Does the phaco TIp position during clear corneal Phacoemulsification Surgery adversely affect corneal endothelium? TIPS study protocol for a randomised, triple-masked, parallel-group trial of bevel-up versus bevel-down phacoemulsification

Abstract

Introduction: Globally, at least 30 million cataract surgeries are required annually to prevent cataract-related blindness. Corneal endothelial decompensation is one of the most common causes of poor visual outcome following cataract surgery, particularly in those with predisposing factors. The increasing ageing population and reduced visual impairment threshold for cataract surgery have resulted in rising cataract surgical rates and hence, an increase in corneal endothelial decompensation is expected. The role of phaco tip position on corneal endothelial damage is ambiguous. Previous studies have reported contradictory results and were also underpowered to detect a significant difference due to small sample sizes. With no consensus regarding the most cornea-friendly phaco tip position (bevel-up versus bevel-down) during phacoemulsification, we propose a randomised clinical trial with a robust design using direct chop phaco-technique. Objective: To compare the effect of phaco tip position (bevel-up vs. bevel-down) on corneal endothelial cell count during phacoemulsification. Methods: A randomised, multicentre, parallel-group, triple-masked (participant, outcome assessor, and statistician) trial with 1:1 allocation ratio is proposed. By adopting stratified randomisation (according to cataract grade), we will randomly allocate 480 patients aged >18 years with immature cataract into bevel-up and bevel-down groups at two centres. History of significant ocular trauma, previous intraocular surgery, shallow anterior chamber, low endothelial cell count, pseudoexfoliation syndrome, intraocular inflammation, and corneal endothelial dystrophy are the key exclusion criteria. The primary outcome is postoperative endothelial cell count at one month. Secondary outcomes are central corneal thickness on postoperative days 1, 15, and 30, and intraoperative complications. Trial registration: Clinical Trial Registry of India CTRI/2019/02/017464 (05/02/2019).

Statistical analysis plan for the phaco TIp position during clear corneal Phacoemulsification Surgery (TIPS) randomized controlled trial

“…The trial was prospectively registered in the Clinical Trial Registry of India (CTRI/2019/02/017464; registered on 5 February 2019) with all items from the World Health Organization Trial Registration Data Set. This is trial protocol version 2.0 and is published [ 8 ].…”

“…We included the patients if they met all the inclusion criteria and none of the exclusion criteria as listed in the study protocol and published previously [ 8 ].…”

“…Details of interventions published in the protocol and Fig. 2 of the published protocol show the steps of the surgery [ 8 ].…”

“…This document describes the detailed set of statistical analyses to be performed on the data produced by the TIPS trial, to conform with the trial’s protocol. Details on the TIPS design can be found in its protocol [ 8 ]. Here, we replicate the main characteristics relevant to understand the data analysis strategy chosen.…”