Laser versus manual cataract surgery

July 1, 2014

In a randomized study including 65 patients undergoing femtosecond laser-assisted or standard phacoemulsification, there were no significant differences between groups in central corneal thickness or endothelial cell loss at 1 week or 1 month postsurgery.

 

Take Home

In a randomized study including 65 patients undergoing femtosecond laser-assisted or standard phacoemulsification, there were no significant differences between groups in central corneal thickness or endothelial cell loss at 1 week or 1 month postsurgery.

 

Using femtosecond laser technology, the anterior capsulorhexis, nuclear fragmentation, and corneal incisions are created. (Video courtesy of Georgina Givaudan-Pedroza, MD)

 

By Cheryl Guttman Krader; Reviewed by Georgina Givaudan-Pedroza, MD

Mexico City-Results of a prospective, randomized trial comparing two procedures-femtosecond laser-assisted and standard cataract surgery-show that the laser procedure reduces the need for ultrasound energy and is associated with less early corneal edema. However, the difference in central corneal thickness (CCT) between procedures is short-lived, and endothelial cell loss is similar for the two techniques, said Georgina Givaudan-Pedroza, MD.

“Corneal edema and endothelial cell loss after cataract surgery can result in permanent decreases in vision," said Dr. Givaudan-Pedroza, private practice, Asociación Para Evitar la Ceguera en México, Mexico City.

There is evidence that these corneal complications are minimized with procedures involving lower effective phacoemulsification (phaco) time, including using a femtosecond laser. No persistent advantage for the femtosecond laser procedure was found in the study, but the potential benefit may vary depending on nuclear hardness, she noted.

“Clearly, longer follow-up is needed to determine if the femtosecond laser provides better endothelial safety," Dr. Givaudan-Pedroza said. "The laser has changed the way we perform cataract surgery and has reduced certain complications by automating several steps.

"However, it is important to carefully evaluate any new technology in terms of how it elevates costs and whether there are benefits to justify the increased expense,” she added.

 

Understanding the research

The study included 65 patients operated on between May and August 2013. Eligible patients were >45 years of age without any history of ophthalmic surgery, corneal opacities, or inability to achieve adequate pupil dilation.

All surgeries were performed by two surgeons with the same level of expertise. All standard procedures were done using a phaco-chop technique and the same phacoemulsification unit was used in all cases (Infiniti Vision System with OZil, Alcon Laboratories). The femtosecond laser procedures were performed using the same femtosecond laser platform (LenSx Laser, Alcon Laboratories) for nuclear fragmentation and to create a 4.8-mm anterior capsulorhexis, 2.2-mm principal incision, and 1-mm side incision.

Patients were evaluated at baseline and at 1 day, 1 week, and 1 month after surgery using ultrasonic pachymetry to measure CCT and specular microscopy to determine the endothelial cell count (ECC).

Despite the randomization, the patients in the standard phaco group were significantly older than those having the femtosecond laser procedure (mean age 72.2 vs. 66.7 years). There was also a significant difference between the phaco and femto groups in mean preoperative cylinder (-0.81 versus -1.30 D). However, there were no significant differences between the phaco and femtosecond laser groups preoperatively in mean CCT, ECC, anterior chamber depth, axial length, or IOP.

Mean LOCS III cataract grade was 1.4 in the femtosecond laser group and 1.56 for the phaco group, and the difference was not statistically different.

 

Findings

Although there was no significant difference in mean percentage of phaco energy comparing the femtosecond laser and phaco groups, the laser group had significantly lower values than the phaco group for both mean phaco time (24.87 versus 32.24 sec) and mean effective phaco time (4.17 versus 8.21 sec).

At baseline, mean ECC was 2,230 cells/mm2 in the phaco group and 2,327 cells/mm2 for eyes undergoing the femtosecond laser procedure. Both groups exhibited a loss of ECC on the first day after surgery, but there was no significant difference between groups in mean ECC at any follow-up visit.

Mean CCT at baseline was 558 µm for the femtosecond laser group and 566 µm in eyes having conventional surgery. Both groups showed an increase on the first day after surgery, and the change in the phaco group was significantly greater compared with that observed for the femtosecond laser group.

Day 1 mean CCT was 596.3 µm in the femtosecond laser group and 602.5 µm in the phaco group. However, mean CCT had decreased in both groups after 7 days and returned to baseline levels at 1 month, and there were no significant differences between groups at either of those visits.

 

Georgina Givaudan-Pedroza, MD

E: gina.givaudan@gmail.com

Dr. Givaudan-Pedroza has no relevant financial interests to disclose.