Potential influence of irrigation temperature on immediate post-vitrectomy choroidal microvascular dynamics

Dear Editor, The choroid is a thermosensitive, highly vascular structure with rapid autoregulatory capacity. Experimental studies in animal and human models have shown that modest thermal modulation can alter choroidal vascular tone, blood flow, and stromal fluid balance.[1–4] These observations provide a physiological basis to consider whether intraoperative temperature—particularly irrigation temperature during pars plana vitrectomy (PPV)—may influence choroidal behavior during the earliest postoperative period. To date, however, this question has not been specifically addressed in clinical research. The minutes immediately following PPV represent a physiologic transition as the eye shifts from a controlled intraoperative environment toward intrinsic autoregulatory equilibrium. During this interval, transient fluctuations in choroidal thickness, perfusion, and vascular–stromal distribution may occur in response to infusion temperature, intraoperative flow dynamics, light exposure, and intraoperative pressure conditions. Whether variations in irrigation temperature during PPV produce measurable or clinically meaningful differences in these very early choroidal responses remains to be elucidated. Importantly, intraoperative thermodynamic studies have demonstrated that irrigation rapidly drives intraocular temperatures toward room temperature, followed by progressive rewarming as physiologic homeostasis resumes, suggesting a plausible period in which temperature-related vascular modulation may occur.[5] Direct measurement of posterior segment temperature in human eyes is limited by sterility and safety constraints. Thus, intraoperative bottle- or infusion-line temperature monitoring serves as a practical surrogate for delivered irrigation temperature, a method adopted in prior real-world vitrectomy studies.⁶ Although such indirect measurements do not capture localized intraocular temperature gradients and are influenced by rapid mixing and perfusion, they provide a clinically feasible and ethically appropriate indicator of thermal input during routine surgery. Additionally, while pneumatic cutter-related heating has been reported, its effect appears transient and is likely mitigated by continuous infusion flow, yet standardization of this parameter may aid future investigations. Despite these physiological and technical considerations, optical coherence tomography (OCT) imaging performed in the operating room or within the first postoperative minutes offers a feasible and noninvasive means of evaluating acute choroidal behavior in appropriately cooperative patients. To strengthen future research in this evolving area, the following methodological refinements may be valuable: Standardized imaging timing relative to infusion cessation to capture the immediate thermal-vascular recovery phase Comprehensive reporting of surgical parameters, including infusion temperature presets, flow rates, intraocular pressure, illumination, and tamponade exchange Transparent feasibility metrics, including acquisition success rate, cooperation criteria, and minimum acceptable image quality Use of calibrated surrogate temperature methods supplemented by ex vivo or experimental validation when feasible Existing literature demonstrates rapid intraocular temperature decline during fluid infusion and rewarming with air or light exposure, and temperature-related modulation of ocular tissue behavior and tamponade properties.[5] Cold-temperature effects demonstrated in prior human PPV studies also support ongoing investigation into possible posterior-segment thermal responses.[6] However, the influence of such fluctuations on choroidal microvascular behavior in the immediate postoperative period remains unknown. Given the choroid’s high perfusion, metabolic demand, and dynamic vascular-stromal architecture, exploring temperature-related effects in this narrow early recovery window is scientifically justified. Carefully designed, prospective studies may clarify whether irrigation temperature represents a modifiable factor relevant to surgical physiology and postoperative outcomes. Financial support and sponsorship: Nil. Conflicts of interest: There are no conflicts of interest.