Real-Time Intraocular Pressure Measurements in the Vitreous Chamber of Rabbit Eyes During Small Incision Lenticule Extraction (SMILE)

Abstract

Purpose: To investigate real-time intraocular pressure (IOP) during small incision lenticule extraction (SMILE) in rabbit eyes for myopia correction. Methods: During SMILE, real-time IOP was measured in the vitreous cavity of rabbit eyes with an optic fiber pressure sensor (OFPS). Two groups (n = 6 for each) underwent surgery, one group for a −2.00 diopter (D) refractive spherical correction and the other for a −6.00 D correction. Results: During surgery, the IOP increased once the glass contact attached to the cornea (Pre-suction), and peaked 83.94 mmHg (SD ± 23.87 mmHg) for the −2.00 D group and 89.17 mmHg (SD ± 22.66 mmHg) for the −6.00 D group, both average values were less than 110 mmHg when suction was initiated to fix the glass contact onto the cornea (Suction on). It then fell to 74.81 mmHg (SD ± 20.64 mmHg) and 76.94 mmHg (SD ± 27.43 mmHg), respectively, and remained stable during lenticule creation (Cutting). After suction stopped (Suction off), IOP fell steeply. During lenticule separation/extraction, the change in IOP was 32.26 mmHg (SD ± 2.91 mmHg). Notably, the average duration of elevated IOP during the surgery was 166.05 s (no longer than 3 min). Conclusions: The IOP fluctuations in the vitreous cavity using an OFPS in a rabbit model during SMILE showed that real-time IOP significantly was increased during Pre-suction, Suction on, Cutting, Suction off, and lenticule separation/extraction compared to baseline IOP, although, peaked at Suction on. Neither the degree of myopic correction nor central corneal thickness significantly affected these changes in IOP.