Our Doctor

​​​​​Dr. Mosier is a board certified ophthalmologist specializing in Comprehensive Ophthalmology. He is an accomplished and highly skilled cataract and anterior segment eye surgeon with extensive experience in the diagnosis and treatment of eye diseases.

Dr. Mosier completed his residency in Ophthalmology at the University of California, Irvine School of Medicine. He is a former Associate Clinical Professor of Ophthalmology at the University of California, Irvine and is the founder and medical director of the Mosier Eye Center Medical Group in Fullerton, California.

Dr. Mosier is a Fellow of the American Academy of Ophthalmology and a member of the American Society of Cataract and Refractive Surgery, California Association of Ophthalmology, California Medical Association, Orange County Medical Association, and the Orange County Society of Ophthalmology. He is an active member of the medical staff at St. Jude Medical Center, Fullerton.

Dr. Mosier and his staff are committed to providing his patients with only the highest quality medical and surgical eye care, and vision care. His golden rule has always been to “treat my patients as I would expect to be treated”. Dr. Mosier has contributed to the Southern California community in many ways throughout his career and has been recognized by the California State Senate and Orange County Board of Supervisors for his volunteerism in providing charitable specialty care services to medically indigent residents in Orange County.

Dr. Mosier and his wife have three children, and three grandchildren. He enjoys the outdoors- camping, hiking, and fishing- as well as, gardening and cooking.

​​​​​Dr. Mai Pham is a highly respected, accomplished, board-certified, Comprehensive Ophthalmologist and fellowship-trained Cornea Subspecialist, with extensive training and experience in the medical and surgical treatment of eye disease. As a comprehensive eye physician and surgeon, she diagnoses and treats a wide variety of eye conditions such as cataract, glaucoma, diabetic retinopathy, macular degeneration, and ocular inflammation. She specializes in traditional and advanced technology cataract surgery, minimally invasive glaucoma surgery, refractive surgery, treatment of corneal disease, and therapy of dry eye conditions.

Dr. Pham attended the University of California, Los Angeles with a National Merit Scholarship, completing her undergraduate degree with distinction in Molecular, Cell, and Developmental Biology. She earned her Doctor of Medicine degree with honors from Boston University School of Medicine. Dr. Pham then completed her Internal Medicine Internship, Ophthalmology Residency and Chief Residency at Geisinger Medical Center, in association with Wills Eye Hospital, in Pennsylvania. She completed an additional year of Corneal Fellowship studies and an assistant professorship at the University of Missouri Mason Eye Institute.

Dr. Pham is a Fellow of the American Academy of Ophthalmology, a member of the American Society of Cataract and Refractive Surgery, California Medical Association, Orange County Medical Association, and the Orange County Society of Ophthalmology. Dr. Pham has led research studies in the areas of dry eye disease, conjunctivitis, and the safety of cosmetics in the ocular area. She has also partnered with industry to bring the best and latest evidence-based medications, surgical techniques, and devices to her patients.
Dr. Pham considers practicing medicine a great privilege and an honor. She believes that the most important and rewarding aspect of her career as an ophthalmologist is the relationship that she builds with each of her patients. Her compassion, technical skills, ability to educate, and dedication to lifetime learning allow her to provide individualized, state-of-the-art patient care to optimize her patients’ health and quality of life.

When not with her patients, Dr. Pham enjoys the many amenities that Southern California has to offer. She enjoys spending time with her family and friends, being outdoors, hiking, swimming, beach-related activities, and, when possible, exploring restaurants and museums, and traveling.

​​​​​Dr. Leung was born and raised in San Francisco but now calls Orange County her home. She earned her Bachelor of Science degree in molecular cell biology from the University of California, Berkley before earning her Doctor of Optometry degree, graduating Beta Sigma Kappa from the Southern California College of Optometry. Her extensive training includes professional internships at the VA Medical Center of West Los Angeles, VA Ambulatory Care Center of Los Angeles and the Optometric Center of Los Angeles. She has also worked at the Foothill Center for the Vision Impaired and Partially Sighted and at the Low Vision Department Rehabilitation Clinic.

Dr. Leung is a glaucoma certified optometrist, licensed by the State Board of Optometry in California and is experienced in the detection, treatment, and management of eye diseases including glaucoma, cataracts, allergies, and dry eyes.

In addition to prescribing eyeglasses and contact lenses, Dr. Leung provides high-quality care for patients with a wide variety of eye conditions, as well as patients who have undergone LASIK and cataract surgery. Dr. Leung is certified in Corneal Refractive Therapy (CRT), which is a non-surgical option that uses specialized contact lenses to correct nearsightedness during sleep. Her mission to provide individualized care with a personal touch drives her to educate her patients about their ocular health and care.

When she is not at work, Dr. Leung enjoys spending time with her husband and two children. She enjoys traveling, playing piano, watching Broadway musicals, and going to Disneyland.

​​​​​Dr. Matthew Y. Nobe is a board-certified ophthalmologist who joined Mosier Eye Center in August 2025. With over a decade of experience in comprehensive eye care, he is known for his thoughtful, patient-centered approach and commitment to clinical excellence. After 11 years of practice in New York, Dr. Nobe returned to his roots in Southern California..

A native of Orange County, Dr. Nobe received his undergraduate degree in Physiological Science from UCLA. He earned his medical degree and completed an Internal Medicine internship at UC Irvine, followed by residency training in Ophthalmology at SUNY Stony Brook in New York. His clinical expertise encompasses the full spectrum of ophthalmic care, with a particular focus on personalized treatment plans and long-term visual health.

Outside the clinic, Dr. Nobe enjoys spending quality time with his family and friends, staying active through sports, and indulging in his passion for music—though his daughter now curates most of his playlist. Whether cheering from the sidelines or relaxing at home, he brings the same warmth and dedication to his personal life that he offers his patients every day.