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

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.