Eyeworld

EW RESIDENTS 62 July 2016 including large randomized, con- trolled trials, will be necessary to provide definitive data in this regard. EW References 1. Nagy Z, et al. Initial clinical evaluation of an intraocular femtosecond laser in cataract surgery. J Refract Surg. 2009;25:1053–60. 2. Abell RG, et al. Toward zero effective phacoemulsification time using femtosec- ond laser pretreatment. Ophthalmology. 2013;120:942–8. 3. Conrad-Hengerer I, et al. Corneal endo- thelial cell loss and corneal thickness in conventional compared with femtosecond laser-assisted cataract surgery: three- month follow-up. J Cataract Refract Surg. 2013;39:1307–13. 4. Grewal DS, et al. Comparison of morpholog- ic features of clear corneal incisions created with a femtosecond laser or a keratome. J Cataract Refract Surg. 2014;40:521–30. 5. Mastropasqua L, et al. Scanning electron microscopy evaluation of capsulorhexis in femtosecond laser-assisted cataract surgery. J Cataract Refract Surg. 2013;39:1581–6. 6. Abell RG, et al. Anterior capsulotomy integ- rity after femtosecond laser-assisted cataract surgery. Ophthalmology. 2014;121:17–24. 7. Bartlett JD, et al. The economics of femto- second laser-assisted cataract surgery. Curr Opin Ophthalmol. 2016;27:76–81. 8. Schultz T, et al. Changes in prostaglandin levels in patients undergoing femtosecond laser-assisted cataract surgery. J Refract Surg. 2013;29:742–7. 9. Roberts TV, et al. Capsular block syndrome associated with femtosecond laser-assisted cataract surgery. J Cataract Refract Surg. 2011;37:2068–70. 10. Roberts TV, et al. Surgical outcomes and safety of femtosecond laser cataract surgery: a prospective study of 1500 consecutive cases. Ophthalmology. 2013;120:227–33. 11. Hatch KM, et al. Laser-assisted cataract surgery: benefits and barriers. Curr Opin Ophthalmol. 2014;25:54–61. 12. Abell RG, et al. Femtosecond laser-as- sisted cataract surgery versus standard phacoemulsification cataract surgery: outcomes and safety in more than 4000 cases at a single center. J Cataract Refract Surg. 2015;41:47–52. 13. Ewe SY, et al. A comparative cohort study of visual outcomes in femtosecond laser-as- sisted versus phacoemulsification cataract surgery. Ophthalmology. 2016;123:178–82. 14. Cahoon JM, et al. Comparison of venturi and peristaltic vacuum in phacoemulsification. J Cataract Refract Surg. 2015;41:428–32. 15. Gilbert M, et al. Safety profile of venturi versus peristaltic phacoemulsification pumps in cataract surgery using a capsular surro- gate for the human lens. Am J Ophthalmol. 2015;160:179–4. Contact information Barkmeier: Barkmeier.Andrew@mayo.edu receiving preservative-free tetra- caine. All surgeries were done under topical anesthesia. One notable difference between the groups is that the MP group utilized a peristaltic phacoemulsification system, while the FLACS group utilized a venturi system. All of the FLACS cases were done using the same laser platform (Catalys Precision Laser System, Abbott Medical Optics, Abbott Park, Illinois). Scott et al. reported a combined vitreous loss rate for all surgeons of 1.17% for the MP group versus 0.65% for the FLACS group (p<0.05), with exclusions, and 1.40% for the MP group versus 0.77% for the FLACS group (p<0.05), without exclusions. A statistically significant relationship was shown between date of surgery, and thus technique, and vitreous loss cases using a chi- squared analysis with X 2 =9.77 (with exclusions) p<0.01. Using odds ratio analyses, the MP cases were 1.6 times more likely to have vitreous loss in the group with exclusions compared to FLACS cases vs. 1.8 times more likely in the group with- out exclusions. In analyzing the individual sur- geon data, surgeon 1 had the highest number of vitreous loss cases with 35/1,302 cases (2.69%) in the MP group versus 15/907 cases (1.65%) in the FLACS group. Surgeon 2 had 2/289 cases (0.69%) in the MP group versus 1/460 cases (0.22%) in the FLACS group. Surgeon 3 was excluded due to lack of data for MP cases. Surgeon 4 had 3/2,059 cases (0.15%) in the MP group versus 2/1,732 cases (0.12%) in the FLACS group. Surgeon 5 had 4/134 cases (2.99%) in the MP group versus 4/272 cases (1.47%) in the FLACS group. No further statistical analysis was performed regarding individual surgeon data, but the authors note that each surgeon did decrease his or her individual vitreous loss rates during the FLACS period. This study