Ophthalmology

Baylor St. Luke’s Medical Center’s Ophthalmology program is renowned for its medical innovation and groundbreaking procedures. Overcoming congenital blindness through gene therapy, developing accessible tools for analyzing astigmatism data, and activating the nasolacrimal reflex via electric stimulation to treat dry eye, are just a few highlights from this year.

Rare Form of Congenital Blindness Treated with First-of-Its-Kind Therapy

This novel therapy known as LUXTURNA treats patients with RPE65-associated Leber Congenital Amaurosis (LCA), an eye disorder caused by mutations in both copies of the RPE65 gene, which alter a key vision-enabling protein. The newly FDA-approved therapy option developed by Spark Therapeutics, reverses the effects of this condition by replacing the mutated gene that causes the disease with a healthy copy of the gene.

Baylor St. Luke’s Medical Center is one of ten institutions in the United States to offer this therapy and is home to the only retina surgeons in Texas who are specialized and trained in this advancement.

“Spark put a normal copy of the human RPE65 gene into a virus that is designed to infect the right cells in order to make the right protein,” said Dr. Timothy Stout, retina surgeon at Baylor St. Luke’s Medical Center and chair of ophthalmology at Baylor College of Medicine. “We then inject the virus underneath the retina in patients that have this condition and that’s how we can arrest the progression of the disease. The technology is remarkable because we can use a harmless-engineered virus to correct a blinding defect.”
The FDA approved LUXTURNA in December 2017 after a phase 3 clinical trial in which patients who received the drug could navigate a dimly lit obstacle course better (95% confidence level) than those who did not receive the treatment. RPE65-associated LCA patients who have been treated with this novel gene therapy have seen improvements in light sensitivity, visual field or how wide of an area people can see, and sight in dark conditions.

The most recent treatment in Houston was performed by Baylor St. Luke’s retina surgeon Dr. Roomasa Channa on three siblings from Georgetown, Texas, who were all born with the same condition caused by mutations in the RPE65 gene. “These kids have grown up not seeing things we take for granted, such as stars in the night sky or their parents’ faces,” said Channa, who also is a surgeon at Baylor St. Luke’s Medical Center and an assistant professor of ophthalmology at Baylor College of Medicine. “It’s great to hear their stories and the additional things they can slowly start to see after the procedure. Importantly, the therapy corrects the genetic defect and prevents further damage and loss of vision.”

LUXTURNA is the first directly administered gene therapy approved in the United States that targets a disease caused by mutations in a specific gene. This latest advancement signals the potential of gene therapy to successfully treat additional retinal genetic diseases for which there are no other treatments.
“There are millions of people who have problems with the other 300 genes that function as moving parts of the retina,” said Stout, who also was an investigator in a trial that demonstrated the effectiveness of RPE65 gene therapy. “We should treat genetic diseases for which we have no other treatments with gene replacement therapy. It might not cure all inherited retinal diseases, but it seems to work well in reverting or stopping the progression in this disease.”

Developing a Plot Tool for Precise Astigmatism Data Analysis

Dr. Douglas Koch, ophthalmologist at Baylor St. Luke’s Medical Center and Professor in Ophthalmology at the Baylor College of Medicine, served as one of the key figures behind the development of a free, downloadable double-angle plot tool for precise astigmatism data analysis.
“Our goal is to give physicians and researchers around the world a clear and uniform way to analyze their astigmatism outcomes of cataract and LASIK surgery. Double-angle plots are clear and precise for graphic display of astigmatic data. The relationship of data points, the centroids, and the 95% confidence ellipses can only be accurately displayed on a double-angle plot,” explains Dr. Koch.

“This plot is not available in standard software, such as Excel, and can only be found in expensive statistical software such as SPSS, SAS, and XLSTAT costing thousands of dollars. The double-angle plot tool is simple to download and use, and it displays outcomes correctly by simply entering the required data,” he continued.

“I think it is especially useful for in-depth and yet intuitive analysis of our procedures to treat patients’ astigmatism. By offering this to all who use it, we are seeing it become the standard for astigmatism reporting.”

