Abstract
Purpose :
Differences in visual field (VF) sensitivities and retinal nerve fiber layer (RNFL) or macular thickness measurements have been reported in normal subjects of African descent (AD) compared to those of European descent (ED). (Racette, 2010; Girkin, 2010) We tested the hypothesis that the nature of structure-function (SF) relationships was similar in AD vs. ED subjects with established or suspected glaucoma.
Methods :
66 eyes of 43 AD patients and 66 eyes of 45 ED patients matched for age (±5 years) and refraction (± 1 D) were selected. Peripapillary RNFL (12° measurement circle) and macular ganglion cell/inner plexiform layer (GCIPL) thickness measurements (Posterior Pole Algorithm, Spectralis SD-OCT) and VF total deviation values were exported and RNFL sectors and VF clusters were defined (Garway-Heath et al.). The central superior and inferior VF clusters (6 points each) were matched to corresponding macular regions. Spearman correlation and broken-stick regression analyses were used to compare strength and pattern of SF relationships.
Results :
Average (±SD) age and median (IQR) mean deviation were 71.0 (±9.2) and –3.1 (–5.6 to –1.6) dB in AD patients and 71.0 (±9.4) years and –2.8 (–6.0 to –0.4) dB in the ED group. Spearman correlation coefficients between RNFL sectors and corresponding VF clusters were comparable between the 2 groups except for the temporal RNFL sector where the magnitude of the difference was clinically significant despite a p value of borderline statistical significance (Table). Correlation coefficients for the superior and inferior macular GCIPL thickness and the corresponding VF clusters were as follows in the AD vs. ED groups, respectively: superior GCIPL vs. inferior field ρ =0.514 vs. ρ =0.180 (bootstrapped p value for the difference =0.053), inferior GCIPL thickness vs. superior VF: ρ =0.495 vs. ρ =0.248 (p =0.141). Patterns of SF relationships were mostly similar in the two groups (Figure).
Conclusions :
SF relationships appear to be consistent between glaucoma patients of African and European descent except in the temporal area where subjects of African descent tended to show a stronger correlation between structural and functional measurements and an overall thinner macular GCIPL. These findings, if confirmed, have significant clinical implications in detection of glaucoma or its progression in subjects of African descent.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.