Dr. Daniel Ahn , DO
Ophthalmology • Sonoma, CA
181 Andrieux St, Suite 100
Sonoma, CA 954766932
This profile restates public CMS/NPPES data; T-MedInfo gives no medical advice — consult a licensed professional, and call 911 for emergencies.
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NPI assigned on August 31, 2010; this date does not establish years in practice.
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Published CMS data list 4,289 Original Medicare Part B services in 2024.
Source: CMS, Medicare Physician & Other Practitioners – by Provider and Service, 2024. Published rows only; this is not a quality measure.
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Published Part B service records, 2024:
- 92014 — Established patient complete exam of visual system: 903 service units.
- 92250 — Photography of the retina: 810 service units.
- 92012 — Established patient problem focused exam of visual system: 351 service units.
Source: CMS, Medicare Physician & Other Practitioners – by Provider and Service, 2024. Units differ by code; these are not visits or a measure of quality.
CPT® only copyright 2023 American Medical Association. All rights reserved. Service names are shortened from CPT Consumer Friendly Descriptors (CMS data, 2024). CPT notice
See all 21 records in the table · Guide: How to read Medicare Part B data
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Published CMS data list 3,888 Medicare Part D prescriptions, including refills, in 2024.
Source: CMS, Medicare Part D Prescribers – by Provider and Drug, 2024. Published rows only; this is not a quality measure.
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Published Part D records, 2024:
- Prednisolone Acetate — 914 prescription fills, including refills.
- Latanoprost — 618 prescription fills, including refills.
- Ketorolac Tromethamine — 487 prescription fills, including refills.
Source: CMS, Medicare Part D Prescribers – by Provider and Drug, 2024. Drug names come from pharmacy claims. Listing a drug here is not an endorsement or a recommendation.
See all 22 records in the table · Guide: How to read Medicare Part D prescriber data
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More Medicare Part B services than 75% of clinicians listed under Ophthalmology in California (2024, 1,572 clinicians with data). Median for this group: 1,776. Middle half: 600 to 3,873.
Source: CMS, Medicare Physician & Other Practitioners – by Provider and Service, 2024. Billing and prescribing volume is not a quality rating.
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Medicare Part B services went from 3,891 in 2020 to 4,289 in 2024.
Source: CMS, Medicare Physician & Other Practitioners – by Provider and Service, 2020–2024.
Practice Location & Contact Primary Location
181 Andrieux St
Suite 100
Sonoma, CA 954766932
Matched by practice address or phone in NPPES. A shared address or phone does not confirm that this clinician works there.
CMS Doctors and Clinicians lists 1 group name: Horizon Medical Group Pc. See the list
Source: CMS Doctors and Clinicians National Downloadable File, release date unavailable.
Listings do not confirm current availability, employment or a shared ownership network.
Medicare Profile & Education
Source: CMS Doctors and Clinicians National Downloadable File
New York College Of Osteo Medicine Of New York Institute Of Technology
2008
What Public CMS Data Show
Ophthalmology: NPPES taxonomy is a reported classification, not proof of board certification.
Medicare patients
934 people with Original Medicare in 2024
It gives a sense of how many people with Medicare this clinician treated that year.
Source: CMS, Medicare Physician & Other Practitioners – by Provider, 2024.
Medicare-allowed amount
About $474,002 in 2024
The total amount Medicare approved for these services in 2024. It includes what Medicare paid and what patients or their other insurance owed, such as the deductible and coinsurance.
It shows the total cost of this clinician's Original Medicare services under Medicare's fee rules.
What this does not show: Medicare-allowed amount
This is not the clinician's income. Part of it can go to a clinic or group practice, staff, equipment or drugs. It is not the price you will pay.
Source: CMS, Medicare Physician & Other Practitioners – by Provider and Service, 2024.
Paid by Medicare
About $352,353 in 2024
The part of the Medicare-allowed amount that Medicare itself paid in 2024, after patients' deductibles and coinsurance.
The gap between the allowed amount and this number is roughly what patients and their other insurance paid.
What this does not show: Paid by Medicare
This is not the clinician's income and not a measure of quality.
