Pilot Study of Optical Coherence Tomography Measurements of Retinal Vessel Relief Height in the Detection of Glaucoma

Abstract

 

Purpose

 

To investigate diagnostic power of retinal vessel relief height using optical coherence tomography (OCT) for glaucoma.

 

Methods

 

One eye of each participant was scanned with a 100k Hz swept source OCT. Vessel relief height (portion of vessel extending above retinal plane) and diameter of four major vessels from each circular OCT scan were measured at various radii from the disc center (1.2, 1.9, 2.6, 3.0, and 3.5 mm) by a human grader. Retinal nerve fiber layer (RNFL) thickness was measured at a standard radius of 1.7 mm by an automated computer program. Participants also underwent Humphrey visual field (HVF) automated perimetry. Statistical analysis was performed to assess for significant difference between normal and glaucoma participants, diagnostic power, and correlation between diagnostic variables.

 

Results

 

A total of 36 eyes of 36 participants (25 healthy controls, 11 glaucoma participants) were enrolled. Vessel relief height was found to be significantly larger in glaucoma eyes relative to control eyes between 1.9 and 3.5 mm radii, with the largest difference found at a radius of 3.0 mm (control 7.1 ± 4.5 µm, glaucoma 20.8 ± 13.4 µm, p<0.001) (Table 1). The diagnostic power of vessel relief height was greatest at 3.0 mm, with an area under the curve of a receiver operating characteristic value of 0.93 ± 0.04. Combining vessel relief height and RNFL thickness (versus RNFL thickness alone) improved the sensitivity of glaucoma diagnosis from 45% to 82%, and slightly reduced the specificity from 100% to 96%. No significant linear correlation was found between vessel relief height and either RNFL thickness or HVF parameters. Vessel relief height appeared to increase in early glaucoma and then return to near normal levels in late glaucoma.

 

Conclusions

 

Vessel relief height is comparable to RNFL thickness in glaucoma detection sensitivity. Vessel relief height appears more sensitive to early glaucoma, while RNFL thickness is more sensitive to more advanced glaucoma; they appear to be complimentary variables that improved diagnostic sensitivity when combined. A larger study is needed to validate the value of vessel relief height measurement in glaucoma detection.

 

 

Table 1. Vessel Relief Height as a Function of Radial Distance from Optic Disc Center

 

Keywords: 550 imaging/image analysis: clinical • 629 optic nerve • 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)