February 29, 2012 (Abu Dhabi, United Arab Emirates) — Femtosecond (FS) laser for capsulotomy has better accuracy and precision than standard continuous curvilinear circular capsulorhexis techniques, according to the findings of a study presented here at the World Ophthalmology Congress 2012.
In an investigation led by Jose L. Güell, MD, associate professor of ophthalmology at the Autonoma University in Barcelona, Spain, Catalys (OptiMedica) FS laser treatment (n = 39 patients) was compared with manual cataract surgery (n = 29 patients). Study end points were accuracy of incisions and ease of surgical extraction of the fragmented cataract.
Accuracy assessments included deviation from intended diameter, using an average of 4 measurements; shape, defined by circularity using image analysis; deviation from intended center, assessed using still images from Catalys; cumulative dissipated energy (CDE), using Alcon's Infiniti system (an instrument specifically designed for surgeons to monitor the energy delivered during phacoemulsification); and the number of active phacoemulsification steps.
Capsule discs were excised and stained with trypan blue for analysis.
Results showed that FS was superior to manual extraction for all assessed domains.
For deviation from diameter, the measure was lower with FS than with manual surgery (29 μm ± 26 vs 339 μm ± 248; P < .001). "This is a 10-fold improvement in accuracy and precision," said Dr. Güell, "and frankly, this is not a surprise."
This improvement extended to capsulotomy shape. With a perfect circle defined as a score of 1.0, FS achieved a higher score than manual surgery (0.936 ± 0.038 vs 0.774 ± 0.146; P < .001).
"Fragmentation volume is autocustomized to each patient," explained Dr. Güell. "The mean diameter in this dataset was 5.3 ± 0.6 mm, and the mean depth was 4.3 ± 0.5 mm." When translated into the number of phacoemulsification manipulations, or active phaco movements required to split the lens into quadrants, there was a reduction of 45% with FS.
CDE was also lower with FS than with manual surgery (10.39 ± 6.61 vs18.54 ± 12.07; P = .005).
"In the lower degrees of hardness, there is certainly an advantage with Catalys," said Dr. Güell. "This is even more significant in cases where the nucleus is harder, with a 40% reduction of the dissipated energy of the ultrasound needed."
Dr. Güell went on to suggest that with a high degree of control now clearly demonstrated, "it may be that you can improve the final lens position, although this has not yet been clinically proven."
Although there is a consensus that FS laser technology is here to stay, the clinical relevance and economic utility of the technology as it applies to global patient populations remains an open question. After Dr. Güell's presentation, this concern was expressed by one ophthalmologist who asked: "Are we soon going to be looking at $10,000 cataract surgery?"
Dr. Güell responded that "this is a strong debate that all of us are now being involved in. My response is that any improvement in precision for any surgery is good. If the precision merits the expense...that is a question that must be addressed by payers and professional societies."
Peter Wiedemann, MD, professor of ophthalmology at the University of Leipzig in Germany, also expressed concern. "With so much new technology...I don't know that the payer system can endure it," he said. "Is capsulotomy more accurate with the femtolaser? Certainly. But if you are a well-trained surgeon, you may be able to do more or less the same thing."
What has yet to be proven, Dr. Wiedemann asserted, is whether the improved increments in accuracy result in better clinical outcomes. This, regardless of cost, remains to be seen.
Dr. Güell reports financial relationships with Alcon, Calhoun Vision, Carl Zeiss Meditec, Ophtec, OptiMedica, and Visiometrics.
World Ophthalmology Congress (WOC) 2012: Abstract FP-CAT-SA 198 (3). Presented February 18, 2012.
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