Source: CMS, Medicare Physician & Other Practitioners – by Provider and Service, 2024.
30-day fills
4,944 standardized 30-day fills in 2024
CMS converts prescriptions to 30-day supplies so they can be compared. A 90-day prescription counts as about three 30-day fills.
What this does not show: 30-day fills
It is not a count of patients and not a measure of quality.
Part D drug cost
$573,830 in 2024
The total cost of these prescriptions in 2024, paid by Medicare drug plans, patients and other payers together.
It shows the total spending on drugs this clinician prescribed, not what any one patient paid.
What this does not show: Part D drug cost
A higher cost often reflects the type of medicines a specialty uses. It is not your out-of-pocket cost and not a measure of quality.
Source: CMS, Medicare Part D Prescribers – by Provider and Drug, 2024.
Open Payments general payments, program year 2025
All general payments: $2,884.98 across 68 records.
By nature of payment
- Food and Beverage: $2,884.98 across 68 records.
Reporting-company totals (3 largest of 11)
- Alcon Vision LLC: $1,336.88 across 23 records.
- Bausch & Lomb Americas Inc.: $598.90 across 15 records.
- ABBVIE INC.: $421.32 across 15 records.
A reported payment does not necessarily mean the financial relationship is improper and is not a measure of care quality. Clinicians can review and dispute these records.
Source: Calculated by T-MedInfo from CMS Open Payments general-payment records for program year 2025 (published June 30, 2026).
Years since graduation
18 years (graduated 2008)
CMS Doctors and Clinicians data list 2008 as the year this clinician finished professional school.
It tells you roughly how long ago the clinician finished school.
What this does not show: Years since graduation
It is not the number of years in practice, and more years does not mean better care.
Source: CMS Doctors and Clinicians National Downloadable File.
NPI first issued
2010
The year this clinician's National Provider Identifier (NPI) was issued. An NPI is a unique 10-digit ID that US health care providers use for billing.
What this does not show: NPI first issued
NPIs have been issued only since 2005, so this year is not necessarily when the clinician started practicing.
Source: CMS NPPES NPI Registry.
Accepts Medicare assignment
CMS data list this clinician as accepting Medicare assignment. This means agreeing to take the Medicare-approved amount as full payment for covered services.
With Original Medicare, you usually pay only your deductible and coinsurance, and the office sends the claim to Medicare for you.
Medicare assignment applies to Original Medicare. It does not tell you whether the clinician is in a Medicare Advantage plan's network, accepts other insurance, or is taking new patients.
Source: CMS Doctors and Clinicians; Medicare.gov, “Does your provider accept Medicare as full payment?”
No telehealth indicator
CMS shows this indicator only when recent Medicare claims include telehealth services. The clinician may still offer telehealth; ask the office.
Source: CMS, Telehealth Indicator on Medicare Care Compare (fact sheet, January 2023); CMS Doctors and Clinicians.
Enrolled in Medicare (PECOS)
Dr. Ahn has a Medicare enrollment record in PECOS, the CMS system clinicians use to enroll so they can bill Medicare or order services for people with Medicare.
It does not show whether the clinician accepts assignment, is in your plan's network, or is taking new patients.
Source: CMS Medicare Fee-For-Service Public Provider Enrollment (PECOS); CMS Order and Referring file.
Can order Medicare-covered services
CMS lists Dr. Ahn as eligible to order or refer Medicare Part B clinical laboratory and imaging services, durable medical equipment (DME) and home health services for people with Medicare.
Medicare pays for these items and services only when they are ordered by an eligible clinician.
What this does not show: Can order Medicare-covered services
It does not mean the clinician offers these services directly.
Source: CMS Medicare Fee-For-Service Public Provider Enrollment (PECOS); CMS Order and Referring file.
Compared with the same specialty in Sonoma and California
Billing and prescribing volume is not a quality rating.
Medicare Part B services
More Medicare Part B services than 75% of clinicians listed under Ophthalmology in California (2024, 1,572 clinicians with data). Median for this group: 1,776. Middle half: 600 to 3,873.
