Three-dimensional Neuroretinal Rim Analysis of the Optic Nerve Head with Spectral / Fourier domain OCT

Abstract

 

Purpose

 

Glaucoma is the leading cause of irreversible blindness worldwide. Clinical diagnosis of glaucoma has traditionally centered on optic nerve head evaluation, as the optic nerve head undergoes obvious structural changes prior to clinically detectable loss of visual function. With the advent of optical coherence tomography (OCT), the potential for detecting quantitative structural changes of the optic nerve head exist. However, current clinical spectral / Fourier domain OCT system algorithms do yet fully utilize the full volumetric imaging capability of the instruments for optic nerve head (ONH) analysis. Here, we measured the 3D neuroretinal rim band thickness in a cohort of normal and glaucoma subjects, in order to investigate its diagnostic potential.

 

Methods

 

Three-dimensional OCT scans of the optic nerve head were acquired by the Heidelberg Spectralis in 116 open-angle glaucoma patients and 114 normal, healthy controls. As shown in Figure 1A, the retinal pigment epithelium (RPE) termination at the optic disc boundary (red circles) and the ONH (colored surface) were automatically detected. The minimum distance band (mdb) was computed as the shortest distance between the disc boundary and the ONH surface. The thickness of this band could then be determined as a function of clock hour around the optic nerve.

 

Results

 

Among the measured data sets, the mdb thickness could discriminate between open-angle glaucoma and normal, healthy controls (Figure 1B). Plotting the results as a function of angle revealed the expected thickness profiles (Figure 1C, mean +/- S.D.). Moreover, a simple t-statistic showed that best discrimination between normal and glaucoma was achieved in the superior-temporal region as well as the inferior region (Figure 1D).

 

Conclusions

 

In conclusion, we have demonstrated a minimum distance band metric that may have future potential for glaucoma diagnosis, monitoring, as well as an endpoint in clinical trials.

 

 

Keywords: 550 imaging/image analysis: clinical • 629 optic nerve • 627 optic disc