EyeWorld Asia-Pacific December 2016 Issue

December 2016 18 EWAP FEATURE Warming up to posterior polar cataracts by Maxine Lipner EyeWorld Senior Contributing Writer How to spot the signs of posterior polar cataracts and effectively treat them I t’s something most practitioners are periodically faced with: removing a posterior polar cataract. “You’ll see one every couple of months,” said Steven Safran, MD , Lawrenceville, New Jersey. “If it doesn’t ring a bell, it should because it could cause problems with the surgery.” This means being prepared to alter the technique to avoid challenges such as potential weakness in the posterior capsule. Signs of a polar cataract There are distinct signs that help distinguish a polar cataract from a posterior subcapsular one. Visually, a posterior polar cataract has a much denser central white plaque than a posterior subcapsular cataract. “It looks like a little white sticker right in the middle of the lens,” Dr. Safran said, adding that the rest of the lens may be clear. These are bilateral about 60–85% of the AT A GLANCE • With posterior polar cataracts, there can be a higher risk of complications such as capsule weakness. • Use of ultrasound may be needed to determine IOL power. • Avoiding initial hydrodissection in these cases is advisable because a defect in the posterior capsule may be revealed leading to loss of the nucleus. Toric IOL in the bag with defect that developed adjacent to a plaque fortunately re- moved after the lens was in the bag Source : Steven Safran, MD time but may present unilaterally in which case there may be an increased risk of amblyopia. “The patient may tell you, ‘I’ve always had a cataract—I was born with it,’ as these are congenital, but they often progress over time and can become symptomatic when they were not previously,” he said. Patients with posterior polar cataracts may complain of glare while driving at night, but might be able to see around the cataract and have surprisingly good chart vision. “A patient could easily be 20/20 with one of these and still be symptomatic,” he said. “As the cataract progresses, however, symptoms will increase and vision may decrease.” Clara Chan, MD , assistant professor, University of Toronto, pointed out that on slit lamp exam, a posterior polar cataract is easily visible as a round opacity in the central posterior subcapsular area adjacent to the posterior capsule. “With retro-illumination, blockage of the red reflex should be visible,” she said, adding that sometimes there are a few bubble- looking vacuoles adjacent to the opacity. Preoperative testing tends to be straightforward. “Intraocular lens power calculations and routine preoperative testing such as topography, manifest refraction, and discussion about target postop spherical equivalent can be done as for a regular cataract,” Dr. Chan said. Dr. Safran pointed out that those who perform biometry with the IOLMaster (Carl Zeiss Meditec, Jena, Germany) or LENSTAR (Haag-Streit, Koniz, Switzerland) may have to find another way to get their axial length measurements. Most of the time, the IOLMaster won’t be able to see through one of these, and the physician needs to use ultrasound to determine axial length. Also, practitioners need to take a particularly close look at the peripheral retina to make sure there are no holes or tears because there is a higher than normal chance that such cases will require a vitrectomy, he said. Avoiding complications When talking with posterior polar cataract patients about the treatment plan, Dr. Safran makes it clear that there is a higher risk of complications with the surgery, including the possibility of requiring a vitrectomy. He also lets patients know that ultrasound measurements may be needed instead of using the IOLMaster. “I explain to them that this is the only way—light can’t get through the cataract so we have to use sound. It’s good but not as good as IOLMaster because it’s not as accurate,” he said. Likewise, Dr. Chan makes sure to alert patients about the higher risk of complications. “I always tell patients that they may need a second surgery with a retina specialist to clean up bits of the lens that may fall to the back part of the eye,” she said. In performing the surgery, Dr. Chan tries to avoid hydrodissection because these cataracts can be quite adherent to the posterior capsule. “Also, the posterior capsule can be very weak or even absent in the area of the lens opacity, so you would not want to hydrodissect and risk blowing out the bag,” she said. “My preferred technique is to use