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Allison N. McCoy, Harry Quigley, Neil R. Miller, Prem Subramanian, Pradeep Ramulu, Peter Murakami, Helen Danesh-Meyer, Michael V. Boland; Development and Evaluation of a Neurological Hemifield Test. Invest. Ophthalmol. Vis. Sci. 2011;52(14):262.
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© ARVO (1962-2015); The Authors (2016-present)
Visual field defects related to neurologic disease may be overlooked or mistaken for glaucoma. We set out to develop an automated Neurologic Hemifield Test (NHT) to improve the detection of chiasmal or post-chiasmal visual field loss.
Using a scoring system similar to the Glaucoma Hemifield Test (GHT), we converted each point in the 24-2 pattern of the Humphrey Field Analyzer to a number that was inversely proportional to the pattern deviation probability. Field points were then grouped into two symmetric regions of 16 points on either side of the vertical meridian, avoiding the physiologic blind spot. The overall NHT score was the absolute value of the difference in the sum of the point scores for right and left regions.The NHT was evaluated using visual field tests for subjects with known neurologic disease, subjects with glaucoma, and glaucoma suspects (99 subjects each). The glaucoma fields were selected to match the neurological fields based on age and mean deviation, and the glaucoma-suspect fields were matched to the neurological cases based on age alone. An NHT score was assigned to each eye of each subject separately. Performance of the NHT against clinical diagnosis was assessed with Receiver Operating Characteristic (ROC) analysis. Two neuro-ophthalmologists and two glaucoma specialists were asked to assign two scores to each pair of visual field tests in the database, one for the likelihood of neurologic disease and one for the likelihood of glaucoma, using a 5 point scale. The fields were presented to the clinicians without patient identifiers or GHT results. The performance of the NHT and GHT were compared with the performance of skilled clinicians using ROC analysis.
The NHT was effective in discriminating fields from patients with neurologic disease from the combined group of patients with glaucoma or glaucoma suspicion (AUC 0.88, CI 0.836 - 0.922). The test performed similarly to skilled clinicians, with a correlation of 0.75 - 0.79. Despite their different specialties, the clinicians tended to agree with one another, with an inter-rater reliability of 0.87 for neurologic fields and 0.78 for fields from glaucoma patients.
We have developed a hemifield test that can distinguish chiasmal and post-chiasmal visual field defects from defects caused by glaucoma. The NHT rivals the performance of skilled clinicians for discriminating neurologic field defects.
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