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Associations between Retinal Nerve Fiber Layer Thickness, Axial Length, and Generation in the 2-Continent Eye Study
Jost B Jonas1,2,3,4,5,6,7, Rahul A Jonas8,9, Mukharram M Bikbov10
1Rothschild Foundation Hospital, Paris, France.
Purpose:
To assess the associations between peripapillary retinal nerve fiber layer thickness (RNFLT) and ocular and systemic parameters, in particular axial length (A).
Design:
Population based studies.
Methods:
Ocular and systemic examinations including OCT RNFLT measurement.
Participants:
Participants of 4 population-based studies (Beijing Eye Study [n = 3246; age: 40+ years], Ural Eye and Medical Study [n = 5023; age: 40+ years], Ural Very Old Study [n = 407; age: 85+ years], Ural Children Eye Study [UCES, n = 3109; age: 6+ years]).
Outcome Measures:
RNFLT.
Results:
The study cohort consisted of 23 384 eyes (11 785 individuals). In multivariable analysis with exclusion of eyes with an IOP of >21 mmHg, thicker RNFLT was associated (all P < 0.001) with the systemic parameters of younger age, female sex, urban region of habitation, taller body height, higher educational level, lower systolic blood pressure, and higher estimated cerebrospinal fluid pressure; and with lower intraocular pressure. In all studies on adults (Beijing Eye Study, Ural Eye and Medical Study, and Ural Very Old Study), total RNFLT increased with AL up to an AL of 24.0 mm, plateaued, and decreased for an AL >26.5 mm. In the UCES, RNFLT linearly increased with longer AL, also in the highly myopic range. Differentiated sectorially, temporal RNFLT in the UCES linearly increased with AL (including the highly myopic range), while in the adult studies it plateaued beyond an AL of 26.0 mm. In all other sectors in all cohorts, the sectorial RNFLT decreased with longer AL in the highly myopic range.
Conclusions:
The AL-related increase in RNFLT up to an AL of 24 mm, found in all ages, may correspond to an AL-related larger retinal surface area with a higher number of retinal ganglion cells per eye. The RNFLT decrease beyond an AL of 26.5 mm in adults corresponds to an increased prevalence of optic neuropathies in highly myopic eyes. The sectorial differences in the RNFLT/AL relationship corresponds to the axial elongation-related RNFL shift to the macula, with a secondary RNFL crowding temporally and a geometrically explained RNFLT decrease nasally. Sectorial normative RNFLT data depend on AL.
Financial Disclosures:
Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.