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EW GLAUCOMA 82 February 2015 this. "Less than 6 months is associ- ated with a higher risk of failure," Dr. Mura said. In cases where the functioning of the filtering surgery is compromised (which are more frequent in complicated trabeculec- tomies), cataract surgery must be performed earlier. Physicians should discuss risk of visual impairment with patients, Dr. Mura said. When using the aggressive anti-inflammatory treatment, Dr. Mura's specific regimen includes prednisolone 1% every 2 hours for 2 weeks, then every 4 hours for 1 week and the last week QID; he uses NSAIDs TID for 6 weeks. Adjust- ments in treatment can frequently occur, he said. "Also, remember that we can use mitomycin or 5-FU in those patients," Dr. Mura said. "Personally, I use mitomycin 0.02% 0.1 ml superior to the bleb, using a 30-gauge needle at the end of cataract surgery." EW Editors' note: Dr. Mura has no financial interests related to this article. Contact information Mura: jmurac@vtr.net Tips for cataract surgery continued from page 81 by Tony Realini, MD, MPH, EyeWorld Contributing Writer Macular OCT imaging in glaucoma The next step in our diagnostic evolution? P erimetry has been a staple of glaucoma diagnosis and monitoring since the time of Albrecht von Graefe in the 1850s. The value of perimetry in glaucoma management has long been established, as has its limitations. These include high intra-test and inter-test variability, long test times, low sensitivity in early disease, and a universal dislike for the test by patients because it is tedious, stressful, and difficult to perform. There is substantial unmet need for a better test than the visual field for glaucoma evaluation. We have come to appreciate the remarkable resolution that optical coherence tomography (OCT) provides when imaging the peripapillary nerve fiber layer. But have we been looking in the wrong place? Should we be using OCT to look at the macula? OCT and visual field correlation The first step in validating macular OCT as a useful test for glaucoma is to confirm that its results correlate with established tests' results. Brandon DeCaluwe, a medical student at Wayne State University, Detroit, and his colleagues compared macular OCT to standard Humphrey visual fields in a predominantly African-American population of 186 glaucoma patients and suspects. The retrospective study included patients who had undergone both OCT and visual field testing within 3 months of one another. Macular thickness was determined in each of the 4 quadrants and was correlated with the mean deviation and the pattern standard deviation of the visual field using linear regression analysis. "Both the mean deviation and the pattern standard deviation correlated with macular thickness," Mr. DeCaluwe said. "Eyes with thinner macular thickness had more negative mean deviation scores and higher pattern standard deviation scores." Macular thickness in the inferior quadrant was most highly correlated with visual field parameters (mean deviation, r=0.476, p<0.0001; pat- tern standard deviation, r=–0.491, p<0.0001). Macular thickness values in the remaining 3 quadrants were also significantly correlated with visual field parameters, although the strength of association was not as great as with the inferior macular thickness, he said. The importance of the inferior macula was also revealed in a study conducted by Sarah Nowroozizadeh, MD, a glaucoma fellow, and her colleagues at UCLA. They evaluated visual fields, OCT, and contrast sensitivity in 70 eyes of 42 patients with advanced glau- coma. Their OCT measurements included both full thickness and ganglion cell/inner plexiform layer (GC/IPL) thickness values. "A significant correlation was found between contrast sensitivity at 12 cycles/degree and inferotem- poral GC/IPL thickness, inferior GC/ IPL thickness, inferior central mac- ular thickness, and superior central visual field mean deviation," Dr. Nowroozizadeh said. What layers of the macula matter? The studies above support the value of OCT macular thickness in glaucoma assessment. But what macular OCT parameters are most valuable? These studies divided the macula into quadrants and also divided the macula into layers. Livia Brandao, MD, and colleagues at the University of Basel, Switzerland, asked whether "a separate analysis of the segmented macular ganglion cell layer, rath- er than the full thickness analysis of the central retina, will increase structure-function correlation in glaucoma." Her group conducted OCT imaging, visual field testing, and multifocal ERG evaluation in 20 subjects (4 normal controls, 10 open-angle glaucoma patients with field defects, and 6 preperimetric open-angle glaucoma patients). Interestingly, full macular thickness showed only a trend toward significant correlation with the ERG output, while the macular ganglion cell thickness was signifi- cantly correlated with functional ERG assessment. Also, the 6 patients without a central field defect on perimetry (3 POA, 3 preperimetric glaucoma patients) had abnormal ERG results and thinner macular ganglion cell thickness values than normal subjects. Even with normal standard automated perimetry, 3 patients with preperimetric glauco- ma had an abnormal multifocal ERG and significant thinner ganglion cell layer values. Disease severity Medical student James Zhang and colleagues at the University of Cal- ifornia, San Diego also conducted a study comparing macular OCT and visual field parameters in patients with glaucoma. Their database study included 76 healthy eyes, 146 glau- comatous eyes, and 152 glaucoma suspect eyes, all of which underwent standard 24-2 and 10-2 perimetry and spectral domain OCT with determination of the macular GC/IPL thickness. As in the studies above, these researchers found significant correla- tions between GC/IPL thickness and visual field sensitivities. "Eyes with more severe glaucoma displayed stronger macula structure-function correlation than eyes with less severe glaucoma," he said. Practical applications While the OCT may not be a replacement for the visual field, its value in glaucoma is becoming clearer. "Glaucoma patients with dam- age to the inferior macular area are at higher risk of functional disabili- ty," Dr. Nowroozizadeh said. Mr. DeCaluwe agreed in his analysis. "We propose that the use of full thickness macular scans, especially the inferior quadrant, may be a potential tool for screening, evaluation, and staging of disease states in glaucoma patients." Dr. Brandao pointed out, "Structure-function analysis in glaucoma correlates better when macular ganglion cell thickness is included rather than just the full macular thickness." Mr. Zhang added, "There is a stronger macula structure-function relationship in eyes with more severe disease." EW Editors' note: The sources have no financial interests related to this article. Contact information Brandao: Livia.Brandao@usb.ch DeCaluwe: bgdecalu@gmail.com Nowroozizadeh: sarahno@gmail.com Zhang: jzhang127@gmail.com

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