JUL 2013

EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.

Issue link: https://digital.eyeworld.org/i/146899

Contents of this Issue


Page 21 of 66

July 2013 selected gene, and a few that do a panel of variants. Dr. Gorin said there are multiple tests that are CLIA-approved, but there are only three that offer a risk estimate based on the test results. Of those three, only Macula Risk and RetnaGene use clinical data to determine the risk estimate. In terms of accuracy of these tests, Dr. Gorin said all of these tests employ methods that provide a high reliability for determining the sequence or variant for which they are testing. "However, if you are asking about the accuracy or reliability of the risk estimates derived from the genetic testing, then the answer is much less encouraging," he said. Dr. Gorin noted that there are some problems and limitations with the Macula Risk and RetnaGene tests. "The RetnaGene test is very specific in what it is intended to be used for," he said. "It is designed to be used on people over the age of 64 who have AMD and for whom one is trying to calculate the risk of developing wet AMD." The RetnaGene test relies on a combination of genetics, clinical findings, and smoking exposure. However, it is not optimal for figuring out the risk of developing geographic atrophy from AMD or for predicting whether a younger patient will develop AMD. "At this time none of these tests are effective in that respect," Dr. Gorin said. AMD genetic tests are being heavily promoted to the public, Dr. Gorin said, adding that the Macula Risk test is being promoted to optometric practitioners as well. "However, the benefits are limited," he said. "Though the Macula Risk website does provide guidelines for following up on people based on their degree of AMD risk, it doesn't add much to the care." Dr. Gorin stressed a similar point with the RetnaGene test, saying that there is limited benefit because the results of the test would not drastically shift management of AMD. "At this time, I feel that these tests are of limited benefit and, more often than not, can lead to misinterpretation and poor clinical guidance," he said. Patients considering a multifocal IOL Dr. Holekamp indicated that it could be valuable for cataract surgeons to make genetic testing available to patients who are contemplating a multifocal IOL. However, she said that the tests should only be used for those with a strong family history of AMD if the patient is already showing some evidence of AMD, like drusen. Dr. Gorin has seen a number of patients who have had complications arise with their AMD by having a multifocal IOL, so the ability to assess the risk of developing this ahead of time could prove beneficial. If a patient has a family history, he or she could be more likely to develop AMD, but it is not guaranteed. "If you excluded those people with a positive AMD family history from having these lenses, you would block a disproportionate amount who would have benefitted from that lens," Dr. Gorin said. "If you use the argument of a negative AMD family history to justify the use of the lens, then you will be putting the lens in a lot of people who eventually develop AMD." He said that relying on only genetic variants is not sufficient to identify the risk of AMD because there is not enough sensitivity and specificity to guarantee it. "At this time, the best recommendation would be to do a careful clinical assessment of the retina with diagnostics that can detect subtle drusen (especially reticular drusen) using high resolution spectral domain OCT, multispectral imaging and autofluorescence," he said. Negatives of genetic testing Though there are advantages of AMD genetic testing, there are negatives to consider as well. "One potential negative would be providing false genetic counseling," Dr. Holekamp said. "That is why ensuring these LDTs are accurate and valid is so important." She said another possible negative would be performing the test without properly counseling and educating the patient. This could cause a misunderstanding of the results. "Finally, a potential negative would be driving up the costs of healthcare, as each of these tests are reimbursed by Medicare and cost upward of $1,000 per test," Dr. Holekamp said. Dr. Gorin also shared his concerns of genetic testing, one of which is some doctors may use it to try to coerce patients to alter their behavior or gain compliance by asserting that a certain person is at a high risk for the disease based on the results of the test. "Of course the flip side of this is that a low risk profile might make a person less likely to abide by good health practices," he said. "The current preventive therapies for AMD have relatively low risk and cost and thus genetic profiling has limited benefits. This may change dramatically if a therapy with substantial costs and/or risk for AMD prevention is developed and it becomes critical that we limit such therapies to those whose risk for disease warrant these treatment costs and risks." Dr. Gorin said the genetic tests are not highly predictive unless a patient has the highest or lowest risk profile, but the truth is that most individuals will fall within an intermediate range of risk, where the risk models are not sufficiently discriminating to predict a patient's future. EW Editors' note: Dr. Holekamp has financial interests with ArcticDx and Sequenom CMM. Dr. Gorin has financial interests with Optherion (New Haven, Conn.) and Sequenom. Contact information Gorin: gorin@jsei.ucla.edu Holekamp: nholekamp@gmail.com EyeWorld factoid 50% of people between the ages of 75 and 85 have lost some vision because of a cataract INFINITI® VISION SYSTEM CAUTION: Federal law restricts this device to sale by, or on the order of, a physician. As part of a properly maintained surgical environment, it is recommended that a backup IOL Injector be made available in the event the AutoSert® IOL Injector Handpiece does not perform as expected. INDICATION:The INFINITI® Vision System is indicated for emulsifcation, separation, and removal of cataracts, the removal of residual cortical material and lens epithelial cells, vitreous aspiration and cutting associated with anterior vitrectomy, bipolar coagulation, and intra-ocular lens injection. The INTREPID® AutoSert® IOL Injector Handpiece is intended to deliver qualifed AcrySof® intraocular lenses into the eye following cataract removal. The following system modalities additionally support the described indications: -Ultrasound with UltraChopper® Tip achieves the functionality of cataract separation. -AquaLase® Liquefracture Device achieves the functionality for removal of residual cortical material and lens epithelial cells. -The INTREPID® AutoSert® IOL Injector Handpiece achieves the functionality of injection of intraocular lenses. The INTREPID® AutoSert® IOL Injector Handpiece is indicated for use with AcrySof® lenses SN60WF, SN6AD1, SN6AT3 through SN6AT9, as well as approved AcrySof® lenses that are specifcally indicated for use with this inserter, as indicated in the approved labeling of those lenses. WARNINGS: Appropriate use of INFINITI® Vision System parameters and accessories is important for successful procedures. Use of low vacuum limits, low fow rates, low bottle heights, high power settings, extended power usage, power usage during occlusion conditions (beeping tones), failure to sufciently aspirate viscoelastic prior to using power, excessively tight incisions, and combinations of the above actions may result in signifcant temperature increases at incision site and inside the eye, and lead to severe thermal eye tissue damage. Adjusting aspiration rates or vacuum limits above the preset values, or lowering the IV pole below the preset values, may cause chamber shallowing or collapse which may result in patient injury. When flling handpiece test chamber, if stream of fuid is weak or absent, good fuidics response will be jeopardized. Good clinical practice dictates the testing for adequate irrigation and aspiration fow prior to entering the eye. Ensure that tubings are not occluded or pinched during any phase of operation. The consumables used in conjunction with ALCON® instrument products constitute a complete surgical system. Use of consumables and handpieces other than those manufactured by Alcon may afect system performance and create potential hazards. AES/COMPLICATIONS: Use of the NeoSoniX®, OZil® torsional, U/S, or AquaLase® handpieces in the absence of irrigation fow and/or in the presence of reduced or lost aspiration fow can cause excessive heating and potential thermal injury to adjacent eye tissues. ATTENTION: Refer to the directions for use for a complete listing of indications, warnings and precautions. Source: University of Michigan Kellogg Eye Center © 2013 Novartis 6/13 INT13015JAD

Articles in this issue

Links on this page

Archives of this issue

view archives of Eyeworld - JUL 2013