Diagnosis of eccentric fixation using a calibrated ophthalmoscope: defining clinically significant limits

Summary Visuscopy and other ophthalmoscopic methods are widely applied in the assessment of fixation behaviour in amblyopia, although the reliability and inter‐examiner variability of this test has not been established. Typically eccentric fixation is diagnosed solely on the basis of retinal position, but this fails to address the accompanying sensorimotor adaptations. A double‐blind (masked) trial of a paediatric population was undertaken ( n =30, age range 3 years 9 months to 11 years, mean 5.6±1.5 years), involving three examiners applying a detailed protocol. The criteria for eccentric fixation were established from the non‐amblyopic eyes. The most reliable criterion for the diagnosis of fixation was established from the results of the study. No single parameter proved 100% reliable, and amplitude showed greatest inconsistencies. It is recommended that a consensus of at least three parameters from position, zero retinomotor point, principal visual direction and percent foveation is required to diagnose the fixation status reliably.