CHANGES IN CORNEAL ENDOTHELIUM CAUSED BY CATARACT SURGERY

It has been suggested that femtosecond laser-assisted cataract surgery (FLACS) may reduce required ultrasound energy, a factor known to be directly related to endothelial cell density (ECD) loss. Several studies demonstrate either no difference or less ECD loss with FLACS than with conventional phaco (CPS). In most studies, however, the degree of corneal endothelial cell damage is expressed only by ECD loss, while other changes in endothelial appearance like coefficient of variation (CV), polymegathism and pleomorphism of cells and increase of central corneal thickness (CCT) are rarely investigated. The purpose of the study was to evaluate how recent technological advancements such as FLACS  and newer viscoelastics (OVDs) with additional endothelial protection, affect corneal endothelium changes due to cataract surgery, and whether newer OVDs may contribute to better endothelial protection.

Prospective randomized study in a clinical setting.

A total of 250 eyes (n=150 in CPS on Centurion, Alcon vs. n=100 in FLACS on Alcon LenSx) were enrolled. Patients were stratified by age group, cataract density and preoperative endothelial cell count. Corneal endothelium was protected with either combination of hyaluronic acid and chondroitin sulfate or hyaluronic acid and taurin. All surgeries were performed by same surgeon using same surgical technique. The equivalent Phaco power (EqUSP), total ultrasound time (TUT) and cumulative dissipated energy (CDE) were recorded for each group. The endothelial cell count (ECC, in cells/mm²), CV (%) and CCT (µm) were noted on specular microscopy at baseline, at follow-up visit at 1,3 and 6 months postoperatively; and compared between groups.

EqUSP during surgery ranged from 10.1% to 22.3%, TUT  from 18 to 57 sec, and CDE from 7.07 to 24.5.  At 1,3 and 6 months of follow-up, there was a decline in the endothelial cell count in both groups (362 ± 156, 433±123 and 457± 48 in phaco vs. 244± 170, 278± 140 and 305 ± 60 in FLACS). The CV at 1,3 and 6 months also changed in both groups: from preop 45 to 58, 56 and 56 in phaco vs. 44 to 50, 48 and 46 in FLACS. CCT values at 1,3 and 6 months changed from 553±47 to 613±160, 580±125 and 576±70 in phaco vs. 556±24 to 583±84, 560±90 and 555±78 in FLACS. Eyes in which new OVD containing taurine was used, performed very well at 1 month postop, showing EC loss of 305± 87 in phaco and only 210± 60 in FLACS. Lower ECD loss, and less changes in CV and CCT were recorded in all cases operated by FLACS, regardless which OVD was used for endothelial protection. 

Corneal endothelial cell damage caused by cataract removal was lower in FLACS compared with CPS throughout 6 postoperative months. EC damage was correlated to EqUSP, TUT and CDE used. Addition of taurine into OVD, an apoptosis reducing agent, provided good endothelial protection.