Relationship between visual field changes and optical coherence tomography measurements in advanced open-angle glaucoma.

AIM: To assess relationships between functional changes in visual field and structural changes in advanced open-angle glaucoma (OAG) found using spectral-domain optical coherence tomography (SD-OCT).

METHODS: Thirty-one eyes of 25 patients with OAG were included in this study. Besides the routine ophthalmological exam the patients underwent standard automated perimetry (SAP) (Humphrey Field Analyzer) and SD-OCT (RTVue-100) performed within 6 months. The global perimetric indices in the study group were as follows: mean deviation (MD) 12.33±6.18 dB and pattern standard deviation (PSD) 9.17±3.41 dB. The relationship between OCT measurements and MD and PSD was evaluated by correlation analysis (Pearson's correlation coefficient) and regression analysis (linear and nonlinear regression models).

RESULTS: Thickness measurements of the lower halves of ganglion cell complex (GCC) and retinal nerve fiber layer by two scanning protocols (ONH and 3.45) showed these to be thinner than the upper halves, but the difference failed to reach statistical significance. The correlations between global indices MD/PSD and most of the analysed quantitative OCT measurements were moderate (r in the range between 0.3 and 0.6). The correlation between MD and GCC showed nonlinear cubic regression (R2=0.417, P=0.004). Good correlation was found between MD and GLV (R2=0.383; P=0.008). Linear regression (P<0.05) was found only between MD and Cup area (R2=0.175, P=0.024) and between MD and RNFL by 3.45 protocol (R2=0.131, P=0.045).

CONCLUSION: Nonlinear regressive models appear to be more appropriate in the assessment of the correlations between functional and structural changes in eyes with advanced glaucoma. The correlations we found were moderate.