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MANAGING OPEN ANGLE GLAUCOMA

While ancillary objective imaging has become invaluable, particularly in early (pre-perimetric) disease, it is im-
portant to remember that imaging informs but does not replace clinical assessment. Although optical coherence
48
tomography is exquisitely reproducible within individuals, significant inter-patient variability and reference da-
tabase limitations make it, at present, an impractical stand-alone screening tool.
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Finally, when justified by clinical suspicion, automated visual field (AVF) analysis is employed to identify the
functional loss that both defines the stage of the disease and ultimately impacts the individual patient. A so-
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bering statistic continues to plague present-day functional assessment: up to 40% of the retinal ganglion cells
may be lost in glaucoma before a visual field defect is detected through the current gold standard, standard
automated perimetry (SAP). Further, AVF analysis is highly variable, and defects require confirmation across
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multiple tests. Perimetry using frequency doubling technology (FDT) may be a useful initial test for those
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deemed at-risk following structural assessment. However, detectable visual field loss characterizes moder-
ate, not early glaucoma, making AVF analysis in isolation an ineffective screening test for the detection of
disease. 53,54
In summary, no single procedure currently identifies glaucoma with adequate sensitivity and specificity to be used
as a stand-alone screening tool. However, in the context of a comprehensive eye examination – the type of exam
that optometrists perform each and every day – the complete clinical picture can be visualized, and glaucoma more
readily identified. Once glaucoma is suspected based on the results of the comprehensive eye examination, a pa-
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tient should be scheduled for more in-depth assessment including pachymetry, gonioscopy, threshold visual field
testing, and ancillary imaging of the optic nerve head (ONH), RNFL and macula.
Clinical Recommendation for the primary eye care examination:
• An optic nerve evaluation should go beyond merely a cup-to-disc ratio and include, at minimum,
an estimate of optic nerve size and qualification of the ISNT rule.

THE COMPREHENSIVE GLAUCOMA ASSESSMENT

CLINICAL EXAMINATION AND CLINICAL FEATURES OF POAG
A comprehensive examination for the diagnosis of POAG may be initiated following identification of risk factors
and/or clinical characteristics of glaucomatous optic neuropathy in the initial primary eye care examination. De-
tailed case history, specific anterior segment examination, tonometry, pachymetry and gonioscopy, as well as dilated
fundus examination should be included with a view to ruling out secondary causes of glaucoma and determining
the level of suspicion for a diagnosis of POAG. Structural assessment of the optic nerve, retinal nerve fiber layer, and
macular ganglion cell layer, and tests of visual function (most commonly visual field analysis) are invaluable in the
diagnosis and ongoing management of glaucoma.

The tests outlined below and summarized in Table 1 should be undertaken to further investigate for the presence of
disease and begin to develop a solid baseline.

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