AC is better than EDI for LC visibility

February 10, 2015

If the goal is to improve lamina cribrosa (LC) visibility, adaptive compensation (AC) is better than enhanced depth imaging (EDI), according to new research.

If the goal is to improve lamina cribrosa (LC) visibility, adaptive compensation (AC) is better than enhanced depth imaging (EDI), according to new research published in Investigative Ophthalmology and Visual Science. Visibility of the posterior LC remains poor, so it is probably not realistic to use LC thickness as a glaucoma biomarker.

The researchers, from Singapore, French Polynesia and London, compared LC visibility in optic disc images obtained from 60 patients with glaucoma and 60 patients serving as controls. They used three optical coherence tomography (OCT) devices, with and without EDI and AC: They obtained a horizontal B-scan through the centre of the disc using two spectral-domain OCT devices (Spectralis, Heidelberg Engineering; Cirrus, Carl Zeiss Meditec - both with and without EDI) and a swept-source OCT device (DRI, Topcon). The investigators applied AC after they obtained the scans, to improve image quality.

Four masked observers evaluated LC visibility by grading the 1,200 images in random order. They graded the anterior LC on a 0-to-4 scale, the LC insertions on a scale of 0 to 2, and the posterior LC either as 0 or 1. The observers used generalized estimating equations to evaluate the effect on LC visibility of EDI, AC, glaucoma severity and other clinical and demographic factors.

The observers found that anterior LC was the most detectable feature, then LC insertions. “AC improved anterior LC visibility independent of EDI,” they wrote. “Cirrus+EDI+AC generated the greatest anterior LC visibility grades.”

Regarding LC insertions visibility, they said, “DRI+AC was the best method. Visibility of the posterior LC was consistently poor. Neither glaucoma severity nor clinical/demographic factors consistently affected LC visibility.”