The importance of disc hemorrhage in the prognosis of chronic open angle glaucoma.

The progression of field damage of 48 eyes with chronic simple glaucoma and a splinter hemorrhage on the disc was compared with that of 48 chronic simple glaucoma eyes without hemorrhage. The incidence of visual field progression was substantially higher among those with a hemorrhage. Similar visual field progression was substantially higher in 29 eyes with elevated introcular pressure and a disc hemorrhage when compared with 29 ocular hypertensive patients with no hemorrhage. The prognostic importance of a disc hemorrhage is discussed.

Comparative reproducibility of the digital photogrammetric procedure utilizing three methods of stereophotography.

The reproducibility of digital photogrammetry of optic nervehead photographs taken with the Zeiss fundus camera with Allen stereoseparator, the Donaldson fundus camera, and the Zeiss fundus camera with twin-prism separator were evaluated. Reproducibility of the various quantitative factors was significantly better when the two types of simultantic cups. Larger per cent errors were encountered with shallower optic cups. Substantial improvements in parameter reproducibility were obtained when finer sampling intervals were used during film digitization.

Analog vs. digital photogrammetry for optic cup analysis.

This report compares the reproducibility of analog and digital photogrammetry for topographical analysis of the optic cup. Ten simultaneous stereophotographs of each of three optic discs were taken with the Zeiss fundus camera plus a twin-prism stereoseparator. Digital processing produced photogrammetric contours of the optic cup and estimates of its geometry. Optic cup contours from the same stereopairs were also drawn with an analog stereoplotter and were analyzed by manual planimetry. The reproducibility of digital photogrammetry and analysis for estimation of cup depth, cup width, cup cross sectional area, and cup volume was concluded to be generally superior to the reproducibility of analog photogrammetry and manual analysis.

Studies of hemorrhage on the optic disc.

The general medical and laboratory findings in 60 patients having a sector hemorrhage on the optic disc were compared with the findings in 102 patients with intraocular pressure elevation but without a disc hemorrhage. Of 22 parameters studied, systemic hypertension was the only abnormality which occurred significantly more frequently in the hemorrhage group. A study of the intraocular pressures suggests that hemorrhage may not be related to the level of intraocular pressure. Examinations of 50 patients with systemic hypertension and of 50 patients with cardiac abnormalities revealed no hemorrhage on the optic disc. These factors by themselves may not be responsible for the occurrence of hemorrhages.

Twin-prism stereo-separator.

We describe a twin-prism stereoseparator for the Zeiss fundus camera which gives high-quality stereophotographs of the optic disc and simultaneously records both images on the same frame of film. The stereobase of photographs taken with this system ranges from 2.0 to 4.5 mm. It varies linearly with the entrance pupil which ranges from 4.0 to 6.5 mm. The instrument provides a reliable method for monitoring changes in optic disc topography.

Simultaneous stereophotography. Its value in clinical assessment of the topography of the optic cup.

Simultaneous stereophotography achieves reproducible records of the optic cup topography. The clinical usefulness of sterophotographs remains unknown. This study compares the optic cup evaluation from contact lens examination with the evaluation from stereophotograph examination. Both methods of examination were used by each of 2 examiners to record their estimates of 12 parameters describing the optic cup topograhy. One eye of each of 50 patients was studied. In only 3 of the parameters studied were there statistically significant differences between the 2 methods of examination. Simultaneous stereophotography achieves a permanent record of the optic disc which is reproducible, objective and convenient. This method provides an excellent tool for following optic cup configuration.