Effect of bevel position on the corneal endothelium after phacoemulsification

Abstract

Purpose: To compare the extent of corneal endothelial (CE) cell loss changes in two groups of eyes submitted to phacoemulsification, with the conventional bevel-up tip position in one eye and with the bevel-down tip position in the fellow eye. Methods: This prospective clinical trial comprised 25 patients with bilateral cataracts subjected to lens removal by phacoemulsification with the conventional bevel-up tip position (GI) in one eye and with the bevel-down tip position (GII) in the fellow eye. The nuclei were graded clinically on the basis of hardness. The endothelial cell count (ECC) was evaluated preoperatively and 1, 3 and 6 months postoperatively. Total surgical time, effective ultrasound time and complications were also compared between the groups. Statistical analysis was performed by the Tukey Studentized Range test, with repeated measures for the selected periods. For the other parameters a paired t test was used. Data are presented as mean ± SD, with the level of significance set at p<0.05. Results: The mean effective ultrasound time was 8.08 ± 6.75 seconds in group I and 7.00 ± 5.75 seconds in GII (P=0.1792) and total surgical time was 10.01 ± 2.46 minutes in GI and 9.86 ± 2.17 minutes in GII (p=0.6267), respectively. The paired t test revealed no statistical differences between the groups. Complications were also similar between the groups. Mean endothelial cell count loss was 6.9% in GI and 2.8% in GII at one month; 6.9% in GI and 3.6% in GII at three months and 11.9% in GI and 7.6% in GII at six months postoperatively. Comparison of endothelial cell count (ECC) showed a statistically significant difference between the groups during the postoperative period. Conclusion:The conventional bevel-up tip position has a negative effect on corneal endothelial cells compared with the bevel-down position. Since the results of other surgical parameters were similar, the bevel-down tip position should be considered as an option in non-complicated phacoemulsification. Keywords: Cataract extraction; Phacoemulsification/methods; Endothelium, corneal/surgery; Comparative study RESUMO Objetivo: Comparamos duas técnicas de cirurgia de catarata. A técnica cirúr-gica tradicional, em que direciona a abertura do bisel da ponteira de facoemulsificação para o endotélio corneano, com a técnica oposta, onde a reversão da posição de abertura permite o direcionamento da energia de emulsificação para o núcleo. Estudamos seus efeitos sobre a córnea e possíveis complicações. Métodos: O trabalho foi divido em quatro tempos: pré-operatório e após 30, 60 e 180 dias. Os pacientes foram divididos em dois grupos: o grupo 1, tratado com a técnica cirúrgica tradicional, com a abertura da ponteira direcionada para o endotélio, e grupo 2, que recebeu tratamento com técnica oposta, direcionada diretamente para o núcleo ou para os fragmentos nucleares. Após as cirurgias, foram estudados: perda endotelial após 30, 60 e 180 dias, tempo total de cirurgia e tempo efetivo de faco. Resultados: Os resultados intraoperatórios apresentaram...

Combined 30-degree bevel up and down technique against 0-degree phaco tip for phacoemulsification surgery of hard cataracts

“…On Medline search, there were no studies on NET in bevel up and down position of the phaco tip. However, Raskin et al calculated total surgical time in the study on effect of bevel position on corneal endothelium after phacoemulsification 10. NET in both the groups of our study was less than that in the study conducted by Raskin et al…”

Effects of ultrasound energy on the porcine corneal endothelium – Establishment of a phacoemulsification damage model

“…We used the bevel‐down orientation, which in our opinion – represented in a coherent endothelial cell layer – could result in a more homogenous energy distribution towards the endothelium, whereas bevel‐up orientation, emitting energy directly towards the endothelium, is more likely to cause uneven and rather localized ECL (Raskin et al. ; Rouhbakhshzaeri et al. ).…”

“…We used the bevel-down orientation, which in our opinionrepresented in a coherent endothelial cell layercould result in a more homogenous energy distribution towards the endothelium, whereas bevel-up orientation, emitting energy directly towards the endothelium, is more likely to cause uneven and rather localized ECL (Raskin et al 2010;Rouhbakhshzaeri et al 2018). Current literature is not completely congruent on this aspect and ongoing investigations are further addressing this issue (Frohn et al 2002;Coelho et al 2005;Raskin et al 2010;Faramarzi et al 2011;Kaup et al 2016). Furthermore, the correct anatomical structures and proportions are essential for a reliable ex vivo model to correctly respect fluidics and energy distribution during phacoemulsification.…”

Central corneal thickness changes in bevel-up versus bevel-down phacoemulsification cataract surgery: study protocol for a randomised, triple-blind, parallel group trial

“… 9 However, Faramarzi et al 10 hypothesise that in the bevel-up technique, the phaco tip, and therefore the source of heat, are farther from the endothelial cells than in the bevel-down technique and this decreases the chance of endothelial cell damage. Further another clinical trial by Raskin et al 11 concluded in their study that bevel-up tip position has a negative effect on corneal endothelial cells compared with the bevel-down position. Hence, there is a difference of opinion among ophthalmologists with respect to the phaco tip position during phacoemulsification.…”