Capsulorhexis

This multicentre, international, randomised, parallel-group study compared the efficacy and safety of IC Mydrane (Mydrane group) to a standard topical regimen (reference group) for cataract surgery. Mydrane is a proprietary injectable salt-balanced and pH-balanced solution of two mydriatics (tropicamide 0.02% and phenylephrine 0.31%) and one anaesthetic agent (lidocaine 1%) for IC delivery just prior to beginning cataract surgery. The standard topical regimen was tropicamide 0.5% (Mydriaticum 0.5%; Laboratoires Théa) and phenylephrine 10% (Neosynephrine 10% Faure; Laboratoires Europhta, Monaco). The hypothesis was that Mydrane was non-inferior to the standard topical regimen for inducing mydriasis to perform capsulorhexis without any additional mydriatics or pupil-expanding devices.
This study was conducted between September 2011 and February 2013 at 68 investigational centres in nine countries (see online supplementary appendix). Eligible patients were aged 40–88 years old, scheduled to undergo phacoemulsification with foldable IOL implantation under topical anaesthesia with clear self-sealing corneal incisions. Only one eye per patient could be included in this study. At the selection visit, a pupil diameter of at least 7 mm had to be obtained within 30 min following instillation of one drop of tropicamide 0.5% and one drop of phenylephrine 10% (maximum of three combined instillations at 10 min intervals, if necessary), otherwise, the patient was excluded. Main non-inclusion criteria were a history of intraocular surgery or combined procedures, iatrogenic, traumatic or congenital cataract, corneal, epithelial, stromal or endothelial residual or progressive corneal disease, history of ocular trauma, infection or inflammation within the previous three months, pseudoexfoliation and exfoliation syndrome.
The randomisation procedure for assigning patients into the Mydrane group or reference group is presented in figure 1. At the selection visit (between 60 and 7 days preoperatively), an equal number of eligible patients were randomly assigned to one of the two study groups. The surgeon and surgical team were masked to the type of regimen and group enrolment for each eye until 30–60 min preoperatively. Figure 2 presents the preoperative and perioperative protocol for both groups. At the end of surgery, 0.1 mL of cefuroxime solution (10 mg/mL) was injected in the anterior chamber.
All the cataract surgeries were video-recorded. Pupil diameter measurement was centralised and performed by independent and masked operators using VLC media player software (VideoLAN Non-Profit Organization, Paris, France). Pupil diameter was measured on screen captures taken at five specific stages during surgery: just before the corneal incision (T1), just before injection of viscoelastic (Duovisc; Alcon, Fort Worth, Texas, USA) (T2), just before capsulorhexis (T3), just before IOL insertion (T4) and just before cefuroxime injection (end of surgery, T5). The measurement of pupil diameters was as follows. First, the real horizontal visible iris diameter (HVID) (ie, horizontal white-to-white measurement) was measured during the selection visit with a surgical calliper (precision=0.1 mm). Then, the exact pupil size during surgery was obtained using the following formula:
Corrective factor=real HVID/HVID on photograph.
All other medications used to obtain and maintain mydriasis or anaesthesia preoperatively or intraoperatively were noted. Follow-up was performed at 1 day, 1 week and 1 month postoperatively.