Visible and near-infrared optical coherence tomography (vnOCT) in glaucoma suspect, pre-perimetric, and perimetric glaucoma

Abstract

Purpose : Early diagnosis of glaucoma is essential for preventing vision loss. Preclinical studies have shown that retinal nerve fiber layer (RNFL) spectroscopic markers measured through visible and near-infrared optical coherence tomography (vnOCT) are more sensitive to ganglion cell loss than RNFL thinning. This study aims to validate whether RNFL spectroscopic markers measured through vnOCT can distinguish glaucoma from glaucoma suspects in a clinical setting.

Methods : Patients >18 year old with a clinical diagnosis of glaucoma or glaucoma suspect in at least one eye received vnOCT imaging at the peripapillary region (Fig. 1). Glaucoma is determined by abnormal readings from either conventional OCT or Humphrey visual field (HVF) testing, while glaucoma suspects demonstrating normal results despite other risk factors. Spectroscopic markers determined by comparing the visible light signal to the near infrared signal (VN ratio) were compared between glaucoma and glaucoma suspect cases by T-test and one-way ANOVA. The HVF mean deviation readings were also compared to VN ratio through Spearman correlation.

Results : RNFL VN ratio decreased from 1.52 ± 0.08 (n=7) in suspect eyes to 1.11±0.09 (n=20) in glaucomatous eyes (p=0.004, T-test) (Fig. 2). This trend is statistically significant from suspect, pre-perimetric (n=10) to perimetric glaucoma (n=10) (p=0.0484, one-way ANOVA). Among all the perimetric eyes (n=20), a significant correlation (r = 0.424) was found between RNFL VN ratio and HVF mean deviation (p=0.0312, Spearman).

Conclusions : The data in this pilot clinical study validated that RNFL VN ratio is strongly correlated with the severity of glaucoma, and correlated with HVF mean deviation. This trend is consistent with prior preclinical results demonstrating that the RNFL VN ratio is reduced with more severe glaucoma damage. This study demonstrates the potential of using RNFL VN ratio by vnOCT as an additional, non-invasive imaging marker for early detection of glaucoma.

This is a 2020 ARVO Annual Meeting abstract.

 

Fig. 1 (a) The photography of our vnOCT system in Boston Medical Center eye clinics. (b) Representative vnOCT images at the peripapillary region from a glaucomatous eye (POAG, male, 62 years old).

 

Fig. 2 (a) RNFL VN ratio in suspect eyes and glaucoma eyes. (b)The correlation test between deep RNFL VN ratio and HVF mean deviation in all the perimetric glaucoma eyes.