Comparison Of Corneal Endothelial Cell Loss Among Vitrectomy, Phacoemulsification, And Combined Phacoemulsification-vitrectomy Patients

Abstract

Purpose: : A wide range of endothelial cell loss has been reported in the literature (from 4% to 25%) for cataract surgery. No modern study has investigated endothelial cell loss in vitrectomy or phacoemulsification-vitrectomy surgeries. This can help surgeons in their decision-making paradigm regarding combining pars plana vitrectomy and phacoemulsification surgeries.

Methods: : A prospective cohort study of 174 eyes of 159 patients undergoing pars plana vitrectomy and/or phacoemulsification-IOL implantation. All patients gave informed consent. Patients were divided into 3 study arms: 1) combined phacoemulsification-IOL implantation and pars plana vitrectomy by one surgeon (60 eyes of 58 patients), 2) pars plana vitrectomy alone by the same surgeon (44 eyes of 44 patients), and 3) phacoemulsification-IOL implantation alone by 4 different surgeons (73 eyes of 59 patients). All patients had one pre-operative visit to measure their baseline Best Corrected Visual Acuity (BCVA) and corneal endothelial cell count by spectral microscopy. The same measurements were taken 3 months post-operatively. The primary outcome was the percentage of endothelial cell loss in each group. Sample size calculation was based on independent t-test and equal variances.

Results: : Preliminary data analysis revealed a mean endothelial cell loss of 16.13% +/- 12.93 in group 1 (42 eyes), 13.65% +/- 11.09 in group 2 (37 eyes), and 23.92% +/- 16.22 in group 3 (29 eyes). Complete data will be available in February 2012. Paired student t-test showed that both groups 1 and 2 have significantly less endothelial cell loss compared to group 3 (p=0.018 when comparing groups 1 and 3, and p=0.003 when comparing groups 2 and 3). The endothelial cell loss was not statistically different between groups 1 and 2 (p=0.18).

Conclusions: : Data analysis revealed that patients undergoing either vitrectomy or phacoemulsification-vitrectomy surgeries have less endothelial cell loss compared to patients undergoing cataract surgery (control group). This can be expected based on different fluid circulations in vitrectomy compared to cataract surgery, explaining the different endothelial cell loss between groups 2 and 3. Using low-flow anterior chamber circulation (low bottle height) and use of the scleral tunnel approach used in group 1 are possible reasons for the similar endothelial cell loss among groups 1 and 2, and for group 1 showing less endothelial cell loss compared to group 3. Our results suggest that performing combined phacoemulsification-vitrectomy is a reasonable option to vitrectomy when the patient has a moderate degree of cataract, anticipated to worsen following a vitrectomy and require separate surgery.

Keywords: cornea: endothelium • vitreoretinal surgery • cataract