Aim  To describe the clinical features of an under-recognised small esodeviation and horizontal diplopia on distance fixation seen in elderly patients not associated with lateral rectus underaction or coexisting neurological abnormalities.

Methods  87 elderly patients (age range 62–91 years) with constant or intermittent horizontal diplopia at distance were prospectively recruited and assessed from February 2008 until February 2012. Ocular alignment, fusion amplitudes, and horizontal eye movements were measured for distance and near.

Results  Distance esodeviation varied from 2–18 prism dioptres (PD) esotropia (ET). At near fixation, deviation ranged from 10 PD exophoria to 12 PD esophoria. Divergence fusional amplitude at distance ranged from 0–10 PD while the divergence fusional amplitude at near ranged from 2–18 PD. Horizontal ductions and versions were full in all patients. Six patients presented with an increase of distance esodeviation combined with a decrease of divergent fusional amplitude over a period of 6–12 years. All patients were successfully treated with prisms, ranging from 2–16 PD base-out.

Conclusions  Our findings indicate that patients with age-related distance ET may experience a slight increase in distance esodeviation over time, with a slow decrease of fusional divergence amplitudes with normal ocular motility. The aetiology is still unclear. However, patients may be assured that this is a benign condition with slow progression, and can be successfully treated with prism correction. Surgery may be reserved for the minority of cases with severe esodeviation.