Analysis: confocal laser scanning tomography of the optic nerve head
Parameter:
(1) rim area in square mm (lower in glaucoma)
(2) rim volume in cubic mm (lower in glaucoma)
(3) retinal nerve fiber layer thickness in mm (lower in glaucoma)
(4) cup shape measure (higher in glaucoma)
(5) cup volume in cubic mm (higher in glaucoma)
(6) cup area in square mm (higher in glaucoma)
discriminant function =
= (0.3 * (rim area)) + (3.7 * (rim volume)) + (4.3 * (retinal nerve fiber layer thickness)) - (3.7 * (cup shape)) - (3.1 * (cup volume)) - (0.9 * (cup area)) - 2.77
Interpretation:
• The discriminant function for a normal eye is close to 0 (ideally > 0).
• The discriminant function for an eye with glaucomatous damage appears to be in -2 or less.
Performance:
• The sensitivity of the multivariate model to distinguish normal and pre-glaucoma was 42% and the specificity was 95%.
• The sensitivity of the multivariate model to distinguish eyes with glaucoma was 84% and the specificity was 96%.
