For refractive specialists, “the year 2017 becomes a landmark one when considering that so many technologies are now available to treat patients who previously had been left untreated,” said Arun C. Gulani, MD, MS.
For example, crosslinking (CXL) facilitates stabilization of the cornea before or after refractive surgery. New-generation multifocal toric lens implant options—and even refractive algorithm-based laser systems—are available that provide more precise applications, even in patients with irregular corneas, said Dr. Gulani, who is in private practice, Jacksonville, FL.
“These technologies can turn patients who are not candidates for refractive procedures into those who are candidates for vision corrective surgery,” he said.
CXL, customized CXL
The year 2017 was the start-up year for CXL for treating keratoconus and ectasia, in that many more patients were being treated, especially those with keratoconus, said Peter Hersh, MD, clinical professor, and director, Cornea and Refractive Surgery, Institute of Ophthalmology and Visual Science, both at Rutgers-New Jersey Medical School, Newark, NJ, and in private practice at the Cornea and Laser Eye Institute in Teaneck, NJ.
In the United States, the standard CXL procedure with epithelial removal and 30 minutes of ultraviolet light remains among the most effective of the CXL techniques.
U.S. clinical trials also have been conducted of accelerated CXL and CXL with pulsing, a technique that in theory allows more oxygen to be introduced into the cornea. Completion and results of these studies are awaited.
In the CXL arena, the standard epithelial-off protocol received previous FDA approval. The epithelial-on protocols are currently under evaluation. Historically and internationally, they have achieved mixed results.
In the United States, research studies of epithelial-on protocols are ongoing, and upcoming studies of these protocols in the United States will evaluate different approaches regarding pulsing and oxygen techniques that might lead to more robust clinical results, Dr. Hersh noted.
Customized CXL is another approach under study and is typically performed using the Avedro KXL II unit because two factors need to come into play in the customized procedures (i.e., eye tracking and creation of different treatment shapes). Customized CXL means the pattern of energy distribution in the cornea can be changed to obtain different CXL effects across the entire geometry of the cornea, making placement of the proper energy and the proper shape of the treatment essential, Dr. Hersh explained.
Photorefractive intrastromal CXL (PiXL) for refractive procedures, also one of the newer potential uses of CXL, is used to treat mild myopia, hyperopia, and astigmatism. To treat myopia with PiXL, a small optical zone size is used with large energy delivery; for treating astigmatism, a bow-tie shape; and for hyperopia, an angular shape. These studies are currently ongoing internationally.