Quick answers
- Where does Constance C. Twu see patients?
- Medicare's clinician data lists 2 practice locations, including Ontario, CA and Fontana, CA. Call before your visit to confirm the address.
- What is Constance C. Twu's specialty?
- Medicare lists Optometry as the primary specialty.
- Does Constance C. Twu accept Medicare assignment?
- Yes. Medicare's clinician data says Constance C. Twu accepts Medicare assignment (the Medicare-approved amount as full payment for covered services), as of 2026-10-02. Ask the office to confirm before your visit.
- What is the phone number for Constance C. Twu?
- (909) 724-5000, as listed in official Medicare / NPI Registry data.
- What is Constance C. Twu's NPI number?
- 1619028669. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Practice locations
Addresses where Constance C. Twu is enrolled with Medicare (CMS data updated 2026-10-02).
- 2295 S Vineyard AveOntario, CA 91761 (909) 724‑5000
- 9961 Sierra AveFontana, CA 92335 (909) 427‑5000
Group practices
Medicare enrollment lists Constance C. Twu as a member of this group (CMS data updated 2026-10-02).
- Southern California Permanente Medical Group11,293 clinicians in the group
Specialties
- Optometryprimary
Other optometrists in Ontario
Clinicians with the same Medicare primary specialty in Ontario, CA — not a recommendation.
Clinician information
| Credential | OD |
|---|---|
| Medical school | Southern California College Of Optometry |
| Graduation year | 2002 |
| Gender (as listed) | Female |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| NPI (National Provider Identifier) | 1619028669 |
| Corrections | Report an error or suggest an update → |
Most corrections must be made at the source: clinicians update their NPI Registry record (NPPES) and their Medicare enrollment (PECOS); this page follows the next data release.
Sources
- National Downloadable File (Doctors and Clinicians) — CMS, data updated 2026-10-02, retrieved 2026-10-29
- NPI Registry — U.S. Department of Health and Human Services (NPPES), the clinician’s official record
- Medicare Care Compare — official Medicare tool to look up clinicians