EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
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40 EW FEATURE Phaco and vitrectomy January 2014 Phaco continued from page 38 Iris repulsion syndrome or reverse pupillary block caused by fluid misdirection in a post-vitrectomy eye undergoing cataract surgery have to question whether there has been any zonular trauma during the vitrectomy or any posterior capsular trauma, and you need to look for that." Dr. Fram said there are several factors that can cause complications in cataract surgery when there was a previous pars plana vitrectomy. These factors include white or brunescent cataract development and the possibility of pre-existing posterior capsular rent. There is "potential for zonular weakness, which may lead to fluid misdirection, causing paradoxical shallowing of the anterior chamber," Dr. Fram said. She also cited compromised fluidics due to the lack of vitreous support resulting in excessive deepening of the anterior chamber as a possible factor for complications. Special pearls for phaco surgeons Lowering the bottle height and using a second instrument placed under the iris to release the iris from the anterior capsule Source (all): Nicole Fram, MD eyes that have previously undergone vitrectomy or retinal procedures. "Wide incision techniques have a much greater intraoperative fluctuation of eye pressure, there is greater zonular stress as the cataract is less well supported by the anterior vitreous face, and there is the rare possibility of weakening of the posterior capsule during previous vitreous surgery," Dr. Huang said. "If capsular rupture occurs, retained lens material commonly results in increased eye pressure, inflammation, and cystoid macular edema," he said. Additionally, these eyes could be more prone to exacerbation of pre-existing retinal disease, which could include recurrent retinal tear or retinal detachment (especially in highly myopic eyes), CME in patients undergoing vitrectomy for neovascular complications of diabetes or vein occlusion, or reopening of macular hole. "Surgeons should be mindful that cataract surgery may increase the likelihood of neovascular AMD, iris neovascularization, or neovascular glaucoma," Dr. Huang said. Dr. Braga-Mele said that phaco in a post-vitrectomy eye presents a higher risk. This means the eye would have little or no vitreous in it. And for these cases, it is important to know that the eye would have a deeper chamber because of the lack of support. She noted that the chamber would likely be bouncier as well during phacoemulsification. "The other things you have to worry about, that a lot of people don't think of with these post-vitrectomized eyes, is obviously they have been entered through the pars plana," Dr. Braga-Mele said. "So you Dr. Braga-Mele said that one key point to remember in these patients is that because of the anterior/posterior movement of the lens, the patients will feel more pain. "Be very liberal with the use of intracameral lidocaine, and you may even consider a peribulbar block, depending on the case," she said. This could be particularly helpful for a super dense nucleus or if there is any concern for other complications occurring. "I also would advise making a shorter rather than longer wound because you will be working more deeply within the eye due to lack of vitreous support, and if you make too long of a wound, you will have striations within the cornea and you may find it harder to see what you're doing especially when removing the cataract in the bag," she said. Dr. Braga-Mele advised to be very aware of the possible lack of integrity of the posterior capsule, as well as to check the zonular integrity. "With respect to zonular integrity, you may want to consider, if there's a loose zonular complex, suturing the lens in," she said. She said if using hydrodissection for these cases to be cautious, or it may be beneficial to use viscodissection as an alternative. Dr. Braga-Mele said planning the case is extremely important. She often tries to make a larger capsulorhexis so that she is able to flip the nucleus out of the bag so it is not necessary to work so deep in the capsular bag-zonular complex. This technique allows the surgeon to bring the nucleus into the anterior segment to deal with it there. "If you are going to work in the bag, make sure you optimize your fluidics," she said. This can be done by lowering bottle height or putting in a posterior chamber maintainer. It is important for cataract surgeons to be aware of any previous vitreoretinal conditions that patients have had surgery for, Dr. Huang said. "Preoperative retinal consultation may be considered, and patients should be aware that factors may exist that can retard recovery." Additionally, "surgical techniques that limit zonular stress and stabilize the capsule should be employed." Using the vertical chop, a capsular tension ring, viscoelastic, and meticulous attention to fluidics can aid in avoiding complications. "Patients and staff should be educated about symptoms not typically associated with routine surgery, especially the onset of new photopsia, floaters, and decreased peripheral vision," Dr. Huang said. "In the event of complications, a team approach to management may optimize therapy." Dr. Fram offered several pearls for the factors contributing to complications that she mentioned, which include fluidics, white or brunescent cataracts, posterior capsule rent, and zonular weakness. For an excessively deep anterior chamber, she suggested lowering the bottle height. "Lowering the bottle height allows for more stable fluidics in the setting of an eye without vitreous support," Dr. Fram said. "In addition, one should lower the aspiration rate accordingly to maintain a stable chamber." However, she noted that it is important to remember that fluidic controls can vary from machine to machine. Reverse pupillary block (iris retropulsion syndrome) is a common occurrence during cataract surgery in post-vitrectomy eyes. This syndrome is caused by altered fluidics leading to posterior apposition of the iris to the anterior capsule.1,2 It is helpful to place a second instrument under the iris and gently lift anteriorly to release the reverse pupillary block. In eyes with low scleral rigidity (high myopes) reverse pupillary block may be a repeated occurrence during surgery. Placing one iris hook to break prolonged pupillary block is sometimes necessary.3 Diffuse zonulysis can lead to a floppy bag. If the eye is soft and the