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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 pandemic, as COVID-19 can be transmitted via aerosolization during AGMPs. Setting Laboratory DESIGN:: In this laboratory-based simulation, phacoemulsification cataract surgery was performed on porcine eyes. At a fixed distance, a DustTrak DRX Aerosol Monitor Model 8534 (DustTrak) was positioned to quantify particle generation during surgery. Experiments were run in triplicate for two wound sizes, 2.4 and 2.75mm. Positive controls were established by measuring particle generation from an aerosolizing spray-bottle. Negative controls were established while the phacoemulsification machine was not running. Methods The DustTrak was used to measure particulate matter (PM) mass fractions for each of three particle sizes, PM1, PM2.5, and PM4 (in microns), every 2 seconds during surgery and for one 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 2.75mm 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.

Skin photosensitivity is the most common side effect of photodynamic therapy (PDT) and in clinical situations needs to be avoided or at least minimized. However, because of the accessibility of skin tissue, skin photosensitivity represents a useful test system in vivo for evaluation of the pharmacokinetics of photosensitizers and light sources. Pig skin resembles in many aspects human skin and, therefore, is most suitable for these tests. Using pig skin photosensitivity as an end point, we evaluate the effect of cell loading with a photosensitizer, benzoporphyrin derivative (BPD verteporfin) following its intravenous administration either as a rapid bolus or slow infusion. Skin response to light activation indicated a very similar cell content of BPD. These results were in agrement with those obtained in an in vitro model. In addition, in the same pig skin photosensitivity model we compared the efficiency of activation of BPD with either laser (690 plus or minus 3 nm) or light-emitting diode (LED; 690 plus or minus 12 nm) light. Results indicated the equivalency of the two light sources in this test system, with LED light being slightly more efficient, due possibly to a fluence rate lower than laser light.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Uptake and release/retention of the photosensitizer, benzoporphyrin derivative, monoacid ring A (BPD; 1 - 20 (mu) g/mL) was studied using cell lines (K562, L1210) and normal, non- activated and Concanavalin A-activated murine splenocytes. Concentrations of BPD in cell lysates were determined by fluorescence (440 nm excitation, 694 nm emission). The results showed that BPD was taken up and released rapidly by all types of cells within the same time frame. Maximum of BPD depended on the type of cells and was greatest in tumor cells, lowest in normal, non-activated cells and intermediate in activated cells. In addition, the maximum uptake depended on BPD concentration in the medium, length of incubation and presence of serum. All cells, regardless of type, retained a constant proportion (20 - 30%) of the amount of BPD taken up. This proportion was independent of length of incubation, BPD concentration in the medium and presence of serum. However, due to differences in maximum amounts of BPD taken up under the same conditions, tumor cells retained more BPD than normal cells and activated cells more than non-activated. The retained BPD was able to photosensitize the cells. The results were found to be relevant to the in vivo studies.

Benzoporphyrin derivative monoacid ring A (BPD) is taken up rapidly (within 30 minutes) by most cells. Rapidly dividing tumor cell lines and mitogen activated murine T lymphocytes were found to take up significantly more (5 - 10 fold) BPD than do normal splenic lymphocytes making them a potential PDT target. Experiments have shown that BPD can be activated in the blood of animals by whole body irradiation with red light, shortly after intravenous administration, in the absence of skin photosensitivity. During the treatment time, plasma levels of BPD were between 0.7 and 1.0 (mu) g/mL. The light treatment resulted in between 70 and 80% photoinactivation of circulating BPD. When L1210 tumor cells were preincubated with BPD and injected i.v. into mice immediately before total body light treatment, significant reductions in circulating clonogenic tumor cells were observed in blood samples taken immediately following treatment. This `transdermal' treatment has been shown to be effective in preventing the development of hind limb arthritis in MRL/1pr mice.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

In vitro experiments with benzoporphyrin derivative monoacid ring A (BPD) confirmed earlier studies that it was taken up rapidly (within 30 min) to maximum concentrations by all cells tested. It was also confirmed that rapidly dividing tumor cell lines and mitogen-activated murine T lymphocytes took up significantly more (5-10-fold) BPD than did normal splenic lymphocytes. Further experiments were undertaken to determine whether BPD could be activated by whole-body irradiation with red light in the blood of animals, shortly after intravenous (i.v.) administration, in the absence of skin photosensitivity. It was found that shaved and depilated mice injected i.v. 60 min earlier with BPD at between 0.5 and 1.0 mg/kg could tolerate 160 J/cm2 of broad-band red light (560-900 nm) delivered, at a relatively low rate, over a 90 min time interval without developing skin photosensitivity or general phototoxicity. During the treatment time, plasma levels of BPD were between 0.7 and 1.0 μg/mL. The light treatment resulted in between 70 and 80% photoinactivation of circulating BPD. When LI 210 tumor cells were preincubated with BPD and injected i.v. into mice immediately before total-body light treatment (160 J/cm2 of 590-900 nm light delivered over 90 min), significant reductions in circulating clonogenic tumor cells were observed in blood samples taken immediately following treatment. This indicated that sufficient light was being delivered to BPD in the blood flowing in the peripheral vasculature to effect cytotoxicity to cells containing the photosensitizer without causing either vascular or skin photosensitivity. Thus, activation of this photosensitizer in the circulation can be achieved by transdermal light exposure without causing skin photosensitivity provided that light exposure is performed at a time when the first phase of plasma clearance is complete and when the drug has not yet accumulated in skin.