PURPOSE: To develop a fully automated algorithm (AP) to perform a volumetric 
measure of the optic disc using conventional stereoscopic optic nerve head (ONH) 
photographs, and to compare algorithm-produced parameters with manual 
photogrammetry (MP), scanning laser ophthalmoscope (SLO) and optical coherence 
tomography (OCT) measurements.
METHODS: One hundred twenty-two stereoscopic optic disc photographs (61 
subjects) were analyzed. Disc area, rim area, cup area, cup/disc area ratio, 
vertical cup/disc ratio, rim volume and cup volume were automatically computed 
by the algorithm. Latent variable measurement error models were used to assess 
measurement reproducibility for the four techniques.
RESULTS: AP had better reproducibility for disc area and cup volume and worse 
reproducibility for cup/disc area ratio and vertical cup/disc ratio, when the 
measurements were compared to the MP, SLO and OCT methods.
CONCLUSION: AP provides a useful technique for an objective quantitative 
assessment of 3D ONH structures.