By Lisa B. Arbisser, MD
This comparative case series found that femtosecond laser–generated clear corneal incisions (CCIs) had significantly lower endothelial gaping, endothelial misalignment, Descemet membrane detachment and posterior wound retraction than steel keratome–created CCIs. Additionally, femotosecond laser–created CCIS were within 10 percent of intended length, depth and angle measurements.
There are so many variables related to the parameters used to create incisions (such as energy of laser pulses, pulse duration, diameter of laser spots, distance between adjacent laser spots, and distance between rows or line-spot separation) that it will be hard to standardize between machines and to isolate effects of density and intensity between machines, but this surely is the future. I wish the authors had compared femetosecond lasers to diamond keratomes, in addition to metal.
In the current study, they performed a retrospective analysis of the records of 20 consecutive patients who underwent femtosecond laser–assisted cataract surgery (Catalys) at one hospital between November 2012 and March 2013. Their results were compared to 16 randomly selected age-matched controls who underwent conventional phacoemulsification with a keratome (2.65 mm steel) during the same period. All patients underwent anterior segment OCT one month after surgery.
The respective mean values in the femtosecond and keratome groups were CCI length, 1.99 mm versus 2.04 mm (P = 0.39); endothelial gaping, 0.14 mm versus 0.19 mm (P = 0.03); and endothelial misalignment, 0.04 mm versus 0.08 mm (P = 0.022).
No eye in the femtosecond group and three eyes in the keratome group had a Descemet membrane detachment (P = 0.04). Six femtosecond eyes and 11 keratome eyes had posterior wound retraction (P = 0.02).
Mean CCI length in the femtosecond group was 94.9 percent of the intended 2.1 mm, the posterior plane depth was 93.3 percent of the intended 70 percent, and the posterior side-cut angle was 91.7 percent of the intended 45 degrees.
The authors conclude that the architectural differences between the groups support the hypothesis that corneal incisions for cataract surgery created by a femtosecond laser have a better morphology than keratome-created incisions. Also the CCIs created with the femtosecond laser had a high degree of in vivo accuracy.
Further studies are needed to evaluate long-term architectural changes in the CCIs between the two groups and assess wound strength in femtosecond laser–generated corneal incisions.