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J. Eur. Opt. Society-Rapid Publ. 21, 10( 2025)
Table 1. System parameters for lenticule and flap cuts. The spots and track distances were set to 3.2 lm and 3.1 lm. Eyes were held within 5 h of procuring, stored in Normal Saline at 23 ° and manually de-epithelialized( Amoils brush).
ID
Thickness [ lm ]
Diameter [ mm ]
Lenticule
Incision angle [°]
Repeat #
Energy [ nJ ]
ID
Thickness [ lm ]
Diameter [ mm ]
Flap
Incision angle [°]
Repeat #
1 |
164 |
6.3 |
115 |
3 |
90 |
1 |
80 |
7.5 |
45 |
3 |
75 |
2 |
157 |
6.3 |
115 |
3 |
90 |
2 |
220 |
9.6 |
135 |
5 |
100 |
3 |
112 |
6.3 |
115 |
3 |
90 |
3 |
220 |
7.5 |
45 |
3 |
75 |
4 |
151 |
8.3 |
115 |
3 |
85 |
4 |
150 |
8.0 |
70 |
3 |
75 |
5 |
152 |
7.3 |
115 |
3 |
90 |
5 |
115 |
9.6 |
115 |
4 |
75 |
6 |
91 |
8.3 |
115 |
3 |
85 |
6 |
185 |
8.5 |
95 |
3 |
100 |
7 |
117 |
7.3 |
115 |
3 |
90 |
7 |
80 |
9.6 |
45 |
3 |
75 |
8 |
87 |
6.1 |
115 |
4 |
85 |
8 |
150 |
8.0 |
70 |
3 |
75 |
9 |
150 |
8.3 |
115 |
3 |
90 |
9 |
220 |
9.6 |
45 |
3 |
110 |
10 |
135 |
8.3 |
115 |
3 |
90 |
10 |
80 |
9.6 |
70 |
4 |
75 |
11 |
27 |
6.1 |
115 |
3 |
95 |
11 |
115 |
9.0 |
135 |
3 |
75 |
12 |
54 |
6.3 |
115 |
3 |
95 |
12 |
80 |
9.6 |
45 |
3 |
75 |
13 |
151 |
8.3 |
115 |
3 |
90 |
13 |
220 |
9.6 |
135 |
3 |
75 |
Energy [ nJ ] unit [ 47 ]. With a wet lab handling, the epithelium of each eye was first removed, and the eyes were placed under the laser for further processing [ 48 ]. The treatments were performed with the SCHWIND ATOS femtosecond laser system( SCHWIND eye-tech-solutions, Germany). The OCT images were collected from 83 ex vivo porcine eyes underwent laser treatments leading to either flap or lenticule creation. Due to the incomplete cuts or faint traces, 23 eyes were excluded from the study. The remaining cohort of ex vivo treated eyes was divided into two groups of 24( lenticule) and 36( flap) eyes. The intended substructure geometries for all eyes are summarized in Table 1.
For both flap and lenticule creations, a combination of key parameters was employed to achieve versatility through the generation of customized intrastromal substructures. The values were chosen to represent the full spectrum of possibilities, including the most extreme cases, for both flap and lenticule creation. The intended cap thickness for all lenticule substructures was set to 150 lm.
All animal specimens used in this study were procured as a by-product from a local approved slaughterhouse, and the handling of these specimens was not part of the study, since eyes were enucleated post-mortem. All the treatments were performed on ex vivo porcine eyes within five hours of procuring the eyes. The eyes were stored in Normal Saline solution at room temperature( 23 ° C), during transportation and before treatment ensuring cornea’ s health and transparency. For all treatments, the eyes were mounted on a holder and de-epithelialized manually prior to treatments( as a standard routine) using an Amoils brush, to have consistent smooth corneal surfaces, which is important for creating exact substructures. Intraocular pressure was controlled using a specialized ex vivo eye holder to ensure consistent experimental conditions. These conditions could preserve optimal condition for corneal integrity and ensure proper standardization for laser cutting. The study did not involve live animal experimentation and used the eyes ex vivo as a suitable animal model.
Each eye then was docked with the disposable patient interface and held with a vacuum level of 250 mmHg. The treatment specifications were set before each treatment to minimize the handling time for the treatment and image acquisition. The porcine eyes were treated and, immediately( peri-operatively) after treatment, placed under the OCT instrument to capture images. Neither flap cuts were lifted nor lenticule volumes were extracted after imaging.
Subsequently, two independent users manually performed measurements using the Thorlabs OCT software, where they loaded images and employed the integrated measurement tool. In these measurements, the refractive index was set to 1.37 to ensure consistency. The users’ expertise ensured that the measurements were conducted with a high degree of precision.
Emphasis was placed on establishing a systematic process to ensure tissue homogeneity throughout the experiment, from preparation to OCT scans. This approach aimed to minimize variability and ensure consistent and reliable results across all stages of the procedure.
Representative images from each category of treatments are provided in Figure 1. All scans( raw data) were imported using ThorImageOCT – Version: 5.4.8 – software into our Python routine for characterization.
The OCT GAN111 is a configurable high-resolution spectral-domain OCT( SD-OCT) system equipped with an 880 nm center wavelength [ 47 ]. It supports A-scan rates of up to 20 kHz, enabling fast and precise imaging. The system offers imaging depths in air( eye) of up to 3.4 mm( 2.5 mm), with axial resolutions of 6.0 lm in air( 4.4 lm in eye). Its sensitivities range from 96 dB( at 20 kHz) to 106 dB( at 1.5 kHz), allowing for the cornea and anterior imaging( Table 2).