Central Retinal Vessel Trunk Caliber Changes After Short-term Intraocular Pressure Elevation

Area of Science:

• Ophthalmology
• Retinal Vascular Physiology

Background:

• Intraocular pressure (IOP) plays a critical role in ocular health.
• Understanding the dynamic response of retinal vasculature to IOP fluctuations is crucial for diagnosing and managing various eye conditions.

Purpose of the Study:

• To investigate the short-term changes in the calibers of the central retinal vein trunk (CRVT) and central retinal artery trunk (CRAT) in response to a controlled elevation of IOP.

Main Methods:

• A prospective observational study involving 101 eyes of acute primary angle-closure suspects.
• Participants underwent a 2-hour dark room prone provocative test (DRPPT) to induce short-term IOP elevation.
• Measurements of CRVT and CRAT calibers were performed using fundus photography before and after the DRPPT, alongside tonometry.

Main Results:

• A significant increase in mean CRVT caliber (101.8±25.9 to 107.7±26.6 μm, P<0.001) was observed following IOP elevation.
• CRVT widening was more pronounced at lower IOP rises (<6 mmHg) and diminished at higher IOP rises (>15 mmHg).
• The CRAT caliber showed no significant change (110.3±24.2 vs. 109.7±21.5 μm, P=0.54) during the IOP elevation.

Conclusions:

• Short-term IOP elevation can cause CRVT widening at lower levels, suggesting a physiological response.
• At higher IOP levels, the increased pressure may lead to CRVT compression.
• Retinal artery diameters appear to be less sensitive to short-term IOP fluctuations due to higher intraluminal pressure.