Abstract
Purpose: :
Early glaucomatous visual field defects can occur outside the central 30°, which are usually examined in perimetric tests used for glaucoma diagnosis and follow-up. Aim of this study was to evaluate the diagnostic usefulness of perimetric examination of the peripheral nasal visual field with exact threshold determination in glaucoma by assessing the amount of defects in normal, ocular hypertensive and glaucoma subjects.
Methods: :
Ninty-one eyes of 91 subjects from the Erlangen Glaucoma Registry were included in this study. 26 ocular hypertensive eyes, 26 "preperimetric" open-angle glaucoma eyes, 18 "perimetric" open-angle glaucoma eyes and 21 control eyes underwent a glaucoma screening including standard 30° automated perimetry (Octopus 500, program G1) and visual field examination with the program "nasal step" of the Humphrey Field Analyzer (model 750i). This test grid consists of 14 points localized mainly in the nasal periphery between 30° and 50° eccentricity, extending from 3° to 9° above and under the horizontal. The full threshold bracketing strategy was used for determining exact sensitivity values. Minimal and maximal criteria were used to classify the results as normal or abnormal. Sensitivies and deviations were compared. Specificity and sensitivity was calculated for every single test point for all diagnosis groups.
Results: :
Most of the perimetric glaucoma patients showed moderate or severe defects (16/18; 83.3%) in the nasal periphery followed by the preperimetric group (5/26; 19.2%). Ocular hypertensive (1/26; 3.9%) and normal subjects (2/21; 9.5%) showed only rare abnormal results. Ten out of 14 test points differed significantly (p<0.05) when comparing thresholds of the normal and preperimetric group. Mean deviation was also significanty lower in the glaucoma groups (p<0.01).
Conclusions: :
. Most glaucoma subjects with visual field defects in the standard 30° perimetry have also defects in the nasal periphery. Glaucoma patients without typical central visual field alterations have significantly more such peripheral defects than ocular hypertensive and normal subjects. This corresponds to neuroretinal rim loss predominantly in the inferior and superior sector in early glaucomatous optic disc atrophy. Peripheral nasal threshold perimetry should be performed in subjects with "preperimetric" glaucoma.
Clinical Trial: :
www.clinicaltrials.gov NCT 00494923