7. Ophthalmic practice: special precautions

Importance of proper precautions in ophthalmic practices:

Close proximity of patients and doctors during eye examination
Potential aerosol or droplets from “air puff” tonometry
Reported conjunctivitis in COVID-19 patients
The presence of SARS-CoV-2 in tears/conjunctival secretions
Eye centres could harbour asymptomatic patients with COVID-19

References
Atkinson J, Organization WH, Chartier Y & Pessoa-Silva CL (2009): Natural Ventilation for Infection Control in Health-care Settings. World Health Organization.
Guan W, Ni Z, Hu Y, et al. (In press): Clinical Characteristics of Coronavirus Disease 2019 in China. New England Journal of Medicine.
Rachael J & Lisa B (2015): Aerosol Transmission of Infectious Disease. Journal of Occupational and Environmental Medicine 57: 501-508.
Xia J, Tong J, Liu M, Shen Y & Guo D (2020): Evaluation of coronavirus in tears and conjunctival secretions of patients with SARS-CoV-2 infection. Journal of Medical Virology: In press.

7.1 Slit lamp shield (home-made)

Slit-lamp examination: physical barrier between doctors and patients is advisable to prevent droplet transmission. Commercially available breath shields are available, but producing home-made shields is not difficult.

Material: Should be highly transparent to avoid view blocking, rigid enough not to collapse, and thin enough to be cut into desired shape. A clear polyvinyl chloride document holder is a good choice.
Size: A3-sized transparent plastic sheet with round corners and a round hole of 64 mm (fit for Haag-Streit models)
Tool: Round cutter or simple cutter
Procedures (A to C): The eye piece and the microscope modules of the slit-lamp are carefully dissembled. The plastic sheet is fit into the microscope module through the circular hole. The two modules are finally resembled.

7.2 General Precautions

7.3 Special Precautions

7.3.1 Disinfection of Ophthalmic Instruments

General equipment

Slit-lamp
Non-contact tonometer
Autorefractor

Disinfect with 70-75% ethanol or isopropyl alcohol immediately after each patient

Instruments that had direct contact with patient’s ocular surface

Goldmann applanation tonometer prisms
Diagnostic contact lenses

Disinfect by immersion in either 1:10 diluted bleach solution with sodium hypochlorite or 3% hydrogen peroxide for at least 5 minutes.

Other surgical instruments

Sterilized according to standard protocols.

7.3.2 Risk with Non-contact Tonometry (NCT)

The air jet impacted on the tear film was reported to generate micro-aerosols.
SARS-CoV-2 was reported to be present in tears and conjunctival secretions from COVID-19 confirmed patients with conjunctivitis
Extra caution in patients with red eyes
Operators should wear proper face mask or respirator
Alternative methods to NCT: rebound tonometry

7.3.3 Ophthalmic Operations

General cases

Surgical mask should be worn by all patients entering operating rooms
Adhesive tape could be applied across the nose bridge area to ensure complete coverage of patient’s nose and mouth
Require patients changing their clothes and putting on surgical caps

Suspected respiratory infection cases (urgent operations)

Scheduled as last case of operation
Thorough disinfection afterwards
Be cautious and vigilant against sharp needles or blades injury

High risk or confirmed cases

Refer to hospitals that have adequate facilities such as negative-pressure isolation rooms

References
Britt JM, Clifton BC, Barnebey HS & Mills RP (1991): Microaerosol Formation in Noncontact ‘Air-Puff’ Tonometry. Archives of Ophthalmology 109: 225-228.
李纯纯, 唐媛, 陈张艳, et al. 非接触式眼压计测量产生气溶胶密度变化及其对疫情防护的意义.中华实验眼科杂志. In press.