Too few clinicians listed under Ophthalmology in Sonoma have Medicare Part B data for 2024 to compare.
Medicare-allowed amount
A higher Medicare-allowed amount than 75% of clinicians listed under Ophthalmology in California (2024, 1,572 clinicians with data). Median for this group: $209,264. Middle half: $67,828 to $437,264.
Too few clinicians listed under Ophthalmology in Sonoma have Medicare Part B data for 2024 to compare.
Paid by Medicare
A higher Medicare payment amount than 75% of clinicians listed under Ophthalmology in California (2024, 1,572 clinicians with data). Median for this group: $152,036. Middle half: $48,721 to $320,363.
Too few clinicians listed under Ophthalmology in Sonoma have Medicare Part B data for 2024 to compare.
Medicare Part D prescriptions
More Part D prescriptions than 90% of clinicians listed under Ophthalmology in California (2024, 1,966 clinicians with data). Median for this group: 1,025. Middle half: 297 to 2,233.
Too few clinicians listed under Ophthalmology in Sonoma have Medicare Part D data for 2024 to compare.
Part D drug cost
A higher Part D drug cost than 90% of clinicians listed under Ophthalmology in California (2024, 1,966 clinicians with data). Median for this group: $79,352. Middle half: $13,075 to $224,408.
Too few clinicians listed under Ophthalmology in Sonoma have Medicare Part D data for 2024 to compare.
3 active clinicians are listed under Ophthalmology with a practice address in Sonoma, CA (2,902 in California).
Addresses are self-reported to NPPES and may be out of date.
CMS data by year
Changes may reflect reporting, coverage or privacy limits, not changes in care quality.
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Medicare Part B services
Medicare Part B services increased 10% from 3,891 in 2020 to 4,289 in 2024.
- 2020: 3,891
- 2021: 4,253
- 2022: 3,896
- 2023: 3,923
- 2024: 4,289
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Medicare-allowed amount
Medicare-allowed amount increased 12% from $423,341 in 2020 to $474,002 in 2024.
- 2020: $423,341
- 2021: $463,880
- 2022: $400,383
- 2023: $388,017
- 2024: $474,002
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Paid by Medicare
Paid by Medicare increased 13% from $313,126 in 2020 to $352,353 in 2024.
- 2020: $313,126
- 2021: $345,273
- 2022: $291,409
- 2023: $283,505
- 2024: $352,353
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Medicare Part D prescriptions
Medicare Part D prescriptions increased 87% from 2,081 in 2020 to 3,888 in 2024.
- 2020: 2,081
- 2021: 2,636
- 2022: 2,685
- 2023: 3,001
- 2024: 3,888
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30-day fills
30-day fills increased 73% from 2,862 in 2020 to 4,944 in 2024.
- 2020: 2,862
- 2021: 3,572
- 2022: 3,619
- 2023: 3,955
- 2024: 4,944
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Part D drug cost
Part D drug cost increased 118% from $263,565 in 2020 to $573,830 in 2024.
- 2020: $263,565
- 2021: $337,529
- 2022: $378,850
- 2023: $478,146
- 2024: $573,830
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Industry payments (Open Payments)
Industry payments (Open Payments) went from $252.73 in 2021 to $2,884.98 in 2025.
- 2021: $252.73
- 2022: $900.66
- 2023: $1,619.68
- 2024: $1,634.90
- 2025: $2,884.98
Sources: CMS Medicare Physician & Other Practitioners (2024), CMS Medicare Part D Prescribers (2024), CMS Open Payments (2025), CMS Doctors and Clinicians, CMS NPPES NPI Registry. Specialty names follow the NUCC Health Care Provider Taxonomy.
Text: T-MedInfo · Report an error.
