Evaluation of corneal hysteresis after pars plana vitrectomy combined phacoemulsification and intraocular lens implantation

Abstract

We evaluated the early effects of pars plana vitrectomy (PPV) on corneal biomechanics by comparing corneal hysteresis (CH) after cataract surgery (phacoemulsification and aspiration with intraocular lens implantation; PEA + IOL) alone and PPV combined with cataract surgery. This study included 20 eyes (18 patients), who underwent cataract surgery alone (PEA + IOL group), and 28 eyes (27 patients) who underwent PPV combined with cataract surgery (PPV triple group). The CH was 11.1 ± 1.1, 10.4 ± 1.1, and 11.0 ± 1.0 mmHg in the PEA + IOL group and 11.0 ± 1.4, 9.8 ± 1.4, and 10.6 ± 1.6 mmHg in the PPV triple group, preoperatively, at 2 weeks, and 3 months after surgery, respectively. The CH was not significantly different after surgery in the PEA + IOL group, but decreased significantly in the PPV triple group 2 weeks following surgery (p < 0.01). Intraocular pressure (IOP) and central corneal thickness (CCT) did not change significantly after surgery in either group. Preoperatively, there was a positive correlation between CH and CCT in the PPV triple group, but the correlation disappeared postoperatively. In PPV combined with cataract surgery, CH temporarily decreased postoperatively, independent of IOP and CCT. Removal of the vitreous may reduce the elasticity and rigidity of the entire eye.

Figure 1

The postoperative to preoperative CH ratio of the PEA + IOL group was 0.94 ± 0.08, 1.00 ± 0.08, and for the PPV triple groups was 0.89 ± 0.09, 0.98 ± 0.13, 2 weeks, and 3 months postoperatively, respectively. The CH ratio was significantly smaller in the PPV triple group compared to the PEA + IOL group at 2 weeks postoperatively (**p < 0.05).

Figure 2

The Goldmann applanation tonometry (GAT) (A) (preoperatively, 2 weeks, and 3 months after surgery) of the PEA + IOL group was 12.7 ± 2.7, 12.1 ± 2.4 and 11.2 ± 1.6 mmHg, and PPV triple group was 13.8 ± 2.4, 13.7 ± 2.9 and 13.7 ± 2.9 mmHg. The IOPcc (B) of PEA + IOL group was 12.3 ± 2.6, 12.1 ± 2.6, and 11.0 ± 1.1 mmHg, and PPV triple group was 13.5 ± 2.6, 15.1 ± 3.4, and 14.2 ± 3.7 mmHg preoperatively, 2 weeks, and 3 months after surgery. The IOPg (C) PEA + IOL group was 12.0 ± 2.8, 11.0 ± 3.1, and 10.9 ± 3.3 mmHg, PPV triple group was 13.2 ± 2.4, 13.8 ± 3.7, and 13.7 ± 3.5 mmHg, preoperatively, 2 weeks, and 3 months after surgery, respectively. There was no significant difference in postoperative compared to preoperative IOP in both groups (p > 0.05).

Figure 3

The CCT of the PEA + IOL group was 530.1 ± 35.9, 543.8 ± 40.7, and 528.5 ± 38.6 μm, the PPV triple group was 541.5 ± 32.2, 555.1 ± 33.5, and 543.8 ± 34.1 μm, preoperatively, 2 weeks, and 3 months after surgery, respectively. There was no significant difference in postoperative compared to preoperative CCT in both groups (p > 0.05).

Figure 4

In PEA + IOL group (A), positive correlation between CH and CCT at all-time points; r = 0.448, p = 0.026 preoperatively, r = 0.618, p = 0.007 at 2 weeks postoperatively, r = 0.698, p = 0.002 at 3 months postoperatively. In the PPV triple group (B), positive correlation between CH and CCT preoperatively (r = 0.555, p = 0.003), but there was no correlation after surgery; r = 0.322, p = 0.084 at 2 weeks postoperatively, r = 0.364, p = 0.058 at 3 months postoperatively.