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American Surgery Center of South Texas

Our Surgeons


John F. Kozlovsky, MD

Specialty: Ophthalmology

Dr. Kozlovsky is a board-certified ophthalmologist. He received his undergraduate degree from St. Mary's University in San Antonio and attended medical school at the Baylor College of Medicine in Houston. Dr. Kozlovsky completed his internship at the Baylor University Medical Center in Dallas and his residency at the University of Arkansas for Medical Sciences in Little Rock.

Dr. Kozlovsky belongs to several organizations including the Bexar County Medical Society, the Texas Medical Association, the Texas Ophthalmological Society and the American Academy of Ophthalmology. In addition to practicing, he is also an assistant professor in the Department of Ophthalmology at the University of Texas Health Science Center and is on the Medical Advisory Board at the Methodist Ambulatory Surgery Center of Central San Antonio.

Sebastian A. Mora, DO


Specialty: Ophthalmology

Dr. Sebastian Mora at American Surgery Center of South Texas

Sebastian A. Mora, D O was born at Brooke Army Medical Center (BAMC) and has exclusively used the surgical center since 1992. He is board certified by the American Osteopathic Board of Ophthalmology, American Board of Ophthalmology and the America Board of Eye Surgery (cataract/implant surgery).

Dr. Mora is the principal investigator for Corona Research Clinical Studies and has been doing clinical research trials for the past ten years as well as accepting new patients.

He is a polyglot speaking English, Spanish and French.

He enjoys spending his free time with his wife, Anne-Catherine and their three children.

Raymond H. Hernandez III, MD


Specialty: Ophthalmology

Dr. Hernandez is proud to have been born and raised in San Antonio, Texas. He graduated from Clark High School in 1983, earning academic scholarships including designation as a National Merit Scholar. Dr. Hernandez dreamed of a career in medicine since childhood, influenced by his father and his uncle, both local physicians. As a young boy, he developed an interest in archeology after finding arrowheads at his father's H ill Country ranch. While at Texas A&M University, he took advantage of the opportunity to further this interest and earned a degree in Anthropology in 1987. Dr. Hernandez then moved to Northern California to study at Stanford University School of Medicine. Following graduation in 1991, he completed an internship in Internal Medicine. He then traveled to New Orleans for residency in Ophthalmology at the Ochsner Clinic. Because of a special interest in glaucoma, Dr. Hernandez performed an additional year of sub-specialty training (Glaucoma Fellowship) at Northwestern University Medical School in Chicago.

Dr. Hernandez was pleased to return to his native Texas in 1996 to enter group practice. In the summer of 2000, he opened his own office, North Central Ophthalmology, in the Stone Oak area. While many of his patients appreciate the convenience of an Eye M.D. in the neighborhood, Dr. Hernandez is honored to have patients who travel from as far as Del Rio to have him care for their eyes. Dr . Hernandez is board certified by the American Board of Ophthalmology. He has received the Physician's Recognition Award in Continuing Medical Education from the American Medical Association. Dr . Hernandez has assembled a highly qualified and friendly staff to assist with your eye care needs. We are pleased to offer comprehensive eye care in a people-friendly environment.

Timithy D. Dunham, MD


Specialty: Ophthalmology

Dr. Dunham is a board-certified ophthalmologist with 29 years of experience in the field. He is a graduate of the University of Minnesota Medical School, graduating in 1981. He interned the following year at the Hurley Medical Center in Flint Michigan. He completed his residency at the University of Texas Health Science Center in Dallas in 1985, and underwent a fellowship in 1986 at the King Khalid Eye Center in Riyadh, Saudi Arabia in 1986.

In addition to practicing at the American Surgery Center of South Texas, Dr. Dunham also practices at the Medical Center Eye Institute, also located in San Antonio.

Sanjiv R. Kumar, MD


Specialty: Ophthalmology

Dr. Kumar is a Board Certified Ophthalmologist. Dr. Kumar is a Phi Beta Kappa graduate of Johns Hopkins University in Baltimore, Maryland. He earned his medical degree from Harvard Medical School in Boston, Massachusetts. He completed his Ophthalmology Residency at USC Medical Center in Los Angeles, California. Dr. Kumar has published numerous articles and publications on specialized ophthalmology procedures and treatments.

Dr. Kumar speaks Spanish and has practiced in South Texas since 1995.

Nader G. Iskander, MD


Specialty: Ophthalmology

Photo of Dr. Iskander at American Surgery Center of South Texas

Dr. Nader Iskander is a Board-Certified Ophthalmologist and fellowship-trained refractive surgeon with extensive experience in LASIK vision correction, advanced cataract extraction procedures and anterior segment reconstruction techniques. Dr. Iskander is considered one of the expert eye surgeons in San Antonio, Texas and has personally performed more than 12,000 laser vision correction, cataract, and eyelid procedures.

A third generation ophthalmologist, Dr. Iskander has helped thousands of patients see better since 1995. Dr. Iskander brings an international experience to San Antonio Eye Specialists. He attended the University of London prior to joining Alexandria University Medical School where he received his Doctor of Medicine degree and graduated with honors at the top of his medical school class. Dr. Iskander completed his residency training at the the world renowned Cleveland Clinic and the prestigious Kresge Eye Institute in Michigan. He undewent further sub-specialty fellowship training in refractive surgery at the world famous Gimbel Eye Center in Calgary, Canada where he was mentored by Dr. Howard Gimbel, M.D., who is widely considered to be one of the most influential refractive and anterior segment surgeons of the twentieth and twenty-first centuries. This fellowship together with Dr. Iskander's extensive experience made him an expert in a wide array of vision correcting procedures and state-of-the-art technologies that he provides to his patients.