Dr. Koch collaborated with Adi Abulafia, Jack Holladay, Li Wang, and Warren Hill in the tool’s development. Download the tool here.
Dr. Douglas Koch
Ophthalmologist at Baylor St. Luke’s Medical Center and Professor in Ophthalmology at the Baylor College of Medicine

Using Nerve Stimulation to Treat Dry Eye

Dr. Stephen Pflugfelder, ophthalmologist at Baylor St. Luke’s Medical Center and Professor in Ophthalmology at the Baylor College of Medicine, led a clinical trial to determine if Allergan’s TrueTear, a nasal nerve stimulator, can aid in the production of tears to treat dry eye.
The user inserts the device into their nasal cavity and pushes a button to release electrical pulses that activate the nasolacrimal reflex and alert eye glands to produce tears.
Dr. Pflugfelder and his team performed a randomized, double-masked, placebo-controlled study among 15 subjects and found that the device stimulated degranulation of goblet cells in the conjunctiva.
“Because the patients are stimulating their own tears, it could be a mainstay in therapy with patients who are willing to use it,” says Dr. Pflugfelder, who is widely considered the premier researcher in dry eye.
He would recommend it for patients with episodic pain. “It also can be for people traveling a lot or going into dry environments. It’s good for any aqueous tear patient who has the capability of responding to it,” he added.
Dr. Stephen Pflugfelder
Ophthalmologist at Baylor St. Luke’s Medical Center and Professor in Ophthalmology at the Baylor College of Medicine

Analyzing Intraoperative Aberrometry for IOL Surgical Decisions

Compiling outcomes data and reviewing multiple studies, Douglas Koch, MD, Ophthalmologist at Baylor St. Luke’s Medical Center and professor and Chair in Ophthalmology at Baylor College of Medicine, recently defended the position that intraoperative aberrometry is not the optimal solution for achieving consistent refractive accuracy.
“The outcomes that can be achieved using advanced biometry on an optimized cornea and ever-improving IOL formulas will always surpass those attainable with intraoperative aberrometry,” he explains.
Eyes that have undergone myopic LASIK or PRK present a challenge for achieving the refractive target after lens replacement surgery, and published studies often report no significant benefit of utilizing intraoperative aberrometry compared to standard preoperative calculations. However, it may prove valuable when performing more limited preoperative IOL calculations.
Analyzing 129 eyes with a history of laser refractive surgery, Dr. Koch concluded that the preoperative predicted IOL power disagreed with the intraoperative measurement in 97 of them. Fifty-seven of these eyes received an intraocular lens based on the recommendation of intraoperative aberrometry, and 40 received the implant according to the preoperative plan.
In the 57 eyes where the IOL changed following the guidance of intraoperative aberrometry, the tool proved beneficial in only about 50% of the cases. Among the 40 eyes where the selected IOL did not change to the intraoperative aberrometry recommendation, the outcomes of following the preoperative plan turned out to be the better decision in about two-thirds of the cases.
“In other words, using the intraoperative aberrometry data in this subset of eyes would have hurt our results,” said Dr. Koch.
Studies analyzing the use of intraoperative aberrometry in virgin eyes conclude with mixed results, but the evidence leans more against than in favor of the tool.
“Essentially, intraoperative aberrometry is trying to predict the effective lens position on an altered eye. We know that perfection in IOL calculation requires a pristine cornea, and without meeting that condition, intraoperative aberrometry has hit a ceiling in its accuracy, no matter how many data points go into its software to refine its performance,” he said.
However, preoperative measurement requires extensive time for the technician and surgeon to analyze the data, and intraoperative aberrometry does offer a preoperative time-saving benefit. Other studies have investigated its use in guiding selection and alignment of toric IOLs.
“Intraoperative aberrometry is a wonderful tool that has served our patients well and will continue to do so for many practices,” Dr. Koch concludes. “However, it is expensive technology, and it, too, takes up surgeon time in the operating room.”