Eyeworld

EW GLAUCOMA 96 October 2015 thus underestimate both the cup size and the glaucoma risk." Clinical implications Studies have shown that eyecare providers—even glaucoma special- ists—made mistakes when evaluat- ing the optic nerve. Knowing the mistakes we are prone to making can help reduce our error rates. Peo- ple aren't perfect, but we will never be replaced by machines. Machines cannot think for themselves, and a careful optic nerve examination requires thoughtful consideration of all the features that can inform us about glaucoma risk. "The risk of progression is very high in patients with beta-zone peri- papillary atrophy anywhere other than temporally, with acquired ON pits, with disc hemorrhages, and with double notches superiorly and inferiorly," Dr. Susanna said. As Dr. Coote pointed out, "Giv- en the prevalence of normal tension glaucoma, the only information to alert you to the possible presence of glaucoma during a routine examina- tion may be the optic disc appear- ance." EW Editors' note: Dr. Medeiros has financial interests with Carl Zeiss Meditec (Jena, Germany), Heidelberg Engineering (Heidelberg, Germany), and Topcon (Oakland, N.J.). Drs. Coote and Susanna have no financial interests related to this article. Contact information Coote: mcoote@bigpond.net.au Medeiros: fmedeiros@glaucoma.ucsd.edu Susanna: rsusanna@terra.com.br for both detecting deterioration in patients already diagnosed with glaucoma as well as to clarify the diagnosis in those who are suspected of the disease," he concluded. Clinical exam: A systematic approach "Examination of the optic nerve is important for the diagnosis of glaucoma, for detection of glauco- ma progression, and for assessing the risk of future progression," said Remo Susanna, MD, Brazil. He described a stepwise process for systematically evaluating the optic nerve. First is a careful look at the neu- ral rim for evidence of notching and nasal cupping, which are strongly associated with glaucoma, he said. One should also be aware of the optic nerve size, which puts the cup size into perspective. "A modest cup in a small nerve may also be a red flag for early or moderate glauco- ma," he said. Similarly, asymmetry of the cup-disc ratio of 0.2 units or greater in similar-sized optic nerves should raise suspicion of glaucoma. A deeper look into the cup may reveal laminar changes, such as elongation of the laminar pores or an acquired pit of the optic nerve, the latter of which strongly suggests the presence of glaucoma. Next is an inspection of the peripapillary region for signs of beta- zone atrophy or disc hemorrhage. "Beta-zone atrophy is weakly associ- ated with glaucoma, unless it occurs elsewhere than temporally, in which case the relationship is stronger. Also, the presence of a disc hemor- rhage is a very strong indicator of future glaucoma progression." The nerve fiber layer—best examined using red-free illumina- tion—can reveal focal defects that are strongly associated with glauco- ma. Diffuse loss, he said, is harder to see clinically. Knowing our faults Michael Coote, MD, Australia, has developed a web-based optic nerve assessment study in which more than 6,000 people have now evalu- ated and interpreted a series of optic nerve head photographs. He has identified a number of features that lead to systematic errors in nerve assessment. "People tend to overestimate the risk in patients with large optic nerves," he said, "because these nerves have physiologic large cups that are entirely normal for them." Likewise, small nerves lead to un- derestimation of risk because even modest cupping in a small nerve can be worrisome. Tilted optic nerves also lead people to suspect glaucoma when it is absent—likely because the tilting looks like temporal sloping from focal rim loss. "The presence of peripapillary atrophy is also problematic," he explained. "People mistake the exposed sclera for optic disc rim and Strategy continued from page 94 View the EyeWorld CME and non-CME supplements at: cmesupplements. eyeworld.org supplements. eyeworld.org Optic nerve features of glaucoma should be looked for. The Glaucomatous Optic Neuropathy Evaluation (GONE) Project showed that they are easily missed. Source: Michael Coote, MD

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