Structural and functional relationships in glaucoma using standard automated perimetry and the Humphrey Matrix.

PURPOSE

To evaluate and compare correlations between structural and functional loss in glaucoma as assessed by optical coherence tomography (OCT), scanning laser polarimetry (GDx VCC, as this was the model used in this study), standard automated perimetry (SAP), and the Humphrey Matrix (Matrix).

METHODS

Ninety glaucomatous eyes identified with SAP and 112 eyes diagnosed using Matrix were independently classified into six subgroups, either S1/M1 (MD>-6dB), S2/M2 (-12<MD<-6dB) or S3/M3 (MD<-12dB), according to the mean deviation (MD) of each test. Average and sectoral retinal nerve fiber layer (RNFL) thickness and percentage of abnormal classifications using the internal normative databases of OCT and GDx VCC were compared among the six subgroups.

RESULTS

In the SAP subgroups, RNFL thickness values obtained by OCT in the nasal and temporal quadrants and the inferior averages of GDx VCC did not differ between the S1 and S2 subgroups (p=0.137, 0.738 and 0.149, respectively). In the Matrix subgroups, no measurement parameters differed between the M1 and M2 groups except for the overall mean and average inferior RNFL thickness given by OCT and the NFI values of GDx VCC (p=0.013, 0.016 and 0.029, respectively). When abnormal classifications were compared, all measurement parameters, without exception, were significantly different in both the SAP and the Matrix subgroups.

CONCLUSIONS

SAP subgroups showed a good correlation of structural and functional defects when assessed using OCT and GDx VCC. These correlations were weaker in the Matrix subgroups, especially in the early stages of glaucoma.