LACTOSE control score for exotropia
Reviewed by Fiona Rowe

The purpose of this study was to determine the extent of change in control over multiple measurements in a single clinic visit using the Look and Cover, then Ten seconds of Observation Scale for Exotropia (LACTOSE) scoring system in patients with intermittent exotropia. The study included 95 patients; 55 female and aged 7.16 ±6.72 years (range three to 63). Mean angle of deviation was 25.54 ±6.83PD at distance and 25.68 ±7.81PD at near. Mean stereoacuity was 117.94 ±125.72”. Change in control was defined as at least one-point change on the scale and this was noted in 45 patients. The remainder had consistent scores. A one-point change was noted in 27 patients and two-point change in 18. The mean interval between measures was 1.64 hours if assessed twice and 4.36 hours if assessed three times. There was no difference in change for near / distance angle measurements. Patients with scores of seven to eight or poor control of exotropia had large angles and worse stereoacuity. Multiple measurements provided more consistent information on control, further, if the level of control was either very good or very poor on initial assessment, it was significantly likely to stay that way.

Assessing variability of control within a single day in intermittent exotropia.
Prile SM, Kim J, Moon Y, Lim HT.
JOURNAL OF PEDIATRIC OPHTHALMOLOGY AND STRABISMUS
2020;57:378-83.