This study investigated the influence of body position, eyelid manipulation, and jugular vein compression on intraocular pressure (IOP) in healthy horses. Maintaining optimal IOP is critical for equine ocular health, yet various physiological and positional factors may transiently alter pressure measurements, potentially affecting clinical interpretation. Twelve adult horses (6 mares, 6 geldings; age range 5–12 years) with no history of ocular disease were enrolled. IOP was measured using a rebound tonometer under standardized conditions. Three experimental interventions were applied in randomized order: (1) body position changes, including standing, left lateral recumbency, and right lateral recumbency; (2) eyelid manipulation involving gentle manual retraction of the upper eyelid; and (3) jugular vein compression achieved via light manual occlusion for 10 seconds. Measurements were recorded before, during, and after each intervention, with a minimum 10-minute washout period between trials.

Results demonstrated that body position significantly influenced IOP, with lateral recumbency producing higher readings (mean ± SD: 22.3 ± 2.1 mmHg) compared to standing (18.7 ± 1.9 mmHg; p < 0.01). Eyelid manipulation caused a modest but statistically significant increase in IOP (mean increase: 1.8 mmHg; p = 0.04), while jugular vein compression resulted in transient elevations of 3–4 mmHg that returned to baseline within 30 seconds. No adverse effects were observed during any intervention.