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C CLINICAL RESEARCH

4. Assess the Region of parapapillary atrophy (PPA)

PPA may be qualitatively tracked through serial fundus photography, and investigators are beginning to
utilize en face enhanced depth imaging (EDI) OCT for both qualitative and quantitative analyses includ-
ing the differentiation of glaucomatous from myopic (zone-gamma) and age-related PPA. 197,245-247 The
present clinical reality, however, is that PPA is often more confounding than diagnostic. 248,249

5. Look for Retinal and disc hemorrhages
The transient nature of DH makes clinical detection difficult: unfortunately, OCT is not helpful in iden-
tifying DH, although it is able to quantify resultant NRR/RNFL loss. Given that DH are not considered
250
independently diagnostic of glaucomatous optic neuropathy, this is more of an observation about, than a
limitation of OCT.
Clinical Recommendation for use of OCT in glaucoma:
• In suspect patients identified through clinical exam, targeted OCT assessment can identity RNFL thinning
up to six years before a visual field defect is detected on automated visual field analysis.

GLAUCOMA: A DISEASE OF THE MACULA?
While our clinical exam focuses on the ‘Five R’s’ of the ONH and RNFL, OCT has confirmed earlier suspicions that
macular damage is common in early glaucoma. 251-253 Although RNFL analysis remains a diagnostic cornerstone, as-
sessment of the ganglion cell/inner plexiform layer (GCIPL) or ganglion cell complex (GCIPL + macular RNFL)
should be part of every baseline, particularly in the presence of an anomalous or focally notched ONH, or suspected
NTG. Like the NRR and RNFL, the inferior-temporal macula is most susceptible to glaucomatous damage, and
254
asymmetry between eyes is suspicious. Unique to macular analysis, intra-eye asymmetry across the horizontal
255
raphe is also suggestive of glaucoma. 256,257 However, glaucomatous macular damage can also be diffuse, which may
impact vision-related quality of life more than focal loss. 258,259 See Figure 11 for a case highlighting the importance
of imaging the macula in addition to the RNFL. Regardless of pattern, macular RGC thinning is strongly associated
with central visual field loss. For this reason, a 10-2 VF grid is also recommended as part of a baseline assessment.
260
Any concurrent macular disease, including age-related macular degeneration, diabetic macular edema, vitreo-mac-
ular traction, or epiretinal membrane, can confound ganglion cell analysis.
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When warranted by clinical suspicion of glaucomatous optic neuropathy, given that no single parameter is foolproof
in isolation, clinicians are wise to utilize all the tools at their disposal, obtaining baseline RNFL, ONH, and macular
RGC (structural) assessments and complementary 24- and 10-2 AVF (functional) analyses. 55

32 CANADIAN JOURNAL of OPTOMETRY | REVUE CANADIENNE D’OPTOMÉTRIE VOL. 79 SUPPLEMENT 1, 2017