Pharma & Medical Device Financial Disclosures
Payments and other transfers of value that drug and medical device companies reported to CMS Open Payments
Program year 2025 (payments made January 1 – December 31, 2025): 68 records totaling $2,884.98.
| Manufacturer | Payment Nature | Product | Type | Amount ($) |
|---|---|---|---|---|
| Alcon Vision LLC |
Food and Beverage
In-kind items and services
|
TRYPTYR | General | $149.42 |
| Globus Medical, Inc. |
Food and Beverage
Cash or cash equivalent
|
Senza | General | $147.59 |
| Alcon Vision LLC |
Food and Beverage
In-kind items and services
|
Rhopressa | General | $146.20 |
| Alcon Vision LLC |
Food and Beverage
In-kind items and services
|
Clareon | General | $135.52 |
| Alcon Vision LLC |
Food and Beverage
In-kind items and services
|
Clareon PanOptix Pro | General | $133.95 |
| Bausch & Lomb Americas Inc. |
Food and Beverage
In-kind items and services
|
enVista MX60 IOL | General | $131.14 |
| Bausch & Lomb Americas Inc. |
Food and Beverage
In-kind items and services
|
MIEBO | General | $126.69 |
| Alcon Vision LLC |
Food and Beverage
In-kind items and services
|
Clareon PanOptix Pro | General | $123.87 |
| Alcon Vision LLC |
Food and Beverage
In-kind items and services
|
UNITY | General | $123.82 |
| Alcon Vision LLC |
Food and Beverage
In-kind items and services
|
Clareon | General | $117.21 |
| Alcon Vision LLC |
Food and Beverage
In-kind items and services
|
UNITY | General | $108.44 |
| Bausch & Lomb Americas Inc. |
Food and Beverage
In-kind items and services
|
MIEBO | General | $107.75 |
| ABBVIE INC. |
Food and Beverage
In-kind items and services
|
DURYSTA | General | $75.59 |
| Alcon Vision LLC |
Food and Beverage
In-kind items and services
|
Clareon PanOptix Pro | General | $34.49 |
| ABBVIE INC. |
Food and Beverage
In-kind items and services
|
DURYSTA | General | $34.08 |
| ABBVIE INC. |
Food and Beverage
In-kind items and services
|
DURYSTA | General | $33.95 |
| SUN PHARMACEUTICAL INDUSTRIES INC. |
Food and Beverage
In-kind items and services
|
Cequa | General | $33.94 |
| Tarsus Pharmaceuticals, Inc. |
Food and Beverage
In-kind items and services
|
XDEMVY | General | $33.90 |
| ABBVIE INC. |
Food and Beverage
In-kind items and services
|
DURYSTA | General | $33.58 |
| Rayner Intraocular Lenses Limited |
Food and Beverage
Cash or cash equivalent
|
RAYNER CATARACT SET 1 | General | $33.06 |
| Alcon Vision LLC |
Food and Beverage
In-kind items and services
|
Clareon | General | $32.49 |
| ABBVIE INC. |
Food and Beverage
In-kind items and services
|
DURYSTA | General | $32.48 |
| ABBVIE INC. |
Food and Beverage
In-kind items and services
|
DURYSTA | General | $32.18 |
| Alcon Vision LLC |
Food and Beverage
In-kind items and services
|
Clareon PanOptix Pro | General | $31.41 |
| ANI Pharmaceuticals, Inc. |
Food and Beverage
In-kind items and services
|
PURIFIED CORTROPHIN GEL | General | $31.39 |
(top 25 shown)
Source: CMS Open Payments, program year 2025, released June 30, 2026.
Performed Procedures & Service Volume
CPT® is a registered trademark of the American Medical Association. CPT codes, descriptions and other data only are copyright 2016–2023 American Medical Association. All rights reserved. Applicable FARS/HHSARS apply. Descriptions of CPT codes are the AMA's CPT Consumer Friendly Descriptors as published by CMS in the Medicare Physician & Other Practitioners – by Provider and Service data, 2017–2024; they are plain-language summaries, not for clinical coding or documentation. HCPCS Level II codes and descriptions are from CMS. Fee schedules, relative value units, conversion factors and/or related components are not assigned by the AMA, are not part of CPT, and the AMA is not recommending their use. The AMA does not directly or indirectly practice medicine or dispense medical services. The AMA assumes no liability for data contained or not contained herein.
