Myelinated Retinal Nerve Fibre: Prevalence and its Association with Ocular and Systemic Parameters in Tromsø.

Abstract

Background: Myelinated retinal nerve fibres (MRNFs) are congenital anomalies of the fundus that occur in about 1% of the population. Clinically, they appear as grey or white well-separated patches with feathery borders along the retinal nerve fibre layer. MRNF has been reported to occur in association with some ocular parameters as well as stroke. However, most cases of MRNF occur in isolation and are asymptomatic. Purpose: To determine the prevalence, ocular and systemic associations of MRNF in Tromsø. Methods: The present study included 7396 participants aged 40–84 years from the Tromsø Eye Study, a sub-study of the population-based Tromsø Study in Norway. Data on ocular and systemic parameters were collected from self-report questionnaires, clinical examinations, and laboratory measurements. Retinal images from both eyes were assessed for the presence of MRNF. Logistic regression models were used to assess the association between MRNF and ocular and systemic parameters. Results: Readable fundus photographs of at least one eye were available in 7396 (88.0%) of 8346 participants of the Tromsø eye study (TES). The study cohort included 3979 (55.8%) females and 3417 (46.2%) males. The mean age in the whole study cohort was 62.9 ± 10.4 years with 62.8 ± 10.4 and 63.1 ± 10.4 years in females and males respectively. The prevalence of MRNF in the study sample was 1.1%. In a multivariable logistic regression analysis, MRNF was associated with male sex (OR, 1.785; 95% CI, 1.138–2.799; P, 0.012) and glycosylated haemoglobin (HbA1c) (OR, 0.559; 95%CL, 0.316 – 0.989; P, 0.046). MRNF was not associated with age, systemic conditions or ocular parameters such as visual acuity, refractive error, or intraocular pressure. Conclusion: This population-based study is the first to provide data on the prevalence of MRNF in the Nordic population. It is also the first study to report an association between MRNF and HbA1c, although this may be a chance finding and must be explored further. This study tends to affirm the general perception that MRNF is without serious clinical implications, however, this must also be investigated further in future studies.