Retinal Microcirculatory Responses To Suction-Induced Iop Elevation During Femtosecond Lasik: Interaction Between Flap Platform And Baseline Iop

To evaluate retinal microcirculatory changes following suction-induced transient intraocular pressure (IOP) elevation during femtosecond LASIK flap creation using VisuMax 500 and WaveLight FS200, and to determine whether baseline IOP modifies these responses.

Tianjin Aier Eye Hospital, Tianjin, China.

This prospective study included 120 eyes undergoing femtosecond laser-assisted in situ keratomileusis (FS-LASIK). Flap creation was performed using VisuMax 500 (n = 60) or FS200 (n = 60). Eyes were further stratified by baseline IOP into high-IOP (≥20 mmHg) and low-IOP (<20 mmHg) subgroups. Optical coherence tomography angiography (OCTA) was performed preoperatively, immediately postoperatively, postoperative Day 1, and Week 1. Primary outcome measures included superficial and deep retinal vascular density and outer retinal flow area.

Immediately after surgery, FS200-treated eyes showed a greater increase in outer retinal flow area (57.57 ± 21.54%) compared with VisuMax-treated eyes (33.81 ± 28.54%). Although partial regression occurred by Day 1, flow remained elevated at Week 1 in the FS200 group (3.55 ± 6.18%), whereas it decreased below baseline in the VisuMax group (-7.40 ± 20.83%). In high-IOP eyes, FS200 treatment was associated with prolonged microcirculatory alteration, with persistent elevation at Week 1 (9.55 ± 18.50%), whereas VisuMax-treated high-IOP eyes showed recovery toward or below baseline. In contrast, low-IOP eyes exhibited transient changes with no sustained inter-platform difference at Week 1.

Retinal microcirculatory responses to suction-induced IOP elevation during FS-LASIK are influenced by both suction platform and baseline IOP. High baseline IOP is associated with more pronounced and prolonged microvascular alteration, particularly with higher suction pressure systems. These findings indicate that surgical impact on retinal perfusion reflects an interaction between device-induced IOP elevation and individual ocular baseline status, and that baseline IOP may serve as a clinically relevant factor when selecting femtosecond platforms, particularly in patients with ocular hypertension or glaucoma susceptibility.