Commentary: Inhale, exhale - Fighting the invisible enemy with every breath!

No one could fathom the devastating impact that the air we breathe could have, that was laden with the invisible novel coronavirus! The scale of previous air-borne epidemics like Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS) are no match to what we saw with the rapid spread of COVID-19 through human travel and human interaction around the world. The novel coronavirus can spread through various routes such as droplets or aerosols, fomite based, blood-borne, airborne, surface transmission, and possible faecal-oral spread.[1] Various laboratory studies have sought to replicate the normal human cough conditions in an attempt to understand the transmission of the COVID-19 virus particles using high powered jet nebulizers under controlled conditions. The studies have found SARS-CoV-2 virus RNA in air samples within aerosols ranging from 3 hours to 16 hours with a superior dynamic aerosol efficiency compared to MERS-CoV.[23] The size of the aerosol particles determines the time taken by them to settle at a distance of 5 feet in still air with 1 μm taking 12 hours and 100 μm taking just 5.8 seconds.[4] Barrier care including N95 masks for all physically close ophthalmic procedures and universal precautions for all patients was one of the five mandatory measures recommended very early on as the pandemic was relentlessly spreading around the globe.[5] A study by Liu et al. compared the position of the slit lamp breath shields and found that shields that are more anterior and attached to the objective lens arm were more effective than posteriorly positioned ocular shields of comparable size. The breath shields ranged in surface area from 116 to 924 cm2, and the amount of overspray varied from 54% to virtually none. The largest breath shield (924 cm2) hung near the oculars had prevented essentially all overspray.[6] Poostchi et al. sought to examine the efficacy of facemasks and standard and augmented proximal slit lamp breath shields using a breathing simulator during the slit lamp examination. They found that with no shield in place, the mean log particle count was 3.59 that reduced to 3.01 with the standard shield, 2.63 with the augmented shield, and 2.62 with the facemask secured in front of the nebulizer. With the mask and large shield both in place, the mean log count dropped to 2.47 which was the most effective method to decrease the transmission risk.[7] Ophthalmologists around the world have rapidly improvised with various materials from plastic to acrylic sheets to create slit lamp shields to protect themselves from the possible airborne transmission of the virus from the patients. Major industry manufacturers of slit lamps like Topcon, Zeiss, and Haag Streit created free protective breath shield programs in a bid to help fight the potential risk while examining patients at close distances.[8910] However, all of these innovations are predominantly focussed on the slit lamp shield being placed posteriorly and hung on the oculars. In the current article, the authors describe a novel method to position the shield more distally on the slit lamp to protect the working parts of the instrument and more importantly the hands, arms, and the torso of the examining ophthalmologist as well. They found that the surface area of the slit lamp presumably contaminated by patient's breath when using the “proximal barrier” was 567.50 cm2 whereas the surface of the slit lamp presumably contaminated by patient's breath when using the distal barrier was 222.93 cm2 which was a significant difference.[11] Most of the proximal slit lamp shields might not be effective enough to prevent contamination of the slit lamp instrument that is operated by the ophthalmologist. This is an important aspect as the risk of transmission will not just be airborne but also places the ophthalmologist at risk through surface transmission from the contaminated parts of the slit lamp. Viable SARS-CoV-2 virus and/or RNA detected by RT-PCR can be found on contaminated surfaces (fomites) for periods ranging from hours to days, depending on the ambient environment (including temperature and humidity) and the type of surface. There are still limitations in understanding the physics of aerosol movement in real-life environments but these studies lend an important insight into the possible risks involved. Every effort must be made to minimize the risk of possible exposure with the rising number of asymptomatic cases in the community. The majority of the slit lamp shields should also be combined with masks, gloves, and handwashing to decrease the possible risk of transmission of infection. Wearing of masks, maintaining social distancing and hand hygiene are of utmost importance during the current ongoing global crisis of the pandemic. Every breath matters, every precaution matters, every life matters! Let us never let our guard down as we continue to fight not just avoidable blindness but a new invisible enemy that lurks around in the air we breathe.