Ratio of hemi-papillary rim volumes and glaucoma diagnosis with Heidelberg retina tomograph.

PURPOSE: To test if inclusions of the ratios of hemi-papillary parameters in the discriminant function could improve the precision in glaucoma diagnosis with the Heidelberg Retina Tomograph (HRT).

MATERIALS AND

METHODS

Papillary topographs obtained with HRT were reviewed in 202 patients with primary open angle glaucoma, exfoliation glaucoma, pigment glaucoma, ocular hypertension, or glaucoma heredity. A hemi-papillary HRT parameter was obtained by horizontally dividing the optic nerve head image into two halves. A ratio was calculated for each of the HRT parameters with the greater value of the two halves as numerator. The hemi-papillary HRT parameters, together with the ordinary HRT papillary parameters, were evaluated with discriminant analysis to estimate their significance in the glaucoma diagnosis.

RESULTS

The new discriminant function is: the ratio of hemi-papillary rim volumes * 1.110 + cup/disc area ratio * 2.560 + rim area * -1.674 -0.040, established in a group of 66 eyes. The sensitivity of this discriminant function was 84.0%, and the specificity 92.7% in this group. When this discriminant function was applied to a test group of 74 eyes the sensitivity was 89.2% and specificity 87.0%. The sensitivity with the new discriminant function was 81.8% at the early stage of glaucoma and 100.0% at moderate or advanced glaucoma damage.

CONCLUSION

The new discriminant function, including the ratio of hemi-papillary rim volumes, the total rim area, and the cup-disc area ratio improves the precision in glaucoma diagnosis with HRT.