Evaluation of Structure-Function Relationships in Longitudinal Changes of Glaucoma using the Spectralis OCT Follow-Up Mode

The detection of glaucoma progression is an essential part of glaucoma management. Subjectivity of standard automated perimetry (SAP) prevents the accurate evaluation of progression, thus the detection of structural changes by optical coherence tomography (OCT) is attracting attention. Despite its objectivity, there is controversy about the appropriateness of the use of OCT, because many previous studies have indicated OCT results may not reflect the deterioration of visual field. A reason for this dissociation may be the test-retest variability of OCT, a major cause of which is misplacement of the measurement location. Recent advantages of spectral-domain OCT (SD-OCT), especially Spectralis OCT with an eye-tracking system (follow-up mode) enable measurement at approximately the same location as previous examinations. In addition to utilizing Spectralis follow-up mode, we introduced structure-function relationship map and nonlinear relationship between SAP and OCT results in considering structure-function relationship in longitudinal changes. The introduction of these two ideas in our study population improved the correlation between the SAP and OCT (R = 0.589 at most). The results of this study support the practical use of OCT in glaucoma progression but also stress the importance of focus on the corresponding focal changes and the consideration of disease severity.