Dr. John Ilsun Ryu , OD
Optometrist β’ Simi Valley, CA
690 E Los Angeles Ave, Suite A
Simi Valley, CA 930651857
This profile restates public CMS/NPPES data; T-MedInfo gives no medical advice — consult a licensed professional, and call 911 for emergencies.
Practice Location & Contact Primary Location
690 E Los Angeles Ave
Suite A
Simi Valley, CA 930651857
Matched by practice address or phone in NPPES. A shared address or phone does not confirm that this clinician works there.
What Public CMS Data Show
Optometrist: NPPES taxonomy is a reported classification, not proof of board certification.
Open Payments general payments, program year 2019
All general payments: $136.63 across 3 records.
By nature of payment
- Entertainment: $94.15 across 1 record.
- Food and Beverage: $42.48 across 2 records.
Reporting-company totals
- OPTOS, INC.: $94.15 across 1 record.
- Alcon Vision LLC: $31.85 across 1 record.
- ABB Con-Cise Optical Group LLC: $10.63 across 1 record.
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 2019 (published June 30, 2026).
NPI first issued
2006
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.
Medicare assignment not listed
CMS data do not show whether this clinician accepts Medicare assignment. This does not mean they do not accept Medicare. Ask the office.
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, βDoes your provider accept Medicare as full payment?β
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. Ryu 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. Ryu 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 Simi Valley and California
22 active clinicians are listed under Optometrist with a practice address in Simi Valley, CA (8,312 in California).
Addresses are self-reported to NPPES and may be out of date.
Telehealth indicator in Simi Valley
0% of these 22 clinicians have the CMS telehealth indicator.
45.5% of these 22 clinicians are listed by CMS as accepting Medicare assignment.
CMS data by year
Changes may reflect reporting, coverage or privacy limits, not changes in care quality.
-
Industry payments (Open Payments)
CMS data for industry payments (Open Payments) are available for 2019 only.
Sources: CMS Open Payments (2019), CMS Doctors and Clinicians, CMS NPPES NPI Registry. Specialty names follow the NUCC Health Care Provider Taxonomy.
Text: T-MedInfo Β· 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 2019 (payments made January 1 β December 31, 2019): fewer than 11 records totaling $136.63.
| Manufacturer | Payment Nature | Product | Type | Amount ($) |
|---|---|---|---|---|
| OPTOS, INC. |
Entertainment
Cash or cash equivalent
|
P200DTx | General | $94.15 |
| Alcon Vision LLC |
Food and Beverage
In-kind items and services
|
ReSTOR | General | $31.85 |
| ABB Con-Cise Optical Group LLC |
Food and Beverage
Cash or cash equivalent
|
Contact Lens | General | $10.63 |
Source: CMS Open Payments, program year 2019, released June 30, 2026.
Specialties & License Numbers Reported to NPPES
Self-certified to NPPES: 2024-07-15NUCC Taxonomy Code: 152W00000X
Doctors of optometry (ODs) are the primary health care professionals for the eye. Optometrists examine, diagnose, treat, and manage diseases, injuries, and disorders of the visual system, the eye, and associated structures as well as identify related systemic conditions affecting the eye. An optometrist has completed pre-professional undergraduate education in a college or university and four years of professional education at a college of optometry, leading to the doctor of optometry (O.D.) degree. Some optometrists complete an optional residency in a specific area of practice. Optometrists are eye health care professionals state-licensed to diagnose and treat diseases and disorders of the eye and visual system.
Medicare (PECOS) Enrollment & Ordering Eligibility
Source: CMS PECOSPRACTITIONER - OPTOMETRY
I20040625000951
CA
1557347002
Sources: CMS Provider Enrollment and Order and Referring. Medicare enrollment is a billing status, not an accreditation or quality rating.
Career & Practice History Timeline
Changes recorded in monthly NPPES data files: addresses, names, credentials, specialties and NPI status
Registered at 1194 KNOTTINGHAM ST, SIMI VALLEY, CA 930655167 (Tel: 6263763513)
NPI status registered as active in NPPES database
Registered at 690 E LOS ANGELES AVE, SUITE A, SIMI VALLEY, CA 930651857 (Tel: 6263763513)
Registered at 556 E PALM AVE, UNIT 303, BURBANK, CA 915012192 (Tel: 6263763513)
Recorded as JOHN RYU, O.D.
Optometrist (license number reported to NPPES: CA 11209T)
First registered as active Individual Practitioner in NPPES Database.
NPI Administrative Meta
Other Optometrists in Simi Valley
- Dr. Yara Chiha, OD
- Dr. William Shields, OD
- Dr. Maurice Feldman, OD
- Dr. Nelson Murata, OD
- Dr. Karlyn Murata, OD
- Dr. Joanne Parungao, OD
Mailing Address
1194 Knottingham St
Simi Valley, CA 930655167
Phone: 6263763513