Assessing Variability of Control Within a Single Day in Intermittent Exotropia

To assess intra-individual hour-to-hour variability of control in intermittent exotropia using a simple office scale: Look And Cover, then Ten seconds of Observation Scale for Exotropia (LACTOSE).

In this prospective cross-sectional study, the degree of control for distance and near was measured using the LACTOSE, a 5-point scale ranging from 0 to 4. A single investigator performed multiple measurements of the control of each patient with at least an hour interval between measurements.

Of the 95 patients with intermittent exotropia enrolled, 66 (69.5%) were assessed two times and 29 (30.5%) were assessed three times for their control. Most patients had consistent control scores across multiple assessments for distance (n = 63, 66.3%) and near (n = 70, 73.7%). Forty-five (47.4%) patients demonstrated variable control for either distance or near, mostly (n = 27, 60.0%) showing a one-step difference. None presented with more than a two-step difference in the control score on repeated measurements. An initial LACTOSE score of 4 (very poor control) or 1 (very good control) remained unchanged in subsequent assessments for both distance (P = .049) and near (P < .001).

One-third of patients with intermittent exotropia showed variable control scores even during a single day across multiple measurements using the LACTOSE scale. Those who showed consistent control had very good or very poor control, whereas those with variable control had not had very good or very poor control on their initial LACTOSE measurements. [J Pediatr Ophthalmol Strabismus. 2020;57(6):378-383.].