Correlation of asymmetry of visual field loss with optic disc topography in normal-tension glaucoma
K. Nyman, G. Tomita, C. Raitta and M. Kawamura
Department of Ophthalmology, University of Helsinki, Finland.
OBJECTIVE: To compare the differences in optic disc configuration with
different stages of visual field loss in normal-tension glaucoma. DESIGN:
Interocular pairwise comparisons. SETTING: Glaucoma clinic of a teaching
hospital. PATIENTS: Thirteen patients with normal-tension glaucoma and
asymmetric visual field loss of at least 2.5 dB in the mean defect of the
visual field indexes. INTERVENTIONS: Areas under the optic disc profiles
mapped from values for radial sections of the optic disc measured at
intervals of 30 degrees and expressed as percentages of the area of a
rectangle were obtained from stereophotographs with a computerized image
analysis system. Visual fields were tested with automated perimetry
(OCTOPUS), using program G1. MAIN OUTCOME MEASURE: Correlation analyses
between the interocular differences in the areas under the optic disc
profile and the interocular differences in the visual field indexes.
RESULTS: The correlation coefficients between the interocular differences
in mean defect and those of the area under the optic disc profile in the
superior to temporal sections ranged from -.71 to -.61 (.007 < P <
.028). The interocular differences in loss variance correlated with the
differences in the area under the optic disc profile in the superior
section (r = -.61, P = .0252). CONCLUSION: The differences in visual field
loss between the two eyes in normal-tension glaucoma appear mainly to
reflect morphometric changes in the superior half of the optic disc.
