Vein Specialists of New York

Our Team



Ross T. Lyon, MD, FACS

Dr. Lyon is a board certified vascular and endovascular surgeon with over 20 years experience in the treatment of vein disorders.  Dr. Lyon graduated from the prestigious Pritzker School of Medicine in Chicago with internships at Barnes Hospital, St. Louis, and the San Diego Medical Center at the University of California.  His extensive experience includes 12 years as surgeon and associate professor of surgery at Weil-Cornell Medical Center/NY Presbyterian Hospital, attending surgeon at Memorial Sloan Kettering Cancer Center, New York Hospital and Jacobi Medical Center, and Director at Montefiore and Weiler Hospital, Non-Invasive Vascular Laboratories.

Board certified by the American Board of Surgery, Dr. Lyon is also a member of the American College of Surgeons, the New York Society of Cardiovascular Surgery, New York Surgical Society, Peripheral Vascular Society, Society of Vascular Technology and the Society of Diagnostic Medical Sonographers.

Dr. Lyon has written and contributed to over 50 articles and research papers and continues to contribute his experience and enthusiasm to improving the field of Vascular Medicine.


Nicholas Diacou, RVT, RVS

Nicholas is a registered vascular technologist with a physics background.  He developed special expertise in the evaluation of venous problems, especially venous insufficiency and varicose veins through his ultrasound training at Cornell Medical Center in New York. Nicholas' ultrasound exams are detailed and surpass the quality at many university-based hospital systems.
Cassy Clay, PA
Cassy is a Physicians Assistant with training at Lincoln Medical and Mental Health Center and Beth Israel Hospital in New York.  She is the "first assistant" vascular surgery cases in these hospital settings and brings this experience to her work at VSNY.  Cassy is an expert in the treatment of varicose veins and sclerotherapy.  Her patients receive the highest level of care.  Cassy received her MS from Mercy College, Bronx, NY and her BS from Bloomsburg University, PA.
Mary Kay Allen, Office Manager

Mary Kay's background combines business management and human resources.  She is able to effectively advocate for our patients to optimize insurance benefits and her professional enthusiasm allows patients to feel comfortable while their medical problems are being treated.  Mary Kay received her BS in Business Administration from the University of Connecticut.

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