Abstract
Purpose: :
To determine differences between individuals in the slope of the linear relationship between the thickness of the retinal nerve fibre layer (RNFL) measured with spectral domain optical coherence tomography (SD-OCT) (Topcon, Marck II), and a set of filters with known optical density (OD).
Methods: :
SD-OCT 3D volume scans of the optic disc were performed in ten healthy volunteers, using Topcon 3D OCT-1000 (Topcon Medical Systems). A set of six artificial filters with a known OD ranging from 0.04-0.75 was used. The linear correlation was calculated between the change in RNFL (Δ RNFL) and the change in OD (Δ OD) for each individual. All measurements were done in duplo and each individual was measured on two occasions.
Results: :
Ten right eyes of ten healthy volunteers were included in this study. Linear regression demonstrated a difference in slope between individuals, describing the relation between Δ RNFL and Δ OD. The slope varied between 29.4 and 106.8. Repeat measurements on two different occasions were highly correlated (r = 0.99).
Conclusions: :
There exists a linear correlation between the Δ OD and the Δ RNFL, measured with SD-OCT. This could be used to correct RNFL measurements for the OD of a natural occurring media opacity like cataract. However, the difference in slope between individuals of the linear correlation between delta OD and delta RNFL calls for an individual correction.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • nerve fiber layer • cataract