Abstract
Background: :
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).
Purpose: :
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.
Methods: :
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.
Results: :
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).
Conclusions: :
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.
Keywords: neuro-ophthalmology: optic nerve • clinical (human) or epidemiologic studies: outcomes/complications • visual impairment: neuro-ophthalmological disease