Discriminant analysis models for early detection of glaucomatous optic disc changes

Aim-To evaluate and compare four different mathematical formulas for the ea rly detection of morphometric optic nerve head changes in chronic open angl e glaucoma. Methods-The optic nerve heads of 161 patients with perimetrically defined g laucomatous optic nerve damage and of 194 normal subjects were examined by confocal laser scanning tomography. Using four formulas of Linear discrimin ant analysis and the optic cup shape measure as the single optic disc varia ble, the predictive power of each of these methods was examined to differen tiate between the normal eyes and the glaucoma eyes. Results-The highest predictive power had an optic disc sector based formula , in particular in eyes with medium and large optic discs. This optic disc sector based formula was the one with the best agreement with the other for mulas examined. It achieved a better predictability than any single optic d isc variable evaluated. Conclusions-Combining quantitative optic disc variables by discriminant ana lysis functions, the predictive power of semiautomatic quantitative optic n erve head evaluation can be improved by providing the ophthalmologist with a diagnostic score for the detection of glaucomatous optic nerve damage. Be cause of the pattern of glaucomatous neuroretinal rim loss, an optic disc s ector based discriminant formula may have a higher diagnostic precision tha n other formulas in detecting early glaucomatous damage.