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

Takafumi Suzuki,1,2 Takao Fukutome,1 Chisato Otaki,1 Yoshiki Ueta,1 Tone Suzuki3,4 1Department of Ophthalmology, Shinseikai Toyama Hospital, Imizu, Toyama, Japan; 2Department of Ophthalmology, University of Tokyo Hospital, Bunkyo, Tokyo, Japan; 3Department of Ophthalmology, Dokkyo Medical University Saitama Medical Center, Koshigaya, Saitama, Japan; 4Hikari Eye Clinic, Yoshikawa, Saitama, JapanCorrespondence: Takafumi Suzuki, Department of Ophthalmology, University of Tokyo Hospital, 7-3-1 Hongō, Bunkyo, Tokyo, 113-8655, Japan, Tel +81 3 3815 5411, Email [email protected]: 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.Keywords: intraocular pressure, accommodation, intermittent exotropia, strabismus surgery