UTILISATION OF THE STRUCTURE OF THE RETINAL NERVE FIBER LAYER AND TEST STRATEGY IN VISUAL FIELD EXAMINATION, ACTA UNIVERSITATIS OULUENSIS D Medica 1057

The aim of this study was to create a mathematical model of the retinal nerve fiber layer and of the\nentire hill of vision, and to compare different perimetric methods and test grids in the detection of\nvisual field loss in glaucoma and optic neuritis.\nA mathematical model of the retinal nerve fiber layer was developed, based on traced nerve\nfiber bundle trajectories extracted from 55 fundus photographs of 55 human subjects. The model\nresembled the typical retinal nerve fiber layer course within 20° eccentricity from the foveola. The\nstandard deviation of the calculated corresponding angular location at the optic nerve head\ncircumference ranged from less than 1° up to 18° (mean 8.8°).\nA smooth mathematical model of the hill of vision was created, based on 81\nophthalmologically healthy subjects. The model fit R2 was 0.72.\nApplying individually condensed test grids in 41 glaucomatous eyes of 41 patients enhanced\nremarkably the detection of progression. Seven out of 11 (64%) of the progressive scotomata\ndetected by spatially condensed grids would have been missed by the conventional 6° × 6° grid.\nIn 20 eyes of 20 patients with advanced glaucoma, the comparability of visual field areas\nobtained with semi-automated kinetic perimetry and automated static perimetry was satisfactory\nand within the range of the test-retest reliability of automated static perimetry.\nUsing a standardized grid of 191 static targets within the central 30° visual field, the most\ncommon finding in 100 eyes of 99 patients with acute optic neuritis were central scotomas,\naccounting for 41% of all visual field defects in affected eyes.\nIn conclusion, a model of the retinal nerve fiber layer was developed, which provided a detailed\nlocation specific estimate of the magnitude of the variability on the courses of retinal nerve fiber\nbundle trajectories in the human retina. A smooth mathematical model of the hill of vision with a\nsatisfactory model fit was described for the 80° visual field. Individually condensed grids enabled\nthe detection of a glaucomatous visual field progression more frequently and also earlier than\nconventional grids. Semi-automated kinetic perimetry was found to be a valuable alternative to\nautomated static perimetry in monitoring advanced glaucomatous visual field loss. Using a grid\nwith a higher spatial resolution may enhance the detection of small central visual field loss in optic\nneuritis.

ISBN-10:
978-951-42-6200-5
Kieli:
eng.
Sivumäärä:
154 s.
Tekijät:
Nevalainen Jukka
Tuotekoodi 013978
21,50 €