Eyeworld

EW RESIDENTS 64 August 2016 by Musa Abdelaziz, MD, Amir Moarefi, MD, Christina Kytasty, MD, Achal Patel, MD, Nathan Carpenter, MD, Brian Chon, MD, Tamer Hadi, MD, and Jane Caty, MD, Case Western Reserve University cataract surgery: A laboratory study with corroborative clinical obser- vations," Koplin et al. published a retrospective evaluation of live cat- aract surgery and experimental flow and fluid dynamic studies. The study consisted of 3 different parts. In part 1, using HDV (high definition vid- eography) at both normal and slow speeds, they analyzed alterations of fluid dynamics of 100 live cataract surgeries using 3 PE platforms: Infiniti (Alcon, Fort Worth, Texas), Centurion (Alcon), and Stellaris (Bausch + Lomb, Bridgewater, New Jersey). The appropriate proprietary sleeve configuration was used with the respective PE machine. In part 2, hydrodynamic fluid analysis of ante- rior chamber irrigation was explored using the Kitaro simulated cataract surgical eye system. Infusion fluid dynamics were studied using micro- beads examined by the Photron MC2 high speed camera during var- ious needle-sleeve complex surgical manipulations. In part 3, iris leaflet movement was observed by color flow Doppler ultrasound during PE in the setting of various surgical manipulations. Live surgery videography demonstrated that infusion sleeves were constrained at the fulcrum created at the corneal incision. This resulted in fluid obstruction on 1 side of the sleeve causing a rush of V isually significant cataracts are the most common cause of reversible vision loss in the world, affecting an estimated 24.5 million Americans and 250 million across the globe. 1 In the 5 decades since phacoemulsification (PE) was first introduced, this technology has rev- olutionized the treatment of patients with symptomatic cataracts, and it is now the standard of care for the management of visually significant cataracts. It is estimated that 3.6 million PE surgeries are performed annually in the U.S. and 20 million surgeries worldwide. 2 Several complications of cataract surgeries can occur unexpectedly, including iris flutter and retained lens fragment in the vitreous with- out posterior capsule rupture. These complications have been seen more frequently with the advent of chop- ping and other PE techniques with increased manipulation and frag- mentation of lens material. 3 A pre- vious study by de Castro exhibited more repulsion of polystyrene beads irrigated from a phacoemulsification tip using longitudinal over torsional delivery. This study explored the followability in the setting of both torsional and longitudinal energy. 4 In "Untoward events associated with aberrant fluid infusion during fluid on the contralateral side of the sleeve. In all 3 PE platforms, fluid was noted exiting the unobstructed side of the sleeve impacting the iris and causing fluttering of normal iris, which compromised follow- ability of nuclear lens material. The second part of the study using the Kitaro system showed the number of micro-beads was diminished on the side of the occluded port and increased on the unobstructed side of the port. Color flow Doppler ultrasound confirmed that aberrant infusion of fluid resulted in not only misdirection of lens material, but also flopping of the iris, which is typical of iris movement seen in intraoperative floppy iris syndrome (IFIS) patients. Excess of fluid from the unobstructed port can compli- cate an otherwise normal PE surgery by billowing of the iris and decrease in lens material followability. The current study demonstrated aberrant fluid dynamics associated with a fulcrum effect at the corneal wound. The paper does an excellent job combining clinical observa- tions with further studies of fluid dynamics in the Kitaro model eye and B-scan Doppler ultrasound. The Kitaro eye allowed visualization of fluid dynamic changes that are not as obvious during recordings of live surgery. Doppler ultrasound showed how changes with fluidics manifest with responses from the iris. The paper showed these effects occurred with multiple phacoemulsification machines and sleeve designs, which broadens its generalizability, inde- pendent of platform. One weakness of this study is the absence of discussion of corne- al wound construction. It is well established that position, width, and length of the wound contrib- ute to fluidics, and exploration of these variables were absent in this study. Another weakness is the lack of quantitative data reported on the fluid dynamic changes. While qual- itatively the velocity changes seem obvious, the technology should permit quantifying the degree of change in velocity. Intuitively, the change may be linear, such that the velocity from one side of the sleeve doubles with occlusion of the other half of the sleeve, but this information is absent. The article did not specify how many of the 100 patients were on alpha blockers and did not provide a sub analysis of IFIS patients compared to normal patients. Furthermore, more work is needed to establish the correlation between fluidics and propulsion of lens fragments into the vitreous with the described technique in cadaver or animal eyes. The article highlights the pos- sibility that fluid infusion during Review of "Untoward events associated with aberrant cataract surgery: A laboratory study with corroborative Case Western Reserve University residents Brian Chon, MD, Achal Patel, MD, Christina Kytasty, MD, Musa Abdelaziz, MD, Jane Caty, MD, Nathan Carpenter, MD, and Amir Moarefi, MD Source: Case Western Reserve University Manasvee Kapadia, MD, program director, University Hospitals Eye Institute, Case Western Reserve University Untoward events during phaco are not generally associated with the infusion sleeve—until now. I asked the Case Western residents to review this paper that appears in this month's JCRS issue. –David F. Chang, MD, EyeWorld journal club editor EyeWorld journal club

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