Latest advances in intraoperative management

Femtosecond laser-assisted cataract surgery
Surgical advances in cataract removal include technologies and devices that reduce the phacoemulsification energy required. One such technology is femtosecond laser-assisted cataract surgery (FLACS), which became available at Mass Eye and Ear in 2014. The femtosecond laser can create corneal and astigmatic relaxing incisions, perform anterior capsulotomy, and fragment the nucleus. The many patterns of nuclear softening and fragmentation available may benefit eyes with very dense lenses, zonular compromise, or endothelial dysfunction.

 In addition, FLACS presents a useful adjunct for refractive cataract surgery with the ability to form a precisely placed and circular capsulotomy, which is important for IOL centration and preventing IOL tilt, as well as arcuate corneal incisions for keratometric astigmatism management. These laser incisions may be carefully programmed in their location, degree, and depth, including the ability to form sub-epithelial incisions which may be opened postoperatively for titration. The femtosecond laser does require an adequate optical path and pupil dilation to acquire OCT imaging and application of the laser and is an additional out-of-pocket expense for patients. A meta-analysis of 73 studies comparing FLACS to conventional phacoemulsification found greater circularity of the capsulotomy and lower cumulative dissipated energy with FLACS. Among randomized controlled trials, there was no statistically significant difference in anterior or posterior capsular ruptures.

miLOOP
The miLOOP (Zeiss) is a microinterventional cataract fragmentation device that is designed to reduce phacoemulsification energy and minimize capsular stress with centripetal force. This single-use surgical device consists of a retractable nitinol ring that is placed through the main incision. After capsulorrhexis formation and hydrodissection, the retracted ring is expanded horizontally under the lens capsule and rotated vertically to extend around the posterior equator of the lens. When retracted in situ, the nitinol loop mechanically bisects the nucleus. The process is typically repeated after rotating the nucleus 90 degrees, resulting in four quadrants sectioned without any phacoemulsification energy. The miLOOP can particularly benefit patients with dense brunescent lenses, especially those with a leathery posterior plate that is difficult to crack, and patients with endothelial compromise such as Fuchs’ dystrophy.

Intraoperative aberrometry
Intraoperative aberrometry (IA) is another important adjunctive surgical technology. Following lens removal and cortical cleanup, an aphakic refraction is performed using the aberrometer which is mounted on the surgical microscope. Utilizing pre-operative biometry, this aphakic refraction, and a large pool of postoperative data, the analyzer then recommends the IOL power to achieve the target refraction. This technology has potential benefits for fine-tuning results for toric or advanced technology IOLs, post-laser refractive surgery patients, or eyes that are outside the average range.

A recent review of 166 studies compared IA to the Barrett Universal II and Hill RBF formulas (for eyes without prior refractive surgery), the Barrett toric calculator (for toric IOLs), and the Barrett True-K (for post-refractive surgery eyes) and showed similar refractive results; however, when other formulas are used, IA showed better refractive outcomes. The aberrometer needs calibration each time it is mounted. It also decreases the brightness of the surgeon’s view in the microscope by 10%, which can be noticeable.