EyeWorld Asia-Pacific September 2012 Issue

23 EWAP CAtArACt/IOL September 2012 In the clinic Audrey R. Talley Rostov, MD, Northwest Eye Surgeons, Seattle, Wash., USA, has found that both technique and technology can An eye post-DSAEK. With the advent of the surgery (pictured here), the corneal endothelium has received significant attention. Source: Mark Gorovoy, MD make a difference here. She prefers a biaxial phacoemulsification technique, using two small incisions. “I find that works extremely well for Y.C. LEE, FRCS, FRCOph Chairman, Lee Eye Centre 44-46, Persiaran Greenhill, 30450, Ipoh, Perak, Malaysia Tel. no. +605-2540095/+605-2544951 Fax: +605-2540273 yc_lee@lec.com.my www.lec.com.my E ndothelial cells are damaged in many ways during phacoemulsification, by the heat generated, the turbulence of the fluid with lens particles striking against the endothelial cells, the free radicals released, cavitation pressure wave changes during implosion, inadvertent instrument contact with the endothelial cells during surgery, and the inappropriate use of non-physiological intraocular solutions and drugs. Damage to these cells is more severe in certain individuals with corneal pathology, glaucoma and systemic diseases such as diabetes mellitus. Advanced age is also a risk factor. Preservation of these functionally important endothelial cells during phacoemulsification is obligatory. Strategies to minimize this damage are directed towards causative factors. Power modulation and torsional or elliptical phacoemulsification are important advances that reduce heat generation and improve efficiency. These advances reduce surgery time. Less heat, pressure waves and toxic free radicals are produced. Coupling these with meticulous surgery away from the endothelial surface and the judicious use of ocular visco surgical devices (OVDs) such as the soft shell technique further protects the endothelium. Dispersive OVD with negative ions that bind with the endothelial cells stays in the anterior chamber longer and has better scavenger effects than its cohesive counterparts. Customizing the use of OVDs in accordance with their individual properties facilitates phacoemulsification. Frequent re-introduction of OVDs in difficult and prolonged surgery especially in dense rock-hard cataracts maintains clarity of the post operation cornea. Non-physiological intraocular fluids and drugs are toxic to the sensitive endothelial cells. Non-preserved drugs with the appropriate pH should be carefully selected before intracameral use. In patients with compromised cornea and if prolonged intraocular surgery is expected, BSS plus may be an advantage. Turbulent fluid flow can be minimized by balancing the inflow outflow rates and vacuum pressure. Unnecessarily high inflow rates damage endothelial cells especially if small nuclear chips are present. The optimum state is reached when the anterior chamber is stable after adjusting the above mentioned parameters. This can be customized for each individual eye. Each of the above mentioned strategies is effective in minimizing endothelial cell loss. However, a holistic approach by combining these strategies will be more efficient. Assessing the patient for surgery should include a careful examination of the diseased tissue, the whole eye, the orbit and the patient in general. Coexisting systemic diseases and abnormalities have to be addressed as they will influence a negative outcome if ignored. Editors’ note: Prof. Lee has no financial interests related to his comments. minimizing my cell loss,” she said. State-of-the-art technology should not be overlooked. “I would say that with the newer phaco machines that allow you to use less energy, less phaco power, the decreased duration and amount of phaco that you use can help preserve corneal endothelial cells,” Dr. Talley Rostov said. She pointed out that there has been a lot of talk about torsional phaco in which the handpiece delivers side-to-side oscillating ultrasonic movements, which can be helpful in sparing the endothelium. However, she doesn’t see this technology as the “holy grail.” “The torsional phaco is good but I’d say that any of the newer phaco machines are actually quite good,” she said. “By using any of the newer phaco technologies I think that you can minimize the amount of cell loss because you’re maximizing your phaco efficiency, and that’s really what it’s about.” Viscoelastic devices can also help with deferring endothelial cell loss. For some patients Dr. Talley Rostov finds a dispersive agent to be preferable. “A dispersive OVD such as Viscoat [Alcon, Fort Worth, Texas, USA/Hünenberg, Switzerland] or Duovisc [Alcon], which has a Viscoat-type molecule in it, those are going to coat the endothelium more,” she said. “But for the average cataract, do you need to use that? I think the answer is no.” Dr. Talley Rostov reserves this for special situations such as cases involving a patient who has undergone a previous corneal transplant or someone with Fuchs’ endothelial dystrophy. Viscoelastic devices can also help with deferring endothelial cell loss. Overall, Dr. Afshari sees the fortune of the corneal endothelium as dramatically improving. “There was a study in which there was only a 1.2% cell loss after phacoemulsification,” she said. “We have come a long way and we are doing great; the rate has gone way down to nearly insignificant.” Because of all of the improvements in technique and technology, practitioners are seeing much less pseudophakic bullous keratopathy. “We have changed the fate of the corneal endothelial cells for the better because of these advances,” Dr. Afshari said. EWAP Editors’ note: Dr. Afshari has financial interests with Bausch + Lomb (Rochester, NY, USA). Dr. Talley Rostov has financial interests with Abbott Medical Optics (Santa Ana, Calif., USA). Contact information Afshari: 919-681-3937, natalie.afshari@duke.edu talley rostov: 206-528-6000, ATalley-Rostov@nweyes.com