Optimization of the Lens Nucleus Fragmentation Pattern During Hybrid Phacoemulsification with Different Cataract Densities

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Purpose: comparative study of the energy and hydrodynamic parameters of phacoemulsification using different patterns of femtosecond laser fragmentation of the lens nucleus in patients with grade III and IV cataracts.Patients and methods. Femtosecond laser (hybrid) phacoemulsification was performed in 252 patients (252 eyes) with grade III cataracts (group 1), and 237 patients (237 eyes) with grade IV cataracts according to the Buratto classification (group 2). In subgroup 1A, the pizza pattern (10 radial incisions) was used for femtosecond laser fragmentation of the nucleus. In subgroup 1B — the cylinder pattern (a combination of 8 radial incisions with 5 circular incisions), and in subgroup 1C — the grid pattern (8 radial incisions in combination with multiple incisions in the central zone in the form of a grid with a cell of 0.5 mm). In subgroup 2A, the pizza pattern was used for femtosecond laser fragmentation of the nucleus, in subgroup 2B — the cylinder pattern, and in subgroup 2C — the mesh pattern. Anterior capsulorhexis and preliminary fragmentation of the lens nucleus were performed using the VICTUS femtosecond laser surgical system. The effective ultrasound time and volume of the irrigation solution consumed at the stage of emulsification of the nuclear fragments were calculated. Corneal endothelial cell loss was assessed in 3 months after the surgery.Results. In group 1, the shortest effective ultrasound time was revealed if the mesh pattern 1.65 ± 0.69 s, it was significantly less than the cylinder pattern — 2.33 ± 0.72 s (p < 0.05) and the pizza pattern — 3.18 ± 0.83 (p < 0.01). In group 2, the shortest effective ultrasound time was revealed when using the “grid” pattern 3.96 ± 0.81 s, it was significantly less than the “cylinders” pattern — 4.93 ± 0.93 s (p < 0.05) and the “pizza” pattern — 6.17 ± 1.13 s (p < 0.05). In group 1, the volume of irrigation solution consumed during emulsification of nuclear fragments was significantly less when using the “grid” pattern — 20.3 ± 3.0 ml compared to the “cylinders” patterns — 30.4 ± 5.6 (p < 0.05) and the “pizza” pattern 38.2 ± 7.8 ml (p < 0.01). In group 2, the volume of irrigation solution consumed during emulsification of nuclear fragments was significantly less when using the “mesh” pattern — 39.0 ± 7.9 ml compared to the “cylinder” patterns — 57.5 ± 10.0 ml (p < 0.05) and the “pizza” pattern — 77.0 ± 12.9 ml (p < 0.01). In group 1, after using the “mesh” pattern, the loss of corneal endothelial cells was 3.36 ± 0.93 %, which was significantly less compared to the “cylinder” pattern — 5.04 ± 1.21 % (p < 0.05) and the “pizza” pattern — 6.93 ± 1.53 % (p < 0.05). In group 2, after using the “grid” pattern, the loss of corneal endothelial cells was 8.61 ± 1.65 %, it is significantly less compared to the “cylinders” pattern — 9.83 ± 1.73 % (p < 0.05) and the “pizza” pattern — 11.52 ± 1.91% (p < 0.05).Conclusion. The “grid” pattern allows to minimize the effective ultrasound time, the volume of the spent irrigation solution and, as a consequence, the loss of corneal endothelial cells compared to other patterns of femtosecond laser fragmentation