Considering laser cataract surgery in combined glaucoma procedures

Femtosecond laser-assisted cataract surgery (FLACS) has some benefits for patients and for surgeons, but it remains to be seen if it adds value when used in combined glaucoma-cataract procedures, said Leon W. Herndon Jr., MD.

“Most glaucoma patients are appropriate candidates for FLACS, and FLACS can make cataract surgery easier,” said Dr. Herndon, professor of ophthalmology, Duke University School of Medicine, Hillsborough, NC. “Overall, FLACS has been shown to be safe, and it is growing rapidly. The question remains, however, whether glaucoma surgeons should be making the leap.”

The femtosecond laser can be used in cataract surgery for corneal incisions, capsulotomy, and lens pre-treatment, Dr. Herndon noted. Its use has advantages for customizing the procedure; providing a live OCT of the anterior segment; improving capsulotomy size, shape, and centration; reducing ultrasound energy use through lens pre-treatment; and creating precise arcuate incisions for astigmatism treatment.

The effects of FLACS on surgical outcomes is controversial. Results of a recently published multicenter case-control study from Europe, which included 2,814 FLACS cases and 4,987 eyes undergoing conventional cataract surgery, reported no difference between groups in refractive outcomes or intraoperative complications [Manning S, et al. J Cataract Refract Surg. 2016;42:1779-1790].

However, the incidence of postoperative corrected distance visual acuity (CDVA) worse than preoperative was higher in the FLACS group and could be explained by more postoperative corneal edema, early posterior capsule opacification, and uveitis in the FLACS group.

“One issue to be aware of when performing FLACS is that cortex removal can be more challenging,” Dr. Herndon said.

Issues specific to glaucoma

Potential concerns about performing FLACS in patients with glaucoma relate to effects of the docking procedure and include the development of subconjunctival hemorrhage, which may be an issue if performing a traditional filtering procedure, along with increase in IOP.

“We know IOP can increase to 60 mm Hg or higher during standard cataract surgery and to between 70 and 90 mm Hg during LASIK flap creation,” Dr. Herndon said. “We also know that transient elevations in IOP are well-tolerated in healthy eyes, and we routinely perform cataract surgery in glaucoma patients. The question, however, what is the effect of FLACS on IOP in eyes with glaucoma.”

Results of a study by Darian-Smith et al. [J Cataract Refract Surg. 2015;41:272-277] indicate that the IOP rise after FLACS is less than with some other ocular procedures, although higher in glaucomatous than in non-glaucomatous eyes. These investigators measured IOP at four timepoints using rebound tonometry in glaucomatous and healthy eyes undergoing FLACS. The results showed the mean change in IOP from baseline to vacuum-on was not significantly different between groups nor was the mean change from baseline to after vacuum was undocked. Mean change in IOP after treatment, however, was significantly higher in the glaucomatous eyes compared with healthy controls (17.4 versus 14.1 mm Hg).

Patient selection

Glaucoma patients who may not be good candidates for a FLACS procedure include those with poorly controlled IOP, severe end-stage glaucoma, poor dilation, or who have a thin bleb or scleral patch graft that might preclude docking.

However, outcomes with FLACS can be good in a variety of complex eyes where it may be especially useful for creating the capsulotomy, said Dr. Herndon citing results from a retrospective study by Taravella et al. [J Cataract Refract Surg. 2016;42:813-816].

Their paper reported outcomes in a series of 34 complex eyes, including those with white cataract, dense brunescent cataract, and zonulopathy. Intraoperative complications included incomplete capsulotomy in 3 eyes, small radial anterior capsule tears in 3 eyes, and posterior capsule tears in 4 eyes. Nevertheless, 97% of eyes achieved final CDVA of 20/40 or better.

“The bottom line is that despite these events, visual outcomes were good and perhaps better than we would expect if the surgery had been done with manual techniques instead,” said Dr. Herndon.

He also shared his own experience performing FLACS in the setting of a complex glaucoma patient. The case involved a man aged 71 years who had moderate pseudoexfoliative glaucoma and 3+NS cataracts with pseudoexfoliative material OU. IOP was 16 mmHg OD and 17 mmHg OS with the use of four different glaucoma medications. BCVA was 20/70 OD and 20/50 OS.

Dr. Herndon operated on the right eye first and planned to combine traditional phacoemulsification with a microinvasive glaucoma surgery procedure.

However, significant zonulopathy was encountered intraoperatively, the patient required IOL implantation in the sulcus, and the glaucoma surgery was not performed.

The patient had a good recovery and 2 months later in the operated eye, UCVA was 20/30 and IOP was 12 mmHg on 3 medications.

“Cataract surgery itself can sometimes lead to good reduction in IOP,” Dr. Herndon said.

The patient was also anxious to have the left eye surgery. This time Dr. Herndon noted phacodonesis preoperatively and decided to perform FLACS with a 360° trabeculotomy.

The femtosecond laser treatment was uneventful. The capsule had to be stabilized with capsule retraction hooks intraoperatively, but the cataract and glaucoma surgeries were completed without incident.

Two months later, the patient had BCVA 20/20 OU. IOP was 14 mm Hg OD and 16 mm Hg OS on 3 medications.