Retinal Nerve Fiber Layer Thickness in a Subset of Karachi (Pakistan) Population

Aim: To provide the normal range of retinal nerve fiber layer (RNFL) thickness in a subset of Karachi population by Spectralis OCT and to evaluate the effects of age and gender on it.

Methodology: 300 eyes from 150 healthy subjects aged 40 years and above with no ocular pathologies were examined using standard protocols by a single examiner. Subjects with high myopia, history of diabetic or hypertensive retinopathy, raised intraocular pressure (> 21 mmHg) and previous intraocular or laser surgery were excluded from the study. The mean retinal nerve fiber layer thickness was calculated and was correlated with age and gender difference.

Results: The mean global retinal nerve fiber layer thickness was found to be 99.02±9.08 μm in our set of population. Out of four quadrants the maximum RNFL thickness was found in inferior quadrant (126.45±16.23 μm) followed by the thickness of 121.50±15.03 μm in superior quadrant, 78.99±13.99 μm in nasal quadrant and 68.90±13.10 μm in temporal quadrant. We found strong negative correlation of RNFL thickness with age (P= 0.001) and not significant relation with gender (P= 0.8).

Conclusions: Keeping in mind the variations in RNFL thickness with ethnic differences, this study provides the normal values of RNFL thickness according to our set of population. It is concluded that RNFL thickness decreases significantly with increasing age but gender had no significant effect on it.