Background/aims To compare surgical outcomes between preterm and full-term patients with infantile-onset esotropia.

Methods This study included 56 preterm and 162 full-term patients with infantile-onset esotropia who underwent strabismus surgery. The extent of surgery was reduced by 0.5 mm per muscle in preterm patients who were born at <30 weeks of gestation. Surgical outcomes over time, including surgical success, overcorrection rate, undercorrection rate and surgical dose–response were compared between preterm and full-term patients.

Results The Cox proportional hazards regression model and competing risk analysis showed no statistically significant differences in the rate of surgical success or undercorrection over time between preterm and full-term patients. However, the final overcorrection rate was greater in preterm children than in full-term children (p=0.019). The average surgical dose-response was 3.99 prism dioptres (PD)/mm in full-term children and 4.40 PD/mm in preterm children.

Conclusions The results of this study showed a favourable outcome using a mildly reduced amount of surgery in preterm patients with infantile-onset esotropia. Surgical dose–response was significantly greater in preterm patients than in full-term patients.