Structure-function relationships in glaucoma using enhanced depth imaging optical coherence tomography-derived parameters: a cross-sectional observational study

Abstract

Background To investigate structural and functional correlations in glaucoma patients using enhanced depth imaging spectral-domain optical coherence tomography (EDI OCT)-derived parameters. Methods We prospectively enrolled healthy participants and glaucomatous patients with a wide range of disease stages. All participants underwent visual field (VF) testing (SITA - Standard 24–2; Carl Zeiss Meditec, Dublin, CA) and EDI OCT imaging (Spectralis; Heidelberg Engineering Co., Heidelberg, Germany). The following optic nerve head parameters were measured on serial vertical EDI OCT B-scans by two experienced examiners masked to patients clinical data: lamina cribrosa (LC) thickness and area, prelaminar neural tissue thickness and area, anterior LC depth, Bruch’s membrane opening (BMO) and average, superior, and inferior BMO-minimum rim width (BMO-MRW). Only good quality images were considered, and whenever both eyes were eligible, one was randomly selected for analysis. Scatter plots were constructed to investigate correlations between each anatomic parameter and patient’s VF status (based on VF index [VFI] values). Results A total of 73 eyes of 73 patients were included. All EDI OCT parameters evaluated differed significantly between glaucomatous and control eyes ( P ≤ 0.045). A secondary analysis, in which glaucomatous patients were divided according to VF mean deviation index values into 3 groups (mild [G1; > − 6 dB], moderate [G2; − 6 to − 12 dB] and advanced [G3; <− 12 dB] glaucoma), revealed that average BMO-MRW was the EDI OCT parameter that presented more significant differences between the different stages of glaucoma. Significant structure-function correlations were found between VFI values and prelaminar neural tissue area (R 2 = 0.20, P = 0.017), average BMO-MRW (R 2 = 0.35, P ≤ 0.001), superior BMO-MRW (R 2 = 0.21, P = 0.012), and inferior BMO-MRW (R 2 = 0.27, P = 0.002). No significant correlations were found for LC area and anterior LC depth ( P ≥ 0.452). Conclusions Evaluating the distribution pattern and structure-function correlations of different laminar and prelaminar EDI OCT-derived parameters in glaucomatous patients, we found better results for neural tissue-based indexes (compared to LC-derived parameters). The diagnostic utility of each parameter deserves further investigations. Electronic supplementary material The online version of this article (10.1186/s12886-019-1054-9) contains supplementary material, which is available to authorized users.

Characteristics of Patients Showing Discrepancy Between Bruch’s Membrane Opening-Minimum Rim Width and Peripapillary Retinal Nerve Fiber Layer Thickness

“…Previous studies have revealed that the structure-function relationship is better with the BMO-MRW parameter than other conventional OCT-based and CSLO-based parameters [15,35,36]. Pollet-Villard et al [15] have demonstrated that the structure-function relationship is significantly greater with BMO-MRW than other optic disc OCT parameters including neuro-retinal rim thickness.…”

“…Recently, the structure-function relationship in lamina cribrosa (LC)-derived parameters has been inspected. Lopes et al [36] have found that BMO-MRW has better structure-function correlations than LC-derived parameters including prelaminar neural tissue thickness and area, anterior LC depth, and LC thickness and area. These findings partly support our study results that most (86.1%) included subjects showing normal classification of BMO-MRW and abnormal classification of RNFL demonstrated normal findings on VF tests.…”

Using Enhanced Depth Imaging Optical Coherence Tomography-Derived Parameters to Discriminate between Eyes with and without Glaucoma: A Cross-Sectional Comparative Study

“…We adopted the same glaucoma definition that we used in our previously published studies [16, 17]. In short, characteristic glaucomatous optic neuropathy was defined as a vertical cup-to-disc ratio (VCDR) ≥0.6, asymmetry of VCDR ≥0.2 between eyes, presence of localized or diffuse pRNFL defects and/or neuroretinal rim defects in the absence of any other abnormalities, which could explain such findings [16, 18, 19].…”

“…When it comes to using ONH parameters for glaucoma diagnosis and monitoring (besides the well-established BMO-MRW analysis), more recently, researchers have been investigating new metrics based both on prelaminar neural tissue (PLNT) and laminar analyses [14-16]. In previous studies from our group in this research line [17], we reported on glaucoma-related features within the ONH and on structure-function relationships in glaucoma (considering both laminar and prelaminar parameters) using EDI OCT quantitative analysis. Even though some interesting data about these new EDI OCT-based parameters have been emerging, their usefulness as an additional tool for glaucoma diagnosis is still unclear.…”

Rate of Change in Bruch’s Membrane Opening-Minimum Rim Width and Peripapillary RNFL in Early Normal Tension Glaucoma

“…It has been lately shown that BMO-MRW provides better performance in the diagnosis of glaucoma than traditional NRR parameters [ 8 , 9 , 10 ]. BMO-MRW also shows a better structure-function relationship in glaucoma than other pre-existing peripapillary RNFL and parameters of confocal scanning laser ophthalmoscope [ 10 , 11 , 12 , 13 ]. We have previously described a disagreement between BMO-MRW and RNFL in classification analysis of color-codes [ 14 ].…”