Ganglion cell complex and retinal nerve fiber layer measured by fourier-domain optical coherence tomography for early detection of structural damage in patients with preperimetric glaucoma

Abstract

Aims: To evaluate the capability of Fourier-domain optical coherence tomography (FD-OCT) to detect structural damage in patients with preperimetric glaucoma.

Methods: A total of 178 Caucasian subjects were enrolled in this cohort study: 116 preperimetric glaucoma patients and 52 healthy subjects. Using three-dimensional FD-OCT, the participants underwent imaging of the ganglion cell complex (GCC) and the optic nerve head. Sensitivity, specificity, likelihood ratios, and predictive values were calculated for all parameters at the first and fifth percentiles. Areas under the curves (AUCs) were generated for all parameters and were compared (Delong test). For both the GCC and the optic nerve head protocols, the OR logical disjunction (Boolean logic operator) was calculated.

Results: The AUCs didn't significantly differ. Macular global loss volume had the largest AUC (0.81). Specificities were high at both the fifth and first percentiles (up to 97%), but sensitivities were low, especially at the first percentile (55%-27%).

Conclusion: Macular and papillary diagnostic accuracies did not differ significantly based on the 95% confidence interval. The computation of the Boolean OR operator has been found to boost diagnostic accuracy. Using the software-provided classification, sensitivity and diagnostic accuracy were low for both the retinal nerve fiber layer and the GCC scans. FD-OCT does not seem to be decisive for early detection of structural damage in patients with no functional impairment. This suggests that there is a need for analysis software to be further refined to enhance glaucoma diagnostic capability.

Keywords: GCC; OCT; RNFL; diagnostic accuracy.

Figure 1

Distribution of RNFL average thickness values for patients in normal group and PPG group. Abbreviations: PPG, preperimetric glaucoma; RNFL, retinal nerve fiber layer.

Figure 2

Distribution of RNFL superior thickness values for patients in normal group and PPG group. Abbreviations: PPG, preperimetric glaucoma; RNFL, retinal nerve fiber layer.

Figure 3

Distribution of RNFL inferior thickness values for patients in normal group and PPG group. Abbreviations: PPG, preperimetric glaucoma; RNFL, retinal nerve fiber layer.

Figure 4

Distribution of GCC average thickness values for patients in normal group and PPG group. Abbreviations: GCC, ganglion cell complex; PPG, preperimetric glaucoma.

Figure 5

Distribution of GCC inferior thickness values for patients in normal group and PPG group. Abbreviations: GCC, ganglion cell complex; PPG, preperimetric glaucoma.

Figure 6

Distribution of GCC superior thickness values for patients in normal group and PPG group. Abbreviations: GCC, ganglion cell complex; PPG, preperimetric glaucoma.

Figure 7

Comparison between AUCs. Abbreviations: AUC, area under the curve; avg, average thickness; FLV, focal loss volume; GCC, ganglion cell complex; GLV, global loss volume; inf, inferior thickness; OR, the OR Boolean operator; RNFL, retinal nerve fiber layer; SE, standard error; sup, superior thickness.