Table 4. Environmental control measures at Hong Kong Eye Hospital.

Environmental measures	Details
Cleaning of floors and surfaces	- Interior surfaces such as floors and walls are regularly cleaned with 1:49 bleach containing 5.25% sodium hypochlorite. 1:49 diluted bleach is sufficient in decontaminating surfaces or articles contaminated with secretions, vomitus, and excreta - Extra cleaning staff was hired for cleaning of frequently touched areas; public areas (e.g. door handles) are cleaned every two hours and elevator panels are cleaned every hour - Toilet covers are closed before flushing in order to prevent splashing and possible aerosol generation.
Enhanced ventilation	- The designated rooms are equipped with portable High- Efficiency Particulate Air (HEPA) units (Figure 6)
Instruments	- Slit lamps have been fitted with plastic breath shields to block the exchange of droplets between the ophthalmologist and the patient (Figure 7), and are wiped down with 70% alcohol wipes after each patient - Non-contact tonometer is avoided as much as possible. If clinically indicated, Goldmann tonometers with disposable tips, Tonopen, or iCarePro are used instead