Diagnostic ability of the thickness of the macular inner retinal layers as measured by 8x8 posterior pole and ETDRS protocols to differentiate between ocular hypertension and early primary-open angle glaucoma

Abstract

Purpose : To evaluate the diagnostic ability of two macular OCT protocols to discriminate between ocular hypertension (OHT) and early primary open-angle glaucoma (POAG).

Methods : 57 eyes of 57 OHT patients and 57 eyes of 57 early POAG patients were included. All had reliable macular OCT scans (Spectralis, Heidelberg) both using the 8x8 posterior pole protocol (8x8p) and ETDRS protocol (ETDRSp). Three automatic segmentations were considered for each protocol: macular retinal nerve fiber layer (RNFL), ganglion cell layer (GCL) and inner plexiform layer (IPL). The areas under the receiver operating characteristics curves (AUROC) values were obtained for the thickness of these layers in the 64 cells of the 8x8p and in the 9 sectors of the ETDRSp and were represented quantitatively by heat maps. Thickness of cells/sectors with AUROC values ≥0.7 were combined for each protocol obtaining a global index for the 8x8p (8x8p-GI) and the ETDRSp (ETDRSp-GI).

Results : AUROC values were ≥0.7 in 22 cells of the RNFL, 5 of the GCL and 1 of the IPL in the 8x8p (the highest was the cell 2.6 of RNFL, AUROC=0.755), but only in 3 sectors of RNFL and 1 sector of GCL in the ETDRSp (the highest was the sector I2 of the RNFL, AUROC=0.744). There was a significant difference between the global index AUROC of both protocols: 8x8p-GI (0.786) versus ETDRSp-GI (0.747) (p<0.05, DeLong test).

Conclusions : The 8x8p may have a higher diagnostic ability than the ETDRSp to discriminate between OHT and early POAG.

This is a 2020 ARVO Annual Meeting abstract.

 

The 8x8 posterior pole protocol is represented in blue while the ETDRS protocol is represented in red. Note that one sector of ETDRS protocol (highlighted in orange) includes several cells of the 8x8 posterior pole protocol. Also note that 8x8 posterior pole protocol is tilted along the disc-fovea axis.