making healthcare decisions.
Practice Address
Provider Details
| NPI | 1407903180 |
|---|---|
| Specialty | Ophthalmology Physician |
| Credentials | MD |
| Gender | Male |
| NPI Issued | 01/04/2007 |
Hospital and facility affiliations
Facilities where Thom Thomassen, MD bills Medicare from. Star ratings (1-5) are CMS Hospital Compare's "Hospital overall rating" - a composite of mortality, readmission, patient experience, safety, timely care, and efficient use of medical imaging measures. Source: CMS Care Compare.
Mercy Health System Corporation
Janesville, WI
Affiliations sourced from CMS Doctors and Clinicians National Downloadable File; hospital ratings from CMS Hospital General Information dataset (cross-referenced by facility name + state).
Brand vs generic prescribing mix · Above average
Thom Thomassen, MD - brand share 46.0%
Ophthalmology Physician average
46% brand-name claims vs 54% generic, on 302 2023 Medicare Part D claims.
The federal Medicare Part D Generic Dispensing Rate national benchmark sits near 90% generic / 10% brand for primary-care prescribers, per CMS Office of the Actuary 2024 estimates. Higher brand share is common in specialty prescribing where generic equivalents are not available.
Medicare Part D Prescribing Data
CMS Medicare Part D prescriber-level data for calendar year 2023.
302
Total Claims
$70K
Total Drug Cost
66
Medicare Beneficiaries
Prescribing Breakdown
- 30-Day Fills
- 647
- Total Day Supply
- 18,940
- Brand vs Generic
- 46% brand / 54% generic
- Brand Drug Cost
- $49K
- Generic Drug Cost
- $20K
Patient Demographics
- Average Patient Age
- 77.3 years
- Avg HCC Risk Score
- 1.27
- Gender Split
- 62% female / 38% male
Top Prescribed Drugs (Medicare Part D)
Top drugs by claim count for calendar year 2023. Based on Medicare Part D data only.
What Thom Thomassen, MD prescribes most
Top Medicare Part D drugs by claim count, 2023
- Latanoprost
Latanoprost
98 claims
- Lumigan 24
Lumigan
24 claims
- Dorzolamide-Timolol 19
Dorzolamide-Timolol
19 claims
- Brinzolamide 14
Brinzolamide
14 claims
- Loteprednol Etabon… 14
Loteprednol Etabonate
14 claims
- Dorzolamide Hcl 13
Dorzolamide Hcl
13 claims
- Prednisolone Acetate 13
Prednisolone Acetate
13 claims
- Timolol Maleate 13
Timolol Maleate
13 claims
| Drug | Claims |
|---|---|
| Latanoprost | 98 |
| Lumigan Bimatoprost | 24 |
| Dorzolamide-Timolol Dorzolamide Hcl/Timolol Maleat | 19 |
| Brinzolamide | 14 |
| Loteprednol Etabonate | 14 |
| Dorzolamide Hcl | 13 |
| Prednisolone Acetate | 13 |
| Timolol Maleate | 13 |
| Zioptan Tafluprost/Pf | 12 |
| Restasis Cyclosporine | 11 |
* Counts below 11 are suppressed by CMS for patient privacy. Generic names shown where available from CMS Part D data.
Ophthalmology Physician Overview
How Thom Thomassen, MD fits within the Ophthalmology Physician landscape nationally.
22,082
Ophthalmology Physician Providers in US
56
States with Ophthalmology Physician
1,420
Avg Claims per Provider
Thom Thomassen, MD's 302 claims are below the specialty average of 1,420.
Nearby Ophthalmology Physician Providers in Wisconsin
Other clinicians with the same primary specialty enrolled in Wisconsin, drawn from the same CMS NPPES roster as Thomassen.
Dr. Nausheen Abbas
M.D.
West Bend, WI
Dr. Omar Abdelmegid
MD
Beaver Dam, WI
Dr. Jacob Abou-Hanna
MD
Madison, WI
Dr. Julia Agapov
DO
Madison, WI
Dr. Swati Agarwal-Sinha
MD
Green Bay, WI
Compare Ophthalmology Physician nationally: see state-by-state distribution →
Before you book an appointment
Use this federal record as your verification checklist, not as a recommendation.
