Considerations in the use of slit lamp shields to reduce the risk of respiratory virus transmission in coronavirus disease 2019.

PURPOSE OF REVIEW: The use of slit lamp shields has been recommended by the American Academy of Ophthalmology as an infection control measure during the coronavirus disease 2019 pandemic. However, there is limited evidence regarding its efficacy to reduce viral transmission risks. We aim to provide an evidence-based approach to optimize the use of slit lamp shields during clinical examination. RECENT FINDINGS: Respiratory droplets from coughing and sneezing can travel up to 50 m/s and over a distance of 2 m, with a potential area of spread of 616 cm. Slit lamp shields confer added protection against large droplets but are limited against smaller particles. A larger shield curved toward the ophthalmologist and positioned closer to the patient increases protection against large droplets. A potential improvement to the design of such shields is the use of hydrophilic materials with antiviral properties which may help to minimize splashing of infectious droplets, reducing transmission risks. These include gold or silver nanoparticles and graphene oxide. SUMMARY: Slit lamp shields serve as a barrier for large droplets, but its protection against smaller droplets is undetermined. It should be large, positioned close to the patient, and used in tandem with routine basic disinfection practices.

Building the barricade-DIY slit lamp breath shield.

Ophthalmologists were concerned about the risk of SARS-COV-2 transmission via droplets given the close proximity to the patient during slit lamp examination. There is a need to design a simple, low-cost, waterproof breath shield to minimise risk of infection.Dimensions of the Haag-Streit slit lamp (model BM 900) were recorded to guide accurate design of the breath shield. A questionnaire was circulated among slit lamp users on their perceived risk and concern about SARS-CoV-2 transmission and their perception of how effective different designs of breath shields would be at protecting them from an infection. A number of breath shield prototypes were designed and trialled. Plan, Do, Study, Act (PDSA) cycles were used to improve the design. Materials used to create the breath shields included transparent A3 laminating pouches and laminator, two sheets of A4 paper, scissors, hole punch and a ruler. The breath shield was designed to fit over the objective lens on the slit lamp after temporarily removing the standard, manufacturer-provided breath shield, before replacing it. The breath shields were cleaned after every patient with alcohol wipes and removed for deep cleaning with hand soap and water after each session. We used a proof of concept experiment using fluorescein instilled spray to test the effectiveness of each breath shield at preventing droplet transmission to the slit lamp user.Following four PDSA cycles, a breath shield that is user-friendly, easy to clean was produced. The percentage of confidence that the final design would be effective at preventing droplet transmission increased from 5.6% to 80%.Implementation of a low cost, simple to make, transparent, waterproof breath shield together with other forms of person protective equipment (PPE) creates a safe working environment for clinicians and patients. This intervention can be readily replicated and modified for other slit lamp models.

Rebubbling of detached descemet membrane endothelial grafts at the slit lamp with 50% air fill after PI-less DMEK during COVID-19 era.

PURPOSE: To describe the effective use of only 50% air fill of the anterior chamber for rebubbling partially detached Descemet Membrane Endothelial Keratoplasty (DMEK) grafts at the slit lamp at a time of restricted operating theatre access during the COVID-19 pandemic. METHODS: We present two cases of patients who underwent rebubbling of a partially detached DMEK grafts at the slit lamp following DMEK surgery without peripheral iridotomy. The rebubbling was performed with a 27-gauge needle attached to a 1ml syringe and the patients seated at the slit lamp. Air was injected into the anterior chamber until a 50% air fill was achieved. The patients were instructed to lie supine for 30 min in clinic and the remainder of the day at home. RESULTS: We performed two rebubbling procedures at the slit lamp using the standard needle and syringe. Both cases achieved 50% air fills without any complications. At 3 days post-procedure the air bubble had resolved and the graft appeared attached centrally and at day 14 post-procedure the two patients had a clear and attached corneal graft with corrected visual acuity of 6/7.5 and 6/9, respectively. CONCLUSION: Rebubbling of detached DMEK grafts at the slit lamp with 50% air fill in the anterior chamber is a relatively simple and effective procedure. This provides an alternative approach for managing the complication of partially detached DMEK grafts in the era of COVID-19 with limited operating theatre access and avoids the risk of complications such as pupillary block in 'PI-less' DMEK.

Safe Slit-lamp Shield: Maintaining a balance between ergonomics and safety.

Since the emergence of COVID pandemic, health workers have been facing major challenges every day. Ophthalmology practice has encountered countless modifications in the practice pattern not to jeopardize patient care and at the same time maintain all safety measures to reduce transmission. One such modification we made was the Safe Slit-Lamp Shield (SSS) which has been found to be extremely protective in differentiation to other available shield. Although SSS has a larger surface area when compared to already available shields, it won't compromise the comfort of the clinician at the same time gives satisfactory protection.

Airborne pathogen projection during ophthalmic examination.

PURPOSE: Microscale droplets act as coronaviruses (CoV) carriers in the air when released from an infected person and may infect others during close contact such as ophthalmic examination. The main objective of the present work is to demonstrate how CoV deposited droplets are projected during biomicroscopy and to discuss what kind of precautions should be taken in ophthalmic practice. METHODS: A coupled fluid-structure system comprising smoothed particle hydrodynamics and the finite element method has been built to assess the projection of droplets spreading from an infected person. Different conditions based on the maximum exit flow velocity from the infector's mouth during the ophthalmic examination were modeled. RESULTS: During exhalation, for which the exit flow is ~ 1000 mm/s, the average horizontal distance of the flow front was ~ 200 mm while individual particles can reach up to ~ 500 mm. In case of coughing or sneezing (corresponding to an exit flow of ~ 12,000 mm/s), the average horizontal distance of the flow front was ~ 1300 mm. CONCLUSION: During the ophthalmic examination, the proximity to the patient's nose and mouth was observed to be less than the horizontal distance of flow front particles. Even though mounted breath shields are used, particles flew beyond the shield and contaminate the ophthalmologist. Compared with the current protective breath shields, the use of a larger shield with a minimum radius of 18 cm is needed to decrease viral transmission.