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Wyatt Messenger, Mark Dikopf, Mohsin Ali, Ahmad A Aref; Racial Differences in Optic Nerve Anatomy Among Patients with a Normal Retinal Nerve Fiber Layer Thickness. Invest. Ophthalmol. Vis. Sci. 2017;58(8):3719.
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© ARVO (1962-2015); The Authors (2016-present)
Anatomical differences in optic nerve anatomy among races have been described. However, it is unclear whether these differences in optic nerve morphology persist in eyes without retinal nerve fiber layer (RNFL) thinning as determined by optical coherence tomography (OCT). We performed a retrospective, observational study to evaluate racial differences in patients referred for glaucoma suspicion with a normal RNFL on OCT.
Demographic characteristics, optic nerve anatomy, and glaucoma status were analyzed in African-American, Caucasian, and Hispanic patients undergoing screening for RNFL thinning with a Cirrus spectral domain-OCT in the setting of suspected open angle glaucoma. Between October 2014 and October 2015, a total of 433 eyes were screened in a single center. Exclusion criteria included age less than 18 years; anatomically narrow angles; ocular hypertension; no self-identified race; an OCT signal strength less than 6; and having thinning of any quadrant on the RNFL layer on OCT. In all, 147 eyes (95 patients) were included in the study with an over-representation of African Americans (46 patients, 68 eyes) and Hispanics (35 patients, 57 eyes) compared to Caucasians (14 patients, 23 eyes). Categorical variables were analyzed with a chi-square test and continuous variables were analyzed with ANOVA.
In our study, there was no statistical difference between proportion of females (p=0.33) or percentage of eyes with RNFL thinning in the contralateral eye (p=0.40) However, Hispanics were significantly more likely to be younger (p<0.001). There was no significant difference between RNFL symmetry (p=0.82), rim area (p=0.66), disc area (p=0.41), cup-to-disc ratio (p=0.32), cup volume (p=0.48), vertical disc volume (p=0.29), superior rim thickness (p=0.17), or temporal rim thickness (p=0.17). Caucasians were significantly more likely to have a thinner average RNFL (p<0.03). Specifically, Caucasians had a significantly thinner RNFL in the nasal (p=0.04) and inferior (p=0.001) quadrants. Finally, there was no difference between races in the percentage of patients diagnosed with glaucoma (p=0.25).
Racial differences are important to consider when screening for glaucoma. Our data suggest that screening may underestimate RNFL thinning in African-American and Hispanic populations, specifically in the nasal and inferior quadrants.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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