Marianne Cowley, MD

Medicare activity in 2024

Official CMS public-use data for Marianne Cowley, data year 2024 (released May 21, 2026). It covers Original Medicare (fee-for-service) patients only, not Medicare Advantage or other insurance. It shows volume, not quality or outcomes. CMS hides any count of 10 or fewer patients.

Most frequent services

1. Imaging of retina (92134)459 services
2. Established patient office or other outpatient visit with low level od decision making, if using time, 20 minutes or more (99213)222 services
3. Injection, aflibercept, 1 mg (J0178)198 services
4. Injection of drug into eye (67028)187 services
5. Established patient complete exam of visual system (92014)149 services

Chronic conditions among these patients

Share of this clinician’s Original Medicare patients with each condition, as published by CMS (it describes the patients, not the care given).

• High cholesterol75%
• High blood pressure72%
• Arthritis51%
• Diabetes39%
• Ischemic heart disease30%
• Anxiety23%

Hospitals where Marianne Cowley works

Medicare's Facility Affiliation Data lists Marianne Cowley at these hospitals (updated October 2, 2026). Each hospital page shows its address, phone, emergency services, Medicare rating and all its clinicians. Star rating and emergency services: Hospital General Information (CMS), data updated October 26, 2026.

• The Johns Hopkins HospitalBaltimore, MD · Acute Care Hospital · Medicare rating: 5 of 5 stars · Emergency services: listed by Medicare · CCN 210009

Practice locations

Addresses where Marianne Cowley is enrolled with Medicare (CMS data updated October 2, 2026).

• 161 Thomas Johnson Dr, Suite 275Frederick, MD 21702 (301) 620‑9268
• 6201 Greenleigh AveMiddle River, MD 21220

Group practices

Medicare enrollment lists Marianne Cowley as a member of these groups (CMS data updated October 2, 2026).

• Johns Hopkins University2,909 clinicians in the group
• Johns Hopkins University197 clinicians in the group

Specialties

• Ophthalmologyprimary

Find other Ophthalmology doctors in Maryland →

Other ophthalmologists in Frederick

Clinicians with the same Medicare primary specialty in Frederick, MD — not a recommendation.

• Robert E. Parnes, MD
• Adam S. Wenick, MD
• Adam T. Gerstenblith, MD
• John C. Henry, MD
• Jeremy J. Wood, MD
• Grant Justin, MD
• Ethan Sobol, MD
• Amy L. Nicholas, MD

All ophthalmologists in Frederick →

Other clinicians in Johns Hopkins University

Medicare enrollment lists these clinicians in the same group practice — not a recommendation.

• Fong Liu, MD
• Karen Lindeman, MD
• Norris Nolan, MD
• Mark Kelemen, MD
• David Eisele, MD
• Robert J. Flick, MD

Clinician information

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

1. Facility Affiliation Data — Centers for Medicare & Medicaid Services (CMS), data updated October 2, 2026, retrieved October 29, 2026
2. Hospital General Information — CMS, data updated October 26, 2026, retrieved November 13, 2026
3. National Downloadable File (Doctors and Clinicians) — CMS, data updated October 2, 2026, retrieved October 29, 2026
4. Medicare Physician & Other Practitioners - by Provider — CMS, data year 2024, released May 21, 2026; Medicare Physician & Other Practitioners - by Provider and Service
5. NPI Registry — U.S. Department of Health and Human Services (NPPES), the clinician’s official record
6. Medicare Care Compare — official Medicare tool to look up clinicians