Retinal nerve fibre layer thickness in a healthy Nepalese population by spectral domain optical coherence tomography

Abstract

OBJECTIVE: To determine the normal values for peripapillary retinal nerve fibre layer thickness (RNFL) measured by spectral domain optical coherence tomography (SD- OCT) in a healthy Nepalese population and to compare the RNFL thicknesses between the genders and among the various age groups. MATERIAL AND METHODS: One hundred and fifty six eyes of 156 healthy Nepalese subjects (66 males and 88 females) of various age groups were enrolled in this observational, cross-sectional, hospital-based study. The peripapillary RNFL of the randomly chosen eye of each subject was imaged with a high resolution SD-OCT (Spectralis HRA+OCT, Heidelberg Engineering). The RNFL thickness was measured around the optic nerve head using 16 automatically averaged, consecutive, circular B scans with a 3.4 mm diameter and compared between the genders and among the various age groups. RESULTS: The mean age of the subjects was 38.94±17.00 years (range-14 to 76 years). The average peripapillary RNFL was found to be 102.64±9.56 μm (95% CI 97.01-101.93). The mean±SD peripapillary RNFL measurements at the superior, nasal, inferior and temporal sectors in the study population were 129.51±15.09 μm, 76.55±12.02 μm, 134.53±17.19 μm and 70.74±15.53 μm respectively. The average RNFL thickness was 99.47±10.18 μm in the male whereas it was 105.09±8.31 μm in the female participants. The RNFL decreased by 2.26 μm per age per decade. CONCLUSION: The Average RNFL thickness is 102.64±9.56 μm in the Nepalese population. Gender and age related variation in the RNFL could serve as a useful guideline in the diagnosis of glaucoma in our population.