High BP could increase IOP by increased production of aqueous humor by means of elevated ciliary blood flow and capillary pressure and decrease of aqueous outflow as a result of increased episcleral venous pressure.
The effect of different body positions on blood pressure https://pubmed.ncbi.nlm.nih.gov/17181675/#:~:text=Results%3A%20The%20blood%20pressure%20tended,when%20compared%20the%20other%20positions. The blood pressure tended to drop in the standing position compared with the sitting, supine and supine with crossed legs. Systolic and diastolic blood pressure was the highest in supine position when compared the other positions.