7. Ophthalmic practice: special precautions
Ophthalmic practice involves eye examinations such as direct ophthalmoscopy and slit-lamp examination that are performed in a setting that has close doctor-patient contact, which is less than 1 meter and droplets infection is a real risk. The SARS-CoV-2 present in tears could become a source of cross-infection when small instruments like contaminated laser lenses are used in patients. Moreover, the ultrasonic probe used in phacoemulsification and the air jet produced in non-contact tonometry might generate aerosol of tissue fluids from the eye. Furthermore, eye centers could be crowded with patients and patients with COVID-19 could have subtle or even no symptoms. Therefore, proper precautions should be taken to protect for both patients and workers of the centers from the infection.
It is important to take special and proper precautions in ophthalmic practices, due to the below risks:
•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 centers could harbor asymptomatic patients with COVID-19
The recommendations from ICO, AAO, APJO, RANZCO and RCOpth (UK) can be accessed below for your perusal:
7.1 Major Ophthalmic Resource Centers: ICO, AAO, APJO, RANZCO, RCOphth
1. International Council of Ophthalmology (ICO)
2. American Academy of Ophthalmology (AAO)
3. Asia-Pacific Journal of Ophthalmology (APJO)
4. The Royal Australian and New Zealand College of Ophthalmologists (RANZCO)
5. The Royal College of Ophthalmologists (RCOphth)
7.2 General Precautions
Preventing patients with potential respiratory infection from entering the facilities might minimize the change of exposure. For patients with potential risk, non-urgent ophthalmic consultations will be deferred after appropriate period of quarantine and observation. Patients are screened before entering the facilities by phone screening and triage at the entrance. Face masks should be worn by all personnel and visitors inside the facilities. Visitors wait at an adequately ventilated area, keeping at least 1-meter distance from others. Provide adequate alcohol-based handrubs, rubbish bins and educational material in the waiting area.
If patients are screened as high risk of COVID-19 infection and having ophthalmic emergencies, doctor-in-charge should be informed. Ideally patient should be isolated in a single room, with a dedicated team of healthcare workers entering with full personal protective equipment including N95 respirators for examination. Patients are not allowed to enter the public waiting areas.
7.3 Special Precautions
SARS-CoV-2 was found in tears of COVID-19 patient who had concurrent conjunctivitis and the risk of tear-related transmission of SARS-CoV-2 remains a possibility. Ophthalmic instruments such as Goldman corneal contact measurement of intraocular pressure, gonioscopy (with coupling gel), contact ocular ultrasonography, and laser contact lenses all require direct contact with patients’ mucosal membranes and tears, that could be a source of viral transmission. The potential aerosol or droplets from “air puff” tonometry also pose a high risk for infective transmission. Therefore, high vigilance and special precautions are needed in eye clinics.
7.3.1 Disinfection of Ophthalmic Instruments
- Non-contact tonometer
- 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
- 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
7.4 Slit lamp shield (home-made)
Physical barrier between doctors and patients is advisable during slit lamp examination to prevent droplet transmission. Commercially available breath shields are available, but producing home-made shields is not difficult. The edges of the shield should be smoothened with a sandpaper polisher should it be too rough or sharp. The size of the shield should not be too small in which protection effect will be compromised; or too large in which manipulation of the slit-lamp equipment will become difficult. The size of an A3 size paper or one that is slightly larger would be quite optimal and recommended. The location of the hole is also important. We want the upper portion to be larger to provide more protection while the lower portion to be smaller to allow easier access to slit-lamp manipulation. It should be cleaned and disinfected regularly.
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.
1. Atkinson J, Organization WH, Chartier Y & Pessoa-Silva CL (2009): Natural Ventilation for Infection Control in Health-care Settings. World Health Organization.
2. Guan W, Ni Z, Hu Y, et al. (In press): Clinical Characteristics of Coronavirus Disease 2019 in China. New England Journal of Medicine.
3. Rachael J & Lisa B (2015): Aerosol Transmission of Infectious Disease. Journal of Occupational and Environmental Medicine 57: 501-508.
4. 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.
5. Britt JM, Clifton BC, Barnebey HS & Mills RP (1991): Microaerosol Formation in Noncontact ‘Air-Puff’ Tonometry. Archives of Ophthalmology 109: 225-228.
6. 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.