EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
Issue link: https://digital.eyeworld.org/i/78721
36 EW FEATURE February 2011 Retina co-morbidity for the anterior segment surgeon January 2012 Consider the macula in pre-op cataract patients by Jena Passut EyeWorld Staff Writer AT A GLANCE • A good cataract surgeon should consider the back of the eye and possible hidden maculopathies there before heading to the OR with a patient • A potential acuity meter (PAM) measures how a person might see after cataract surgery • The PAM is useful in determining if visual problems stem from the cataract or macula, according to some, but is not terribly reliable Retina specialists offer ad- vice on what to look for in order to attain best vision S urgical complications arise, even in cataract sur- gery, which reportedly has one of the highest success rates. Yet despite all the various pre-op tests that are per- formed to ensure a successful opera- tion—from measuring the eye and cornea to deciding on the best IOL fit—there are always potential prob- lems that may be overlooked during the procedure, especially from the back of the eye. The most common missed mac- ulopathies that result in unhappy cataract patients are vitreoretinal interface abnormalities, such as epiretinal membranes and vitreoreti- nal traction, according to Michael D. Ober, M.D., Retina Consultants of Michigan, Southfield. "Those are probably the most common disorders, but age-related macular degeneration closely fol- lows," Dr. Ober said. What is a clinician to do pre-op to ensure these retina issues won't pop up or cause vision problems after surgery? Three specialists spoke to EyeWorld about imaging the back of the eye and testing for visual acu- ity before going into the operating room. Imaging the back of the eye Dr. Ober said if there is suspicion from pre-op testing that a maculopa- thy may be present, "an OCT [opti- cal coherence tomography] is probably the best screening tool. It will give you a lot of information. It's not going to help you with a pa- tient who has dry macular degenera- tion that is not high risk or affecting the central vision, but it will give you a much better idea of the vitreo- retinal surface, and it will also tell you whether there is subretinal fluid or macular edema that's pre-exist- ing." Suspicions may include a family history of the disease or if the pa- tient's pre-op vision is not what the doctor would expect based on the level of cataract present. The OCT can help clinicians de- termine beforehand if there's a mac- ular pathology that could lower the patient's visual potential, whereas biomicroscopy or other tests might not pick up on those subtle changes. "OCT evaluation is important to look at the structure of the retina, particularly the macula," said Elias Reichel, M.D., professor and vice chair of ophthalmology, Tufts Uni- versity, Boston. "It is important as a pre-op assessment because even if our view is good, often we can miss subtle maculopathy. Occasionally, we find choroidal neovasculariza- tion from wet age-related macular degeneration that hasn't been seen before. In diabetic patients, we see diabetic maculopathy that's difficult to view through a visually signifi- cant cataract." Dr. Reichel said assessing the macula in cataract surgery patients is "critical for a patient's high expecta- tions." "I don't think it makes a differ- ence whether we're using a multifo- cal IOL or a standard IOL or a toric IOL," Dr. Reichel continued. "I think they all need careful macular evalua- tions. I think the questions are, can we account for visual acuity and can we be sure there is no underlying maculopathy that may explain part of the vision loss?" Although it might not be feasi- ble to have every cataract patient undergo OCT examination, especially if health insurance or Medicare won't pick up the tab, Dr. Reichel said it's important to have a good working relationship with a retina specialist or access to the de- vice to keep track of changes in the back of the eye. "In general, if you're a compre- hensive ophthalmologist or do a lot of cataract surgery, I think it's good to document the structural changes in the macula," he explained. "It's good medicine because it's for docu- mentation of changes, and we want to educate our patients and say, 'We're going to do cataract surgery. I expect this much improvement in vision, but there may be a problem that limits the improvement in vi- sion, or there may be underlying pathology with the human eye that requires vitreoretinal intervention.'" Vision's potential tested Surgeons can use a potential acuity meter (PAM) test to estimate how much a cataract is affecting a pa- tient's vision loss, as well as to assess the patient's potential visual acuity after surgery. The test projects a Snellen chart onto the eye through a small "pin- hole" in the cataract. A chart of let- ters or numbers is then imaged onto the macula to measure its acuity. Prior to the PAM test, a doctor should examine the anterior seg- ment to find the clearest areas of the cataract. The PAM mounts onto the slit lamp, and the background illu- mination should be used at a low level, according to the device's oper- ating manual. The microscopic beam of light is focused on the iris of the patient's right eye, and the operator moves the dot into the pupil while looking through the slit lamp. The patient then reads the lines of the chart as far as he or she can. "When a difficult line is reached, it may be necessary to slowly move the light beam to other areas," the manual states. "Alter- nately, a new quadrant or even the center of the pupil may be slowly scattered. Further encouragement and repositioning of the beam should be made until the examiner is confident that the patient cannot read any smaller numbers or letters." Clinicians remain divided on whether the PAM test is ultimately reliable. "I find it relatively reliable. It does help differentiate patients, meaning a lot of patients do get that much better," said Anne Fung, M.D., Pacific Eye Associates, California Pacific Medical Center, San Francisco. "It is reflective of the post-cataract outcome in my experi- ence." Dr. Fung drawing Lucentis (Genentech, South San Francisco) Dr. Fung consults with a patient Dr. Fung performs an injection on a patient Source: Anne Fung, M.D.