Quality control functions of the Visual Field Reading Center (VFRC) for the Optic Neuritis Treatment Trial (ONTT)

The Visual Field Reading Center (VFRC) was established to assess visual field testing in the Optic Neuritis Treatment Trial (ONTT), to train and certify ONTT technicians, and to monitor the quality of the visual fields through evaluation of the technical aspects of the visual field testing. We describe the functions of the VFRC personnel and the standardized test protocols developed by the VFRC for Humphrey and Goldmann perimetry. We also describe the VFRC procedures for training and certifying visual field technicians, double-checking the eligibility of ONTT patients, assessing the quality of the visual field data, and processing visual field data. In addition, we describe the principles applied by the director and associate director of the VFRC in their clinical classification of the various localized and diffuse visual field defects observed in the Humphrey and Goldmann visual fields. The VFRC has processed more than 14,000 Humphrey and Goldmann visual field tests. The visual field quality control procedures and visual field defect classification process have been shown to be quite reproducible. Through quality control assessment procedures, we have been able to pinpoint a variety of problems at an early stage and promptly implement corrective measures. The standardized test protocols, technician training and certification procedures, and quality control assessment techniques used by the VFRC for the ONTT may serve as a model for future clinical trials employing visual field data as an outcome measure. These procedures can also be used to enhance visual field reliability in ophthalmological practices.