Quantification of aerosol generation during cataract surgery.

PURPOSE: To determine whether phacoemulsification cataract surgery is an aerosol-generating medical procedure (AGMP) and, therefore, to help determine the personal protective equipment required by healthcare providers in the era of the COVID-19. SETTING: The Surgery, Teaching and Research Wet Lab of the Department of Ophthalmology and Visual Sciences, Faculty of Medicine, UBC. DESIGN: Laboratory-based simulation. METHODS: Phacoemulsification cataract surgery was performed on porcine eyes. At a fixed distance, a DRX Aerosol Monitor 8534 (DustTrak) was used to measure particulate matter (PM) mass fractions for each of 3 particle sizes, PM1, PM2.5, and PM4 (in microns), every 2 seconds during surgery and for 1 minute after. The main outcome measure was an increase in the mass fraction of aerosolized particles of various sizes. RESULTS: There was no significant aerosolization of particles during cataract surgery for both the 2.4 and 2.75 mm wound sizes. CONCLUSIONS: Phacoemulsification cataract surgery was not found to be an AGMP. In the midst of the COVID-19 pandemic, ophthalmologists can continue to use droplet precautions while performing this surgery.

Modification of the Miyake-Apple technique for simultaneous anterior and posterior video imaging of wet laboratory-based corneal surgery.

PURPOSE: The aim of this study was to describe a modification of the Miyake-Apple posterior video analysis for the simultaneous visualization of the anterior and posterior corneal surfaces during wet laboratory-based deep anterior lamellar keratoplasty (DALK). METHODS: A human donor corneoscleral button was affixed to a microscope slide and placed onto a custom-made mounting box. A big bubble DALK was performed on the cornea in the wet laboratory. An 11-diopter intraocular lens was positioned over the aperture of the back camera of an iPhone. This served to video record the posterior view of the corneoscleral button during the big bubble formation. An overhead operating microscope with an attached video camcorder recorded the anterior view during the surgery. RESULTS: The anterior and posterior views of the wet laboratory-based DALK surgery were simultaneously captured and edited using video editing software. The formation of the big bubble can be studied. CONCLUSIONS: This video recording camera system has the potential to act as a valuable research and teaching tool in corneal lamellar surgery, especially in the behavior of the big bubble formation in DALK.

Correlation of photosensitizer delivery to lipoproteins and efficacy in tumor and arthritis mouse models; comparison of lipid-based and Pluronic P123 formulations.

PURPOSE: The purpose of this study was the use of animal models to demonstrate the importance of drug delivery (verteporfin) to plasma lipoproteins in order to attain efficacy of photodynamic therapy (PDT) in vivo. METHODS: Photosensitizers appropriately formulated in various vehicles such as pluronics and lipid-based systems were compared to delivery of the drug in DMSO in two in vivo systems. The first was a tumor model using male DBA/2 mice inoculated intradermally with M1 rhabdomyosarcoma cells and in the second, arthritis in the MRL -lpr mouse strain was enhanced by two intradermal injections of complete Freunds adjunct. RESULTS: Those formulations in which the drug was in a monomeric form were better able to transfer drug to lipoproteins, which in turn led to superior PDT in vivo. CONCLUSIONS: The ability to introduce drug in monomeric form into the circulation correlates well with efficacy of photosensitizer formulations in mouse arthritis and tumor models.