Multivariate approach for quantification of morphologic and functional damage in glaucoma.
OBJECTIVE
To determine the usefulness of confirmatory factor analysis in examination of morphometric, electrophysiological, and psychophysical quantitative methods that measure the extent of global glaucomatous damage without referring to a preselected gold standard.


METHODS
In a cross-sectional clinical study, 406 eyes of 203 glaucoma patients and 200 eyes of 100 normal control subjects 18 to 70 years old underwent optic disc morphometry, automated perimetry, measurement of temporal contrast sensitivity by a full-field flicker test, blue-on-yellow visually evoked potential (VEP), and black-and-white pattern-reversal electroretinogram (ERG). Diagnosis of glaucoma was based on a qualitative classification of the optic nerve head and retinal nerve fiber layer independent of intraocular pressure and visual field. Confirmatory factor analysis was performed in the patient group as a whole and in a subgroup showing moderate to advanced glaucomatous optic nerve head damage.


RESULTS
The confirmatory factor analysis models explained the data satisfactorily (P > 0.18, all patients; P > 0.34, subgroup). Global glaucomatous damage was quantified best by the mean defect of automated perimetry (r = 0.81; r = 0.87), followed by the area of the neuroretinal rim (r = 0.64; r = 0.73), the full-field flicker test (r = 0.59; r = 0.65), the pattern-reversal ERG amplitude (r = 0.54; r = 0.55), and the VEP peak time (r = 0.55; r = 0.54).


CONCLUSIONS
Confirmatory factor analysis allows quantification of the validity of established and new procedures that measure global glaucomatous damage using cross-sectional data. The results are not dependent on the preselection of a specific gold standard. Psychophysical testing and morphometry quantified glaucomatous damage best, compared with electrophysiological procedures.
Martus
P
P
Department for Medical Informatics, Biometry, and Epidemiology, University of Erlangen-Nürnberg, Erlangen, Germany. peter.martus@imbe.med.uni-erlangen.de
Jünemann
A
A
Wisse
M
M
Budde
W M
WM
Horn
F
F
Korth
M
M
Jonas
J B
JB
D000293:Adolescent; D000328:Adult; D000368:Aged; D002908:Chronic Disease; D015350:Contrast Sensitivity / Q000502:physiology*; D003430:Cross-Sectional Studies; D004596:Electroretinography; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D005425:Flicker Fusion / Q000502:physiology; D005902:Glaucoma, Open-Angle / Q000175:diagnosis* / Q000503:physiopathology; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009412:Nerve Fibers / Q000473:pathology*; D009898:Optic Disk / Q000473:pathology*; D015203:Reproducibility of Results; D012160:Retina / Q000473:pathology* / Q000503:physiopathology; D058609:Visual Field Tests