Central corneal thickness changes in bevel-up versus bevel-down phacoemulsification cataract surgery: study protocol for a randomised, triple-blind, parallel group trial.
BACKGROUND
Corneal endothelial damage following phacoemulsification is still one of the major concerns of modern day cataract surgery. Although many techniques have been proposed, the risks of posterior capsular rupture and corneal endothelium damage persist. In theory, damage to the corneal endothelium is minimised by delivering the lowest phaco energy only in the direction necessary to emulsify the lens nucleus. Hence, it is believed that the bevel of the needle should be turned towards the nucleus or the nuclear fragment (ie, bevel-down. However, there is a difference of opinion among ophthalmologists with reference to the phaco tip's position (bevel-up vs bevel-down) during phacoemulsification. This subject has not been extensively studied earlier.


METHODS
This is a prospective, triple-blinded (trial participant, outcome assessor and the data analyst), randomised controlled trial with 2 parallel groups and with an allocation ratio of 1:1. It will be conducted in a tertiary care hospital, Mangaluru, India. The objective is to compare the postoperative central corneal thickness changes between the bevel-up and bevel-down techniques of phacoemulsification. Patients aged >18 years with immature cataract undergoing phacoemulsification will be selected for the study. The important exclusion criteria are the history of previous significant ocular trauma or intraocular surgery, corneal pathology, pseudoexfoliation syndrome, intraocular inflammation, a preoperative fully dilated pupil <6 mm, anterior chamber depth <2.5 mm and nuclear sclerosis grade >4. After randomisation, patients will undergo phacoemulsification surgery either by a bevel-up or bevel-down procedure. With an estimated power of 80%, the calculated sample size is 55 patients in each group. The recruitment will start from April 2016.


BACKGROUND
Yenepoya University Ethics Committee, India has approved the study protocol (YUEC/148/2016 on 18 February 2016). It complies with the Declaration of Helsinki, local laws and the International Council for Harmonization-good clinical practices.


BACKGROUND
CTRI/2016/02/006691; Pre-results.
Department of Ophthalmology, Yenepoya Medical College, Yenepoya University, Mangalore, Karnataka, India.
Soujanya
S
Kaup
Department of Community Medicine, Yenepoya Medical College, Yenepoya University, Mangalore, Karnataka, India.
Siddharudha
http://orcid.org/0000-0003-1454-7114
S
Shivalli
Department of Ophthalmology, Yenepoya Medical College, Yenepoya University, Mangalore, Karnataka, India.
Divyalakshmi
D
Ks
Department of Ophthalmology, Yenepoya Medical College, Yenepoya University, Mangalore, Karnataka, India.
Cynthia
C
Arunachalam
Department of Ophthalmology, Yenepoya Medical College, Yenepoya University, Mangalore, Karnataka, India.
Rejitha Chinnu
RC
Varghese
central corneal thickness; endothelial damage; phaco tip position; phacoemulsification
Arch Ophthalmol. 1988 Jul;106(7):920-2
3390055
J Cataract Refract Surg. 1994 Sep;20(5):566-70
7996415
Br J Ophthalmol. 2001 Jan;85(1):18-20
11133705
J Cataract Refract Surg. 2000 May;26(5):727-32
10831904
J Cataract Refract Surg. 1996 Oct;22(8):1079-84
8915805
Ophthalmology. 2010 Apr;117(4):700-4
20079536
Am J Ophthalmol. 2011 Oct;152(4):609-617.e1
21704965
J Ophthalmol. 2015;2015:210716
26417452
Surv Ophthalmol. 1999 Sep-Oct;44(2):123-47
10541151
J Cataract Refract Surg. 1988 Jan;14(1):25-34
3339544
J Cataract Refract Surg. 1993 Nov;19(6):797-802
8271182
Am J Ophthalmol. 1967 Jul;64(1):23-35
6028631
J Cataract Refract Surg. 1991 May;17(3):281-91
1861242
Arq Bras Oftalmol. 2010 Nov-Dec;73(6):508-10
21271025
J Cataract Refract Surg. 2011 Nov;37(11):1971-6
21940143
Arch Ophthalmol. 1997 Jan;115(1):81-8
9006430
J Cataract Refract Surg. 1990 Jul;16(4):436-40
2380923
Arch Ophthalmol. 1993 Jun;111(6):831-6
8512486