ASSOCIATION OF BLUE-ON-YELLOW VISUAL FIELD WITH OPTIC DISC AND RETINAL NERVE FIBER LAYER
P. Teesalu, P. J. Airaksinen
Background: Visual field defects, changes of optic nerve head (ONH) and retinal nerve fiber layer (RNFL) are signs of glaucoma.
Purpose of this study was to test the relationship between quantitative ONH, semi-quantitative RNFL and B/Y visual field test results in normals and patients with glaucoma and ocular hypertension.
Methods: We evaluated 1 randomly chosen eye of 40 normal subjects and 37 patients with ocular hypertension and different stages of glaucoma. The BN and W/W visual field were obtained with a Humphrey perimeter. Perimetry results were adjusted for the patients age and for the yellow coloration of the lens expressed as measure of the lens autofluorescence. A total and hernifield mean deviation (MD) of visual field was calculated as the difference between the measured and expected mean sensitivity values, predicted by the regression model fitted in normal subjects. The optic discs were measured using the Heidelberg Retina Tomograph. Monochromatic RNFL photographs were assessed in a masked fashion.
Results: With forward stepwise logistic regression analysis using B/Y hernifield data 38% of the glaucoma patients "normal" (MD>-2 dB) W/W hernifields were classified abnormal. With the cup shape measure alone in the model 52% of the cases were classified abnormal. The B/Y hernifield data obtained from "normal" W/W hernifields of early glaucoma patients were well correlated with respective RNFL loss scores found to be abnormal in 84% of hemispheres. Duncans multiple range test showed a statistically significant difference between the hernifield MD values of B/Y perimetry obtained from "normal" W/W hernifields of normal subjects and ocular hypertensive patients (zero RNFL loss score).
Conclusions: The results of BN visual field, ONH and RNFL evaluation are well correlated. In patients with glaucoma these parameters may reveal glaucomatous abnormalities in a hernifield found to be normal on W/W perimetry. In subjects with ocular hypertension the functional damage detected by B/Y pertimetry may precede RNFL defects on conversion to glaucoma.
Department of Ophtalmology, University of Tartu, Tartu, Estonia Department of Ophtalmology, University of Oulu, Finland