EyeWorld Asia-Pacific March 2021 Issue

FEATURE 22 EWAP MAR C H 2021 completely blocked any passage of air towards the opposite side (Figure 5). What is probably the most important take away from our study is that securely taping the mask around the nasal bridge reduces the leakage of the exhaled airflow. This has important implications in reducing the transmission of aerosols, thereby reducing contamination of humans as well as surrounding surfaces, equipment, lenses, etc. Figure 2. a. Patient standing in front of the parabolic mirror in the outpatient clinic and breathing normally through an N95 mask that has been taped around the nasal bridge—here we can see some leakage of air around the mouth area but no upward leakage from the upper edge of the mask; b. loose fitting of the mask at the upper edge shows leakage of air in the upward direction. Figure 4. With patient lying supine in the OR and wearing a mask, the overhead lami- nar airflow is turned on. It is seen that there is forceful air draft coming downward, and when patient is asked to cough, the exhaled airflow is being pushed downward and backward by this forceful air draft. Figure 3. A mechanical barrier (plastic face shield) placed in front of the patient’s face blocks the forward propagation of exhaled airflow. Figure 5. Loose fitting of the upper edge of N95 mask in a patient lying supine on the operating room table. This allows air to escape up towards the operating microscope and the surgeon/assistant. Source (all): Raghudeep Eye Hospital, India Another striking finding from our study is that the flow of circulating room air can be used favorably to reduce the dissipation of exhaled air in the breathing zone of the surgeons/staff. A forceful draft of air flowing downwards, onto the examination/surgical area helps in significantly dampening and dissipating the travel of the exhaled airflow towards the surgeon. However, if the surgeon and patient cannot be placed directly under a vertical draft of air, we recommend keeping a table fan in a way that the draft of air is directed towards the patient’s face. We also recommend that surgical procedures be performed such that the surgical field, the surgeon, the patient, and instrumentation remain under a vertical draft of air wherever possible. Since different parts of the world may not have uniform ways of using the PPE and air circulation, this study will help ophthalmologists optimize their infection control practices. The best part is that these measures are easy to incorporate in every practice. EWAP References 1. Tang JW, Settles GS. Images in clinical medicine. Coughing and aerosols. N Engl J Med. 2008;359(15):e19. 2. Tang JW, Settles G. Images in clinical medicine. Coughing and masks. N Engl J Med. 2009;361(26):e62. 3. Tang JW, et al. A Schlieren optical study of the human cough with and without wearing masks for aerosol infection control. J R Soc Interface 6. 2009; (Suppl 6): S727–736. Editors’ note: Dr. Vasavada and Dr. Srivastava are Consultant Ophthalmologists at Raghudeep Eye Hospital, Jaipur, India. Neither declared any relevant financial interests.