Discriminating between normal and glaucoma-damaged eyes with the Heidelberg Retina Tomograph 3.

PURPOSE

To determine and validate the diagnostic ability of a linear discriminant function (LDF) based on global stereometric parameters obtained using the Heidelberg Retina Tomograph version 3 (HRT3) for discriminating between healthy eyes and eyes with glaucomatous visual field loss.

DESIGN

Cross-sectional study.

PARTICIPANTS

The authors prospectively selected 81 consecutive healthy subjects and 85 consecutive patients with open-angle glaucoma. Another prospective sample of 225 normal eyes and 210 glaucoma eyes was used to evaluate how well the LDF performed in another population.

METHODS

Participants were divided into 2 groups depending on the results of standard automated perimetry and intraocular pressure. All participants underwent imaging of the optic nerve head with the HRT3.

MAIN OUTCOME MEASURES

The LDF was calculated according to the stepwise logistic regression results of global optic nerve head parameters and glaucoma probability score numerical values. The diagnostic accuracy of the LDF and other parameters included in the software of the HRT3 was evaluated in another independent population.

RESULTS

Based on the results of the stepwise binary logistic regression analysis, the function proposed was LDF = 8.23 - 8.00 x contour line modulation temporal superior + 9.41 x cup shape measure - 4.07 x rim area. The areas under the receiver operating characteristic curve were 0.875 for the LDF, 0.845 for the Frederick S. Mikelberg (FSM) discriminant function, and 0.838 for the Reinhard O. W. Burk (RB) discriminant function. There were no significant differences between these values. The LDF and the FSM and RB discriminant functions yielded sensitivities of 74.2%, 70.4%, and 67.6%, respectively, at a fixed specificity of 85%.

CONCLUSIONS

Compared with the HRT-provided parameters, the proposed LDF exhibited higher diagnostic ability than most available analyses. The LDF had a better sensitivity and specificity balance than the FSM and RB discriminant functions, regardless of optic disc size.