Near Fixation-Associated Intraocular Pressure Reduction in Intermittent Exotropia: Postoperative Changes After Strabismus Surgery.

PURPOSE: To investigate changes in intraocular pressure (IOP) associated with accommodation in patients with intermittent exotropia (X(T)), and to evaluate how these changes are affected by strabismus surgery.

PATIENTS AND

METHODS

Thirty-one consecutive patients scheduled for strabismus surgery due to X(T) were retrospectively analyzed. IOP was measured using a rebound tonometer (iCare) during strabismus examinations under three conditions: binocular viewing at distance (bIOP-D), binocular viewing at near (bIOP-N), and monocular viewing at near (mIOP-N). Correlations were assessed between IOP changes and accommodation-related parameters, including patient age and the change in angle of deviation (AOD) from distance to near. Postoperative alterations in these IOP dynamics were also investigated.

RESULTS

AOD at near was significantly greater than that at distance (p < 0.0001). bIOP-N was significantly lower than bIOP-D in both the non-fixation eyes (p = 0.017) and fixation eyes (p = 0.003). The decrease in IOP from distance to near under binocular viewing (Δd-nIOP) correlated significantly with age in fixation eyes (p = 0.007, r = -0.473). Δd-nIOP was also significantly correlated with the increase in AOD from distance to near fixation in both non-fixation (p = 0.017, r = 0.424) and fixation eyes (p = 0.002, r = 0.544). Postoperatively, no significant differences between bIOP-D and bIOP-N were found at 1 month (p = 0.230) or 6 months (p = 0.309).

CONCLUSION

In patients with X(T) who exhibited a larger AOD at near than at distance, near fixation led to a significant IOP reduction. This near-fixation-associated IOP decrease was less evident after strabismus surgery, particularly in non-operated eyes. These findings suggest that ocular alignment and accommodative demand may interact to influence IOP, although confirmation in larger studies is warranted.