- Confirm the NPI record is current in the official CMS registry, providers update their own NPPES details, and moves can lag. Verify this NPI
- Check the active license and any disciplinary history with the Wisconsin medical board, federal registration is not a license check. Credential verification guide
- Weigh a second option: compare this provider with a nearby Ophthalmology Physician peer on Medicare volume and prescribing patterns. Compare providers
Medicare Part D and MIPS figures describe practice patterns in federal programs only, they are not quality ratings, and PlainDoctor does not rate, rank, or recommend providers.
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Frequently Asked Questions
What is Thom Thomassen, MD's specialty? ▼
Thom Thomassen, MD specializes in Ophthalmology Physician and practices in Janesville, Wisconsin. Credentials: MD.
How much does Thom Thomassen, MD prescribe under Medicare Part D? ▼
In 2023, Thom Thomassen, MD wrote 302 Medicare Part D claims totaling $70K in drug costs for 66 beneficiaries.
Where is Thom Thomassen, MD located? ▼
Thom Thomassen, MD is located at 3524 E MILWAUKEE ST, Janesville, WI, 53546. Phone: (608) 756-7100.
What is Thom Thomassen, MD's NPI number? ▼
Thom Thomassen, MD's National Provider Identifier (NPI) is 1407903180, issued on 01/04/2007.
Does Thom Thomassen, MD prescribe more brand-name or generic drugs? ▼
Thom Thomassen, MD's prescribing is 46% brand-name and 54% generic drugs by claim count, with $49K in brand drug costs.
How many Ophthalmology Physician providers are there in the US? ▼
There are 22,082 Ophthalmology Physician providers across 56 states in the US. The average Ophthalmology Physician provider writes 1,420 Medicare Part D claims per year.
What drugs does Thom Thomassen, MD prescribe most often? ▼
Based on 2023 Medicare Part D data, Thom Thomassen, MD's most frequently prescribed drugs include Latanoprost, Lumigan, Dorzolamide-Timolol. This reflects Medicare Part D prescriptions only and does not include commercial insurance or other payer types.
Does Thom Thomassen, MD accept Medicare? ▼
Thom Thomassen, MD appears in CMS Medicare data with 302 Part D claims and 66 Medicare beneficiaries in 2023. Contact the provider's office directly to confirm current Medicare enrollment and accepted plans.
How can I verify Thom Thomassen, MD's credentials? ▼
Thom Thomassen, MD's NPI is 1407903180 with credentials MD. You can verify this through the NPPES NPI Registry, check state medical board records, and confirm board certification through the ABMS or AOA.
Data Sources
View source datasets and methodology notes
- Provider Directory
- CMS National Plan and Provider Enumeration System (NPPES), download.cms.gov/nppes, updated monthly. Contains NPI, specialty, credentials, and practice location.
- Specialty Classification
- NUCC Health Care Provider Taxonomy (nucc.org), the industry standard for classifying provider specialties in Medicare and Medicaid billing.
- Prescribing Data
- CMS Medicare Part D Prescriber Public Use File (2023). Includes claims, drug costs, beneficiaries, and opioid prescribing rates.
- Limitations
- Provider data is self-reported to CMS. Prescribing data reflects Medicare Part D only and does not include commercial insurance, Medicaid, or cash prescriptions. Claims below 11 beneficiaries are suppressed by CMS for privacy.
See our complete data methodology for details on how we collect and process government data.
Data as of April 2026 (NPPES) / 2023 (Medicare Part D). Source: Centers for Medicare & Medicaid Services (CMS).
Disclaimer: Data from CMS NPPES and Medicare Part D. PlainDoctor does not rate or rank providers. Provider information is self-reported and may not be current. Always verify information directly with the provider. About · Methodology
Compiled from official public sources by the PlainDoctor editorial team.
Every figure on PlainDoctor is rendered directly from the federal CMS NPPES registry, Medicare Part D, MIPS, and Open Payments records, no number is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of May 2026.