Eyeworld

EW RESIDENTS 106 September 2015 by Purak Parikh, MD, Aida Bounama, MD, Anne Jensen, MD, Anita Kohli, MD, Neepa Shah, MD, Paul Tapino, MD, Scheie Eye Institute, University of Pennsylvania T he advent of phacoemulsi- fication has revolutionized cataract surgery, leading to improved patient safety, better visual outcomes, and shorter surgical time. However, the power from ultrasound energy gen- erates heat, free radicals, and oxida- tive tissue damage leading to corneal endothelial cell loss, iris damage, and cystoid macular edema. 1,2,3 Studies have shown that increased ultrasound energy, typically reserved for more advanced cataracts, leads to a higher incidence of these compli- cations. 4 In the past 6 years, the femto- second laser has offered an alterna- tive approach to several critical steps of cataract surgery, including corneal incisions, capsulotomy, lens soft- ening, and lens fragmentation. In Any advantages of femtosecond laser nuclear fragmentation should be most apparent with dense cataracts. I asked the Scheie Eye residents to review this study, which appears in this month's issue of JCRS. –David F. Chang, MD, EyeWorld journal club editor contrast to phacoemulsification, the femtosecond laser does not pose the same risk of damage to the cornea when softening or fragmenting a lens because of the 12-fold smaller cavitation bubbles it forms and the decreased thermal energy it produc- es. 5 In addition, recent literature has suggested that femtosecond laser use with cataracts of moderate density, graded by the standardized LOCS III scale, 6 can result in decreased addi- tional phacoemulsification energy needed to further soften the lens prior to aspiration. In fact, these re- ports suggest that in moderate densi- ty lenses, zero effective phacoemul- sification time (EPT) is required. 5,7 EPT is a common metric used to measure the amount of ultrasound energy transmitted to the eye during cataract surgery. It is determined by multiplying the total phacoemulsifi- cation time in seconds by the mean power used. 8 Previous studies have estab- lished that pretreatment of lenses with the femtosecond laser reduces EPT, but there has been no study comparing the EPT needed when treating dense, brunescent cataracts compared to lenses of moderate density. In the September issue of the Journal of Cataract & Refrac- tive Surgery, Hatch and colleagues examined this relationship. In this consecutive, prospective, compara- tive study, the authors divided 240 patients into 4 equal groups of 60 patients each. Group 1 underwent conventional phacoemulsification of cataracts of nuclear opalescence (NO) grade 3 (moderate opales- cence). Group 2 included patients with cataracts of the same NO grade 3, but these eyes underwent pre- treatment with the femtosecond la- ser. Group 3 included conventional phacoemulsification of more dense, brunescent NO grade 5 cataracts. Group 4 also included patients with NO grade 5 cataracts, but removal included femtosecond pretreatment. As expected, patients with dense brunescent lenses (groups 3 and 4) were significantly older than the patients in groups 1 and 2 who had less advanced cataracts. How- ever, the age difference between patients treated with conventional phacoemulsification versus fem- tosecond pretreatment was not statistically significant. General exclusion criteria included pupillary dilation less than 5.5 mm, decreased endothelial cell count, axial lengths less than 21 mm or greater than 28 mm, and previous significant ocular disease. The measured endpoints included the EPT and total sur- gical time. For the conventional phacoemulsification group, the surgical time was measured from the initial corneal wound creation until wound closure. For the femtosecond pretreatment group, the total surgi- cal time was measured from the time of vacuum creation during docking of the laser until wound closure. In this study, the femtosecond laser and operating microscope were in the same operating room and their sequential use required only a rota- tion of the operating bed. In this study, within the same grade of cataract opalescence, the EPT was found to be significantly less in the femtosecond pretreat- ment groups (group 2 had signifi- cantly less EPT compared to group 1 and group 4 had significantly less EPT then group 3). In fact, the EPT for all eyes in group 2, patients with moderate opalescence and pretreat- ment with femtosecond laser, was zero (i.e., requiring aspiration only and no phacoemulsification energy). In addition, the EPT required for femtosecond pretreated brunescent cataracts (group 4) was also statisti- cally significantly lower than that of moderate density lenses without pre- treatment (group 1). Surgical times for NO grade 5 brunescent cataracts were significantly higher compared to NO grade 3 moderate density lenses, but there was no difference in surgical time when comparing femtosecond pretreatment to con- ventional phacoemulsification in either the moderate or brunescent lens groups. This study supports previous literature suggesting that with moderate grade cataracts, femtosec- ond pretreatment can lead to zero phacoemulsification energy enter- ing the eye. However, it is the first known study to demonstrate that pretreating a brunescent cataract Review of "Femtosecond laser-assisted for removal of advanced cataracts" Paul Tapino, MD, residency program director, Scheie Eye Institute, University of Pennsylvania EyeWorld journal club Femtosecond laser-assisted compared to standard cataract surgery for removal of advanced cataracts Kathryn M. Hatch, MD, Tim Schultz, MD, Jonathan H. Talamo, MD, and H. Burkhard Dick, MD, PhD J Cataract Refract Surg (Sept.) 2015;41. Article in press Purpose: To compare effective phacoemulsification time (EPT) for the removal of brunescent cataracts treated with laser-assisted cataract surgery (LCS) to standard cataract phacoemulsification techniques. Setting: Ruhr University Eye Hospital, Bochum, Germany Design: Comparative prospective case study Methods: The Lens Opacities Classification System III (LOCS III) grading system was used to measure 240 eyes divided into 4 groups undergoing cataract surgery. Groups 1 (n=60) and 2 (n=60) contained eyes with LOCS III grade NO 3 cataracts treated with standard cataract surgery and LCS, respectively. Groups 3 (n=60) and 4 (n=60) contained brunescent cataracts, LOCS III grade NO 5, treated with standard cataract surgery and LCS, respectively. Results: The EPT for Group 1 ranged from 0.46–3.10 (mean 1.38), while EPT for all eyes in Group 2 was 0 (p<0.001). EPT for Groups 3 and 4 was 2.12–19.29 (mean 6.85) and 0–6.75 (mean 1.35), respectively (p<0.001). A comparison between EPT in Groups 1 and 4 showed that EPT for Group 4 was also lower than that of Group 1 (p=0.013). Groups 4 and 1 were the most statistically similar of all groups compared, suggesting that EPT for a femtosecond (FSL)-treated grade 5 cataract was most similar to that for a standard-treated grade 3 cataract. Conclusions: Femtosecond laser pretreatment for brunescent cataracts allows for significant reduction in EPT compared to manual standard phacoemulsification techniques.

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