Eyeworld

EW RESIDENTS 82 December 2016 by Michael Lin, MD, Elizabeth Rossin, MD, Natalie Homer, MD, Huy Nguyen, MD, and Seanna Grob, MD, MAS, Harvard Medical School ophthalmology residents Background Over the past 5 years, excitement has grown in the field of ophthal- mology over the use of femtosec- ond laser-assisted cataract surgery (FLACS). Since the 1970s, clinicians and researchers have been in search of a laser to use in corneal and cataract surgery that causes minimal thermal damage to adjacent tissues. 1 The femtosecond laser delivers ultra- short pulses of laser energy and thus minimizes collateral tissue damage. 2 Its original use was primarily for cor- neal flap creation in LASIK. Since the first report of femtosecond laser use in cataract surgery in 2009, the tech- nique has been rapidly adopted and implemented by cataract surgeons in the U.S., Europe, and Australia. The steps employed by the femtosecond laser include the creation of clear corneal incisions, corneal astigmatic treatment, creation of the capsuloto- my, and softening of the nucleus to allow more efficient aspiration. Recent studies found that in comparison to conventional phacoemulsification cataract surgery (CPCS), FLACS results in a signifi- cantly greater reproducibility of the capsulotomy (more regularly shaped, accurate, and precise, with better centration and intraocular lens/capsule overlap) and clear cor- neal wounds, as well as a significant decrease in the amount of energy required during phacoemulsifica- tion. 3–5 However, no study to date has rigorously evaluated the tradi- tional and more clinically relevant postop decrease in CDVA (1.0% vs. 0.4%, p=0.001). In addition, FLACS showed a statistically significantly lower percentage of patients achiev- ing vision equal to or better than 0.0 and 0.1 logMAR CDVA (70.8% vs. 76.1% for logMAR 0.0; 87.8% vs. 90.4% for logMAR 0.1; p<0.001 for both). Absolute biometry prediction error (BPE) was greater in FLACS versus CPCS (0.43 D vs. 0.40 D), a finding that was statistically but not clinically significant, and excluding FLACS cases with previous corneal refractive surgery gave a similar BPE of 0.41 D. Separate subgroup analysis of only FLACS patients with monofocal IOL implantation was performed due to the high rate of multifocal IOL use in the FLACS group (35.8% vs. <0.5% in CPCS), and this showed similar CDVA results. Postoperative complications were higher in the FLACS group (3.8% versus 2.3%). This was driven by statistically significant increases in corneal edema, early posterior capsule opacification (PCO) reducing visual acuity, uveitis requiring treat- ment, and uncontrolled IOP. Data on cystoid macular edema was not captured by EUREQUO as a separate postoperative complication. Comments Interest in femtosecond lasers for cataract surgery has been steadily ris- ing over the possibility of automated corneal incisions, corneal astigmatic treatment, anterior capsulotomy, outcome measures including visual acuity, refractive outcomes and rate of complications. Manning et al. are the first to conduct a large, well-powered, matched compari- son of CPCS versus FLACS in terms of the aforesaid clinically relevant outcomes. Study summary This paper reports the results of a multicenter case control study using the European Registry of Quality Outcomes for Cataract and Refrac- tive Surgery (EUREQUO) that was conducted in 18 European countries and Australia. Consecutive FLACS cases performed from December 2013 to May 2015 were compared to CPCS cases performed from January to December 2014. Surgeons had to have completed at least 50 FLACS cases to participate in order to ac- count for the learning curve associ- ated with the new technology, and FLACS eyes were matched to CPCS eyes from the existing EUREQUO CPCS database. In total, there were 2,814 FLACS cases matched to 4,987 CPCS cases. The study intended to have a 1:2 case-control ratio, but only achieved 1:1.8 (only 2,814 of 3,379 [83%] of FLACS cases were able to be matched) because there were not enough CPCS controls in the data- base with matching characteristics. The criteria included exact matching for preoperative logMAR corrected distance visual acuity (CDVA), age within 2 years, and same number (but not type) of ocular comor- bidities (glaucoma, AMD, diabetic retinopathy, amblyopia, other) and same number (but not type) of surgical difficulty variables (previ- ous corneal refractive surgery, white cataract, pseudoexfoliation, previous vitrectomy, corneal opacity, small pupil, other). There were differences in types of ocular comorbidities and surgical difficulty variables between groups because they were not matched exactly for each possible type of ocular comorbidity and sur- gical difficulty variable. The FLACS group included more eyes with amblyopia, previous corneal refrac- tive surgery, and pseudoexfoliation, while the CPCS group included more eyes with diabetic retinopathy, white cataracts, small pupils, and other surgical difficulty variables (deep set eyes, narrow palpebral fissure, pterygia, kyphosis, and inability to position) that prevented safe surgical docking of the femto- second laser device. FLACS was used for corneal incisions in 34.7% of cases in the FLACS group, capsuloto- my in 99.4%, nucleus fragmentation in 94.7%, and corneal astigmatism treatment in 4.5% of cases. The overall intraoperative com- plication rate for FLACS was 2.9%, compared to 1.5% for CPCS. Howev- er, 2% of FLACS complications were minor FLACS-specific complications that are not relevant to CPCS, such as imperforate laser corneal inci- sions, capsular tags, and incomplete laser capsulotomies. Notably, rate of posterior capsule complications was not significantly different (FLACS 0.4 % vs. CPCS 0.7%), and there was no significant difference in rate of vitreous loss or dropped lens mate- rial. The study did not collect data on anterior capsule tears, circularity or centration of the capsulorhexis, or phaco energy used as there were no comparators in the EUREQUO database for matching. The study followed patients for 7 to 60 days, although it did not specify the exact time point at which postoperative outcomes were recorded. Postoperative log- MAR CDVA was worse in FLACS by one letter (FLACS: 0.05, CPCS: 0.03). FLACS also had a statistically significantly lower percentage of patients with postoperative gain of one line of vision compared to CPCS (56.7% vs. 66.1%, p<0.001) and greater percentage of patients with Review of "Femtosecond laser-assisted cataract surgery versus standard phacoemulsification cataract surgery: Case-control study from the European Registry of Quality Outcomes for Cataract and Refractive Surgery" Carolyn Kloek, MD, residency program director, Harvard Medical School Department of Ophthalmology The EUREQUO clinical trial comparing FLACS to manual phaco is the largest prospective, comparative study performed to date. I asked the Harvard Medical School ophthalmology residents to review this important study that appears in this month's JCRS. –David F. Chang, MD, EyeWorld journal club editor Harvard Medical School ophthalmology residents (from left): Michael Lin, MD (second year resident), Seanna Grob, MD, MAS (chief resident and director of ocular trauma service), Lizzy Rossin, MD, PhD (second year resident), Natalie Homer, MD (second year resident), and Huy Nguyen, MD (first year resident) Source: Harvard Medical School continued on page 84

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