Enhanced efficiency and endothelial protection of the intraocular lens shell technique in phacoemulsification: a retrospective stratified analysis by nuclear hardness.

BACKGROUND

The intraocular lens (IOL)-shell technique may improve intraoperative stability during phacoemulsification, but whether its benefits vary by nuclear hardness remains uncertain. This study evaluated the safety and efficiency of the IOL-shell technique and explored its effects across nuclear hardness subgroups.

METHODS

This retrospective study included 200 patients undergoing phacoemulsification: 100 treated with the IOL-shell technique and 100 treated with the conventional technique. Outcomes included operative time, cumulative dissipated energy (CDE), corneal endothelial cell loss, posterior capsule rupture (PCR), corneal edema, and best-corrected visual acuity (BCVA) at 1 month. Subgroup and interaction analyses were performed according to nuclear hardness (≥ Grade IV vs. ≤ Grade III).

RESULTS

Baseline characteristics were comparable between groups. Compared with the conventional group, the IOL-shell group had shorter operative time (12.79 ± 2.00 vs. 15.13 ± 2.52 min, P < 0.001), lower CDE (8.36 ± 2.05 vs. 12.03 ± 2.78 units, P < 0.001), less endothelial cell loss (10.74 ± 3.55% vs. 14.59% ± 3.95%, P < 0.001), a lower corneal edema rate (18.0% vs. 32.0%, P = 0.022), and better 1-month BCVA (0.29 ± 0.08 vs. 0.36 ± 0.12 logMAR, P < 0.001). PCR was numerically lower with the IOL-shell technique but was not statistically significant overall (2.0% vs. 8.0%, P = 0.101). In eyes with nuclear hardness ≥ Grade IV, the IOL-shell technique was associated with shorter operative time, lower CDE, reduced endothelial cell loss, and lower PCR and corneal edema rates. Interaction analysis showed a significant technique-by-nuclear hardness interaction for operative time (β = -1.58, 95% CI: -2.93 to -0.23; P for interaction = 0.022), but not for other outcomes.

CONCLUSIONS

The IOL-shell technique improved surgical efficiency, reduced ultrasound energy use, enhanced endothelial protection, decreased corneal edema, and promoted early visual recovery after phacoemulsification. Its efficiency advantage was particularly evident in eyes with nuclear hardness ≥ Grade IV. The apparent reduction in PCR should be interpreted cautiously because of the limited number of events.