Abstract
Purpose To determine normative values of retinal nerve fibre layer thickness (RNFL) and optic nerve head (ONH) parameters and their association with routine clinical tests such as refractive error (RE), stereoacuity (SA), and contrast sensitivity (CS) in an African population. Methods In a cross-sectional observational study, 100 normal subjects aged 20 to 78 years were evaluated using the Cirrus HD-OCT 5000 and matched with 200 glaucoma patients. Results Average (±SD) RNFL thickness for normal subjects was found to be 102.37 ± 7.45 (range, 82–119 microns) compared with 90.74 ± 14.50 found for glaucoma subjects. Females had higher average RNFL values (104.84 ± 6.90) compared with males (99.80 ± 7.18). Significant associations were calculated between quadrant RNFL thickness and SA, SE, and CS (all p < 0.05). The mean cup to disc ratio (CDR) was 0.49 ± 0.12, and mean optic disc area (DA) was 2.08 mm2 ± 0.40. Smaller DA was recorded for participants aged 60+ years (1.86 ± 0.25), followed by 40–59 age group (2.01 ± 0.41) and then 20–39 age group (2.19 ± 0.41). Significant associations were calculated between SA and ONH parameters, except rim area (all p < 0.05). The mean cup to disc ratio (CDR) was 0.49 ± 0.12, and mean optic disc area (DA) was 2.08 mm2 ± 0.40. Smaller DA was recorded for participants aged 60+ years (1.86 ± 0.25), followed by 40–59 age group (2.01 ± 0.41) and then 20–39 age group (2.19 ± 0.41). Significant associations were calculated between SA and ONH parameters, except rim area (all p < 0.05). The mean cup to disc ratio (CDR) was 0.49 ± 0.12, and mean optic disc area (DA) was 2.08 mm2 ± 0.40. Smaller DA was recorded for participants aged 60+ years (1.86 ± 0.25), followed by 40–59 age group (2.01 ± 0.41) and then 20–39 age group (2.19 ± 0.41). Significant associations were calculated between SA and ONH parameters, except rim area (all Conclusion RNFL thickness in healthy black Ghanaian population was significantly higher than that reported in other races. The values and associations reported in this study can inform clinical decision on the normal variation in RNFL and optic disc parameters.
Highlights
Glaucoma is an asymptomatic ocular disease characterized by a progressive loss of retinal nerve fibres and increased cupping of the optic disc due to several cellular disease phenomena in the eye [1]
That racial background should be considered in designing diagnosis protocols for glaucoma. is study derived the normative data on retinal nerve fibre layer thickness (RNFL) thickness measurements and optic nerve head (ONH) parameters using the Cirrus HD-Optical coherence tomography (OCT) 5000 and its association with clinical ocular measurements
We have presented normative values for standard deviation (SD) Cirrus HDOCT 5000-measured RNFL thickness and ONH parameters in a healthy black Ghanaian population. e average RNFL thickness was 102.01 ± 7.45 μm, thinner than that found for other African countries and significantly higher than that reported in other races using the Cirrus HD-OCT 5000 model
Summary
Glaucoma is an asymptomatic ocular disease characterized by a progressive loss of retinal nerve fibres and increased cupping of the optic disc due to several cellular disease phenomena in the eye [1]. By 2020, about 79.6 million people will have the disease and 11.2 million cases will go blind, making the disease a major public health concern [2, 4]. POAG is known to account for 15% of blind cases annually in Sub-Saharan Africa. In Ghana, a populationbased study showed that the prevalence of POAG was 8.5% in persons 40 years and above, contributing to around 20% of the burden of blindness, making Ghana the highest prevalent country in Africa and second in the world [8,9,10]
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