Assessing the binocular visual field in glaucoma using monocular test results

Purpose. To demonstrate a method of simulating the central binocular visual field using results from merged left and right monocular Humphrey fields. To examine the concordance between results from the simulation and the binocular Humphrey Esterman Visual Field Test (EVFT). Methods. Fifty-nine consecutive patients with bilateral glaucoma each recorded Humphrey 24-2 fields for both eyes and binocular EVFT on the same visit. EVFT results were used to identify patients exhibiting at least one defect (<10 dB) within the central 20° of the binocular field. This criterion has a significant bearing on a patient's legal fitness to drive in the UK. Computer software for visual field analysis (PROGRESSOR) can merge individual sensitivity values from monocular fields to generate a central binocular field. Results are displayed as a grayscale and as symbols representing defects at the <10 dB level. This binocular simulation was used to classify patients that would fail the criterion and concordance with the EVFT results was evaluated. Results. Substantial agreement was observed between the methods in classifying patients with at least one defect (<10 dB) within the central binocular field (Kappa : 0.81; SE: 0.09). Patients failing this criterion using the EVFT results were identified by the binocular simulation with high levels of sensitivity (100%) and specificity (86%). Conclusion. Excellent concordance exists between the binocular simulation and EVFT in classifying glaucomatous patients with central binocular defects. A rapid estimate of a patient's central binocular field and visual functional capacity can be determined without extra perimetric examination.