Purpose: To study the intraocular pressure (IOP) variation during vacuum and docking of femtosecond laser application.
Setting: Department for Ophthalmology, Kepler University Hospital, Johannes Kepler University Linz, Austria.
Design: Experimental study.
Methods: Intracameral intraocular pressure (IOP) was monitored in 30 porcine ex vivo models using a dual femtosecond laser platform (VICTUS). Five different baseline IOP levels (10 to 30 mm Hg) were assessed during fluid-filled (liquid) docking, full-contact (applanating) docking, and vacuum application without docking.
Results: Raising the baseline intracameral IOP from 10 to 30 mm Hg increased the IOP from 27.55 mm Hg ± 5.93 (SD) to 56.85 ± 6.10 mm Hg in the fluid-filled docking group, and from 60.91 ± 8.41 mm Hg to 90.11 ± 6.64 mm Hg in the full-contact docking group. The full-contact docking procedure per se (excluding vacuum effect) increased the IOP by 61.7% (+36.58 ± 5.84 mm Hg). In contrast, fluid-filled docking (excluding vacuum effect) raised the IOP by only 3.1% (+0.72 ± 2.71 mm Hg). Each 5 mm Hg reduction of baseline IOP resulted in a mean IOP reduction of 7.33 ± 3.05 mm Hg in the fluid-filled group, and 7.30 ± 6.88 mm Hg in the full-contact docking group (P < .001). Decreasing baseline intracameral IOP from 15 to 10 mm Hg resulted in the highest IOP reduction between all subgroups (P < .01).
Conclusions: Baseline IOP, docking procedures, and vacuum influenced IOP during femtosecond laser application in a synergistic manner. Lowering the baseline intracameral IOP resulted in a significantly lower IOP during fluid-filled docking for cataract surgery and full-contact docking for refractive surgery. Full-contact (applanating) docking resulted in a significantly higher IOP elevation compared with similar IOP values found during fluid-filled (liquid) docking and the application of the suction ring alone without docking.
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