has several notable strengths. First, this was done in a single-center setting in which all of the surgeons switched over from MP to FLACS on the same day. They reviewed a large number of cases during the MP time period and during the FLACS time period. All surgeons used the same laser interface and phacoemulsification systems. Nonetheless, this study does have several significant weaknesses that may preclude establishment of any definitive conclusions from the data. First and foremost, it appears that the group switched from a per- istaltic phacoemulsification system to a venturi-based system at the same time that they switched from MP to FLACS. Performance charac- teristics between surgical platforms are known to vary significantly (e.g., fluid dynamics, phacoemulsifica- tion efficiency, etc.). Cahoon et al. demonstrated that a venturi-based system increases the efficiency of lens removal at lower vacuum settings and decreases chatter at the phaco tip. 14 Although Gilbert et al. did not identify an increased risk of capsular tears in a human lens capsular surrogate model when us- ing a peristaltic system, 15 it remains possible that this study's concurrent change in surgical platform may be a confounding variable that contrib- uted to the reported decreased rate of vitreous loss. Lastly, it is possible that the results from surgeon 1 played a dis- proportionate role in overall group vitreous loss analysis. This single surgeon had both a large volume of surgical cases and a substantial reduction in vitreous loss rate, decreasing from 35/1,302 (2.69%) to 15/907 (1.65%) following the switch to FLACS. The group pointed out that this was their most senior sur- geon, and thus it is unlikely that this decrease was related to improved surgical skills over time, but rather could be attributed to the FLACS technology. The other 3 surgeons all had either a very low rate of vitreous loss to begin with or low surgical volumes. If surgeon 1's numbers did in fact "carry the group," then this report may best be considered an anecdotal example of a single surgeon's reduced vitreous loss rate following the switch from MP with a peristaltic system to FLACS with a venturi phacoemulsification system, a result that would less likely be gen- eralizable or applicable to the typical surgeon. In conclusion, this study adds to the growing, yet limited, body of literature regarding FLACS and its potential risks and benefits. The debate continues as to whether FLACS offers a true clinical outcome advantage over MP. More research, Review continued from page 60 Comparison of vitreous loss rates between manual phacoemulsification cataract surgery and femtosecond laser-assisted cataract surgery Wendell Scott, MD, Shachar Tauber, MD, James Gessler, MD, Johann Ohly, MD, Rachel Owsiak, MD, and Craig Eck, MD J Cataract Refract Surg (July) 2016;42. Article in press Purpose: To compare the vitreous loss complication rate of the manual phacoemulsification (MP) cataract surgery technique versus the femtosecond laser-assisted cataract surgery (LCS) technique. Setting: Single center. Design: Retrospective case series. Methods: 7,155 cataract surgery cases from 2010–2014 performed by 4 surgeons were audited for rates of vitreous loss. 3,784 cases from 2010–2012 were consecutively performed using MP while 3,371 cases from 2013–2014 were consecutively performed using LCS. Vitreous loss data was statistically analyzed with and without exclusions. Results: In a comparison of MP vs. LCS vitreous loss cases, the group's rate was 1.17% vs. 0.65% with exclusions and 1.40% vs. 0.77% without exclusions. In absolute terms, the rate decreased for every surgeon in the study. The chi-square test revealed a statistically significant association between date of surgery, and thus technique, and vitrectomy cases (X 2 (1)=9.77, p<0.01). Odds ratio analysis with vs. without exclusions indicated that surgeries performed from 2010–2012 using MP were 1.6 vs. 1.8 times more likely to have vitreous loss than those surgeries performed from 2013–2014 using the femtosecond LCS technique. Conclusions: Conversion from MP to LCS resulted in a statistically significant decrease in vitreous loss. Since vitreous loss increases the risk of other serious complications of cataract surgery, this new finding has important implications for the safety of cataract surgery.

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