Dr. Iskander received numerous honors and awards for his contributions to the science of ophthalmology. In addition to his skill and care as a refractive, cataract, and anterior segment specialist, Dr. Iskander’s accomplishments include serving as former medical director for LASIK Plus vision center, San Antonio, and former director of TLC Laser Eye Centers in Northern California. He is also a former Assistant Professor of Ophthalmology at Wayne State University, Michigan where he taught refractive and cataract surgery to ophthalmologists-in-training. He has authored a book chapter and co-authored a textbook on LASIK surgery. He has been published in the journal,Ophthalmology, the Journal of Cataract and Refractive Surgery and other leading medical publications, and is frequently invited to speak at professional conferences and medical schools. Dr. Iskander has also tought courses as an expert to practicing ophthalmologists at the American Academy of Ophthalmology. He has also served on expert panel at the American Society of Cataract and Refractive Surgery.

Lisa Martén, MD

Specialty: Ophthalmology

Dr Lisa Marten at the American Surgery Center of South Texas

Lisa Martén, M.D. is Board Certified by the American Board of Ophthalmology with advanced fellowship training in Cornea and Refractive Surgery. Dr Martén performs the latest techniques involving bladeless iLasik and PRK procedures, Intacs for Keratoconus, Collagen Crosslinking, Implantable Collamer Lenses (ICL) and laser cataract surgery with multifocal lens implants. She trained at a referral center for Lasik, and treated many complications, helping her have a more careful approach when choosing candidates for surgery. She also has a background in nutrition and worked at a center for nutrition research in her home country of Costa Rica. She has extra insight into diseases that affect the eye such as Diabetes and Macular Degeneration.

Dr. Martén received her undergraduate degree from Tulane University, as well as attending their School of Public Health Tropical Medicine for her Master’s Degree in Nutrition. She also earned her Medical Degree from their medical school in 2001. During her studies, she won the AMA Foundation Leadership Award for her work as the president of the Latin American Medical Student Association. She also participated in research and received a grant from the American Heart Association. After completing her internship, Dr. Martén came to San Antonio for her Ophthalmology residency at the UT Health Sciences Center where she is now an assistant clinical professor. She moved to Tennessee where she attended the Wang Vision Institute for her fellowship. Dr. Lisa Martén is currently the medical director and owner of the South Texas Eye Institute, the first clinic in San Antonio to perform Lasik. She has performed thousands of refractive procedures and was recently honored from among her peers as one of the Top 12 Lasik Surgeons in the United States. South Texas Eye Institute also partners with research organizations where Dr. Martén is an investigator for several clinical trials. Dr. Martén has been selected as America’s Top Ophthalmologist with special mention in Cornea and Refractive Surgery, and one of San Antonio’s Top Doctors. She is also proud to be the official Eye Care Provider and Lasik Surgeon for the San Antonio Rampage AHL Hockey Team. Born in New Orleans, LA and raised in San José, Costa Rica, Dr. Martén’s unique combination of cultures allows her to bring her patients quality care and the best service in their native language. Her patients value her dedication and the time she takes to explain eye conditions and their treatments. They also appreciate her donating her time for medical trips to Mexico and Costa Rica.

Gregory Parkhurst, MD


Specialty: Ophthalmology

Dr. Parkhurst Mora at American Surgery Center of South Texas
Gregory D. Parkhurst, M.D. is recognized internationally as an expert and leader in LASIK and Cataract Vision Correction, and was recently listed as #8 on the Top 40 Under 40 Most Influential Ophthalmologists in the world.

  • • Board Certified & Fellowship Trained Cornea Specialist
  • • Medical Director of First LENSAR Laser Cataract Center of Excellence in the United States
  • • Performed over 13,000 successful ocular procedures including LASIK, PRK, ICL, Cataract Surgery and more
  • • Former Chief of Ophthalmology and Refractive Surgery in the military, having helped thousands of soldiers see their best prior to deployment over seas
  • • Highest Volume Implantable Contact Lens surgeon in the US for 2 consecutive years; one of 5 surgeons in North America inducted into the ICL Master’s Club
  • • Author of Multiple Peer Review Publications articles on Refractive Surgery in such prestigious journals as The Journal of Refractive Surgery, Ophthalmology Times, Cataract & Refractive Surgery Today, Refractive Surgery Outlook, and others
  • • Author of Multiple Text Book Chapters on Cataract and Refractive Surgery published in multiple languages worldwide. International teacher and lecturer, Award Winning Medical Researcher
  • • Faculty Instructor for the American Academy of Ophthalmology, the American Society of Cataract and Refractive Surgery, and the European Society of Cataract and Refractive Surgery
  • • President Elect of The Refractive Surgery Alliance, an international society of Refractive Surgeons
  • • Principal Investigator for multiple US FDA Clinical Trials including corneal inlays for the treatment of presbyopia, Corneal Collagen Crosslinking for the treatment of Keratoconus, and excimer lasers used in LASIK surgery
  • • Consultant to Ophthalmic Industry Including Alcon, Staar Surgical, ReVision Optics, LensAR, and others
  • • Refractive Eye Surgeon to professional athletes, TV personalities, fighter pilots, his family members, and a wide range of people desiring reduced dependence on glasses and contact lenses including Country Music Legend George Strait
  • • Had Successful Laser Vision Correction on his own eyes in 2003