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S.E. Feldon, R.W. Scherer, L. Levin, III, S.E. Kelman, K. Dickersin; Visual Fields in the Ischemic Optic Neuropathy Decompression Trial (IONDT): Baseline and Change Over Time . Invest. Ophthalmol. Vis. Sci. 2006;47(13):1087.
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The IONDT included a randomized trial and nonrandomized study of 258 and 160 patients, respectively, with newly diagnosed non–arteritic ischemic optic neuropathy (NAION). Enrolled randomized eyes had acuity of ≤ 20/64 and non–randomized eyes of > 20/64 or refused randomization. Visual fields were measured at baseline, and at 6 and 12 months follow–up, using the Humphrey Field Analyzer (24–2 and size III stimulus).
To develop a computerized classification system to analyze fields of NAION patients and to describe visual field defect pattern and severity at baseline and change in these parameters at follow–up.
We developed and validated a computerized classification system to categorize NAION visual fields by incorporating defect and severity definitions agreed upon by 6 neuro–ophthalmologists into a rule–based system run on Excel®. We used this system to categorize IONDT visual field defects and severity at baseline, and at 6 and 12 months follow–up. We compared baseline visual field pattern and defect severity, and change in pattern and severity over time, by treatment group, visual acuity, age, and co–morbidities.
At baseline, 70% (162/229) of fields from randomized eyes had a central scotoma combined with a superior and/or inferior defect. Those of non–randomized eyes had superior and/or inferior defects without central involvement (92/147; 62.6 %). Eyes with more severe defects or with central scotomas usually had worse visual acuity, and older patients (≥ 65 years) had more severe defects than younger patients (180/220; 81.8% versus 108/156; 69.2%; p = .002). We observed significant changes in the defect distribution within the field from baseline to 6 and 12 months (p = 0.003 and p = 0.02, respectively) for randomized, but not non–randomized eyes. Superior and inferior altitudinal defects were less severe at follow–up than at baseline for both groups. Overall, 74% of fields stayed the same or had improved at 6 months and 76% at 12 months with a positive association between change in acuity and change in the field (p < 0.001 at 6 months and p = 0.01 at 12 months; Kendall’s tau–b).
The most common baseline visual field defect patterns found in IONDT eyes were superior and inferior defects with or without central scotomas. About 75% of IONDT visual fields showed improvement or no change at 6 and 12 months.
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