Here are two videos of a child attempting fixation on the internal target of an autorefractor (hot air balloon at end of road). Rotary nystagmus is evident, greater with the right eye fixating than the left eye. Monocular visual acuities are 20/100 right eye and 20/50 left eye due to an increased latent component, utilizing isolated numbers as the acuity demand. When viewing monocularly, there is head turn to the right and gaze left to seek a null point. When viewing binocularly, acuity approach 20/20. This child had strabismus surgery at age 2, and is now 10 years old, with a variable right exotropia and constant suppression of the right eye on sensory testing with anagylphic or polarized targets. The term “cogwheel” is generally reserved for pursuits, but in a sense better describes the attempt to maintain fixation on a target, with drifts and then corrective saccades back to the target.
The child wear a plus lens Rx for moderate hyperopia of +2.00 OD and +1.50 OS. Maintenance of BVA right eye will be through MFBF activities which will trigger less latent nystagmus than occlusion. That presents a middle ground through which fusion may ultimately be achieved.