Normative Values of Retinal Nerve Fibre Layer Thickness and Optic Nerve Head Parameters and Their Association with Visual Function in an African Population

Stephen Ocansey; Emmanuel Kwasi Abu; Andrew Owusu-Ansah; Shadrack Mensah; John Oduro-Boateng; Rene Abalo Kojo; Samuel Kyei; Samuel Bert Boadi-Kusi; Obed Amoah-Smith; Enyam Komla Amewuho Morny; Charles Darko-Takyi; Carl Halladay Abraham; Benjamin Appiah Nyamekye; Alex Azuka Ilechie

doi:10.1155/2020/7150673

Normative Values of Retinal Nerve Fibre Layer Thickness and Optic Nerve Head Parameters and Their Association with Visual Function in an African Population

J Ophthalmol. 2020 Feb 11:2020:7150673. doi: 10.1155/2020/7150673. eCollection 2020.

Authors

Affiliations

¹ Department of Optometry, School of Allied Health Sciences, College of Health and Allied Sciences, University of Cape Coast, Cape Coast, Ghana.
² Glaucoma Research Group, 2nd Xiangya Hospital of Central South University, Changsha, China.
³ Eye Unit, Nsawam Government Hospital, Nsawam, Eastern Region, Ghana.
⁴ Emmanuel Eye Medical Centre, Adamfio Link East Legon, Accra, Ghana.
⁵ Eye Unit, Directorate of University Health Services, University of Cape Coast Hospital, Cape Coast, Ghana.

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.