| HCPCS Code | Services | Patients | Submitted Charge | Medicare Allowed |
|---|---|---|---|---|
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92014
Established patient complete exam of visual system
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903 | 707 | $242.10 | $133.92 |
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92250
Photography of the retina
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810 | 773 | $155.64 | $39.41 |
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92012
Established patient problem focused exam of visual system
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351 | 236 | $167.08 | $95.38 |
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92133
Imaging of optic nerve
|
316 | 270 | $119.00 | $36.19 |
|
92020
Exam of the internal drainage system of eye
|
292 | 289 | $54.40 | $28.93 |
|
92083
Exam of visual field with extended testing
|
292 | 274 | $178.58 | $67.96 |
|
92134
Imaging of retina
|
261 | 242 | $122.00 | $41.88 |
|
66984
Removal of cataract with insertion of prosthetic lens
|
186 | 100 | $1536.58 | $558.26 |
|
92004
New patient complete exam of visual system
|
168 | 168 | $292.08 | $158.92 |
|
99214
Established patient office or other outpatient visit with moderate level of decision making, if using time, 30 minutes or more
|
140 | 138 | $213.00 | $135.41 |
|
92136
Measurement of corneal curvature and depth of eye
|
138 | 132 | $175.66 | $48.43 |
|
66821
Removal of recurring cataract in lens capsule using a laser
|
116 | 65 | $656.98 | $357.21 |
|
92025
Ct scan of cornea
|
86 | 86 | $73.54 | $34.87 |
|
65855
Laser repair to improve eye fluid flow
|
73 | 38 | $683.66 | $216.64 |
|
66761
Creation of eye fluid drainage tracts in iris using a laser, per session
|
52 | 27 | $660.16 | $299.27 |
|
G2211
Visit complexity inherent to evaluation and management associated with medical care services that serve as the continuing focal point for all needed health care services and/or with medical care services that are part of ongoing care related to a patient's
|
22 | 20 | $43.00 | $17.19 |
|
80048
Blood test, basic group of blood chemicals (calcium, total)
|
20 | 19 | $17.86 | $8.29 |
|
36415
Insertion of needle into vein for collection of blood sample
|
17 | 16 | $15.00 | $8.65 |
|
99204
New patient office or other outpatient visit with moderate level of medical decision making, if using time, 45 minutes or more
|
17 | 17 | $328.00 | $168.71 |
|
76514
Ultrasound scan of cornea to determine thickness
|
15 | 15 | $29.04 | $11.40 |
|
99213
Established patient office or other outpatient visit with low level od decision making, if using time, 20 minutes or more
|
14 | 12 | $144.00 | $92.51 |
Source: CMS Part B by Provider and Service, 2024; services under 11 beneficiaries omitted by CMS. Privacy limits
Submitted charges are billed amounts, not a price quote for your visit.
Medicare Part D Prescribing Profile & Medications
Medicare Part D prescriptions filled, including refills, in 2024.
| Brand Name | Generic Name | Prescriptions | Day Supply | Total Cost | Patients |
|---|---|---|---|---|---|
| Prednisolone Acetate | Prednisolone Acetate | 914 | 20,916 | $29,309.01 | 456 |
| Latanoprost | Latanoprost | 618 | 28,435 | $5,023.49 | 163 |
| Ketorolac Tromethamine | Ketorolac Tromethamine | 487 | 10,788 | $9,373.33 | 272 |
| Ofloxacin | Ofloxacin | 478 | 9,517 | $5,072.75 | 270 |
| Xiidra | Lifitegrast | 268 | 10,243 | $223,460.21 | 108 |
| Neomycin-Polymyxin-Dexameth | Neomycin/Polymyxin B/Dexametha | 226 | 3,296 | $2,423.81 | 105 |
| Lumigan | Bimatoprost | 150 | 7,773 | $70,390.68 | 45 |
| Restasis | Cyclosporine | 118 | 5,280 | $106,538.66 | 50 |
