Purpose To determine the influence of the optic disc–fovea distance (DFD) on the normative classifications based on thickness measurements of macular inner retinal layers with spectral-domain optical coherence tomography (OCT) in healthy subjects.
Methods A total of 182 eyes from 182 healthy subjects were included (mean (SD) spherical equivalent −0.8 (1.9) dioptres). We performed macula and optic disc imaging with the Topcon 3D OCT 2000. The thickness of the macular inner retinal layers (macular retinal nerve fibre layer (mRNFL), ganglion cell-inner plexiform layer (GCIPL) and both combined (ganglion cell complex; GCC)) and the corresponding classifications based on the built-in normative database were recorded. The occurrence of an abnormal normative classification (occurrence of any thickness variable below the fifth percentile) was related to the DFD and other factors (axial length/refraction, optic disc area, fovea–disc angle, age, gender, image quality, visual field mean deviation and peripapillary retinal nerve fibre layer thickness), using logistic regression.
Results The mean (SD) DFD was 4.90 (0.29) mm. A greater DFD was associated with a higher percentage of abnormal normative classification in the OCT parameters describing the thickness of the mRNFL (OR (95%CI) per 0.1 mm increase in DFD: 1.30 (1.13 to 1.50), p<0.001), GCIPL (1.18 (1.02 to 1.38), p=0.023) and GCC measurement (1.29 (1.08 to 1.55), p=0.006).
Conclusions Eyes with a greater DFD are prone to false-positive classifications in the thickness assessment of the macular inner retinal layers. The thicknesses should always be interpreted in the context of DFD.
- macular inner retinal layer
- optic disc-fovea distance
- retinal ganglion cell
- spectral domain-OCT
- normative database
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KQ and BC contributed equally.
Contributors Involved in study design and conduct: MZ, CZ, HC; data collection, management, analysis: KQ, BC, CZ, JY; interpretation: MZ, NMJ, KQ; and manuscript preparation, review or approval: MZ, NMJ, KQ.
Funding The present study was supported by grant no 81486126, from the National Nature Science Foundation of China; by grant no 2014KQNCX075, from the Foundation for Distinguished Young Talents in Higher Education of Guangdong, China; and by the University of Groningen Abel Tasman Talent Program (University Medical Center Groningen/Shantou University Medical College). The funding organisations had no role in the design, conduct, analysis or publication of this research.
Competing interests None declared.
Patient consent Obtained.
Ethics approval The study was designed following the ethical standards of the Declaration of Helsinki and approved by the ethical committee of the Joint Shantou International Eye Center of Shantou University and The Chinese University of Hong Kong.
Provenance and peer review Not commissioned; externally peer reviewed.
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