MARY LEONG O.D.
NPI 1003968249
Optometrist in Brentwood, CA
About Mary Leong O.d. NPPES
Official registry information on file with the National Plan and Provider Enumeration System.
MARY LEONG O.D. (NPI 1003968249) is an individual optometrist in Brentwood, California, licensed in California (11914T) and active in the NPI registry since January 2007. She is enrolled in Medicare PECOS, maintains a secondary practice location in Antioch, and is a graduate of Southern California College Of Optometry (2002).
NPPES Registry Identity
Specialties & Licenses
Secondary Practice Location 1
Accepted Insurance
Medicare Participation & PECOS CMS
Medicare enrollment, assignment, billing reassignment, and ordering and referring status from CMS.
Medicare Enrollment Status
Enrolled in Medicare and accepts Medicare assignment
Mary Leong O.d. is registered in PECOS and agrees to accept the Medicare-approved amount as full payment. Medicare patients are not billed beyond the standard deductible and coinsurance.
Medicare Billing Reassignments
4Medicare enrollment records show Mary Leong reassigns Medicare billing to 4 organizations. Each organization bills Medicare for the services this provider delivers there; the nearest is listed first.
Brentwood, CA 94513
- Reassigned Medicare billing, California enrollment
- 3 clinicians in this Medicare group
Antioch, CA 94531
- Reassigned Medicare billing, California enrollment
- 3 clinicians in this Medicare group
Dublin, CA 94568
- Reassigned Medicare billing, California enrollment
- 2 clinicians in this Medicare group
Stockton, CA 95210
- Reassigned Medicare billing, California enrollment
- 20,078 clinicians in this Medicare group
Source: CMS Revalidation Reassignment List, October 2026 release. Reassignment records can lag staffing changes; confirm a current affiliation with the organization.
Areas of Expertise CMS Part B claims 3
Services this provider delivered to Medicare fee-for-service patients, from the CMS Medicare utilization data. Higher counts generally reflect more experience with a service; care delivered outside Medicare is not included.
Physician Visit Costs CMS claims · ZIP area
Typical Medicare office-visit costs in the 94513 ZIP code area, from fee-for-service claims. These are area statistics, not this provider’s prices; actual charges vary by service and coverage.
Other Providers at the Same Location NPPES
Providers registered at the same practice address, or within the immediate area, according to the NPPES registry.
Frequently Asked Questions NPPES & CMS
Common questions about this NPI record, answered from the official NPPES registry and CMS datasets shown on this page.
What is Mary Leong's NPI number?
The NPI number for Mary Leong is 1003968249. It was assigned to this individual provider in the NPPES registry on January 17, 2007.
Where is Mary Leong located?
Mary Leong practices at 3840 Balfour Rd Ste A, Brentwood, CA 94513. The listed phone number is (925) 513-0323.
What is Mary Leong's specialty?
The primary specialty registered for this NPI is Optometrist with taxonomy code 152W00000X.
Is Mary Leong enrolled in Medicare?
Yes. Mary Leong is registered in the Medicare PECOS system and accepts Medicare assignment, which means accepting the Medicare-approved amount as payment in full for covered services.
Which organizations bill Medicare for Mary Leong's services?
According to the CMS Revalidation Reassignment List (October 2026 release), Mary Leong reassigns Medicare benefits to 4 organizations: Balfour Vision Optix Optometry, Inc. (Brentwood, CA), Winson Ong Od (Antioch, CA), Diamond Valley Optometry (Dublin, CA) and Permanente Medical Group Inc (Stockton, CA). Each reassignment is filed with Medicare on form CMS-855R, signed by both the clinician and the organization, and lets the organization bill Medicare and receive payment for Mary Leong's services. Reassignment records can lag staffing changes; confirm current arrangements with the organization.
What insurance does Mary Leong accept?
Health plans from Providence Health Plan list Mary Leong as in-network in at least one marketplace plan. Coverage varies by plan and year; verify with the insurer or the provider before a visit.
When was this NPI record last updated?
The NPPES record for Mary Leong was last updated on May 25, 2026. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 5 months ago. If this record has changed at CMS more recently, you can request an on-demand re-check against the live CMS registry, directly from this page.
# Mary Leong, O.D. · NPI 1003968249
Optometrist provider in Brentwood, California. Individual provider, active in the CMS NPPES registry since January 17, 2007.
## Identity
- **NPI:** 1003968249 (Entity type: Individual)
- **Enumerated:** January 17, 2007
- **Primary specialty:** Optometrist · taxonomy 152W00000X
- **State license:** 11914T (California)
- **Sole proprietor:** No
## Practice location
- **Address:** 3840 BALFOUR RD STE A, Brentwood, CA 94513-1641
- **Phone:** (925) 513-0323 · **Fax:** (925) 513-8649
## Medicare
- **Medicare:** Enrolled (PECOS); accepts Medicare assignment
- **Ordering & referring:** eligible for Part B labs & imaging, durable medical equipment, home health
- **Bills Medicare through:** 4 organizations under Medicare reassignment (form CMS-855R): Balfour Vision Optix Optometry, Inc. (NPI 1649470741, Brentwood, CA); Winson Ong Od (NPI 1770130932, Antioch, CA); Diamond Valley Optometry (NPI 1285473611, Dublin, CA); Permanente Medical Group Inc (NPI 1548343510, Stockton, CA) · CMS Revalidation Reassignment List, October 2026 release
- **Medical school:** Southern California College Of Optometry, class of 2002
## Record status
- **NPPES last updated:** May 25, 2026
---
Source: [NPI Profile](https://npiprofile.com/npi/1003968249) · Data from the CMS NPPES public registry.