April 2019

GLAUCOMA

Research highlight
Studying IOP changes in glaucomatous eyes undergoing FLACS


by Maxine Lipner EyeWorld Senior Contributing Writer


Patient interface for the LenSx femtosecond laser (Alcon)
Source: Leonard Seibold, MD

 

Femtosecond laser-assisted cataract surgery (FLACS) is a potentially safer way for conducting cataract removal, according to some physicians. But what about in those with glaucoma? Results of a study1 published in the Journal of Cataract & Refractive Surgery showed that while both glaucoma patients and control eyes had a short-term rise in pressure following the FLACS procedure, this was significantly greater in those with glaucoma, said Leonard Seibold, MD.
Investigators wanted to look into this for several reasons. “The first was that we wanted to see if there was a long-term IOP reduction in patients undergoing FLACS similar to what we know occurs after conventional phacoemulsification,” Dr. Seibold said. “The second driver was that in prior studies looking at the use of the femtosecond laser for cataract surgery as well as refractive surgery, there have been documented acute IOP rises during and immediately after docking with the femtosecond laser system.” Investigators wanted to see if that IOP rise continued into the next day and beyond, if there was persistent elevation in IOP, and whether there were any safety concerns about this beyond the procedure itself.
The study included patients undergoing femtosecond laser-assisted cataract surgery at either the University of Colorado Eye Center or Vanderbilt University who were between the ages of 18 and 89. Patients were divided into two groups: (1) healthy control eyes with no prior history of glaucoma, ocular hypertension, or suspicion of glaucoma, and (2) a glaucoma group that included eyes with documented glaucoma, suspicion of glaucoma, or ocular hypertension.

Pressure spikes

Investigators determined that on the day 1 postoperative visit both groups had a significant increase in their IOP. “This was significantly greater in the glaucoma group,” Dr. Seibold said. “On average, mean IOP went up 2 mm Hg in the control group and 3.4 mm Hg in the glaucoma group, both of which were significant.” Also, the glaucoma group’s pressure was significantly higher than the control group, Dr. Seibold said. However, by week 1 that increase in IOP had disappeared and the IOP returned to baseline and continued to decrease to the point where it was significantly lower than baseline by 1 month after surgery in both groups.
The rise in pressure may be linked to the fact that even traditional phacoemulsification cataract surgery can cause an increase in IOP for a variety of reasons. “I think a lot of those still apply to patients undergoing FLACS,” Dr. Seibold said, adding that the addition of docking during the femtosecond laser treatment can cause at least a short-term spike in IOP, and this may persist to the day 1 postoperative visit.
Investigators found that by the 1-month mark the pressure in both groups had come down significantly. This pressure drop did not surprise Dr. Seibold. “We know that cataract surgery can lower IOP, and even though we’re using a laser to help perform the procedure we expected the long-term outcome to still be the same, still having the benefits of removing the lens to reduce the pressure on a long-term basis,” he said. “It was nice to see this in our data, that there was a long-term reduction in IOP, which was evident from the 1-month visit after surgery.”

Clinical implications
In Dr. Seibold’s view, the data suggests that glaucoma patients are more prone to an IOP spike after FLACS compared to a healthy eye or an eye without glaucoma. “I think clinicians should be aware of this and take extra precautions in patients with more advanced glaucoma who may or may not be able to tolerate even a moderate IOP spike right after surgery,” he said. In managing glaucoma patients who want to undergo the FLACS treatment, Dr. Seibold advises to either restart glaucoma medications earlier, such as immediately after surgery, or administer some type of intraoperative or immediately postoperative treatment to help minimize IOP spikes. For example, this might include use of an intracameral miotic or oral acetazolamide, he noted.
In addition to the spike in pressure, the study showed a significant reduction in pressure in both groups beginning at 1 month after surgery, Dr. Seibold reported. “This was seen for 1 year in the control group, after which the pressure returned to the baseline,” Dr. Seibold said. “In the glaucoma group the significant IOP reduction was persistent through 3 years of follow-up.” The other difference was that the IOP reduction long term was significantly greater in the glaucoma group compared to control eyes.
Dr. Seibold hopes that practitioners come away from the study with the understanding that FLACS can achieve long-term IOP reduction after cataract surgery to a similar degree as seen in traditional phacoemulsification, with the only difference being that these eyes are a little more prone to a 1-day postoperative IOP spike.
Dr. Seibold is working on a follow-up study that looks at other safety measures like visual field changes after FLACS to see if the short-term spike has any long-term detrimental effect on this or on other clinical parameters.

About the doctor
Leonard K. Seibold, MD

Associate professor
Director of glaucoma fellowship
University of Colorado Eye Center
Aurora, Colorado

Reference

1. Shah AA, et al. Long-term intraocular pressure changes after femtosecond laser-assisted cataract surgery in healthy eyes and glaucomatous eyes. J Cataract Refract Surg. 2019;45:181–187.

Financial interests
Seibold
: None

Contact information
Seibold
: Leonard.Seibold@ucdenver.edu

Studying IOP changes in glaucomatous eyes undergoing FLACS Studying IOP changes in glaucomatous eyes undergoing FLACS
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