| Timolol Maleate | Timolol Maleate | 108 | 6,007 | $5,180.55 | 30 |
| Simbrinza | Brinzolamide/Brimonidine Tart | 95 | 3,338 | $23,095.26 | 23 |
| Dorzolamide-Timolol | Dorzolamide Hcl/Timolol Maleat | 65 | 4,116 | $1,052.61 | 18 |
| Travoprost | Travoprost | 64 | 3,284 | $11,208.16 | 14 |
| Rocklatan | Netarsudil Mesylat/Latanoprost | 49 | 1,488 | $18,145.16 | 12 |
| Brimonidine Tartrate | Brimonidine Tartrate | 37 | 1,736 | $2,780.24 | 11 |
| Cequa | Cyclosporine | 36 | 1,320 | $25,045.10 | 16 |
| Doxycycline Monohydrate | Doxycycline Monohydrate | 35 | 374 | $620.16 | 25 |
| Brimonidine Tartrate-Timolol | Brimonidine Tartrate/Timolol | 33 | 1,168 | $4,126.98 | — |
| Cyclosporine | Cyclosporine | 29 | 1,635 | $11,920.02 | 15 |
| Rhopressa | Netarsudil Mesylate | 24 | 1,065 | $12,642.99 | — |
| Dorzolamide Hcl | Dorzolamide Hcl | 21 | 1,511 | $293.96 | — |
| Alphagan P | Brimonidine Tartrate | 18 | 630 | $5,976.06 | — |
| Erythromycin | Erythromycin Base | 15 | 131 | $150.41 | — |
Source: CMS Part D by Provider and Drug, 2024; rows below 11 claims omitted by CMS; volume isn’t quality. Privacy limits
Specialties & License Numbers Reported to NPPES
NUCC Taxonomy Code: 207W00000X
An ophthalmologist has the knowledge and professional skills needed to provide comprehensive eye and vision care. Ophthalmologists are medically trained to diagnose, monitor and medically or surgically treat all ocular and visual disorders. This includes problems affecting the eye and its component structures, the eyelids, the orbit and the visual pathways. In so doing, an ophthalmologist prescribes vision services, including glasses and contact lenses.
NUCC Taxonomy Code: 207W00000X
An ophthalmologist has the knowledge and professional skills needed to provide comprehensive eye and vision care. Ophthalmologists are medically trained to diagnose, monitor and medically or surgically treat all ocular and visual disorders. This includes problems affecting the eye and its component structures, the eyelids, the orbit and the visual pathways. In so doing, an ophthalmologist prescribes vision services, including glasses and contact lenses.
Medicare (PECOS) Enrollment & Ordering Eligibility
Source: CMS PECOSPRACTITIONER - OPHTHALMOLOGY
I20160617001599
NY
6406010990
Sources: CMS Provider Enrollment and Order and Referring. Medicare enrollment is a billing status, not an accreditation or quality rating.
Medicare Group Practice Enrollments
Source: CMS Doctors and Clinicians National Downloadable File
Horizon Medical Group Pc
21 Edward J Lempka Dr, Florida, NY 109210001
Phone: 8456511777
Horizon Medical Group Pc
1460 State Route 17m, Chester, NY 109181054
Phone: 8454694211
Horizon Medical Group Pc
90 E Main St, Washingtonville, NY 109922302
Phone: 8454962400
Horizon Medical Group Pc
1460 State Route 17m, Chester, NY 109181054
Phone: 8456511400
Horizon Medical Group Pc
70 Dubois St, Newburgh, NY 125504851
Phone: 8455614400
Horizon Medical Group Pc
30 Hatfield Ln, Goshen, NY 109246768
Clinicians Sharing This Practice Address or Phone
Clinicians sharing this NPPES address, phone or fax; a shared contact does not mean they work together.
Obstetrics & Gynecology
Doctor of Medicine (M.D.)
Chiropractor
Doctor of Chiropractic
Family Medicine
Doctor of Medicine (M.D.)
Internal Medicine
Doctor of Medicine (M.D.)
Orthopaedic Surgery
Doctor of Medicine (M.D.)
Physician Assistant
Career & Practice History
NPI enumerated August 31, 2010.
No changes to the name, practice address, taxonomy or NPI status in this record have been observed in the monthly NPPES data files from January 2017 to August 2026.
NPI Administrative Meta
Mailing Address
181 Andrieux St, Suite 100
Sonoma, CA 954766932
Phone: 7075887939